Syntheses of the sixteen stereoisomers of 3,7,11-trimethyl-2-tridecanol, including the (2S,3S,7S,11R) and (2S,3S,7S,11S) stereoisomers identified as pheromone precursors in females of the pine sawfly Microdiprion pallipes (Hymenoptera : Diprionidae)

All sixteen stereoisomers of 3,7,11-trimethyl-2-tridecanol were synthesised in high stereoisomerical purities (> 95%), for use in the identification o f the stereoisomers present in females of the pine sawfly Microdiprion pall ipes (Fallen) (Hymenoptera: Diprionidae) as the precursor of the actual sex pheromone (which is the propionate), and also for investigation of the bio logical activities of the esters. The key step in the syntheses was the cou pling of each of the enantiomers of cis-3,4-dimethyl-gamma -butyrolactone w ith each of the four pure stereoisomers of 1-lithio-2,6-dimethyloctanes. Th e four corresponding alcohols were obtained by lipase-catalysed (Amano PS) kinetic separation, based on selective acylation of either (2R/S,6S)- or (2 R/S,GR)-2,6-dimethyl-1-octanol (obtained from the optically pure enantiomer s of citronellal). Additionally, a mixture of the 16 possible stereoisomers of 3,7,11-trimethyl-2-tridecanol was also prepared.