Expedient route to the tigliane-daphnane skeleton via oxonium ylide [1,2]-shift.
A short, stereoselective approach to the fused tricyclic carbon skeleton found in the tigliane and daphnane classes of diterpene natural products is described. Convergent coupling of the A- and C-rings, followed by diastereoselective cerium enolate addition and formation of a double acetal set the stage for generation of an oxonium ylide via a transient metallocarbene. An efficient Stevens [1,2]-shift furnished the 7-membered B-ring, possessing the bridgehead oxygenation pattern found in the natural systems.
Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, AB T6G 2G2, Canada.
Craig
C
Stewart
Robert
R
McDonald
F G
FG
West
D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D001688:Biological Products; D004224:Diterpenes; C011309:mezerein