- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- PYRANOQUINAZOLINE DERIVATIVES AND NAPHTHOPYRAN DERIVATIVES
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[Problem] A problem is presented in that conventional photochromic compounds cannot be considered adequate in terms of the colorizing/decolorizing rate and durability, and the production process therefore has many steps. The present invention provides an industrially applicable photochromic compound that has both a rapid colorizing/decolorizing reaction and high durability and can also be synthesized at a low cost. [Solution] This compound is characterized in that etheric oxygen atoms are bonded to the carbon atoms at position 1 of a pyranoquinazoline (8H-pyrano[3,2-f]quinazoline) skeleton and position 10 of a naphthopyran (3H-naphtho[2,1-b]pyran) skeleton, said compound having photochromic properties and being a photochromic compound that has both a rapid colorizing/decolorizing reaction and high durability. Also provided is an industrially applicable photochromic compound that can be synthesized at a low cost.
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Paragraph 0190-0191
(2020/05/14)
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- Reduction over Condensation of Carbonyl Compounds through a Transient Hemiaminal Intermediate Using Hydrazine
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Reduction of carbonyl moieties to the corresponding alcohol using simply hydrazine hydrate has been considerably unfeasible until now due to the well-known condensation reaction. However, herein, we report that using an excess of 20-fold equivalents, the reduction proceeds in excellent yields. 1H NMR study of the reaction and density functional theory (DFT) calculations indicate that the final fate of the hemiaminal intermediate is crucial to obtain the alcohol or the hydrazone.
- Vilches-Herrera, Marcelo,Gallardo-Fuentes, Sebastián,Aravena-Opitz, Mauricio,Yá?ez-Sánchez, Mauricio,Jiao, Haijun,Holz, Jens,B?rner, Armin,Lühr, Susan
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p. 9213 - 9218
(2020/08/14)
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- Selective Deprotection of the Diphenylmethylsilyl (DPMS) Hydroxyl Protecting Group under Environmentally Responsible, Aqueous Conditions
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Two new methods for selective deprotection of diphenylmethylsilyl (DPMS) ethers are described. Unmasking can be achieved with either catalytic amounts of perfluoro-1-butanesulfonyl fluoride (a SuFEx reagent) under mild, aqueous micellar conditions, or using stoichiometric amounts of 18-crown-6 ether in aqueous ethanol.
- Akporji, Nnamdi,Lieberman, Josh,Maser, Michael,Yoshimura, Masahiko,Boskovic, Zarko,Lipshutz, Bruce H.
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p. 5743 - 5747
(2019/11/11)
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- 3, 5-disubstituted hydantoin compound as well as preparation method and application thereof
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The invention provides a 3, 5-disubstituted hydantoin compound as well as a preparation method and an application thereof. The structure of the compound is shown in formula I in the description. The application of the 3, 5-disubstituted hydantoin compound shown in the formula I or solvates, hydrates or salts of the compound in preparation of medicines for treating Alzheimer's disease, vascular dementia and other dementia diseases with memory impairment also belongs to the protection scope. Animal experiments prove that the compound has the effect of saving memory of animal models, has high safety, does not have mutagenicity, can stay in blood for several hours after oral administration and intravenous injection, and can enter the brain.
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Paragraph 0042; 0073; 0074
(2018/10/19)
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- KHF2: A mild and selective desilylating agent for phenol tert-butyldimethylsilyl (TBDMS) ethers
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TBDMS (t-BuMe2Si, tert-butyldimethylsilyl) ethers of a variety of phenols have been deprotected with KHF2 in MeOH, at room temperature. Carboxylic ester and labile phenolic acetate were unaffected under these conditions. In competition reactions between TBDMS ethers of a phenol and two primary benzylic alcohols, the phenolic ether underwent cleavage whereas the alcohol ethers remained intact. From a substrate containing both a phenolic hydroxyl group and a secondary, doubly benzylic hydroxyl group protected as TBDMS ethers, the phenol was rapidly and selectively released. Cleavage of TBDMS, TBDPS, and TIPS ethers of a phenol was also compared. TBDMS and TBDPS ethers underwent cleavage at room temperature within 30 minutes, whereas removal of the TIPS ether required 2.5 hours. Ease of cleavage appears to be TBDMS ≈ TBDPS > TIPS. At 60°C, TBDMS ethers of primary benzylic, allylic, and unactivated alcohols can be efficiently desilylated over a prolonged period (13-17 h). Thus, KHF2 proves to be a mild and effective reagent for the selective desilylation of phenol TBDMS ethers at room temperature.
- Lakshman, Mahesh K.,Tine, Fatou A.,Khandaker, Tashrique A.,Basava, Vikram,Agyemang, Nana B.,Benavidez, Michael S.A.,Ga?i, Marikone,Guerrera, Lisa,Zajc, Barbara
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supporting information
p. 381 - 385
(2017/02/10)
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- 4-oxo-alkylated tetramic acid compounds and preparation method thereof
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The invention relates to novel compounds and a preparation method thereof. The general structural formula is shown as formula I in the description. Animal experiments prove that the compounds have the effect of saving memories of animal models, are high in safety, have no mutagenicity, can remain in blood for hours after oral administration and intravenous injection, can enter brains and can be used for preparing drugs for treating diseases such as Alzihemer's disease, Parkinson's disease, Huntington's disease, vascular dementia, schizophrenia, autism and the like.
