Catalytic Asymmetric Total Syntheses of (+)- and (-)-ar-Elvirol Methyl Ether

Catalytic asymmetric approach to either enantiomer of naturally occurring sesquiterpene, i.e. (+)-ar-elvirol (1a) and (-)-ar-elvirol (ent-1a) has been achieved via a key allylic diazene arrangement (ADR) from an advanced enantioenriched tertiary allyl alcohol. The ADR proceeds via the reductive transposition of olefin under the Mitsunobu reaction with o-nitro benzene sulfonyl hydrazide followed by the decomposition of sulfonyl hydrazide adduct. This ultimately follows a [3,3]-sigmatropic rearrangement via the extrusion of o-nitro benzene sulfinic acid and nitrogen gas. This approach has been utilized for total syntheses of bisabolene sesquiterpenoid, (+)-ar-elvirol methyl ether (1b) and (-)-ar-elvirol methyl ether (ent-1b).