SIMPLE AND EFFICIENT STEREOCONTROL OF RADICAL ALLYLATIONS OF BETA-HYDROXY ESTERS

Highly stereoselective radical allylations of non-protected beta-hydro xy esters have been achieved after formation of chelated aluminum alko xides upon treatment with MeAlR(2). This approach combines very high s electivities, excellent reproductibility and simplicity of the manipul ations. Interestingly, diethyl malate is allylated after treatment wit h 1.1 equiv. of MAD to the three (syn) isomer with almost complete dia stereoselectivity (> 95% ds), this stereochemical outcome is opposite to the one observed in the well-known alkylation of the corresponding enolate. Copyright (C) 1996 Elsevier Science Ltd