- Annulation-retro-Claisen cascade of bifunctional peroxides for the synthesis of lactone natural products
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A new and highly efficient annulation-retro-Claisen cascade, which involves the [4 + 1] or [5 + 1] annulation of α-benzoylacetates with bielectrophilic peroxides and a subsequent debenzoylation process under mild basic conditions, has been developed for the rapid construction of valuable tetrahydrofuran- and dihydropyran-2-carboxylates in good yields. By employing the new reaction, the unified total synthesis of γ- and δ-lactone natural products such as (±)-tanikolide, (±)-goniothalamins, (±)-7-epi-goniodiol, and (±)-plakolide A has been accomplished in 4-7 steps.
- Hu, Lin,Li, Jialin,Li, Xuemin,Xu, Qianlan
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p. 274 - 277
(2022/01/03)
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- Trifluoroethanol as a Unique Additive for the Chemoselective Electrooxidation of Enamines to Access Unsymmetrically Substituted NH-Pyrroles
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An electrochemical method for the synthesis of unsymmetrically substituted NH-pyrroles is described. The synthetic strategy comprises a challenging heterocoupling between two structurally diverse enamines via sequential chemoselective oxidation, addition,
- Baidya, Mrinmay,De Sarkar, Suman,Maiti, Debabrata,Roy, Lisa
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supporting information
(2021/12/23)
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- Amide/Ester Cross-Coupling via C-N/C-H Bond Cleavage: Synthesis of β-Ketoesters
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Activated primary, secondary, and tertiary amides were coupled with enolizable esters in the presence of LiHMDS to obtain good yields of β-ketoesters at room temperature. Notably, this protocol provides an efficient, mild, and high chemoselectivity method
- Chen, Jiajia,Joseph, Devaneyan,Xia, Yuanzhi,Lee, Sunwoo
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p. 5943 - 5953
(2021/04/02)
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- Sulfur-controlled and rhodium-catalyzed formal (3 + 3) transannulation of thioacyl carbenes with alk-2-enals and mechanistic insights
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A rhodium-catalyzed denitrogenative formal (3 + 3) transannulation of 1,2,3-thiadiazoles with alk-2-enals is achieved, producing 2,3-dihydrothiopyran-4-ones in moderate to excellent yields. An inverse KIE of 0.49 is obtained, suggesting the reversibility of the oxidative addition of thioacyl Rh(i) carbenes to alk-2-enals. The late-stage structural modifications of steroid compounds are realized. Moreover, our studies show that thioacyl carbenes have different reactivities to those of α-oxo and α-imino carbenes, and highlight the importance of heteroatoms in deciding the reactivities of heterovinyl carbenes.
- Wu, Qiuyue,Dong, Ziyang,Xu, Jiaxi,Yang, Zhanhui
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supporting information
p. 3173 - 3180
(2021/04/21)
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- Synthesis of Dithiolethiones and Identification of Potential Neuroprotective Agents via Activation of Nrf2-Driven Antioxidant Enzymes
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Oxidative stress is implicated in the pathogenesis of a wide variety of neurodegenerative disorders, and accordingly, dietary supplement of exogenous antioxidants or/and upregulation of the endogenous antioxidant defense system are promising for therapeutic intervention or chemoprevention of neurodegenerative diseases. Nrf2, a master regulator of the cellular antioxidant machinery, cardinally participates in the transcription of cytoprotective genes against oxidative/electrophilic stresses. Herein, we report the synthesis of 59 structurally diverse dithiolethiones and evaluation of their neuroprotection against 6-hydroxydopamine-or H2O2-induced oxidative damages in PC12 cells, a neuron-like rat pheochromocytoma cell line. Initial screening identified compounds 10 and 11 having low cytotoxicity but conferring remarkable protection on PC12 cells from oxidative-mediated damages. Further studies demonstrated that both compounds upregulated a battery of antioxidant genes as well as corresponding genes' products. Significantly, silence of Nrf2 expression abolishes cytoprotection of 10 and 11, indicating targeting Nrf2 activation is pivotal for their cellular functions. Taken together, the two lead compounds discovered here with potent neuroprotective functions against oxidative stress via Nrf2 activation merit further development as therapeutic or chemopreventive candidates for neurodegenerative disorders.
