The Synthesis of (+/-)-Presilphiperfol-7(8)-Ene and Tertiary Tricyclo(5.3.1.0(4,11))undecanols Related to Presilphiperfolan-8-Ol
Functionalization reactions of the double bond of 15-nor-PSP-7(8)-ene were carried out to investigate the possible synthesis of (+/-)-PSP-8-OH from (+/-)-PSP-7(8)-ene. Epoxidation of the double bond with an aqueous buffered m-chloroperbenzoic acid furnished a 2.5:1 mixture of the 7beta,8beta- and 7beta,8beta-epoxides. m-Chlorobenzoic acid catalyzed a facile rearrangement of the 7beta,8beta-epoxide to 15- nor-cameroon-7-one was investigated. Reaction of nor-PSP-7(8)-ene with osmium tetroxide afforded nor-presilphiperfolan-7a,8a-diol, which underwent pinacol rearrangement to 8,10,10-trimethyltricyclo[6.2.1.01,5]undecan-11-one. The same ketone was formed directly by reaction of nor-PSP-7(8)-ene with chromyl chloride. The mechanistic pathways and stereochemical implications of these rearrangements are discussed in detail.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign