Studies in sesquiterpenes-lx reversion of longipinane to himachalane system: revision of structure of isocentdarol

Longipinene on exposure to acids rapidly rearranges to furnish α- and β-himachalenes, longifolene and isolongifolene. Longipinene epoxide, under acid catalysis, gives several products resulting from fragmentation and Wagner-Meerwein rearrangement. All products have been fully characterised. Formation of isocentdarol in this reaction requires revision of its stereochemistry at the centre carrying tertiary hydroxyl function