STEREOSELECTIVE TOTAL SYNTHESIS OF (+ -)-TOCHUINYL ACETATE AND (+/-)-DIHYDROTOCHUINYL ACETATES/

Details of the first total synthesis of the marine natural product dih ydrotochuinyl acetate is described. Cyclopentenone annulation of p-met hylacetophenone via a Claisen rearrangement-Wacker oxidation based seq uence generated the cyclopentenone 3, a known precursor for the sesqui terpenes cuparene, laurene, alpha-cuparenone and beta-cuparenones. Con version of the ketone moiety into a carboxylate followed by stereosele ctive alkylation and reduction transformed the cyclopentenone 3 into t he primary alcohol 19. Birch reduction of the alcohol 19 followed by a cetylation furnished (+/-)-dihydrotochuinyl acetate, whereas direct ac etylation of 19 furnished (+/-)-tochuinyl acetate. (C) 1998 Elsevier S cience Ltd. All rights reserved.