Synthesis of (±)-lineatin by the photochemical cycloaddition of allene to anhydromevalonolactone

Abstract
(.+-.)-Lineatin, the aggregation pheromone of an ambrosia beetle [Trypodendron lineatum], was synthesized in 5 steps from anhydromevalonolactone (5) in 10% overall yield. The key step in the synthesis was a photochemical cycloaddition of 5 and allene. This photolysis produced 2 regioisomers (.apprx. 3:2) and efforts to improve the regioselectivity by varying the photolysis conditions or substituents on the allene were unsuccessful.