- Synthesis of 2-substituted 4-arylidene-5(4h)-oxazolones as potential cytotoxic agents in the presence of lemon juice as a biocatalyst
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Background: The oxazolone class of compounds is known to exert a profound effect on malignant cell proliferation, tumor angiogenesis and /or on the established neoplastic vasculature. Additionally, these compounds are generally known to have a low tendenc
- Anand, Krishnan,Jonnalagadda, Sreekantha B.,Katari, Naresh K.,Lakshmi, Chapala V.,Pal, Manojit,Prasad, Malavattu G.
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p. 625 - 634
(2020/01/21)
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- Copper nitrate-mediated synthesis of 3-aryl isoxazolines and isoxazoles from olefinic azlactones
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A copper nitrate-mediated [2 + 2 + 1] cycloaddition reaction was developed for the expedient synthesis of pharmacologically interesting 3-aryl substituted isoxazolines and isoxazoles through CC bond cleavage. Copper nitrate is employed as a reaction promoter and precursor of nitrile oxides. The given approach features a new mode of cycloaddition from olefinic azlactones, copper nitrate and unsaturated compounds with wide substrate scope, good functional group tolerance and operational simplicity.
- Lin, Yifan,Zhang, Ke,Gao, Mingchun,Jiang, Zheyi,Liu, Jiajie,Ma, Yurui,Wang, Haoyu,Tan, Qitao,Xiao, Junjie,Xu, Bin
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supporting information
p. 5509 - 5513
(2019/06/14)
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- Palladium-catalyzed diastereo- and enantioselective formal [3 + 2]-cycloadditions of substituted vinylcyclopropanes
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We describe a palladium-catalyzed diastereo- and enantioselective formal [3 + 2]-cycloaddition between substituted vinylcyclopropanes and electron-deficient olefins in the form of azlactone- and Meldrums acid alkylidenes to give highly substituted cyclopentane products. By modulation of the electronic properties of the vinylcyclopropane and the electron-deficient olefin, high levels of stereoselectivity were obtained. The remote stereoinduction afforded by the catalyst, distal from the chiral pocket generated by the ligand, is proposed to be the result of a new mechanism invoking the Curtin-Hammett principle.
- Trost, Barry M.,Morris, Patrick J.,Sprague, Simon J.
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supporting information
p. 17823 - 17831,9
(2012/12/12)
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- Palladium-catalyzed diastereo- and enantioselective formal [3 + 2]-cycloadditions of substituted vinylcyclopropanes
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We describe a palladium-catalyzed diastereo- and enantioselective formal [3 + 2]-cycloaddition between substituted vinylcyclopropanes and electron-deficient olefins in the form of azlactone- and Meldrums acid alkylidenes to give highly substituted cyclopentane products. By modulation of the electronic properties of the vinylcyclopropane and the electron-deficient olefin, high levels of stereoselectivity were obtained. The remote stereoinduction afforded by the catalyst, distal from the chiral pocket generated by the ligand, is proposed to be the result of a new mechanism invoking the Curtin-Hammett principle.
- Trost, Barry M.,Morris, Patrick J.,Sprague, Simon J.
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supporting information
p. 17823 - 17831
(2013/01/15)
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- Construction of adjacent spiro-quaternary and tertiary stereocenters through phosphine-catalyzed asymmetric [3+2] annulation of allenoates with alkylidene azlactones
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A novel axially chiral spiro-phosphine-catalyzed highly regio-, diastereo- and enantioselective [3+2] cycloaddition of alkylidene azlactones with various allenic esters has been developed, affording the corresponding functionalized spirocyclic products in
- Wang, De,Wei, Yin,Shi, Min
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supporting information; experimental part
p. 2764 - 2766
(2012/04/05)
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- Asymmetric cyclization reactions of N-benzoyl-α-dehydroarylalanine alkyl esters via photoinduced electron transfer from achiral and chiral amines
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Irradiation of the title compounds [(Z)-1] having (S)-(+)-sec-butyl, (-)- menthyl, and related chiral auxiliaries in methanol and 1,2-dichloroethane containing 2-(diethylamino)ethanol afforded chiral auxiliary-substituted (4S,5S)-, (4R,5R)-, (4R,5S)-, and
- Sasaki, Yuji,Watanabe, Haruo,Igarashi, Tetsutaro,Sakurai, Tadamitsu
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experimental part
p. 1329 - 1353
(2011/07/30)
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- Palladium-catalyzed diastereo- and enantioselective synthesis of substituted cyclopentanes through a dynamic kinetic asymmetric formal [3+2]-cycloaddition of vinyl cyclopropanes and alkylidene azlactones
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An enantioselective preparation of vinylcyclopentanes has been achieved through the title reaction (see scheme). A range of aryl, heterocyclic, alkenyl, and alkyl substituted azlactone alkylidenes have been utilized, giving the cyclopentane products in go
- Trost, Barry M.,Morris, Patrick J.
