A GENERAL METHOD FOR THE SYNTHESIS OF CLERODANE DITERPENOIDS. STEREOSPECIFIC TOTAL SYNTHESES OF (+/-)-15,16-EPOXY-CIS-CLERODA-3,13(16),14-TRIENE AND (+/-)-MAINGAYIC ACID

Article abstract of DOI:10.1016/S0040-4020(01)90099-7

A general method for the syntheses of cis- and trans-clerodane diterpenoids has been developed and its applications to the total syntheses of both representatives 11 and maingayic acid (32) in racemic forms are described.The common Δ⁴-3-octalone intermediates 2a and 2b were prepared from 3,4-dimethyl-2-cyclohexenone by a stereospecific conjugate addition-alkylation sequence and the subsequent thermodynamically controlled annelation.The dimethylcuprate addition to 2a followed by enolate trapping afforded stereospecifically the cis-alcohol 12, from which (+/-)-11 has been synthesized.On the other hand hydrocyanation of 2b gave trans-intermediate 33, and then it has been converted to (+/-)-maingayic acid (32).