An enantioselective total synthesis of (+)- and (-)-saudin. Determination of the absolute configuration.
A short efficient enantioselective synthesis of both (+)- and (-)-saudin, a naturally occurring hypoglycemic diterpene, is described. This synthesis establishes the absolute configuration of natural (-)-saudin for the first time. The key steps include the enantioselective construction of a dimethyl Hagemann's ester by an asymmetric Michael reaction and establishment of the key 1,3 disposed quaternary centers by means of a novel Ti(IV) promoted Claisen rearrangement. The assembly of the polycyclic ketal skeleton was likely under kinetic control proceeding via formation of the C1oxygen-C7 bond through an oxonium ion intermediate in the final stage.
Boeckman
Robert K
RK
Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, USA.
Ferreira
Maria del Rosario Rico
Mdel R
Mitchell
Lorna H
LH
Shao
Pengcheng
P
D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D007004:Hypoglycemic Agents / Q000138:chemical synthesis / Q000737:chemistry; D008968:Molecular Conformation; D010936:Plant Extracts / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
D004224:Diterpenes; D007004:Hypoglycemic Agents; D010936:Plant Extracts; C450680:saudin