Remarkable solvent dependent cyclisation of methyl vinyl ketone across the 8,8a and 3,8a positions of Δ1,8a-2-octalone dienamines. First syntheses of the tricyclo[8.4.0.01,6]tetradecane and tricyclo[6.2.2.01,6]dodecane ring systems. Crystal structures

Abstract

Reaction of the pyrrolidine dienamine of 4a-methyl-Δ^1,8a-2-octalone with methyl vinyl ketone occurs primarily across the 8,8a-positions in methanol to provide the first synthesis of 10-methyltricyclo[8.4.0.0^1,6]tetradecane-3,13-dione (5), whereas in toluene reaction occurs across the 3,8a-positions to give 11-acetyl-6-methyltricyclo[6.2.2.0^1.6]dodecan-9-one (6), the stereochemistry of both structures being determined by X-ray analysis.