Stereoselective chemoenzymatic synthesis of sitophilate: a natural pheromone

The aggregation pheromone of the granary weevil Sitophilus granarius, (2S,3R)-1-ethylpropyl 3-hydroxy-2-methylpentanoate, has been synthesized in 63% total isolated yield and high chemical and enantiomeric purity (98% de, >99% ee) from readily available methyl 3-oxopentanoate. A stereoselective ketone reduction followed by an ester hydrolysis, were the two key steps of the synthesis and were both performed by commercially available enzymes.