Molecular complexity from aromatics: Synthesis and photoreaction of endo-tricyclo[5.2.2.0(2.6)] undecanes. Formal total syntheses of (+/-)-coriolin

摘要

Formal syntheses of coriolin 1, a triquinane metabolite isolated from Coriolus censors, are described. Oxidation of 6-methyl saligenin 2 in the presence of cyclopentadiene gave the tricyclic keto epoxide 4 which was elaborated to tricyclo[5.2.2.0(2.6)]undecenones 5 and 18 containing the major structural and stereochemical features of coriolin, in latent form. Triplet sensitized 1,2-acyl shifts in 5 and 18 gave tetracyclic compounds 6 and 19 in a stereoselective manner. Reductive cleavage of cyclopropane rings in 6 and 19 with H-2/Pd-C and TBTH-AIBN respectively, furnished the functionalised triquinanes 7 and 20b which are known precursors for coriolin. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 35]