Diastéréosélectivité de la réduction des alkyl-2 alkylidène-3 cyclopropyl alkyl cétones. Addition de RLi sur les aldéhydes α-cyclopropylidéniques

Abstract

The addition of RLi on trans 2-alkyl-3-methylene cyclopropane carboxaldehydes is not diastereoselective, while the reduction of trans (2-alkyl-3-alkylidene cyclopropyl) alkyl ketones shows for some compounds a high diastereoselectivity which may reach stereospecificity at low temperatures. This selectivity depends not only on the degree of substitution of the group fixed on the carbonyl but on the radical fixed in position 2 on the ring even though it shows a trans relation with the functional group.The relative configurations of secondary α-cyclopropylidene alcohols are determined from their ir and nmr data.