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.
Dearomatising cyclisation of lithiated 1-naphthamides with a phenylglycinol-derived chiral auxiliary: asymmetric synthesis of an arylkainoid and a kainoid-like pyroglutamate
作者:Ryan A Bragg、Jonathan Clayden、Michael Bladon、Osamu Ichihara
DOI:10.1016/s0040-4039(01)00502-0
日期:2001.5
N-benzylphenylglycinols undergo a diastereoselective dearomatising cyclisation on treatment with t-BuLi and DMPU or HMPA. A new pyrrolidinone ring is formed bearing three new stereogenic centers of defined absolute stereochemistry. Removal of the phenylglycinol auxiliary gives enantiomerically pure substituted lactams exhibiting the stereochemistry of the kainoids. These may be converted to kainoid-like pyroglutamates