- Bai, Feifei,Fang, Jianguo,Song, Zi-Long,Zhang, Baoxin
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p. 2214 - 2231
(2020/03/06)
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- Desymmetrization of meso-dicarbonatecyclohexene with β-Hydrazino carboxylic esters via a Pd-catalyzed allylic substitution cascade
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The desymmetrization of meso-dicarbonatecyclohexene with β-hydrazino carboxylic esters has been achieved via a RuPHOX/Pd-catalyzed allylic substitution cascade for the construction of chiral hexahydrocinnoline derivatives with high performance. Mechanistic studies reveal that the reaction exploits a pathway different from that of our previous work and that the first nitrogen nucleophilic process is the rate-determining step. The protocol could be conducted on a gram scale without any loss of catalytic behavior, and the corresponding chiral hexahydrocinnolines can undergo diverse transformations.
- Xu, Kai,Zheng, Yan,Ye, Yong,Liu, Delong,Zhang, Wanbin
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supporting information
p. 8836 - 8841
(2020/11/30)
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- Bromide-Mediated C-H Bond Functionalization: Intermolecular Annulation of Phenylethanone Derivatives with Alkynes for the Synthesis of 1-Naphthols
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Bromide-mediated intermolecular annulation of phenylethanone derivatives with alkynes has been developed, which allows for the regioselective formation of polysubstituted 1-naphthols. The usage of readily available bromine catalyst, broad substrate scope, and mild conditions make this protocol very practical. Mechanistic investigations reveal that the bromination of phenylethanone derivatives occurs to yield bromo-substituted intermediates, which react in situ with alkynes to furnish the desired 1-naphthols.
- Lu, Tao,Jiang, Ya-Ting,Ma, Feng-Ping,Tang, Zi-Jing,Kuang, Liu,Wang, Yu-Xuan,Wang, Bin
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supporting information
p. 6344 - 6347
(2017/12/08)
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- Regioselective Synthesis of Dihydrothiophenes and Thiophenes via the Rhodium-Catalyzed Transannulation of 1,2,3-Thiadiazoles with Alkenes
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A method for the regioselective synthesis of a wide range of dihydrothiophenes was developed from the rhodium-catalyzed transannulation of 1,2,3-thiadiazoles with aliphatic, aromatic, and heteroaromatic alkenes. Tandem rhodium-catalyzed transannulation of 1,2,3-thiadiazoles with alkenes followed by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidation was also demonstrated for the one-pot regioselective synthesis of various thiophenes. Advantages of the present method include a broad substrate scope, wide functional group compatibility, and high regioselectivity.
- Son, Jeong-Yu,Kim, Jonghye,Han, Sang Hoon,Kim, Sung Hong,Lee, Phil Ho
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supporting information
p. 5408 - 5411
(2016/11/06)
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- 1,5-Diketones Synthesis via Three-Component Cascade Reaction
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A mild and efficient cascade synthesis of 1,5-diketones from readily available N,N-dicyclohexylmethylamine, 1,3-dicarbonyl compounds, and trifluoromethyl β-diketones has been developed. This cascade reaction occurs via an oxidation/Mannich reaction/Cope elimination/Michael addition/retro-Claisen reaction sequence, and provides multiple C-C bond formations in one pot. In addition, exquisite chemoselectivity is achieved in the reaction between 1,3-dicarbonyl compounds and trifluoromethyl β-diketones.
- Xing, Li-Juan,Lu, Tao,Fu, Wei-Li,Lou, Mei-Mei,Chen, Bo,Wang, Zhi-Shen,Jin, Yang,Li, Dan,Wang, Bin
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supporting information
p. 3076 - 3080
(2015/11/03)
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- A palladium-catalyzed carbonylative-deacetylative sequence to 1,3-Keto Amides
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An efficient three-component reaction involving carbon monoxide with a range of aryl bromides and N-substituted acetoacetamides is reported for the synthesis of b-keto amides. This transformation is promoted by Pd-catalysis followed by an acid-mediated deacetylation upon work-up, enabling a large number of b-keto amides to be isolated. Finally, d2-13C-dyclonine could be synthesized in three steps utilizing the developed catalytic system as the key step.
