- Effect of Li on the catalytic activity of MgO for the synthesis of flavanone
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We have investigated the effects of Li on the structure, surface basicity and catalytic activity of MgO for the synthesis of flavanone. Introduction of low amounts of Li (i.e., ≤0.1 wt.%) was found to promote the rate of the Claisen-Schmidt condensation reaction, which is the first step in this process. However, at Li loadings above 0.1 wt.% a detrimental effect was observed, due to a concomitant decrease in surface area and increase in MgO crystallite size. A strong correlation was observed between surface-normalized basicity and catalytic activity. The increase in activity at higher levels of surface basicity can be attributed to the increased ability of Li-O- pairs to abstract a proton from the 2′-hydroxyacetophenone reactant, thus facilitating the adsorption and subsequent surface reactions of this molecule.
- Cortes-Concepcion, Jose A.,Patcas, Florian,Amiridis, Michael D.
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- Oxidation of enol acetate of flavanone with thallium(III) nitrate or phenyliodonium diacetate: A convenient new route to isoflavone and flavone
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A new high-yield method has been described for the preparation of isoflavone by oxidation of enol acetate of flavanone with thallium(III) nitrate or phenyliodonium diacetate in trimethyl orthoformate in the presence of 70 % perchloric acid at room temperature. Flavone could also be prepared in high yield from the enol acetate by oxidation with the same reagents in glacial acetic acid at room temperature. Some key intermediates of these oxidations were investigated with quantum chemical (HF and DFT) methods. Graphical Abstract: [Figure not available: see fulltext.].
- Nemeth, Istvan,Kiss-Szikszai, Attila,Gulacsi, Katalin,Mandi, Attila,Komaromi, Istvan,Kurtan, Tibor,Antus, Sandor
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- Mechano-chemical versus co-precipitation for the preparation of Y-modified LDHs for cyclohexene oxidation and Claisen-Schmidt condensations
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Y-modified LDHs with atomic Mg2+/(Al3++Y3+) of 3 and Al3+/Y3+ ratios of 0.5, 1 and 1.5 were prepared following two preparation methods, i.e. the co-precipitation and mechano-chemical one. The substitution of Al by Y in the brucite-type layer was less effective for the samples prepared by co-precipitation compared to those prepared via mechano-chemical route. In spite the fact yttrium has a larger ionic radius (0.9?) the structural characterizations of these solids confirmed that the layered structure incorporates part of it in the octahedral positions. Further, the reconstruction of the layered structure after an exposure to water for 1 h was more effective for the solid prepared by co-precipitation. The yttrium modified LDHs showed better catalytic activities for cyclohexene oxidation to the corresponding epoxide than the un-modified LDH sample. Then, mixed oxides derived from yttrium-LDH showed very high conversions and selectivities for the synthesis of chalcone.
- Angelescu, Emilian,B?rjega, Ruxandra,Bucur, Ioana Cristina,Parvulescu, Vasile I.,Pavel, Octavian Dumitru,Stamate, Alexandra-Elisabeta,Z?voianu, Rodica
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- The effect of solvents on the heterogeneous synthesis of flavanone over MgO
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The effect of several solvents on the heterogeneous synthesis of flavanone from benzaldehyde and 2-hydroxyaceophenone over a solid MgO catalyst was studied experimentally through kinetic and FTIR spectroscopic studies. High boiling point solvents considered were dimethyl sulfoxide, tetralin, mesitylene, benzonitrile, and nitrobenzene. Dimethyl sulfoxide (DMSO) significantly promoted the rates of both steps used in this synthesis, i.e., the Claisen-Schmidt condensation reaction of benzaldehyde with 2-hydroxyacetophenone and the subsequent isomerization of the 2′-hydroxychalcone intermediate to flavanone. The effect was more pronounced for the second reaction. Even the presence of small amounts of DMSO in other solvents, e.g., benzonitrile and nitrobenzene, resulted in strong promotion of the flavanone synthesis scheme. The results of FTIR studies indicated the formation of strongly held surface sulfate species following the interaction of DMSO with the MgO surface. The presence of these sulfate species affected the adsorption behavior of benzaldehyde and 2-hydroxyacetophenone on the surface of the MgO catalyst and led to the formation of surface benzoate species. These differences might be responsible for the observed change in the catalytic behavior of MgO during the synthesis of flavanone in the presence on DMSO.
- Drexler, Michele T.,Amiridis, Michael D.
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- Synthesis of Flavanone and Quinazolinone Derivatives from the Ruthenium-Catalyzed Deaminative Coupling Reaction of 2′-Hydroxyaryl Ketones and 2-Aminobenzamides with Simple Amines
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The cationic Ru–H complex [(C6H6)(PCy3)(CO)RuH]+BF4– (1) with 3,4,5,6-tetrachloro-1,2-benzoquinone (L1) was found to be a highly effective catalyst for the deaminative coupling reaction of 2′-hydroxyaryl ketones with simple amines to form 3-substituted flavanone products. The analogous deaminative coupling reaction of 2-aminobenzamides with branched amines directly formed 3,3-disubstituted quinazolinone products. The catalytic method efficiently installs synthetically useful flavanone and quinazolinone core structures without employing any reactive reagents.
- Gnyawali, Krishna,Kirinde Arachchige, Pandula T.,Yi, Chae S.
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supporting information
p. 218 - 222
(2022/01/15)
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- Chiral separation materials based on derivatives of 6-amino-6-deoxyamylose
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In order to develop new type of chiral separation materials, in this study, 6-amino-6-deoxyamylose was used as chiral starting material with which 10 derivatives were synthesized. The amino group in 6-amino-6-deoxyamylose was selectively acylated and then the hydroxyl groups were carbamoylated yielding amylose 6-amido-6-deoxy-2,3-bis(phenylcarbamate)s, which were employed as chiral selectors (CSs) for chiral stationary phases of high-performance liquid chromatography. The resulted 6-amido-6-deoxyamyloses and amylose 6-amido-6-deoxy-2,3-bis(phenylcarbamate)s were characterized by IR, 1H NMR, and elemental analysis. Enantioseparation evaluations indicated that most of the CSs demonstrated a moderate chiral recognition capability. The 6-nonphenyl (6-nonPh) CS of amylose 6-cyclohexylformamido-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) showed the highest enantioselectivity towards the tested chiral analytes; the phenyl-heterogeneous (Ph-hetero) CS of amylose 6-(4-methylbenzamido)-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) baseline separated the most chiral analytes; the phenyl-homogeneous (Ph-homo) CS of amylose 6-(3,5-dimethylbenzamido)-6-deoxy-2,3-bis(3,5-dimethylphenylcarbamate) also exhibited a good enantioseparation capability among the developed CSs. Regarding Ph-hetero CSs, the enantioselectivity depended on the combination of the substituent at 6-position and that at 2- and 3-positions; as for Ph-homo CSs, the enantioselectivity was related to the substituent at 2-, 3-, and 6-positions; with respect to 6-nonPh CSs, the retention factor of most analytes on the corresponding CSPs was lower than that on Ph-hetero and Ph-homo CSPs in the same mobile phases, indicating π–π interactions did occur during enantioseparation. Although the substituent at 6-position could not provide π–π interactions, the 6-nonPh CSs demonstrated an equivalent or even higher enantioselectivity compared with the Ph-homo and Ph-hetero CSs.
