Substituent effects in the stereoconvergent synthesis of β-hydroxyphenylalanine derivatives
摘要:
The degree of stereoconvergence in the synthesis of beta-hydroxyarylalanine derivatives from the corresponding beta-bromoarylalanine derivatives is governed by the electronic nature of the aryl substituents, and controlled by facially selective stabilisation of the benzylic cation through the neighbouring ester moiety. introduction of electron donating aryl substituents results in a decrease in selectivity, whereas electron withdrawing substituents induce an increase in selectivity for the threo-beta-hydroxyarylalanine diastereomer. (C) 1997 Elsevier Science Ltd.