Stereoselectivity of the Petasis reaction with various chiral amines and styrenylboronic acids

Abstract

Several chiral amines were investigated for the stereoselective preparation of homo-phenylalanine derivatives using the Petasis reaction. Chiral secondary amines such as N,α-dimethylbenzylamine and N-benzylphenylglycinol gave the best results in terms of both yield and diastereoselectivity. The use of N-benzylphenylglycinol leads directly to 3-alkenyl-4-benzyl-5-phenyloxazin-2-one products. Intriguing variation was observed in the stereoselectivity of reactions employing para-substituted styrenylboronic acid substrates, where presumably only electronic factors are involved. © 2008 IUPAC.