- Gao, Ya-Ya,Zhang, Yu-Hang,Zhang, Shan,Chen, Wei,Bai, Zheng-Wu
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supporting information
p. 899 - 914
(2021/10/07)
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- Preparation of a novel bridged bis(β-cyclodextrin) chiral stationary phase by thiol-ene click chemistry for enhanced enantioseparation in HPLC
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A bridged bis(β-cyclodextrin) ligand was firstly synthesized via a thiol-ene click chemistry reaction between allyl-ureido-β-cyclodextrin and 4-4′-thiobisthiophenol, which was then bonded onto a 5 μm spherical silica gel to obtain a novel bridged bis(β-cyclodextrin) chiral stationary phase (HTCDP). The structures of HTCDP and the bridged bis(β-cyclodextrin) ligand were characterized by the 1H nuclear magnetic resonance (1H NMR), solid state 13C nuclear magnetic resonance (13C NMR) spectra spectrum, scanning electron microscope, elemental analysis, mass spectrometry, infrared spectrometry and thermogravimetric analysis. The performance of HTCDP in enantioseparation was systematically examined by separating 21 chiral compounds, including 8 flavanones, 8 triazole pesticides and 5 other common chiral drugs (benzoin, praziquantel, 1-1′-bi-2-naphthol, Tr?ger's base and bicalutamide) in the reversed-phase chromatographic mode. By optimizing the chromatographic conditions such as formic acid content, mobile phase composition, pH values and column temperature, 19 analytes were completely separated with high resolution (1.50-4.48), in which the enantiomeric resolution of silymarin, 4-hydroxyflavanone, 2-hydroxyflavanone and flavanone were up to 4.34, 4.48, 3.89 and 3.06 within 35 min, respectively. Compared to the native β-CD chiral stationary phase (CDCSP), HTCDP had superior enantiomer separation and chiral recognition abilities. For example, HTCDP completely separated 5 other common chiral drugs, 2 flavanones and 3 triazole pesticides that CDCSP failed to separate. Unlike CDCSP, which has a small cavity (0.65 nm), the two cavities in HTCDP joined by the aryl connector could synergistically accommodate relatively bulky chiral analytes. Thus, HTCDP may have a broader prospect in enantiomeric separation, analysis and detection. This journal is
- Gong, Bolin,Guo, Siyu,Zhang, Ning
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p. 35754 - 35764
(2021/12/02)
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- Stereoselective reduction of flavanones by marine-derived fungi
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Biotransformation is an alternative with great potential to modify the structures of natural and synthetic flavonoids. Therefore, the bioreduction of synthetic halogenated flavanones employing marine-derived fungi was described, aiming the synthesis of flavan-4-ols 3a-g with high enantiomeric excesses (ee) of both cis- and trans-diastereoisomers (up to >99% ee). Ten strains were screened for reduction of flavanone 2a in liquid medium and in phosphate buffer solution. The most selective strains Cladosporium sp. CBMAI 1237 and Acremonium sp. CBMAI1676 were employed for reduction of flavanones 2a-g. The fungus Cladosporium sp. CBMAI 1237 presented yields of 72–87% with 0–64% ee cis and 0–30% ee trans with diastereoisomeric ratio (dr) from 52:48 to 64:36 (cis:trans). Whereas Acremonium sp. CBMAI 1676 resulted in 31% yield with 77–99% ee of the cis and 95–99% ee of the trans-diastereoisomers 3a-g with a dr from 54:46 to 96:4 (cis:trans). To our knowledge, this is the first report of the brominated flavon-4-ols 3e and 3f. The use of fungi, with emphasis for these marine-derived strains, is an interesting approach for enantioselective reduction of halogenated flavanones. Therefore, this strategy can be explored to obtain enantioenriched compounds with biological activities.
- Birolli, Willian G.,Nitschke, Marcia,Porto, André Luiz M.,Santos, Darlisson de A.,de Matos, Iara L.
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- A novel one-pot synthesis of flavones
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In this paper, a one-pot facile route for the BiCl3/RuCl3-mediated synthesis of functionalized flavones is described, including: (i) intermolecularortho-acylation of substituted phenols with cinnamoyl chlorides, and (ii) intramolecular cyclodehydrogenation of the resultingo-hydroxychalcones. The reaction conditions are discussed herein.
- Chang, Meng-Yang,Tsai, Min-Chen,Lin, Chun-Yi
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p. 11655 - 11662
(2021/03/31)
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- B regioselective and chemoselective biotransformation of 2′-hydroxychalcone derivatives by marine-derived fungi
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Eight fungal strains (Penicillium raistrickii CBMAI 931, Cladosporium sp. CBMAI 1237, Aspergillus sydowii CBMAI 935, Penicillium oxalicum CBMAI 1996, Penicillium citrinum CBMAI 1186, Mucor racemosus CBMAI 847, Westerdykella sp. CBMAI 1679, and Aspergillus sclerotiorum CBMAI 849) mediated the biotransformation of the 2′-hydroxychalcone 1a. The main products obtained were from hydrogenation, hydroxylation, and cyclization reactions. Penicillium raistrickii CBMAI 931 catalyzed the chemoselective reduction of 1a to produce 2′-hydroxydihydrochalcone 2a (72%) in 7 days of incubation in phosphate buffer (pH 7). Aspergillus sydowii CBMAI 935 promoted the hydroxylation of 1a to yield 2′,4-dihydroxy-dihydrochalcone 5a (c = 42%) in 7 days of incubation in phosphate buffer (pH 8). The reaction using P. citrinum CBMAI 1186 and M. racemosus CBMAI 847 presented main cyclization products in phosphate buffer (pH 8), but the reactions with these fungi did not present enantioselectivity. Marine-derived fungi were effective and versatile biocatalysts for biotransformation of the 2′-hydroxychalcones yielding different products according to the conditions and microorganism used.
- Nitschke, Marcia,Porto, André Luiz Meleiro,de Matos, Iara Lisboa
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- Chromene, quinoline hybrids as potential anti-cancer agents: A novel and distinct approach for the synthesis of quinoline derivatives
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A series of novel quinoline derivatives (6-phenyl-6H-chromeno[4,3-b]quinoline) have been prepared by using 4-chloro-2-phenyl-2H-chromene-3-carbaldehyde and various substituted isocyanides as starting materials in the presence of HClO4-SiO2 and Methanol. We screened eighteen compounds of this novel series (6a-r) in six different cancer cell lines (A549 (lung cancer cells), DU145 (prostate cancer cells), PC3 (prostate cancer cells), MCF7 (lung cancer cells), HT 29, HCT 116 (colon cancer cells). Most of the compounds showed anti-cancer activity and compound 6b showed good cytotoxicity IC50 = 2.61±0.34 μM against colon cancer on HT29 cell line among all. The key property of cell mi-gration was observed while treatment cells with 6b. Apoptosis in HT29 cells confirmed by annexin V staining, acridine orange/ethidium bromide (AO/EB), DAPI, induced by 6b. This method is operation-ally simple and works with a diverse range of substrates. These results indicate the anticancer potential of these series and warrants future investigations for further anticancer drug development.
- Sultana, Rizuana,Tippanna, Ravinder Reddy
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supporting information
p. 265 - 272
(2021/04/28)
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- Chapter Open for the Excited-State Intramolecular Thiol Proton Transfer in the Room-Temperature Solution
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We report here, for the first time, the experimental observation on the excited-state intramolecular proton transfer (ESIPT) reaction of the thiol proton in room-temperature solution. This phenomenon is demonstrated by a derivative of 3-thiolflavone (3TF), namely, 2-(4-(diethylamino)phenyl)-3-mercapto-4H-chromen-4-one (3NTF), which possesses an - S - H···O= intramolecular H-bond (denoted by the dashed line) and has an S1 absorption at 383 nm. Upon photoexcitation, 3NTF exhibits a distinctly red emission maximized at 710 nm in cyclohexane with an anomalously large Stokes shift of 12 230 cm-1. Upon methylation on the thiol group, 3MeNTF, lacking the thiol proton, exhibits a normal Stokes-shifted emission at 472 nm. These, in combination with the computational approaches, lead to the conclusion of thiol-type ESIPT unambiguously. Further time-resolved study renders an unresolvable (180 fs) ESIPT rate for 3NTF, followed by a tautomer emission lifetime of 120 ps. In sharp contrast to 3NTF, both 3TF and 3-mercapto-2-(4-(trifluoromethyl)phenyl)-4H-chromen-4-one (3FTF) are non-emissive. Detailed computational approaches indicate that all studied thiols undergo thermally favorable ESIPT. However, once forming the proton-transferred tautomer, the lone-pair electrons on the sulfur atom brings non-negligible nπ? contribution to the S1′ state (prime indicates the proton-transferred tautomer), for which the relaxation is dominated by the non-radiative deactivation. For 3NTF, the extension of π-electron delocalization by the diethylamino electron-donating group endows the S1′ state primarily in the ππ? configuration, exhibiting the prominent tautomer emission. The results open a new chapter in the field of ESIPT, covering the non-canonical sulfur intramolecular H-bond and its associated ESIPT at ambient temperature.
