Tetrahedron Letters,Vol.25,No.23,pp 2447-2450,1984 0040-4039/84 $3.00 +-00 Printed in Great Britain 01984 Pergamon Press Ltd. STEREOCONTROLLED TOTAL SYNTHESIS OF ISOCOMENE SESQUITERPENES

Abstract: Four isomers of t!ie sesquiterpene isocomene have been synthesized in high yields and in a stereocontrolled fashion from the tricyclic triquinane 1 obtained by the cyclopentene annulation method. Carbon-13 data was obtained for all of the iSocomene sesquiterpenes. The pursuit of a general synthetic methodology for the preparation of linearly and 2,3 nonlinearly fused triquinanes has led us to the synthesis of ketoester 1. This substance-has been attained by the cyclopentene annulation of a dienic diazoketone possessing the general structural parmneters depicted in 1 and serving as entry for the construction of 4 either hirsutane or isocomen