Stereospecific synthesis of S-(-)-trans-verbenol and its antipode by inversion of sterically hindered alcohols.

S-(-)-trans-Verbenol (1) and its antipode, R-(+)-trans-verbenol (1') have been confirmed as the critical pheromone components of bark beetles. Synthesis of these two active secondary alcohols (1 and 1') from commercially available starting materials S-α-pinene and R-α-pinene was reported. The key steps were mainly depended on the effective SN2 stereo-inversion of the hydroxy group of sterically hindered alcohols (3 and 3'), using Mitsunobu reaction or hydrolysis of mesylate ester, alternatively. Our results provide a new and stereo-selectivity way to obtain optically active insect pheromones.