- Chang, Chao-Che,Chen, Chao-Tsen,Chou, Pi-Tai,Huang, Chun-Hao,Li, Elise Y.,Liao, Yu-Chan,Liu, Yi-Hung,Liu, Zong-Ying,Meng, Fan-Yi,Wang, Chun-Hsiang
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p. 12715 - 12724
(2021/08/30)
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- Convenient synthesis of flavanone derivatives via oxa-Michael addition using catalytic amount of aqueous cesium fluoride
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A total of 36 flavanones, which included polycyclic aromatic and heterocyclic rings, were readily synthesized via oxa-Michael addition from the corresponding hydroxychalcones with a catalytic amount of aqueous cesium fluoride solution under mild conditions. This method could be applied to the scalable synthesis of eriodictyol as a known potent inhibitor of the SARS-CoV-2 spike protein.
- Miura, Motofumi,Shigematsu, Karin,Toriyama, Masaharu,Motohashi, Shigeyasu
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- Divergent synthesis of flavones and flavanones from 2′-hydroxydihydrochalconesviapalladium(ii)-catalyzed oxidative cyclization
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Divergent and versatile synthetic routes to flavones and flavanonesviaefficient Pd(ii) catalysis are disclosed. These Pd(ii) catalyses expediently provide a variety of flavones and flavanones from 2′-hydroxydihydrochalcones as common intermediates, depending on oxidants and additives,viadiscriminate oxidative cyclization sequences involving dehydrogenation, respectively, in a highly atom-economic manner.
- Son, Seung Hwan,Cho, Yang Yil,Yoo, Hyung-Seok,Lee, Soo Jin,Kim, Young Min,Jang, Hyu Jeong,Kim, Dong Hwan,Shin, Jeong-Won,Kim, Nam-Jung
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p. 14000 - 14006
(2021/04/22)
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- Preparation and evaluation of a triazole-bridged bis(β-cyclodextrin)–bonded chiral stationary phase for HPLC
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A triazole-bridged bis(β-cyclodextrin) was synthesized via a high-yield Click Chemistry reaction between 6-azido-β-cyclodextrin and 6-propynylamino-β-cyclodextrin, and then it was bonded onto ordered silica gel SBA-15 to obtain a novel triazole-bridged bis (β-cyclodextrin)–bonded chiral stationary phase (TBCDP). The structures of the bridged cyclodextrin and TBCDP were characterized by the infrared spectroscopy, mass spectrometry, elemental analysis, and thermogravimetric analysis. The chiral performance of TBCDP was evaluated by using chiral pesticides and drugs as probes including triazoles, flavanones, dansyl amino acids and β-blockers. Some effects of the composition in mobile phase and pH value on the enantioseparations were investigated in different modes. The nine triazoles, eight flavanones, and eight dansyl amino acids were successfully resolved on TBCDP under the reversed phase with the resolutions of hexaconazole, 2′-hydroxyflavanone, and dansyl-DL-tyrosine, which were 2.49, 5.40, and 3.25 within 30 minutes, respectively. The ten β-blockers were also separated under the polar organic mode with the resolution of arotinolol reached 1.71. Some related separation mechanisms were discussed preliminary. Compared with the native cyclodextrin stationary phase (CDSP), TBCDP has higher enantioselectivity to separate more analytes, which benefited from the synergistic inclusion ability of the two adjacent cavities and bridging linker of TBCDP, thereby enabling it a promising prospect in chiral drugs and food analysis.
- Shuang, Yazhou,Liao, Yuqin,Wang, Hui,Wang, Yuanxing,Li, Laisheng
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p. 168 - 184
(2019/11/25)
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- Novel chiral stationary phases based on 3,5-dimethyl phenylcarbamoylated β-cyclodextrin combining cinchona alkaloid moiety
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Novel chiral selectors based on 3,5-dimethyl phenylcarbamoylated β-cyclodextrin connecting quinine (QN) or quinidine (QD) moiety were synthesized and immobilized on silica gel. Their chromatographic performances were investigated by comparing to the 3,5-dimethyl phenylcarbamoylated β-cyclodextrin (β-CD) chiral stationary phase (CSP) and 9-O-(tert-butylcarbamoyl)-QN-based CSP (QN-AX). Fmoc-protected amino acids, chiral drug cloprostenol (which has been successfully employed in veterinary medicine), and neutral chiral analytes were evaluated on CSPs, and the results showed that the novel CSPs characterized as both enantioseparation capabilities of CD-based CSP and QN/QD-based CSPs have broader application range than β-CD-based CSP or QN/QD-based CSPs. It was found that QN/QD moieties play a dominant role in the overall enantioseparation process of Fmoc-amino acids accompanied by the synergistic effect of β-CD moiety, which lead to the different enantioseparation of β-CD-QN-based CSP and β-CD-QD-based CSP. Furthermore, new CSPs retain extraordinary enantioseparation of cyclodextrin-based CSP for some neutral analytes on normal phase and even exhibit better enantioseparation than the corresponding β-CD-based CSP for certain samples.
- Zhu, Lunan,Zhu, Junchen,Sun, Xiaotong,Wu, Yaling,Wang, Huiying,Cheng, Lingping,Shen, Jiawei,Ke, Yanxiong
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p. 1080 - 1090
(2020/05/25)
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- Enzyme-assisted cyclization of chalcones to flavanones
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Enzyme catalyzed synthesis is an eco-friendly technique in organic synthesis, having several benefits over conventional methods. In the present work, we describe a simple process of laccase and chloroperoxidase assisted cyclization of chalcones, leading to the formation of flavanones. The reaction proceeds in a mixture of phosphate buffer and ethanol, under oxygen atmosphere at room temperature, yielding the corresponding flavanone in good to moderate yield. The relative configuration of the products at C2 is tentatively assigned as S*-flavanone based on the coupling constants with the methylenic protons H3α,β. In comparison to the chemical methods, we describe a process which can be achieved efficiently under mild conditions using oxygen as oxidant.
- Alonso, Mariana Macías,Boluda, Carlos José,Barajas, Gabriela Díaz,Sánchez, Nallely Caldera,Córdova-Guerrero, Iván,Marrero, Joaquín González
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p. 926 - 931
(2020/12/23)
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- Flavanone-based fluorophores with aggregation-induced emission enhancement characteristics for mitochondria-imaging and zebrafish-imaging
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Fluorophores with aggregation-induced emission enhancement (AIEE) characteristics applied in bioimaging have attracted more and more attention in recent years. In this work, a series of flavanone compounds with AIEE characteristics was developed and applied to fluorescence imaging of mitochondria and zebrafish. The compounds were readily prepared by the thermal dehydration of chalcone that was obtained by the reaction of o-hydroxyacetophenone and benzaldehyde. Two of these compounds showed significant AIEE characteristics by fluorescence performance experiments, including optical spectra, fluorescence spectra, fluorescence quantum yield (?F), fluorescence lifetime, and scanning electron microscopy (SEM). Compared with traditional organic fluorescent dyes, these compounds have high fluorescence emission and high fluorescence quantum yield in solid or aggregated state, which overcomes the shortcoming of aggregation-caused quenching (ACQ). More importantly, the two compounds exhibited low cytotoxicity and good cytocompatibility in A549 lung cells at the experimental concentration range and they specifically targeted mitochondria, which make it of great potential use in mitochondria labeling. In addition, they were embryonic membrane permeable and had different affinities for different tissues and organs of zebrafish, but mainly distributed in the digestive system, providing a basis for the application of such compounds in bioimaging. These AIEE compounds with superior properties could be of great potential use in mitochondria imaging and other in vivo studies.
