Synthesis of Optically Active 9-Oxoisolongifolene

Abstract

9-Oxoisologifolene [6] was synthesized from longifolene [1] and isolongifolene [2].
The treatment of [1] with molecular oxygen for 32∼48 hr at 110∼130°C in polar aprotic solvents (DMSO, DMF and HMPA) yielded 9-oxoisolongifolene [6] as a major product accompanying longicamphene hydrate [3], longi-β-fenchyl alcohol [4], and longiborneol [5] as minor products. Similarly, the olefin [2] selectively gave [6] in good yield.