- Nielsen, Dennis U.,Korsager, Signe,Lindhardt, Anders T.,Skrydstrup, Troels
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p. 3519 - 3524
(2015/01/09)
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- A palladium-catalyzed carbonylative-deacetylative sequence to 1,3-keto amides
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An efficient three-component reaction involving carbon monoxide with a range of aryl bromides and N-substituted acetoacetamides is reported for the synthesis of b-keto amides. This transformation is promoted by Pd-catalysis followed by an acid-mediated deacetylation upon work-up, enabling a large number of b-keto amides to be isolated. Finally, d2-13C-dyclonine could be synthesized in three steps utilizing the developed catalytic system as the key step.
- Nielsen, Dennis U.,Korsager, Signe,Lindhardt, Anders T.,Skrydstrup, Troels
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supporting information
p. 3519 - 3524
(2015/01/09)
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- Direct route to 1,3-diketones by palladium-catalyzed carbonylative coupling of aryl halides with acetylacetone
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Man up your magnesium! By employing a MgCl2/Et3N system, aryl diketones can be generated from the Pd-catalyzed carbonylative α-arylation of acetylacetone with aryl bromides (see scheme). The method is ideal for the introduction of carbon isotopes into more complex structures, since only stoichiometric amounts of carbon monoxide are employed. Copyright
- Korsager, Signe,Nielsen, Dennis U.,Taaning, Rolf H.,Lindhardt, Anders T.,Skrydstrup, Troels
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supporting information
p. 17687 - 17691
(2014/01/17)
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- Expedient synthesis of novel β-ketoesters from the Mizoroki-Heck coupling of ethyl 3-ethoxyacrylate with aryl and pyridyl halides
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It is well known that β-ketoesters are useful intermediates for the synthesis of a range of heterocyclic templates. While there are many useful synthetic methods available to access these intermediates, there are still opportunities for the discovery of useful methodologies for their construction from novel starting materials. In this regard, we report on the discovery of a facile Pd-catalyzed Mizoroki-Heck coupling of ethyl 3-ethoxyacrylate with aryl and heteroaryl halides to form substituted alkoxyacrylates which can be hydrolyzed to form novel aryl and heteroaryl β-ketoesters.
- Kohrt, Jeffrey T.,Conn, Ed,Maguire, Robert,Wright, Stephen W.,Singer, Robert
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p. 7065 - 7068
(2013/12/04)
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- Access to β-keto esters by palladium-catalyzed carbonylative coupling of aryl halides with monoester potassium malonates
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New tricks for an old dog: The Pd-catalyzed carbonylative α-arylation of monoethyl potassium malonates with aryl bromides and reactive aryl chlorides provides a simple and direct route to aryl β-ketoesters. Because only stoichiometric amounts of carbon monoxide are employed, the method is ideal for the introduction of carbon isotopes into more complex structures. Copyright
- Korsager, Signe,Nielsen, Dennis U.,Taaning, Rolf H.,Skrydstrup, Troels
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supporting information
p. 9763 - 9766
(2013/09/23)
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- Novel photosensitized cyclization reactions of ethyl 3-amino-3-phenyl-2- propenoate derivatives to highly substituted pyrroles
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Irradiation of nitrogen-saturated acetonitrile solutions containing ethyl 3-amino-3-phenyl-2-propenoate derivatives with the (Z)-configuration [(Z)- 1] and 10-methylacridinium perchlorate (MAP) at wavelengths longer than 340 nm afforded the corresponding pyrrole derivatives in good to high yields without exhibiting a profound effect related to the substituents. An analysis of the Stern-Volmer plots for the fluorescence quenching of MAP by (Z)-1 showed that this sensitizer fluorescence is efficiently quenched, and hence electron transfer is confirmed to be involved in the primary process of the MAPsensitized cyclization reactions of 1.
- Ishida, Yohsuke,Yoshida, Yuhki,Igarashi, Tetsutaro,Sakurai, Tadamitsu
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p. 1691 - 1698
(2013/09/12)
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- PYRROLE CARBOXYLIC ACID DERIVATIVES AS ANTIBACTERIAL AGENTS
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The present invention provides DNA Gyrase and/or Topo IV inhibitors of Formula (I), which can be used as antibacterial agents. Compounds disclosed herein can be used for treating or preventing conditions caused by or contributed by gram positive, gram negative and anaerobic bacteria, more particularly against, for example, Staphylococci, Streptococci, Enterococci, Haemophilus, Pseudomonus spp., Acenetobacter spp., Mvraxalla spp., Chlamydia spp., Mycoplasma spp., Legionella spp., Mycobacterium spp., Helicobacter, Clostridium spp., Bacteroides spp., Cotynebacterium, Bacillus spp., Enterobactericeae (E. coli, Klebsiella spp., Proteus spp., etc.) or any combination thereof. Also provided, are processes for preparing compounds disclosed herein, pharmaceutical compositions containing compounds disclosed herein, and methods of treating bacterial infections.
