Asymmetric Synthesis of Stegobinone via Boronic Ester Chemistry

Highly stereoselective asymmetric boronic ester chemistry has been used to install all three chiral centers in a convergent synthesis of highly pure stegobinone, the epimerically labile pheromone of the drugstore beetle, Stegobium paniceum, and the furniture beetle, Anobium punctatum. Asymmetric centers were installed via the reaction of (dichloromethyl)lithium with 1,2-dicyclohexylethane-1,2-diol boronic esters. The synthetic strategy utilizes a common (α-chloroalkyl)boronic ester intermediate as the source of both segments and all of the asymmetry of the target molecule. The two segments are joined by an aldol condensation and converted to stegobiol, a minor component of the S. paniceum pheromone and presumably the biogenetic precursor of stegobinone. Stegobiol is stable and easily purified, and is easily converted to pure stegobinone in a single oxidation step.