Total Synthesis of 4α,5α,10β-Trihydroxycadinane and Its C4-Isomer: ­Structural Revision of a Natural Sesquiterpenoid

An efficient approach to cadinane sesquiterpenes starting from (R)-carvone, employing a ring closing metathesis (RCM) reaction and a modified allylic diazene rearrangement as key steps, is described. The first asymmetric total syntheses of 4α,5α,10β-trihydroxycadinane (1) and natural 4β,5α,10β-trihydroxycadinane (2) were accomplished and the structure of natural product A was revised to 2.