Asymmetric [4 + 3] cycloadditions between vinylcarbenoids and dienes: application to the total synthesis of the natural product (-)-5-epi-vibsanin E.
The total synthesis of (-)-5-epi-vibsanin E (2) has been achieved in 18 steps. The synthesis combines the rhodium-catalyzed [4 + 3] cycloaddition between a vinylcarbenoid and a diene to rapidly generate the tricyclic core with an effective end game strategy to introduce the remaining side-chains. The [4 + 3] cycloaddition occurs by a cyclopropanation to form a divinylcyclopropane followed by a Cope rearrangement to form a cycloheptadiene. The quaternary stereogenic center generated in the process can be obtained with high asymmetric induction when the reaction is catalyzed by the chiral dirhodium complex, Rh(2)(S-PTAD)(4).
Schwartz
Brett D
BD
School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane 4072, Queensland, Australia.
Denton
Justin R
JR
Lian
Yajing
Y
Davies
Huw M L
HM
Williams
Craig M
CM
D001688:Biological Products / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D004224:Diterpenes / Q000138:chemical synthesis*; D012238:Rhodium / Q000737:chemistry*
D001688:Biological Products; D004224:Diterpenes; C506848:vibsanin E; D012238:Rhodium