Origins of stereoselectivity in radical additions: reactions of alkenes and radicals bearing oxazolidine and thiazolidine amide groups

Single-crystal X-ray analysis of four alkenes that undergo stereoselective radical addition reactions are reported. The facial selectivity of radical additions to these alkenes is understood based upon their solid-state conformations. Alkenes which have a conformation placing a group at a position in space sterically protecting one the faces from addition undergo radical addition with diastereofacial selectivity. The structures of the alkenes are analyzed by the polar coordinates of groups relative to the alkenes center undergoing addition