- Further study of axial chirality due to an acyclic imide N-Ar bond: Control of rotational barrier by electronic effects of acyl groups
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Studies on stability to racemization in a series of optically active N-aroyl-N-(2-t-butylphenyl)acetamides 2a-g (X=NMe2, OMe, Me, H, F, Cl, CF3), depending on the electronic effect of their aroyl groups, are described. It has been revealed that the stability of 2 bearing stronger electron-withdrawing groups on the aroyl benzene ring was enhanced, with linear correlation between the ΔG? and Hammett's σp para-substituent constant of 2a-g. Furthermore, the absolute configuration of optically active imides 2a-g has been determined by comparison with the CD spectrum of (S)-N-(2-t-butylphenyl)-N-(4-trifluoromethylbenzoyl)propionamide (5b) derived from (Ra,2S)-N-(2-t-butylphenyl)-N-(4-trifluoromethylbenzoyl)-2- acetoxypropionamide (4b), whose absolute configuration was determined by X-ray analysis.
- Kondo, Kazuhiro,Iida, Takeko,Fujita, Hiroko,Suzuki, Tomoko,Wakabayashi, Ryoko,Yamaguchi, Kentaro,Murakami, Yasuoki
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- Atropisomeric amides: Stereoselective enolate chemistry and enantioselective synthesis via a new SmI2-mediated reduction
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The use of certain types of atropisomeric amides, incorporating an N-MEM-ortho-tert-bityariume group, for stereoselective reactions, has been explored. Enolate reactions of these systems are highly diastereocontrolled, and enantiomerically enriched starting materials can be obtained, starting from lactic acid, via a new SmI2 mediated reduction process.
- Hughes, Adam D.,Price, David A.,Simpkins, Nigel S.
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p. 1295 - 1304
(2007/10/03)
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- SmI2-mediated reduction of α-functionalised amides: Highly enantiospecific access to an atropisomeric amide
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SmI2 or SmI2-LiCl mixtures can be used to reduce α-functionalised amides in yields of up to 85% depending upon the amide structure. The method has been applied to the synthesis of an atropisomeric anilide system in highly enantioenriched form, starting with (S)-O-acetyl lactic acid.
- Hughes, Adam D.,Simpkins, Nigel S.
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p. 967 - 968
(2007/10/03)
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