Diastereoselective allylation of alpha-ketoamides bearing camphor N-tosylpyrazolidinone auxiliary: Efficient synthesis of highly optically active two stereoisomers

摘要

Complementary allylation conditions were developed for the synthesis of both diastereomers of tertiary homoallylic alcohols. Treatment of camphor N-tosylpyrazolidinone derived alpha-ketoamides with allyltributylstannane afforded both the individual homoallylic alcohols in high optical purity (up to 98% de) when the reaction was carried out in the presence of Sn(OTf)(2) and PdCl2, respectively. The stereochemical outcome and reversal of stereoselectivity in the reaction are proposed based on C-13 NMR and FTIR studies. (c) 2005 Elsevier Ltd. All rights reserved.