A concise and stereoselective chemoenzymatic synthesis of Sitophilate,the male-produced aggregation pheromone of Sitophilus granarius (L.)

(2S,3R)-Sitophilate, the male-produced aggregation pheromone of the granary weevil Sitophilus granarius (L.) was prepared stereoselectively using a novel chemoenzymatic approach in 50% overall yield. The synthetic design was based on an enantioselective fungal reduction of ethyl 2-methyl-3-oxopentanoate with a strain of Aureobasidium pullulans (CCM H1), followed by a Mitsunobu inversion at C3. The last step in the synthetic sequence was a lipase-mediated transesterification using the commercially available Candida antarctica B lipase (CaL B, Novozym 435) using microwave irradiation under solvent-free conditions.