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.