Conversion of (+)-(R)-Limonene into (+)-(1S,4R)-p-mentha-2,8-dien-1-ol, an intermediate in the synthesis of tetrahydrocannabinoids

Abstract

(+)-(1S,4R)-p-Mentha-2,8-dien-1-ol (3), an important intermediate in the synthesis of (-)-Δ⁹-trans-6a,10a-tetrahydrocannabinol (1) and other tetrahydrocannabinoids, is conveniently prepared from (+)-(R)-limonene (5) by rearrangement of its (1S,2R)-1,2-epoxide (7). Similar rearrangement of the diastereoisomeric (1R,2S)-1,2-epoxide (6) yields (+)-(2S,4R)-p-mentha-1(7),8-dien-2-ol (12), a major constituent of gingergrass oil.