Stereoselective Total Syntheses of(+/-)-Gymnomitrol and (+/-)-Gymnomitrene

Article abstract of DOI:10.1021/jo01309a004

Stereoselective total syntheses of (+/-)-gymnomitrol (2A) and (+/-)-gymnomitrene (2B)in 12 synthetic stages each from 2-methylcyclopentanone (3)are presented.The key features of these syntheses are (a)the conjugate addition of lithium dimethylcopper to enone 8 followed by alkylation of the intermediate enolate anion with allyl chloride to afford ketone 9, (b) stereoselective alkylation of ketone 9,(c) a modified intramolecular Claisen condensation and enolate anion trapping with tert-butyldimethylsilyl chloride to give tricyclic ketone 14B, and (d) convenient utilization of a common intermediate in the construction of both natural products 2A and 2B by sequential chemical manipulation of 15A followed by desilylation to produce either ketone 16 or 18 in one-pot reactions.