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supporting information; experimental part
p. 6167 - 6170
(2011/08/22)
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- Catalyzing the Erlenmeyer Pl?chl reaction: organic bases versus sodium acetate
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An evaluation of organic base versus sodium acetate as the base in the Erlenmeyer Pl?chl reaction was performed. Aldehyde substituents play an important role in these reactions. Organic bases afford fast reactions, but other side reactions were observed. Alternatively, in the presence of solvent, sodium acetate could be used in catalytic amounts rather than the typical stoichiometric quantities. This Letter reports the comparative results for the use of organic bases versus sodium acetate in Erlenmeyer Pl?chl reactions.
- Cleary, Thomas,Rawalpally, Thimma,Kennedy, Nicole,Chavez, Flavio
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supporting information; experimental part
p. 1533 - 1536
(2010/06/13)
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- Novel peptide mimetic inhibitors of hepatitis C serine protease derived from isomannide
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Hepatitis C (HCV) infection is a cause of chronic liver disease such as cirrhosis, carcinoma, or liver failure, and the current therapy is effective in only 50% of patients. Serine proteases, which are present in HCV, are the most studied class of proteolytic enzymes, and are a primary target in the drug development field. In this paper, we describe the synthesis and biological studies of a novel class of peptide mimetic compounds as potential HCV serine protease inhibitors. Georg Thieme Verlag Stuttgart.
- Barros, Thalita G.,Pinheiro, Sergio,Williamson, John S.,Tanuri, Amilcar,Pereira, Helena S.,Brindeiro, Rodrigo M.,Neto, Jose B. A.,Antunes, Octavio A. C.,Muri, Estela M. F.
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scheme or table
p. 620 - 626
(2009/06/28)
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- Preferential formation of cis-4,5-dihydrooxazole derivatives via photoinduced electron transfer-initiated cyclization of N-acyl-α-dehydroarylalanine alkyl esters
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The alkyl, aryl, and acyl substituent effects on the photoinduced electron transfer-initiated cyclization reaction of the title compounds (1) were investigated in polar solvents from mechanistic and synthetic points of view. The irradiation of (Z)-1 in me
- Maekawa, Kei,Hishikawa, Norikazu,Kubo, Kanji,Igarashi, Tetsutaro,Sakurai, Tadamitsu
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p. 11267 - 11281
(2008/03/12)
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- Highly selective conversion of N-aroyl-α-dehydronaphthylalaninamides into 3,4-dihydrobenzoquinolinone derivatives via photoinduced intermolecular electron transfer
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The irradiation of substituted (Z)-N-aroyl-α- dehydronaphthylalaninamides [(Z)-1] in methanol containing triethylamine (TEA) with Pyrex-filtered light was found to give 3,4-dihydrobenzoquinolinone derivatives (2) in high yields along with minor amounts of 4,5-dihydrooxazole derivatives (3). Analysis of the substituent effects on product composition revealed that both the photoreactivity of 1 and the selectivity of 2 are decreased with increasing electron-withdrawing ability of the substituent introduced at the para-position on the N-benzoyl benzene ring. From the analysis of the dependence of the quantum yield for the formation of 2 on the TEA concentration, it was found that back electron transfer occurs efficiently within an (E)-1 anion radical-TEA cation radical pair intermediate. Graphical Abstract
- Maekawa, Kei,Shinozuka, Ayana,Naito, Michiko,Igarashi, Tetsutaro,Sakurai, Tadamitsu
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p. 10293 - 10304
(2007/10/03)
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