- He, Feng,Li, Na,Liu, Liyan,Luo, Huiqing,Wang, Huaqiao,Yang, Depo
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- Synthesis and hplc-ecd study of cytostatic condensed o,n-heterocycles obtained from 3-aminoflavanones
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Racemic chiral O,N-heterocycles containing 2-arylchroman or 2-aryl-2H-chromene subunit condensed with morpholine, thiazole, or pyrrole moieties at the C-3-C-4 bond were synthesized with various substitution patterns of the aryl group by the cyclization of cis- or trans-3- aminoflavanone analogues. The 3-aminoflavanone precursors were obtained in a Neber rearrangement of oxime tosylates of flavanones, which provided the trans diastereomer as the major product and enabled the isolation of both the cis- and trans-diastereomers. The cis- and transaminoflavanones were utilized to prepare three diastereomers of 5-aryl-chromeno[4,3- b][1,4]oxazines. Antiproliferative activity of the condensed heterocycles and precursors was evaluated against A2780 and WM35 cancer cell lines. For a 3-(N-chloroacetylamino)-flavan-4-ol derivative, showing structural analogy with acyclic acid ceramidase inhibitors, 0.15 μM, 3.50 μM, and 6.06 μM IC50 values were measured against A2780, WM35, and HaCat cell lines, and apoptotic mechanism was confirmed. Low micromolar IC50 values down to 2.14 μM were identified for the thiazole- and pyrrole-condensed 2H-chromene derivatives. Enantiomers of the condensed heterocycles were separated by HPLC using chiral stationary phase, HPLC-ECD spectra were recorded and TDDFT-ECD calculations were performed to determine the absolute configuration and solution conformation. Characteristic ECD transitions of the separated enantiomers were correlated with the absolute configuration and effect of substitution pattern on the HPLC elution order was determined.
- Szappanos,Mándi, Attila,Gulácsi, Katalin,Lisztes, Erika,István Tóth, Balázs,Bíró, Tamás,Kónya-ábrahám, Anita,Kiss-Szikszai, Attila,Bényei, Attila,Antus, Sándor,Kurtán, Tibor
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- Synthesis and kinetic study for the interconversion process of some 2'-hydroxychalcones to their corresponding flavanones
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In this work, five substituted2'-Hydroxychalconeswere prepared using Claisen - Schmidt condensation and used as a synthone for substituted flavanones via base catalyzed isomerization process. The latter process has been studied kinetically using HPLC technique in (8:2) (CH3CN:CH3OH) medium at different temperatures (298 K - 318 K). The obtained results were inconsonance with a four-step mechanism which considered the existence of phenoxide ion as the key intermediate. The reaction was achieved as a pseudo first order reaction in which the rate of the studied compounds followed the sequence 1>2>3>4>5, and the activation energy had the same sequence for these compounds. The reaction rate was affected by the electronic behavior of the different substituents at ring B since they played an important role in the stability of the intermediate that led to the final product.
- Majed, Zainab Waleed,Said, Said Abdelqader,Shareef, Omar Adil
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p. 4379 - 4386
(2020/12/09)
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- Synthesis and cytotoxicity of novel (E)-2-phenylchroman-4-one-O-((1-substituted-1H-1,2,3-triazol-4-yl)methyl) oxime derivatives
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A series of new flavanone-triazole hybrids (7a–m) were synthesized from flavanone oximes (6a–c) via multistep synthetic strategy, involving Cu (I) catalyzed azide, alkyne 1,3-dipolar cycloaddition by Click reaction. All the synthesized compounds were tested for their cytotoxicity against HCT-15, HeLa, NCI-H522, and HEK-293 (normal cell line) cell lines. Compounds 6a, 7a, 7b, 7d, 7e, 7j, and 7m showed the significant cytotoxicity, wherein compound 7b showed potential cytotoxicity against NCI-H522 cell line and compounds 6a and 7a were offensive with HEK-293 in their toxicity profile.
- Gutam, Madhu,Mokenapelli, Sudhakar,Yerrabelli, Jayaprakash Rao,Banerjee, Somesh,Roy, Partha,Chitneni, Prasad Rao
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p. 1883 - 1891
(2020/05/13)
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- Organocatalytic Approach for Assembling Flavanones via a Cascade 1,4-Conjugate Addition/oxa-Michael Addition between Propargylamines with Water
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A DBU-catalyzed one-pot cascade reaction of propargylamines and water for the synthesis of flavanones has been developed. This process proceeds via a sequence of 1,4-conjugate addition of water to alkynyl o-quinone methide (o-AQM), followed by the alkyne-allene isomerization and subsequent intramolecular oxa-Michael addition. This strategy provides a convenient method for accessing a broad range of flavanones in good to excellent yields with good functional-group tolerance, in particular, the reactive halo functional groups.
- He, Xinwei,He, Xinwei,Xie, Mengqing,Li, Ruxue,Choy, Pui Ying,Tang, Qiang,Shang, Yongjia,Kwong, Fuk Yee
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p. 4306 - 4310
(2020/06/05)
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- Thermally regulated molybdate-based ionic liquids toward molecular oxygen activation for one-pot oxidative cascade catalysis
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One-pot oxidative cascade catalysis plays a central role in the synthesis of key pharmaceutical and industrial molecules. Although ionic liquids are one of the most promising solvents and reaction media, the breakthrough of their catalysis in aerobic oxidation is very challenging due to the difficulty in the direct activation of molecular oxygen. Herein, a family of novel thermally regulated molybdate-based ionic liquids (Mo-ILs) has been designed and developed for the first time toward molecular oxygen activation for highly efficient tandem oxidative catalysis. Three diverse one-pot oxidative cascade processes for the syntheses of various flavones, imines, and benzyl benzoates were achieved with good to excellent yields using the Mo-IL [Bmim]2[MoO4] as a catalyst under air conditions. The results of spectroscopic investigations and quantum-chemical calculations further demonstrated that a thermally regulated proton migration between the cation [Bmim] and anion [MoO4] was the key to forming N-heterocyclic carbene and thereby to effortlessly promoting the generation of O2- active species from molecular oxygen, which results in excellent catalytic performance in these three aerobic tandem oxidations. Our work extends the application area of ILs as the sole catalyst to one-pot aerobic oxidative cascade catalysis, which could have pronounced implications in future work.
- Song, Zhibin,Huang, Wei,Zhou, Yan,Tian, Zi-Qi,Li, Zhang-Min,Tao, Duan-Jian
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p. 103 - 109
(2020/01/21)
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- Not only AIE: Light-sensitivity of 4-dimethylamino-2′-hydroxychalcones beneficial to highly efficient photochemical synthesis of 4′-dimethylaminoflavanones
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4-dimethylamino-2′-hydroxychalcone in crystals is well known for its aggregation induced emission (AIE) in the red region of spectrum. We however observe that in liquid solutions this dye and its analogues undergo reversible wavelength-dependent light-induced cyclization to the flavanone derivatives. Special care thus should be taken when this compound is used for optoelectronic applications requiring high purity, especially via solution-processed methods. The discussed intramolecular cyclization proceeds faster in nonpolar medium and is quenched completely in the presence of protic solvents or via formation of aggregates in crystal phase. In spite of that quantum yield of a single photoinduced transformation does not exceed 1%, continuous irradiation affords 92% of product which makes it the most efficient preparation route for 4′-dimethylminoflavanone and its derivatives among the ones reported before. According to the DFT and TDDFT calculations supported by the experimentally investigated spectral features, the mechanism of photoinduced formation of a 4′-dimethylaminoflavanone involves several transformations: excited state intramolecular proton transfer (ESIPT), excited and ground state rotational isomerization from s-trans to s-cis isomer, cyclization and enol-keto tautomerization via proton transfer in the ground state.
