Concise Stereoselective Routes to Advanced Intermediates Related to Natural and Unnatural Pinnaic Acid This work was supported by the National Institutes of Health (Grant Numbers: CA28824). Postdoctoral Fellowship support is gratefully acknowledged by M.W.C. (U.S. Army BCRP, DAMD17-98-1-8154), M.F.H. (5T32 CA62948-05), and D.T. (Schering Research Foundation, Berlin). We thank Dr. George Sukenick of the MSKCC NMR Core Facility for NMR and mass spectral analyses.

Abstract

Important intermediates: in an effort to synthesize and determine the stereochemistry of pinnaic acid, C14-epimeric aldehydes 1 and 2 were generated from Meyers' lactam 3. A key step in the parallel syntheses is a highly stereoselective vinylogous Michael cyclization; Boc = tert-butoxy carbonyl, TFA = trifluoroacetic acid.