Preparation of three diastereoisomers of 2-(1-methyl-1-phenylethyl)-5-methylcyclohexan-1-ol from (R)-(+)-pulegone

Abstract

New isolation of (1R,2S,5R)-(-)-2-(1-methyl-1-phenylethyl)-5-methylcyclohexan-1-ol ((-)-8-phenylmenthol, Ia), prepared from (R)-(+)-pulegone, is described. The method consists in the preparation of phenylcarbamate of Ia and its transesterification with ethanol. Further two diastereoisomers of (-)-8-phenylmenthol were isolated: the (1S,2R,5R)-isomer IIa and the (1R,2R,5R)-isomer IIIa. Compounds Ia, IIa and IIIa were converted into their respective glyoxylates Ic, IIc and IIIc.