- Bojarski, Piotr,Kubicki, Aleksander,Mońka, Michal,Serdiuk, Illia E.
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- Preparation method of chiral flavanone
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The invention relates to the technical field related to flavonoid compounds, and particularly provides a preparation method of chiral flavanone. The first aspect of the invention provides a preparation method of chiral flavanone, which comprises the following steps: carrying out hydroacylation reaction on salicylaldehyde of which the hydroxyl is vinylated as shown in the formula (1) under the action of transition metal and chiral ligand to form a chiral flavanone compound as shown in the formula (2); wherein the R and R1 in the formula (1) and the formula (2) are independently hydrogen, alkylor aryl respectively, and the R' is any one of hydrogen, alkyl, aryl, alkoxy, aryloxy, ester group, nitro, halogen, cyano, benzyl and heterocyclic substituent.
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Paragraph 0051-0058
(2020/10/05)
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- Organic Solvent-free Asymmetric 1,4-Addition in Liquid- or Solid-State using Conventional Stirring Catalyzed by a Chiral Rhodium Complex Developed as a Homogeneous Catalyst
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Organic solvent-free asymmetric 1,4-addition of arylboronic acids to enone substrates was performed by using a chiral rhodium complex catalyst developed as a homogeneous catalyst. Reactions catalyzed by [RhOH(cod)]2 with chiral diphosphine ligands in liquid- or solid-state proceeded to give chiral 1,4-adducts in high yield with enantioselectivities up to ca. 100 % ee by conventional stirring without mechanochemistry such as ball milling. The solid-state reactions under a static condition also proceeded, but with a slight decrease in enantioselectivity of the 1,4-adduct. SEM observations of the solid-state reactions indicated that no nanoparticles catalyst was generated. The organic solvent-free reaction could be applied to gram-scale synthesis by performing a greener purification using a minimum necessary organic solvent.
- Korenaga, Toshinobu,Kori, Hiroto,Asai, Shota,Kowata, Ryo,Shirai, Masayuki
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p. 6059 - 6066
(2020/10/28)
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- Scalable Aerobic Oxidation of Alcohols Using Catalytic DDQ/HNO3
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A selective, practical, and scalable aerobic oxidation of alcohols is described that uses catalytic amounts of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and HNO3, with molecular oxygen serving as the terminal oxidant. The method was successfully applied to the oxidation of a wide range of benzylic, propargylic, and allylic alcohols, including two natural products, namely, carveol and podophyllotoxin. The conditions are also applicable to the selective oxidative deprotection of p-methoxybenzyl ethers.
- Arseniyadis, Stellios,Clavier, Louis,Copin, Chloé,Fournier, Jean,Giffard, Jean-Fran?ois,Jean, Alexandre,Katsina, Tania,Macedo Portela Da Silva, Nayane,Tamion, Rodolphe
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supporting information
p. 856 - 860
(2020/07/14)
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- HPLC with cellulose Tris (3,5-DimethylPhenylcarbamate) chiral stationary phase: Influence of coating times and coating amount on chiral discrimination
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Coating cellulose tris (3,5-dimethylphenylcarbamate) (CDMPC) on silica gels with large pores have been demonstrated as an efficient way for the preparation of chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC). During the process, a number of parameters, including the type of coating solvent, amount of coating, and the method for subsequent solvent removing, have been proved to affect the performance of the resultant CSPs. Coating times and the concentration of coating solution, however, also makes a difference to CSPs' performance by changing the arrangement of cellulose derivatives while remaining the coating amount constant, have much less been studied before, and thereby, were systematically investigated in this work. Results showed that CSPs with more coating times exhibited higher chiral recognition and column efficiency, suggesting that resolution was determined by column efficiency herein. Afterwards, we also investigated the effect of coating amount on the performance of CSPs, and it was shown that the ability of enantio-recognition did not increase all the time as the coating amount; and four of seven racemates achieved best resolution when the coating amount reached to 18.37%. At the end, the reproducibility of CDMPC-coated CSPs were further confirmed by two methods, ie, reprepared the CSP-0.15-3 and reevaluated the effect of coating times.
- Wei, Qiuhong,Su, Hongjiu,Gao, Diannan,Wang, Shudong
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p. 164 - 173
(2019/01/18)
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- Three-State Switchable Chiral Stationary Phase Based on Helicity Control of an Optically Active Poly(phenylacetylene) Derivative by Using Metal Cations in the Solid State
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An unprecedented three-state switchable chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) was developed using a helical poly(phenylacetylene) bearing a chiral (R)-α-methoxyphenylacetic acid residue as the pendant (poly-1). The left- and right-handed helical conformations were induced in poly-1-based CSP upon coordination with a catalytic amount of soluble sodium and cesium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate salts (MBArF), respectively, which are soluble in the HPLC conditions [hexane-2-propanol (95:5, v/v)]. The switch between the two different helical states of poly-1 can be easily achieved by rinsing the poly-1-based CSP with MeOH and the subsequent addition of the proper MBArF salt. Using this dynamic helical CSP, we demonstrate how changes on the orientation of the secondary structure of a chiral polymer (right-handed, left-handed, and racemic helices) can alter and even invert the elution order of the enantiomers. This study was done without adding chiral additives or changing the mobile phase, which could produce changes on the retention times and make it more difficult to determine the role of the secondary structure during the chiral recognition process.
- Hirose, Daisuke,Isobe, Asahi,Qui?oá, Emilio,Freire, Félix,Maeda, Katsuhiro
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- Three-State Switchable Chiral Stationary Phase Based on Helicity Control of an Optically Active Poly(phenylacetylene) Derivative by Using Metal Cations in the Solid State
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An unprecedented three-state switchable chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) was developed using a helical poly(phenylacetylene) bearing a chiral (R)-α-methoxyphenylacetic acid residue as the pendant (poly-1). The left- and right-handed helical conformations were induced in poly-1-based CSP upon coordination with a catalytic amount of soluble sodium and cesium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate salts (MBArF), respectively, which are soluble in the HPLC conditions [hexane-2-propanol (95:5, v/v)]. The switch between the two different helical states of poly-1 can be easily achieved by rinsing the poly-1-based CSP with MeOH and the subsequent addition of the proper MBArF salt. Using this dynamic helical CSP, we demonstrate how changes on the orientation of the secondary structure of a chiral polymer (right-handed, left-handed, and racemic helices) can alter and even invert the elution order of the enantiomers. This study was done without adding chiral additives or changing the mobile phase, which could produce changes on the retention times and make it more difficult to determine the role of the secondary structure during the chiral recognition process.
- Hirose, Daisuke,Isobe, Asahi,Qui?oá, Emilio,Freire, Félix,Maeda, Katsuhiro
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p. 8592 - 8598
(2019/06/13)
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- Homochiral Metal-Organic Frameworks for Enantioselective Separations in Liquid Chromatography
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Selective separation of enantiomers is a substantial challenge for the pharmaceutical industry. Chromatography on chiral stationary phases is the standard method, but at a very high cost for industrial-scale purification due to the high cost of the chiral stationary phases. Typically, these materials are poorly robust, expensive to manufacture, and often too specific for a single desired substrate, lacking desirable versatility across different chiral analytes. Here, we disclose a porous, robust homochiral metal-organic framework (MOF), TAMOF-1, built from copper(II) and an affordable linker prepared from natural l-histidine. TAMOF-1 has shown to be able to separate a variety of model racemic mixtures, including drugs, in a wide range of solvents of different polarity, outperforming several commercial chiral columns for HPLC separations. Although not exploited in the present article, it is worthy to mention that the preparation of this new material is scalable to the multikilogram scale, opening unprecedented possibilities for low-energy chiral separation at the industrial scale.
