Enantioselective radical allylation of alpha-iodoamides using chiral aluminum based Lewis acids

We report here the first examples of enantioselective radical alkylations directed by chiral Lewis acids where complexated radicals are directly generated by a carbon-halogen bond homolysis. N-(2-Iodopropionyl)oxazolidinones are allylated with allylstannane in the presence of chiral aluminum based Lewis acids prepared from Me(3)Al and chiral diols/diamides ligands. The observed enantioselectivities are still modest (less than or equal to 34% ee). By analogy to cycloaddition reactions, a model is proposed to rationalize the sense of the enantioselectivity. (C) 1997 Elsevier Science Ltd.