Catalytic enantioselective alkylation of aldehydes using chiral hydrogen phosphoramidates and hydrogen phosphinamides and their thio analogs

Article abstract of DOI:10.1002/recl.19951140404

Chiral (enantiomerically pure) hydrogen thiophosphoramidates and hydrogen phosphoramidates and their phosphinamide analogs derived from norephedrine and other chiral (enantiomerically pure) amino alcohols catalyze the enantioselective addition of dialkylzincs to aldehydes.The presence of titanium tetraisopropoxide increases the enantioselectivity, providing enantiomerically enriched secondary alcohols with up to 98percent ee.The enantioselectivities of thiophosphoramidates and thiophosphinamides are higher than those of the oxygen analogs.The phosphoramidates and thiophosphoramidates, without the hydroxyl group, also catalyze the addition of dialkylzinc to aldehydes in the absence of Ti(O-i-Pr)4.