- Corella-Ochoa, M. Nieves,Tapia, Jesús B.,Rubin, Heather N.,Lillo, Vanesa,González-Cobos, Jesús,Nú?ez-Rico, José Luis,Balestra, Salvador R.G.,Almora-Barrios, Neyvis,Lledós, Marina,Gu?ll-Bara, Arnau,Cabezas-Giménez, Juanjo,Escudero-Adán, Eduardo C.,Vidal-Ferran, Anton,Calero, Sofiá,Reynolds, Melissa,Martí-Gastaldo, Carlos,Galán-Mascarós, José Ramón
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p. 14306 - 14316
(2019/10/11)
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- Water-mediated phosphorylative cyclodehydrogenation: An efficient preparation of flavones and flavanones
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A new synthetic strategy utilizing POCl3-water for the conversion of 2′-hydroxychalcones to flavanones and flavones has been developed. The reagent efficiently promoted one-pot conversion of 2′-hydroxychalcones to flavones through flavanones involving cyclization and oxidative dehydrogenation. By changing the stoichiometery of the reagents, the reaction can be tuned to generate either flavanone or flavone. The developed protocol was found to be applicable for a variety of 2′-hydroxychalcones.
- Vimal, Manorama,Pathak, Uma,Halve, Anand Kumar
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supporting information
p. 2805 - 2814
(2019/08/12)
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- Synthesis and kinetic investigations for the isomerization process of 2–hydroxy chalcone derivatives
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The wide biological activities of flavanones are mainly depends on their physical and chemical properties, thus a number of substituted 2-Hydroxy chalcones have been synthesized, and their isomerization to their corresponding flavanones was studied. In order to determine the rate constant, kinetic experiments were performed using HPLC technique in (9:1) (CH3CN:H2O) medium at different temperature (298-318) K. The obtained results were interpreted by four steps mechanism, which considered the existence of phenoxide ion as the key intermediate. This study performed with a pseudo first order (reaction in which the rate for the studied compounds follow the sequence 5 > 2 > 1 > 4 > 3, the activation energy have the same sequence for these compounds .The effect of substituents on the rate showed that electronic and steric factors play reasonable role on the stability of the product .
- Shareef, Omar A.,Said, Said A.,Abdulrazaq, Ali Y.
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p. 1046 - 1054
(2020/01/09)
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- Synthesis and application of lactone analogue with flavone framework
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The invention relates to synthesis and application of a lactone analogue with a flavone framework. The structural general formula of the compound is (I), wherein R1 or R2 represents a hydrogen atom, C1-C5 alkyl, phenyl, halogen-substituted phenyl, benzodioxole, furan, thiophene and other aromatic heterocycles. According to the method, o-hydroxyacetophenone and aldehyde or ketone are used as raw materials, and a series of lactone analogues with flavone parent nucleus structures are synthesized through multi-step reaction. The broomrape seed germination activity of the compound is tested, wherein the result shows that the compound has good seed germination activity, is a parasitic weed seed germination agent with a wide application prospect, can be practically applied to parasitic weed herbicides, and especially can be applied to prevention and control of parasitic weeds broomrape and striga asiatica in agriculture.
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-
Paragraph 0020; 0021; 0022
(2020/01/11)
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- Discovery of a Prenylated Flavonol Derivative as a Pin1 Inhibitor to Suppress Hepatocellular Carcinoma by Modulating MicroRNA Biogenesis
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Peptidyl-prolyl cis-trans isomerase Pin1 plays a crucial role in the development of human cancers. Recently, we have disclosed that Pin1 regulates the biogenesis of miRNA, which is aberrantly expressed in HCC and promotes HCC progression, indicating the therapeutic role of Pin1 in HCC therapy. Here, 7-(benzyloxy)-3,5-dihydroxy-2-(4-methoxyphenyl)-8-(3-methylbut-2-en-1-yl)-4H-chromen-4-one (AF-39) was identified as a novel Pin1 inhibitor. Biochemical tests indicate that AF-39 potently inhibits Pin1 activity with an IC50 values of 1.008 μm, and also displays high selectivity for Pin1 among peptidyl prolyl isomerases. Furthermore, AF-39 significantly suppresses cell proliferation of HCC cells in a dose- and time-dependent manner. Mechanistically, AF-39 regulates the subcellular distribution of XPO5 and increases miRNAs biogenesis in HCC cells. This work provides a promising lead compound for HCC treatment, highlighting the therapeutic potential of miRNA-based therapy against human cancer.
- Zheng, Yuanyuan,Pu, Wenchen,Li, Jiao,Shen, Xianyan,Zhou, Qiang,Fan, Xin,Yang, Sheng-Yong,Yu, Yamei,Chen, Qiang,Wang, Chun,Wu, Xin,Peng, Yong
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supporting information
p. 130 - 134
(2018/11/30)
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- Synthesis of Flavanones via Palladium(II)-Catalyzed One-Pot β-Arylation of Chromanones with Arylboronic Acids
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A total of 47 flavanones were expediently synthesized via one-pot β-arylation of chromanones, a class of simple ketones possessing chemically unactivated β sites, with arylboronic acids via tandem palladium(II) catalysis. This reaction provides a novel route to various flavanones, including natural products such as naringenin trimethyl ether, in yields up to 92percent.
- Cho, Yang Yil,Jang, Hyu Jeong,Kim, Dong Hwan,Kim, Nam Yong,Kim, Nam-Jung,Kim, Young Min,Lee, Soo Jin,Lee, Yong Sup,Park, Boyoung Y.,Son, Seung Hwan,Yoo, Hyung-Seok
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supporting information
p. 10012 - 10023
(2019/08/30)
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- Oxygen mediated highly efficient cobalt(ii) porphyrin-catalyzed reduction of functional chromones: experimental and computational studies
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The highly efficient oxygen mediated reduction of functional chromones with sodium borohydride (NaBH4) catalyzed by cobalt(ii) porphyrins afforded biologically active chroman-4-ols as the reduction products in 80-98% yields. Oxygen assists in the formation of hydridocobalt(iii) porphyrin as a key intermediate, which releases hydride rapidly to reduce the chromones. Additionally, the correlation between quantum calculation results of the catalysts' conversions, yields, times and logarithms of the rate constants for the oxygen assisted reduction reaction was studied. The mechanism of the reaction was also justified by establishing a quantitative relationship between the rate constant, the α-HOMO orbital of the catalytic complex and the stabilization energy of the complex with oxygen.
- Poonam,Kumari, Pratibha,Grishina, Maria,Potemkin, Vladimir,Verma, Abhishek,Rathi, Brijesh
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p. 5228 - 5238
(2019/03/29)
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- Synthesis of 2-sulfonyl indenes and indanes
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In this paper, we developed facile and high-yield synthetic routes for the preparation of 2-sulfonyl indenes and indanes, including: (i) Amberlyst-15-promoted Knoevenagel reaction of β-ketosulfones and arylaldehydes in refluxing toluene; (ii) Grignard reagent (R′MgBr) or reducing reagent (NaBH4) promoted regio-and/or stereocontrolled 1,4-Addition or 1,4-/1,2-reduction of the resulting sulfonyl chalcones in THF or MeOH/THF at 25 °C; and then (iii) Amberlyst-15 mediated intramolecular Friedel-Crafts annulation of the corresponding β-ketosulfones or β-hydroxysulfones in toluene at reflux. This present method describes a highly efficient (3 + 2) annulation via the formation of two carbon-carbon (C-C) bonds. The DFT calculations were utilized to rationalize the regioselectivity of the addition reaction.
