| Abstract
| - A 17 step synthesis of 55, a late intermediate in Danishefsky's guanacastepene A synthesis, hasbeen completed in 4% overall yield. Key features include the use of vinylmagnesium bromide inthe Pd-catalyzed coupling with triflate 13 to give triene 16 without the formation of Heck products,a novel extension of the Stork−Jung vinylsilane Robinson annulation that provides tricyclic2-hydroxymethylcyclohexenone 42 from 23b in four steps and 51% yield, the ability to obtain almostexclusively α‘-alkylation of 35ba by the proper choice of protecting groups, and the ability to obtainthe desired β-alcohol selectively by reduction of keto alcohol 42 rather than keto ester 53.
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