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- HETEROCYCLIC COMPOUNDS FOR THE INHIBITION OF PASK
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Disclosed herein are new heterocyclic compounds and compositions and their application as pharmaceuticals for the treatment of disease. Methods of inhibiting PAS Kinase (PASK) activity in a human or animal subject are also provided for the treatment of diseases such as diabetes mellitus.
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Page/Page column 57
(2012/11/08)
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- Unusual anion effects in the iron-catalyzed formation of 3-hydroxyacrylates from aromatic aldehydes and ethyl diazoacetate
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Due to the lability of one of the CO ligands in irans-[Fe(PNP)(CO) 2Cl]+ this compound is an efficient catalyst for the coupling of a series of aromatic aldehydes with ethyl diazoacetate (EDA), which give, in most cases, selectively 3-hydroxyacrylates rather than β-oxo esters. This reaction is strongly dependent on the nature of the counterion, Whereas with BF4- the reaction proceeds with conversions up to 90%, in the case of the counterions NO3-, CF 3COO-, CF3SO3-, SbF 6-, and BAr'4- [Ar' = 3,5-(CF 3)2C6H3] no reaction took place. In the case of PF6- only up to 20% conversion was achieved. A conceivable mechanism for the coupling of aromatic aldehydes with EDA was established by means of DFT/B3LYP calculations, which allowed the rationalization of both the chemoselectivity and the role of the counterions.
- Alves, Luis Goncalo,Dazinger, Georg,Veiros, Luis F.,Kirchner, Karl
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experimental part
p. 3160 - 3166
(2011/01/05)
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- PYRROLE CARBOXYLIC ACID DERIVATIVES AS ANTIBACTERIAL AGENTS
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The present invention provides DNA Gyrase and/or Topo IV inhibitors of formula I, which can be used as antibacterial agents. Compounds disclosed herein can be used for treating or preventing conditions caused by or contributed by gram positive, gram negative and anaerobic bacteria, more particularly against, for example, Staphylococci, Streptococci, Enterococci, Haemophilus, Pseudomonus spp., Acenetobacter spp., Muraxalla spp., Chlamydia spp., Mycoplasma spp., Legionella spp., Mycobacterium spp., Helicobacter, Clostridium spp., Bacteroides spp., Cotyne bacterium, Bacillus spp., Enterobactericeae (E.coli, Klebsiella spp., Proteus spp.,etc.) or any combination thereof Also provided, are processes for preparing compounds disclosed herein, pharmaceutical compositions containing compounds disclosed herein, and methods of treating bacterial infections
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Page/Page column 61
(2010/04/03)
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- SUBSTITUTED PIPERAZINES AS CB1 ANTAGONISTS
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Compounds of Formula (I) or pharmaceutically acceptable salts, solvates, or esters thereof, are useful in treating diseases or conditions mediated by CB1receptors, such as metabolic syndrome and obesity, neuroinflammatory disorders, cognitive disorders and psychosis, addiction (e.g., smoking cessation), gastrointestinal disorders, and cardiovascular conditions.
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Page/Page column 161
(2009/03/07)
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- Structure-activity relationships of 1,4-dihydropyridines that act as enhancers of the vanilloid receptor 1 (TRPV1)
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Vanilloid agonists such as capsaicin activate ion flux through the TRPV1 channel, a heat- and ligand-gated cation channel that transduces painful chemical or thermal stimuli applied to peripheral nerve endings in skin or deep tissues. We have probed the SAR of a variety of 1,4-dihydropyridine (DHP) derivatives as novel 'enhancers' of TRPV1 activity by examining changes in capsaicin-induced elevations in 45Ca2+-uptake in either cells ectopically expressing TRPV1 or in cultured dorsal root ganglion (DRG) neurons. The enhancers increased the maximal capsaicin effect on 45Ca2+-uptake by typically 2- to 3-fold without producing an action when used alone. The DHP enhancers contained 6-aryl substitution and small alkyl groups at the 1 and 4 positions, and a 3-phenylalkylthioester was tolerated. Levels of free intracellular Ca2+, as measured by calcium imaging, were also increased in DRG neurons when exposed to the combination of capsaicin and the most efficacious enhancer 23 compared to capsaicin alone. Thus, DHPs can modulate TRPV1 channels in a positive fashion.
- Roh, Eun Joo,Keller, Jason M.,Olah, Zoltan,Iadarola, Michael J.,Jacobson, Kenneth A.
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experimental part
p. 9349 - 9358
(2009/04/06)
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- Synthesis and biological activity of 7-phenyl-6,9-dihydro-3H-pyrrolo[3,2-f] quinolin-9-ones: A new class of antimitotic agents devoid of aromatase activity
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The newly synthesized 7-phenyl-3H-pyrrolo[3,2-f]quinolinones 16-26 and previously 27 and 28 were assayed for their in vitro antiproliferative activity on tumor cell lines, and the lead compound 16 in vivo on a singenic hepatocellular carcinoma in Balb/c m
- Gasparotto, Venusia,Castagliuolo, Ignazio,Chiarelotto, Gianfranco,Pezzi, Vincenzo,Montanaro, Daniela,Brun, Paola,Palù, Giorgio,Viola, Giampietro,Ferlin, Maria Grazia
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p. 1910 - 1915
(2007/10/03)
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- Niobium(V) chloride-catalyzed C-H insertion reactions of α-diazoesters: Synthesis of β-keto esters
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Aldehydes react readily with ethyl diazoacetate in the presence of 5 mol% of NbCl5 in dichloromethane to produce the corresponding β-keto esters in good yields with high selectivity. This method is very useful for the preparation of β-keto esters from both electron-rich as well as electron-deficient aromatic aldehydes under mild reaction conditions.
- Yadav,Subba Reddy,Eeshwaraiah,Reddy
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p. 875 - 878
(2007/10/03)
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- Pharmaceutical xanthene compounds
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A pharmaceutical compound of the formula: STR1 in which A is carboxy, tetrazolyl, --SO2 H, --SO3 H, --OSO3 H, --CONHOH, or --P(OH)OR', --PO(OH)OR', --OPO(OH)OR' B is a bond, C1-6 alkylene or C2-6 alke
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- Simple and high yielding syntheses of β-keto esters catalysed by zeolites
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Simple and high yielding syntheses of several β-keto esters, catalysed by zeolite Hβ are reported. The methods developed include condensation of aldehydes with ethyl diazoacetate and transesterification of β-keto esters with primary, secondary, allylic and benzylic alcohols etc., all catalysed by Hβ. It was further observed that under microwave irradiation the yields of many aromatic β-keto esters were enhanced appreciably.
- Balaji,Chanda, Bhanu M.
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p. 13237 - 13252
(2007/10/03)
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- KETOCOUMARINS. A NEW CLASS OF TRIPLET SENSITIZERS
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Several derivatives of 3-ketocoumarins were prepared and are shown to have many of the photophysical criteria required for efficient triplet sensitizers.These compounds include 3-aroylcoumarins (1) and 3,3'-carbonyl-biscoumarins (2).The aryl groups in 1 are either phenyl and substituted phenyl derivatives or heterocyclic groups such as thienyl and benzofuryl.The substituents on the coumarin moiety in 1 and 2, if any, are alkoxy or dialkylamino.These compounds, with absorption maxima between 330 and 450 nm, have extinction coefficients in the range of 1E4 to almost 1E5, which is an important criterion for efficient sensitization of thin films of polymers as those used in photoresists and litography.The singlet-triplet intersystem crossing (isc) efficiencies of several derivatives approach unity.In others, however, a radiationless decay process competes with the isc.The decay process is particularly dominant in the assymetrically substituted derivatives of 2, but seems to be considerably supressed in polymeric matrices.The triplet energies of these compounds range from ca. 48 to 60 kcal/mol.Some of these ketocoumarins show phosphorescence spectra that suggest the presence of "frozen-in" rotamers.
- Specht, Donald P.,Martic, Peter A.,Farid, Samir,++
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p. 1203 - 1211
(2007/10/02)
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