- Chang, Meng-Yang,Wu, Yan-Shin,Tsai, Yu-Lin,Chen, Hsing-Yin
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p. 11699 - 11723
(2019/10/02)
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- Copper(II) Acetate Mediated Synthesis of 3-Sulfonyl-2-aryl-2 H -chromenes
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This paper describes a concise, easy-operation, high-yielding method for the synthesis of 3-sulfonyl-2-aryl-2 H -chromenes by a one-pot, straightforward two-step synthetic route, which includes (i) Cu(OAc) 2 /PyBOP-mediated intermolecular [4+2] annulation of substituted salicylic acids with β-sulfonylstyrenes in the presence of DMAP in refluxing DMF, and (ii) sequential O -alkylation of the resulting sulfonylflavanones with n -butyl bromide. A plausible mechanism is proposed and discussed. This protocol provides a highly effective annulation via one carbon-oxygen (C-O) and one carbon-carbon (C-C) bond formations.
- Chang, Meng-Yang,Chen, Han-Yu,Chen, Yu-Hsin
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p. 3419 - 3430
(2019/09/07)
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- A cationic cyclodextrin clicked bilayer chiral stationary phase for versatile chiral separation in HPLC
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A cationic cyclodextrin (CD) clicked bilayer chiral stationary phase (CSP) was developed via click chemistry for chiral separations in multimode high-performance chromatography (HPLC). The versatility of this new CSP was evaluated using 17 model racemic pairs including aromatic alcohols, flavonoids and isoxazoline enantiomers in both reversed-phase (RP) and normal-phase (NP) HPLC. The CD functionality-enhanced chiral selectivity was elucidated in different elution modes. Higher chiral resolutions were shown in the RP-elution mode due to the inclusion complexation in comparison to the NP-elution mode. The highest chiral resolution of 4.40 was achieved for 4ClPh-OPr, with 12 racemic pairs baseline separated in RP-HPLC. The addition of organic modifiers in mobile phases plays an important role in optimizing the enantioselectivities of the cationic CD bilayer CSP in NP-HPLC.
- Zhou, Jie,Yang, Bo,Tang, Jian,Tang, Weihua
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p. 3526 - 3533
(2018/03/06)
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- An Efficient Synthesis of 6-oxa-spiro[3.4]octan-1-one Derivates Through 3-diazochroman-4-one and Alkene
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Spiro[2,2-dimethyl-benzofuran,bicyclo [4.2.0]octane]-7′-one with fused and spirocyclic oxygen-containing rigid skeleton structure is obtained via Wolff rearrangement and cycloaddition with good yields. Then Spiro[2,2-dimethyl-benzofuran,hexahydro-isobenzofuran]-7′-one is synthesized by further Baeyer-Villiger oxidation. These two kinds of products have a special fused and spirocyclic oxygen-containing rigid skeleton structure and are reported by our group. (Figure presented.).
- Xiao, Meiling,Zhang, Fuming,Du, Zhe,Ma, Baochun
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supporting information
p. 911 - 916
(2018/01/22)
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- Synthesis of Hierarchically Porous Zeolite Composites with Enhanced Catalytic Activity: Effect of Different Long-Chain Structure Directing Agents
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A two-section temperature strategy was employed to achieve micromesoporous composites with five kinds of long-chain alkyl quaternary ammonium salts as single template. Zeolites with an ordered two-dimensional hexagonal mesopore and crystallized MFI domain were successfully obtained. Gemini quaternary ammonium salt surfactants C18N2 and C22N2 are effective in directing the structure of MCM-41 than CTAB at 100 °C and will transform to lamellar MFI structures at 150 °C gradually. While single quaternary ammonium salts C18N and C22N direct lamellar M41s at 100 °C and transform to mesoporous structure at a higher temperature of 150 °C, it is possible to get a composite of microporous and mesoporous material with a surface area as high as 1046 m2 g-1. Catalytic performance of typical hierarchical zeolites was evaluated by Claisen-Schmidt condensation of bulky reactants. The excellent conversion suggested the synergy effects of improved large molecule diffusion in mesopores and highly separated MFI domains as catalytic centers in the hierarchical zeolites, which can be explained by an apple-tree model.
- Ding, He,Zhang, Yixiao,Xiao, Zixing,Zhang, Jingshuang,Bai, Peng,Li, Najun,Guo, Xianghai
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p. 1730 - 1737
(2018/03/21)
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- Palladium-catalyzed redox cascade for direct β-arylation of ketones
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Herein we report a full article about the detailed design and development of two palladium-catalyzed redox cascade methods that enable direct β-arylation of ketones. Palladium-catalyzed ketone dehydrogenation, aryl-X bond activation and conjugate addition were merged into a redox-neutral catalytic cycle. Non-metal-based aryl electrophiles were used as both the oxidant and the aryl source. The β-arylation with aryl iodides was achieved site-selectively with Pd(TFA)2/P(i-Pr)3 as the precatalyst and AgTFA as the iodide scavenger. Both cyclic and linear ketones can react to give β-aryl ketones with excellent functional group tolerance. The β-arylation with diaryliodonium salts was realized without stoichiometric heavy metal additives, and proved to be redox-neutral. A wider substrate scope regarding aryl groups and ketones was obtained for the arylation with diaryliodonium salts, and the possible involvement of palladium nanoparticles as the active catalyst was examined and discussed.
- Huang, Zhongxing,Dong, Guangbin
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supporting information
p. 3253 - 3265
(2018/05/04)
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- Unusual Olefinic C-H Functionalization of Simple Chalcones toward Aurones Enabled by the Rational Design of a Function-Integrated Heterogeneous Catalyst
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Flavonoids, which are ubiquitous plant secondary metabolites obtained from chalcones, mostly possess 6-membered C-rings derived from 6-endo-trig cyclization of chalcones. However, aurones, which are a class of flavonoids that rarely occur naturally, possess unusual 5-membered C-rings biosynthesized from chalcones by mainly performing B-ring oxidation. Therefore, the chemical catalytic transformation from simple chalcones into aurones is attractive, because it overcomes the drawback of known limited enzyme catalysis. The catalytic transformation, however, has not yet been reported because of the preferential 6-membered ring formation as with the biosynthesis and the need for rare intramolecular olefinic C-H functionalization. Here, we developed the catalytic olefinic C-H functionalization of simple chalcones toward various aurones enabled by the rational design of a function-integrated heterogeneous catalyst - a Pd-on-Au bimetallic nanoparticle catalyst supported on CeO2 - using O2 in air as the sole oxidant without any additives. In this system, the four conditions that were required for the challenging transformation toward aurones were achieved by the respective components of the catalyst: (a) a supported Pd catalyst: a catalyst for the olefinic C-H functionalization of chalcones toward aurones, (b) an Au promoter: an improvement in the catalytic activity by stabilizing Pd(0), (c) a CeO2 support: the inhibition of the 6-endo-trig cyclization utilizing the adsorption of chalcones, and (d) a Pd-on-Au structure: the inhibition of Au-catalyzed flavone synthesis. This catalytic transformation will promote not only the pharmaceutical study of aurones but also the rational design of a heterogeneous catalyst for the development of organic reactions that are not yet realized by homogeneous catalysts or biocatalyst.
- Yatabe, Takafumi,Jin, Xiongjie,Mizuno, Noritaka,Yamaguchi, Kazuya
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p. 4969 - 4978
(2018/06/08)
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- One-Pot Catalytic Cleavage of C=S Double Bonds by Pd Catalysts at Room Temperature
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The C=S double bonds in CS2 and thioketones were catalytically cleaved by Pd dimeric complexes [(N∧N)2Pd2(NO3)2](NO3)2 (N∧N, 2,2′-bipyridine, 4,4′-dimethylbipyridine or 4,4′-bis(trifluoromethyl)) at room temperature in one pot to afford CO2 and ketones, respectively, for the first time. The mechanisms were fully investigated by kinetic NMR, isotope-labeled experiments, in situ ESI-MS, and DFT calculations. The reaction is involved a hydrolytic desulfurization process to generate C=O double bonds and a trinuclear cluster, which plays a pivotal role in the catalytic cycle to regenerate the dimeric catalysts with HNO3. Furthermore, the electronic properties of catalyst ligands possess significant influence on reaction rates and kinetic parameters. At the same temperature, the reaction rate is consistent with the order of electronegativity of N∧N ligands (4,4′-bis(trifluoromethyl) > 2,2′-bipyridine > 4,4′-dimethylbipyridine). This homogeneous catalytic reaction features mild conditions, a broad substrate scope, and operational simplicity, affording insight into the mechanism of catalytic activation of carbon sulfur bonds.
