A Highly Enantioselective Synthesis of the Odorant, 3-hydroxy-4-phenylbutan-2-one

Abstract

An efficient and highly enantioselective synthesis of 3-hydroxy-4-phenylbutan-2-one was developed involving the asymmetric epoxidation of an enone and hydrogenolysis of an α,β-epoxyketone. 1-Phenyl-3-buten-2-one was epoxidised with t-butyl hydroperoxide using a chiral La-BINOL-Ph3P=O complex as the catalyst to give ( 3S,4R)- or ( 3R,4S)-3,4-epoxy-4-phenylbutan-2-one in ~90% yield and 97% ee. The resultant optically active epoxyketone was reduced in the presence of Pd/C (5 mol%) and H2 (3 bar) in THF at room temperature to produce ( S)- or ( R)-3-hydroxy-4-phenylbutan-2-one in ~80% yield with more than 90% enantiomeric excess.