Total Synthesis of 5-epi-Eudesm-4(15)-ene-1β,6β-diol via Decarbonylative Radical Coupling Reaction.

A mild radical-based coupling method was devised for intermolecular installation of quaternary carbons. Treatment of α,α-dialkoxyacyl telluride with Et3B/O2 at room temperature promoted the formation of a highly reactive α,α-dialkoxy carbon radical, which coupled with 2-cyano-3-methyl-2-cyclohexen-1-one to forge the sterically cumbersome bond between the tetrasubstituted and quaternary carbon centers. The present convergent strategy was successfully applied to a seven-step total synthesis of 5-epi-eudesm-4(15)-ene-1β,6β-diol (1).