A Novel Synthesis of Sex Pheromone from the Longicorn Beetle ( Psacothea hilaris )

An asymmetric synthesis of (8 Z ,21 R )-21-methylpentatriacont-8-ene, the sex pheromone of the yellow-spotted longicorn beetle Psacothea hilaris , has been achieved using Evan’s induction as the key step. Based on the asymmetric methylation product of chiral ( R )-4-benzyl-1,3-oxazolidin-2-one, the carbon chain of the target molecule was assembled through a C 5 +C 12 +C 11 +C 8 sequence. (2 R )-4-(Benzyloxy)-2-methylbutan-1-ol, which can be obtained from γ-lactone following Evan’s protocol, was connected to a C 12 alkyl group. The chiral methyl group remained the key moiety (97% ee ). After another Wittig reaction and catalytic hydrogenation step, the designed key intermediate (13 R )-13-methylheptacosan-1-ol was obtained. Finally, after oxidation and Wittig reaction, the synthesis of the target molecule was completed in 10 linear steps with an ultra-high overall yield of 36.2%.