Stereospecific formation of tetrasubstituted centres from trisubstituted centres during dearomatising anionic cyclisations
摘要:
Dearomatising anionic cyclisation of tertiary naphthamides bearing chiral N-substituents (such as alpha-methylbenzyl) proceeds with overall retention of configuration at the newly formed tetrasubstituted chiral centre. The cyclisation is stereospecific overall, with the configuration of the starting trisubstituted stereogenic centre controlling the stereochemistry of the product. Highly substituted pyrrolidinone rings may be formed as single enantiomers from enantiomerically pure starting materials. (C) 1999 Elsevier Science Ltd. All rights reserved.
Stereodynamics of Bond Rotation in Tertiary Aromatic Amides
摘要:
The degree to which the rotations about the C-N and Ar-CO bonds of aromatic amides occur in a concerted manner was investigated by a variety of NMR and kinetic techniques. Otherwise complex kinetic analyses were simplified by exploiting symmetry and asymmetry in the N-substituents of amides. In 2-unsubstituted 1-naphthamides bearing branched N-substituents, most conformational changes about the amide group were by correlated rotation, though uncorrelated Ar-CO rotation also occurred to some extent. In 2-substituted 1-naphthamides, correlated rotation accounted for all of the Ar-CO rotations, though a significant amount of uncorrelated C-N rotation also occurred. Naphthamides bearing branched N-substituents thus turn out to be efficient molecular gears.
Stereospecific formation of tetrasubstituted centres from trisubstituted centres during dearomatising anionic cyclisations
作者:Ryan A. Bragg、Jonathan Clayden
DOI:10.1016/s0040-4039(99)01765-7
日期:1999.11
Dearomatising anionic cyclisation of tertiary naphthamides bearing chiral N-substituents (such as alpha-methylbenzyl) proceeds with overall retention of configuration at the newly formed tetrasubstituted chiral centre. The cyclisation is stereospecific overall, with the configuration of the starting trisubstituted stereogenic centre controlling the stereochemistry of the product. Highly substituted pyrrolidinone rings may be formed as single enantiomers from enantiomerically pure starting materials. (C) 1999 Elsevier Science Ltd. All rights reserved.
Stereodynamics of Bond Rotation in Tertiary Aromatic Amides
作者:Ryan A. Bragg、Jonathan Clayden、Gareth A. Morris、Jennifer H. Pink
The degree to which the rotations about the C-N and Ar-CO bonds of aromatic amides occur in a concerted manner was investigated by a variety of NMR and kinetic techniques. Otherwise complex kinetic analyses were simplified by exploiting symmetry and asymmetry in the N-substituents of amides. In 2-unsubstituted 1-naphthamides bearing branched N-substituents, most conformational changes about the amide group were by correlated rotation, though uncorrelated Ar-CO rotation also occurred to some extent. In 2-substituted 1-naphthamides, correlated rotation accounted for all of the Ar-CO rotations, though a significant amount of uncorrelated C-N rotation also occurred. Naphthamides bearing branched N-substituents thus turn out to be efficient molecular gears.