Stereoselective synthesis of (±)-eremophil-3,11-diene and related compounds. Concerning the structure of eremophilene

Abstract

An efficient, stereoselective synthesis of (±)-eremophil-3,11-diene (3) is described. The key step of the synthetic sequence involves the conjugate addition of lithium dimethylcopper to the octalone 7, which produces (±)-eremophil-11-en-3-one (12) in good yield. The latter is converted, via the tosylhydrazone derivative 13, into compound 3. Comparison of 3 with eremophilene indicates that the initial structural proposal for the latter sesquiterpene is in error. Evidence is presented which demonstrates that eremophilene is correctly represented by structure 4.