Abstract
Spectroscopic and stereochemical evidence is provided which suggests that single electron transfer (SET) accounts for the difference in selectivity observed in the reaction of metalated pivalamides and oxazolines with carbonyls.
Low temperature ESR experiments and stereochemical evidence indicate, that, whereas lithiated amides and oxazolines add to carbonyls by a SET mechanism, the corresponding organomagnesium compounds add by a polar mechanism. These results are explained in the context of the Pross “single electron shift” hypothesis.