269060-81-3Relevant academic research and scientific papers
Further study of axial chirality due to an acyclic imide N-Ar bond: Control of rotational barrier by electronic effects of acyl groups
Kondo, Kazuhiro,Iida, Takeko,Fujita, Hiroko,Suzuki, Tomoko,Wakabayashi, Ryoko,Yamaguchi, Kentaro,Murakami, Yasuoki
, p. 4115 - 4122 (2007/10/03)
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.
A chiral axis due to an acyclic imide-Ar bond: A study of steric effects of acyl groups on racemization
Kondo, Kazuhiro,Iida, Takeko,Fujita, Hiroko,Suzuki, Tomoko,Yamaguchi, Kentaro,Murakami, Yasuoki
, p. 8883 - 8891 (2007/10/03)
Studies on the racemization in a series of optically active compounds 3a-e, including the steric effect of their acyl groups, are described. The first example of optically active compounds 3c and 3d, which possess axial chirality based on an acyclic imide-Ar bond, has been reported. A quite interesting result has been revealed, namely, that 3a bearing a bulky acyl group rather than a relatively small one racemized more easily. To explain this observed phenomenon, 13C NMR experiments and the reaction with benzylamine of 3a-e were undertaken. These results suggested that the t-BuCO-N bond in 3a which racemized easily, is more twisted, compared with the RCO-N bonds in 3b-e which are relatively stable to racemization. Furthermore, the absolute configuration of 3b and 3c has been determined to be R by the CD spectrum and the X-ray crystallographic analysis of racemic 3f has been accomplished. (C) 2000 Published by Elsevier Science Ltd.
A new chiral axis due to N(open-chain imide)-Ar bond: Unexpected racemization effect of an acyl group
Kondo, Kazuhiro,Fujita, Hiroko,Suzuki, Tomoko,Murakami, Yasuoki
, p. 5577 - 5580 (2007/10/03)
The first example of optically active compound 3c which possesses axial chirality based on the N(open-chain imide)-Ar bond rotation, is described. Furthermore, a quite interesting result is also described, namely, that 3a bearing a bulky acyl group rather than a small one racemized more rapidly. To explain this phenomenon, 13C NMR experiments and the reaction with benzylamine of 3a-d were undertaken. These preliminary results suggest that the t-BuCO-N bond in 3a which racemized easily, is more twisted, compared with the CO-N bonds in 3b-d which were relatively stable to racemization.
