Synthesis of (±)-Clavularin B

Abstract

(±)- Clavularin B (2b) was prepared from cyclohepta-2,6-dienone (4) via a Michael reaction of the lithium dienolate anion (5a) with the trimethylsilyl -substituted methyl vinyl ketone (11). The structures of the clavularins A and B were thus unambiguously established as cycloheptenone derivatives (2a) and (2b). The Mukaiyama reaction between the silyl dienol ether (5b) and but-3-en-2-one gave 8-acetyl-4- methylbicyclo[3.2.2]nonan-6-one (9).