The key intermediates of the sex pheromone of the pine sawfly 2-methyl-octanol and 2-methyl- decanol were synthesized from n-octanol and n-decanol sucessively via the oxidation with pyridinium chlorochromate(PCC), Mannich reaction, catalytic transferhydrogenation over Pd/C and reduction by LiAlH 4 in the total yield of 23.4% and 38.8%, respectively. Using acetic acid as solvent of pH=7, the yield of α-hexyl-acrolein in Mannich reaction was up to 70.1% in the optimized condition. 2-Methyl-dodecanol was similarly synthesized with the same procedure in the total yield of 48.2%.
The total synthesis of 3,7-dimethyl-2-tridecanyl propionate, the active component of the sex pheromone of pine sawfly Diprion jingyuanensis is reported. The new synthesis process starts from 2-methyloctanal, then through hydroxyethylenation, transetherification, Claisen rearrangement, hydroxymethylation, hydrogenation to give 3,7- dimethyl-2-tridecanol. Esterification of 3,7-dimethyl-2-tridecanol affords 3,7-dimethyl-2-tridecanyl propionate.
