The preparation and absolute configuration of the optically active forms of the diastereoisomers of 2-(1-phenylethyl)amino-1-phenylethanol and their use as chiral auxiliaries in the asymmetric reduction of acetophenone with modified lithium aluminium hydrides

Abstract

(1S,2S)-(–)-2-(1-Phenylethyl)amino-1-phenylethanol (4b)(α-form) and the(1S,2R)-(+)-diastereoisomer (4f)(β-form) were prepared by lithium aluminium hydride reduction of the optically active amides derived from the appropriate mandelic acids and 1-phenylethylamines. The preparative methods give the absolute stereochemistry. The aminoethanols (4) were used along with the lower alcohols to prepare chirally modified lithium aluminium hydrides which were in turn used to reduce acetophenone. The optical yields varied, giving at best, under low temperature conditions and use of [LiAlH(OMe)(PhCHOCH₂NCH(Me)Ph)] a 25% optical yield.