- Zhu, Ting,Wu, Xiaoxi,Yang, Xinzheng,Sharma, Bigyan,Li, Na,Huang, Jiaming,Wang, Wentao,Xing, Wang,Zhao, Zhenwen,Huang, Hui
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supporting information
p. 9266 - 9273
(2018/08/17)
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- Ultrafast chiral separations for high throughput enantiopurity analysis
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Recent developments in fast chromatographic enantioseparations now make high throughput analysis of enantiopurity on the order of a few seconds achievable. Nevertheless, routine chromatographic determinations of enantiopurity to support stereochemical investigations in pharmaceutical research and development, synthetic chemistry and bioanalysis are still typically performed on the 5-20 min timescale, with many practitioners believing that sub-minute enantioseparations are not representative of the molecules encountered in day to day research. In this study we develop ultrafast chromatographic enantioseparations for a variety of pharmaceutically-related drugs and intermediates, showing that sub-minute resolutions are now possible in the vast majority of cases by both supercritical fluid chromatography (SFC) and reversed phase liquid chromatography (RP-LC). Examples are provided illustrating how such methods can be routinely developed and used for ultrafast high throughput analysis to support enantioselective synthesis investigations.
- Barhate, Chandan L.,Joyce, Leo A.,Makarov, Alexey A.,Zawatzky, Kerstin,Bernardoni, Frank,Schafer, Wes A.,Armstrong, Daniel W.,Welch, Christopher J.,Regalado, Erik L.
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supporting information
p. 509 - 512
(2017/01/13)
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- Functionalities tuned enantioselectivity of phenylcarbamate cyclodextrin clicked chiral stationary phases in HPLC
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The mixed chloro- and methyl- functionalities can greatly modulate the enantioselectivities of phenylcarbamate cyclodextrin (CD) clicked chiral stationary phases (CSPs). A comparison study is herein reported for per(4-chloro-3-methyl)phenylcarbamate and per(2-chloro-5-methyl)phenylcarbamate β-CD clicked CSPs (i.e., CCC4M3-CSP and CCC2M5-CSP). The enantioselectivity dependence on column temperature was studied in both normal-phase and reversed-phase mode high performance liquid chromatography (HPLC). The thermodynamic study revealed that the stronger intermolecular interactions can be formed between CCC4M3-CSP and chiral solutes to drive the chiral separation. The higher enantioselectivities of CCC4M3-CSP were further demonstrated with the enantioseparation of 17 model racemates in HPLC.
- Tang, Jian,Lin, Yuzhou,Yang, Bo,Zhou, Jie,Tang, Weihua
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p. 566 - 573
(2017/08/26)
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- Preparation and evaluation of regioselectively substituted amylose derivatives for chiral separations
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Six novel regioselectively substituted amylose derivatives with a benzoate at 2-position and two different phenylcarbamates at 3- and 6-positions were synthesized and their structures were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy. Their enantioseparation abilities were then examined as chiral stationary phases (CSPs) for high-performance liquid chromatography (HPLC) after they were coated on 3-aminopropyl silica gels. Investigations indicated that the substituents at the 3- and 6-positions played an important role in chiral recognition of these amylose 2-benzoate serial derivatives. The derivatives demonstrated characteristic enantioseparation and some racemates were better resolved on these derivatives than on Chiralpak AD, which is one of the most efficient CSPs, utilizing coated amylose tris(3,5-dimethylphenylcarbamate) as the chiral selector. Among the derivatives prepared, amylose 2-benzoate-3-(phenylcarbamate/4-methylphenylcarbamate)-6-(3,5-dimethylphenylcarbamate) exhibited chiral recognition abilities comparable to that of Chiralpak AD and may be useful CSPs in the future. The effect of mobile phase on chiral recognition was also studied. In general, with the decreased concentration of 2-propanol, better resolutions were obtained with longer retention times. Moreover, when ethanol was used instead of 2-propanol, poorer resolutions were often achieved. However, in some cases, improved enantioselectivity was achieved with ethanol rather than 2-propanol as the mobile phase modifier.
- Tang, Shouwan,Jin, Zhaolei,Sun, Baishen,Wang, Fang,Tang, Wenyuan
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p. 512 - 521
(2017/08/26)
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- Synthesis, crystal structure and antitumour activity evaluation of 1H-thieno[2,3-c]chromen-4(2H)-one derivatives
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A series of 1H-thieno[2,3-c]chromen-4(2H)-one derivatives were synthesised through Knoevenagel condensation of substituted flavanones with thiazolidine-2,4-dione in ethanol in the presence of piperidine. The mechanism of the reaction was proposed. All synthesised compounds were characterised by IR, 1H NMR, 13C NMR, HRMS, and elemental analysis. The structure of 2-(3-chlorophenyl)-1H-thieno[2,3-c]chromen-4(2H)-one was confirmed by a single crystal X-ray diffraction analysis. A preliminary antitumour screening showed that 2-(2-fluorophenyl)-1H-thieno [2,3-c]chromen-4(2H)-one had moderate to good activity against A549, BGC-823, HCT116 and MDA-MB-453 cancer cell lines, and 2-(3,4-dimethoxyphenyl)-1H-thieno[2,3-c]chromen-4(2H)-one displayed similar activity against these four kinds of cancer cells compared with the reference drug.
- Yu, Huchang,Li, Yan,Feng, Zhiyuan,Jiang, Hongwu,Zhao, Yinglan,Luo, Youfu,Huang, Wencai,Li, Zicheng
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- Ruthenium-Catalyzed C-H Activation of Salicylaldehyde and Decarboxylative Coupling of Alkynoic Acids for the Selective Synthesis of Homoisoflavonoids and Flavones
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Homoisoflavonoids were formed in DMSO exclusively, and flavones were formed in t-AmOH when salicylaldehyde and alkynoic acids reacted with [Ru(p-cymene)Cl2]2 and CsOAc. They were formed through C-H activation of salicylaldehyde and decarboxylative coupling of alkynoic acid. This reaction system showed good yields, broad substrate scope, and good functional group tolerance. It was found that chalcone was an intermediate in the formation of both homoisoflavonoid and flavone.
- Raja, Gabriel Charles Edwin,Ryu, Ji Yeon,Lee, Junseong,Lee, Sunwoo
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supporting information
p. 6606 - 6609
(2017/12/26)
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- Efficient Access to Chromeno[4,3- b ]quinolines Related to Dependensin
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We report a robust synthesis of novel chromeno[4,3- b ]quinoline derivatives structurally similar to the natural product dependensin. The target compounds are accessed through the acid-catalysed condensation of 2-aminoacetophenones or 2-aminochalcones with substituted flavanones, which are in turn obtained from 2-hydroxyacetophenones and benzaldehydes.
- Dobrowolski, Jeremy C.,Fraser, Benjamin H.,Bhadbhade, Mohan,Black, David Stc.,Kumar, Naresh
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p. 1979 - 1983
(2017/09/13)
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- A Borane-Catalyzed Metal-Free Hydrosilylation of Chromones and Flavones
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A Piers-type hydrosilylation of chromones and flavones has been successfully realized for the first time using 0.1 mol % of borane catalyst generated in situ by hydroboration of pentafluorostyrene with HB(C 6 F 5) 2 to afford a variety of chromanones and flavanones in 60-99% yields. An attempt for the asymmetric transformation with chiral diyne and HB(C 6 F 5) 2 gave chromanones and flavanones in high yields with up to 32% ee.
- Ren, Xiaoyu,Han, Caifang,Feng, Xiangqing,Du, Haifeng
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supporting information
p. 2421 - 2424
(2017/11/04)
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