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Paragraph 0070; 0071
(2017/12/09)
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- 4-oxo-alkylated tetramic acid compound as well as preparation method and application thereof
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The invention relates to a novel compound as well as preparation method and application thereof. The structural formula of the novel compound is as shown in a formula I. Animal tests show that the compound provided by the invention has a memory effect of rescuing animal models, is high in security and free of mutagenicity induction, can be retained for hours in blood after oral taking and intravenous injection, can be fed into brains and can be used for preparing medicines for treating senile dementia, Parkinsonism, Huntington diseases, vascular dementia, schizophrenia, autism and the like.
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Paragraph 0070-0072
(2018/01/09)
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- A well-defined monomeric aluminum complex as an efficient and general catalyst in the Meerwein-Ponndorf-Verley reduction
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The metal-catalyzed Meerwein-Ponndorf-Verley (MPV) reduction allows for the mild and sustainable reduction of aldehydes and ketones but has not found widespread application in organic synthesis due to the high catalyst loading often required to obtain satisfactory yields of the reduced product. We report here on the synthesis and structure of a sterically extremely overloaded siloxide-supported aluminum isopropoxide capable of catalytically reducing a wide range of aldehydes and ketones (52 examples) in excellent yields under mild conditions and with low catalyst loadings. The unseen activity of the developed catalyst system in MPV reductions is due to its unique monomeric nature and the neutral donor isopropanol weakly coordinating to the aluminum center. The present work implies that monomeric aluminum alkoxide catalysts may be attractive alternatives to transition-metalbased systems for the selective reduction of aldehydes and ketones to primary and secondary alcohols.
- McNerney, Brian,Whittlesey, Bruce,Cordes, David B.,Krempner, Clemens
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supporting information
p. 14959 - 14964
(2015/01/08)
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- Pd-catalyzed direct arylation approach to the 6H-dibenzo[c,h]chromenes: Total synthesis of arnottin I
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An efficient synthesis of 6H-dibenzo[c,h]chromenes has been achieved from 2-bromobenzyl-α-naphthyl ethers via a Pd-catalyzed Intramolecular direct-arylation using easily available Pd(PPh3)4 or Pd(OAc)2/PPh3 at elevated temperature. The reaction affords biaryl-coupling products in good to excellent yields in 6-9 h (up to 94% yields). A tentative mechanism has been proposed to understand the reaction pathway. Applying the methodology, a straightforward and concise total synthesis of arnottin I has been demonstrated by converting the biaryl-coupling products to the 6H-benzo[d]naphtho[1,2-b]pyran-6-one using pyridinium chlorochromate (PCC) mediated oxidation.
- De, Subhadip,Chaudhuri, Saikat,Mishra, Sourabh,Mamtani, Himanshu,Bisai, Alakesh
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p. 1871 - 1884
(2014/01/17)
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- Synthesis and in vitro antibacterial activity of gemifloxacin derivatives containing a substituted benzyloxime moiety
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A series of novel gemifloxacin (GMFX) derivatives containing a substituted benzyloxime moiety with remarkable improvement in lipophilicity were synthesized. The target compounds evaluated for their in vitro antibacterial activity against representative strains. Our results reveal that most of the target compounds have considerable potency against all of the tested Gram-positive strains including MRSA and MRSE (MIC: 90: 1 μg/mL) is 8-fold more active than GMFX, and 2-fold more active than GMFX and moxifloxacin against MRSE clinical isolates (MIC90: 4 μg/mL). Crown Copyright
- Feng, Lianshun,Lv, Kai,Liu, Mingliang,Wang, Shuo,Zhao, Jing,You, Xuefu,Li, Sujie,Cao, Jue,Guo, Huiyuan
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p. 125 - 136
(2012/11/07)
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- Discrete iron complexes for the selective catalytic reduction of aromatic, aliphatic, and α,β-unsaturated aldehydes under water-gas shift conditions
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Iron-catalyzed reductions: Selective iron-catalyzed reduction of aldehydes with hydrogen generated in situ by the water-gas shift reaction is presented (see scheme). The generality and selectivity of this mild procedure are demonstrated by the efficient reduction of various aromatic, aliphatic and α,β-unsaturated aldehydes.
