Structural Revision of Terpenoids with a (3<i>Z</i>)-2-Methyl-3-penten-2-ol Moiety by the Synthesis of (23<i>E</i>)- and (23<i>Z</i>)-Cycloart-23-ene-3β,25-diols

Abstract

Synthesis of (23E)-cycloart-23-ene-3beta,25-diol (1) and its 23Z-isomer 2 was achieved by using cycloartenol as a starting material, thus revising the proposed structure of natural 2 to 1 unequivocally. These synthetic studies revealed that the structural revision (Z-form --> E-form) should also be applied to terpenoids such as (23Z)-3beta-acetoxyeupha-7,23-diene-25-ol, (23Z)-tirucalla-7,23-diene-3beta,25-diol, quadrangularol A, quadrangularic acid K, and daurichromene C.