Total Syntheses of (+)-Longicamphor and (+)-Longiborneol

Abstract

Recent total syntheses within the longifolane class of sesquiterpenes have included such elaborately bridged structures as longicyclene,¹ longifolene,^2,3 isolongifolene,⁴ and culmorin.⁵ A tricyclic member of this interesting group of naturally occurring compounds; namely, longicamphor (6) has previously been synthesized from natural (+)-longifolene via (+)-longiborneol (7).⁶ Longiborneol (Juniperol, macrocarpol) was isolated from Cupressus macrocarpa, the famous Monterey cypress.^7,8 We wish to report herein stereoselective total syntheses of (+)-longicamphor (6) and (+)-longiborneol (7).