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A Novel Cis-Selective Cyclohexanone Annulation as the Key Step of a Total Synthesis of the Sesquiterpene Isoacanthodoral

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journal contribution
posted on 2009-11-05, 00:00 authored by Thomas Hampel, Reinhard Brückner
Isoacanthodoral (1) is a structurally unique sesquiterpene in that it is a bicyclo[4.4.0]dec-1-ene with a cis- rather than the common trans-junction between the constituting rings. An efficient construction of this motif has been accomplished by a novel cis-selective cyclohexanone annulation, combining the lithium enolate of ester 8, the α,β-unsaturated ester 6, and vinylmagnesium bromide in a single synthetic operation. For completing the total synthesis of 1, a Shapiro-olefination/hydrogenation sequence and a reductive cyanation were employed.