- Tlili, Anis,Schranck, Johannes,Neumann, Helfried,Beller, Matthias
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p. 15935 - 15939
(2013/02/21)
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- Reductive coupling of carbonyl compounds promoted by cobalt or titanium nanoparticles
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The reaction of a series of aldehydes and ketones with readily prepared cobalt or titanium nanoparticles, under mild reaction conditions, led to the obtention of different reductive dimerization products depending on the nature of the transition metal used. Cobalt nanoparticles (CoNPs) allowed the selective transformation of the starting carbonyl compounds into vicinal diols, whereas the reaction promoted by titanium nanoparticles (TiNPs) led to the formation of the corresponding alkenes. In this last case, the use of trimethylsilyl chloride (TMSCl) as additive, at 0 °C, also allowed the obtention of vicinal diols after acidic aqueous work-up. ARKAT-USA, Inc.
- Nador, Fabiana,Mascaro, Evangelina,Castro, Melisa,Vitale, Cristian,Radivoy, Gabriel
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experimental part
p. 312 - 326
(2011/06/17)
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- NOVEL DXR INHIBITORS FOR ANTIMICROBIAL THERAPY
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The present invention generally concerns particular methods and compositions for antimicrobial therapy. In particuarl embodiments, the compositions target DXR. In specific embodiments, the compositions are electron-deficient heterocyclic rings.
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Page/Page column 67; 71
(2011/05/05)
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- Coordination chemistry based approach to lipophilic inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase
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1-Deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) in the non-mevalonate pathway found in most bacteria is a validated anti-infective drug target. Fosmidomycin, a potent DXR inhibitor, is active against Gram-negative bacteria. A coordination chemistry and structure based approach was used to discover a novel, lipophilic DXR inhibitor with an IC50 of 1.4 μM. It exhibited a broad spectrum of activity against Gram-negative and -positive bacteria with minimal inhibition concentrations of 20-100 μM (or 3.7-19 μg/mL).
- Deng, Lisheng,Sundriyal, Sandeep,Rubio, Valentina,Shi, Zheng-Zheng,Song, Yongcheng
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supporting information; experimental part
p. 6539 - 6542
(2010/04/04)
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- An improved and versatile method for the rapid synthesis of aryldihydrobenzofuran systems by a boron tribromide-mediated cyclization reaction
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Boron tribromide is presented as a highly reactive reagent that simultaneously allows the demethylation and fully diastereoselective cyclization of different precursor molecules, obtained by an aldol-type reaction, to a series of hydroxylated aryldihydrobenzofuran systems in racemic form. The latter are often found as key structures in natural compounds of different classes. Syntheses of educts, which mainly took advantage of a versatile Rieche formylation, are also described.
- Detterbeck, Richard,Hesse, Manfred
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p. 343 - 360
(2007/10/03)
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- Efficient deprotection of tetrahydropyranyl ethers by bismuth(III) salts
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Treatment of tetrahydropyranyl(THP) ethers with bismuth(III) salts including BiC13, Bi(TFA)3 and Bi(OTf)3 in methanol provides a simple and efficient process for deprotection of these ethers and the parent alcohols were obtained in excellent yields.
- Mohammadpoor-Baltork, Iraj,Kharamesh, Bahram,Kolagar, Sadegh
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p. 1633 - 1637
(2007/10/03)
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- One pot conversion of carboxylic acids to aldehydes with DIBAL-H
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A mild and selective reduction of carboxylic acids to aldehydes is described. This process involves in situ protection of carboxylic acid as its TMS ester which was reduced to aldehyde using stoichiometric amounts of DIBAL-H.
- Chandrasekhar,Kumar, M. Suresh,Muralidhar
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p. 909 - 910
(2007/10/03)
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- Structure-Reactivity Studies and Catalytic Effects in the Photosolvolysis of Methoxy-substituted Benzyl Alcohols
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The photosolvolysis of several methoxy-, dimethoxy-, and hydroxy-substituted benzyl alcohols has been studied in aqueous solution.The primary photochemical event is photodehydroxylation, to give a benzyl cation intermediate, which can be trapped by added external nucleophiles.The reaction is via the singlet excited state, based on observation of fluorescence quenching by hydronium ion in a complementary manner with acid catalysis of reaction observed for several derivatives.Solvent isotope effects on fluorescence efficiency and reaction for (7) and (8) provide additional support of singlet-state reactivity for these compounds.Dimethoxy-substituted alcohols are more reactive than monosubstituted compounds, with quantum yields of methanolysis of up to 0.31 for the most reactive compound, 2,6-dimethoxybenzyl alcohol (8).Using a kinetic argument, the quantum yields of the primary photodehydroxylation process has been estimated to be 1.0 +/- 0.1 for this compound.The results observed for the dimethoxy-substituted derivatives suggest the existence of additivity of substituent effects in these photodehydroxylation reactions.
- Wan, Peter,Chak, Becky
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p. 1751 - 1756
(2007/10/02)
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- DEOXYGENATION OF ALDEHYDES AND KETONES WITH SODIUM CYANOBOROHYDRIDE
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Treatment of hydroxy-substituted aromatic aldehydes and ketones with sodium cyanoborohydride yields the corresponding methylene compounds under conditions which favor intermediate carbonium ion formation.
- Elliger, Carl A.
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p. 1315 - 1324
(2007/10/02)
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