Sex pheromone of pine sawflies: Enantioselective lipase catalysed transesterification of erythro-3,7-dimethylpentadecan-2-ol, diprionol

Abstract

(2 S,3 S,7 R/ S)-3,7-Dimethylpentadecan-2-ol (2S,3S,7R/S)- 1 was prepared with less then 0.5% of (2 R,3 R,7 R/ S)-3,7-dimethylpentadecan-2-ol via Pseudomonas sp. (PSL) catalysed transesterification of a 1:1:1:1 mixture of the four erythro-3,7-dimethylpentadecan-2-ols and vinyl acetate in n-heptane at initial low water activity (a w < 0.1). (2 S,3 S,7 S)-3,7-Dimethylpentadecan-2-ol (Diprionol) is the precursor to the behaviourally active diprionyl acetate used by the female pine sawfly Neodiprion sertifer as a sexual pheromone. Several lipases, solvents and reaction conditions were tested, and the best results (enantiomeric ratio E = 110) were obtained with Pseudomonas sp. (PSL) and vinyl acetate in iso-octane at initial water activity a w < 0.32. When using Candida rugosa (CRL, immobilised on polypropylene) as the catalyst in an esterification reaction with rac-4-methyl-dodecanoic acid and eicosanol at a w = 0.8 in cyclohexane a pronounced enantioselectivity was obtained (E = 19).