A convenient preparative method for mintlactone and isomintlactone

Abstract

Abstract Various 2‐(2′‐hydroxy‐4′‐methyl‐1′‐cyclohexylidene) carboxylic acid lactones were synthesised in good yield from carboxylic acids and 4‐methylcyclohexanone. For example, mintlactone ( VI ) and isomintlactone ( VII ) were prepared from 2‐(1′‐ hydroxy‐4′‐methylcyclohexan‐1′‐yl) propanoic acid ( III ) which was obtained by reaction of propanoic acid ( I ) with 4‐methylcyclohexanone ( II ) using lithium naphthalenide in the presence of diethylamine. Compound ( VI ) could be separated from compound ( VII ) by silica gel column chromatography. Several new 2‐(2′‐ hydroxy‐4′‐methyl‐1′‐cyclohexylidene) carboxylic acid lactones which may be used as perfumery materials, were obtained in good yield by this method.