Preparation of (−)-guaia-1(10),11-dien-15,2-olide and (−)-2α-hydroxyguaia-1(10),11-dien-15-oic acid, fragrant sesquiterpenes in agarwood ( Aquilaria agallocha Roxb.)

Abstract

The fragrant sesquiterpene (−)-guaia-1(10),11-dien-15,2-olide ( 8), isolated from agarwood ( Aquilaria agallocha Roxb.), was synthesized starting from (−)-1,10-epoxybulnesene, which is readily available from α-bulnesene in patchouli oil. The absolute configuration of the natural 8 was established by direct comparison of its optical rotation with that of the synthesized 8. It was found that (−)-2α-hydroxyguaia-1(10),11-dien-15-oic acid ( 9), a synthetic intermediate of 8, also occurs in agarwood.