ASYMMETRIC-SYNTHESIS OF ANTI-ALPHA-ALKYL-BETA-AMINO ACIDS
被引:134
作者:
DAVIES, SG
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机构:Dyson Perrins Laboratory, University of Oxford, Oxford OX1 3QY, South Parks Road
DAVIES, SG
WALTERS, IAS
论文数: 0引用数: 0
h-index: 0
机构:Dyson Perrins Laboratory, University of Oxford, Oxford OX1 3QY, South Parks Road
WALTERS, IAS
机构:
[1] Dyson Perrins Laboratory, University of Oxford, Oxford OX1 3QY, South Parks Road
来源:
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1
|
1994年
/
09期
关键词:
D O I:
10.1039/p19940001129
中图分类号:
O62 [有机化学];
学科分类号:
070303 ;
081704 ;
摘要:
An investigation into the asymmetric induction accompanying alkylations of enolates derived from the highly diastereoselective conjugate addition of lithium (R)-N-benzyl-N-alpha-methylbenzylamide (R)-1 to crotonate and cinnamate esters has been performed. The access to different enolate geometries afforded by the conjugate addition process and subsequent enolate regeneration by deprotonation of the beta-amino ester conjugate adducts enabled two disparate sets of selectivity data to be compiled. Although both approaches furnished predominantly anti-alpha-alkyl-beta-amino esters. the two-step procedure proved to be considerably more selective. Several factors which play a major role in determining the alkylation selectivity are identified. including the cooperative influence of the alpha-methylbenzylamino stereocentre. Since debenzylation and hydrolysis of the alkylated products was straightforward, this methodology provides a direct route to anti-alpha-alkyl-beta-amino acids in homochiral form.