Terpenoids. XXXIII. Chemical Conversion of Enmein into Enmelol

Abstract

After several preliminary experiments, enmein (1) was converted into enmelol (2). The route consists of the following steps : (i) Enmein (1) was converted into lactone ester 40 via 3, 8, 9, and 10. (ii) An acyloin product 42 derived from 40 was transformed into 15-kaurene derivative 61, via epoxide 56, 1β-ol 57, acetate 58, and 15-ol 59. (iii) By photosensitized oxygenation of 61, allyl alcohol 62 and αβ-unsaturated ketone 63 were yielded. (iv) Enmelol (2) and 15-epienmelol (69) were derived from 63 and 62, respectively.