Total synthesis of zizaane sesquiterpenes: (−)-khusimone, (+)-zizanoic acid, and (−)-epizizanoic acid

Abstract
Three sesquiterpenes of the zizaane family, khusimone (1), epizizanoic acid (3), and zizanoic acid (2) have been synthesized in optically active form from the ammonium salt of (−)-l-10-camphorsulfonic acid in sixteen, nineteen, and twenty steps respectively.