Exploration Work Toward The Total Synthesis Of The Sex Pheromone Of Euproctis Pseudoconspersa Strand

Applying sex pheromones to control target pests is one of the ideal measures to Intergrated Pests Management-IPM, Furthermore, it has great significance for the harmlessly controlling pests. Euproctis pseudoconspersa Strand is a kind of insect which causes most damages to tea production in our nation. Up to now, this pest control mainly relies on chemical pesticides that are currently subject to strong restrictions and regulatory requirements. Thus, it has brought the pests improved resistance ability to insecticides and the excessive levels of pesticide residue in products of teas. Thanks to the hard work of Wakamura et al and Zhao et al, the active chemical compound of this pheromone is characterized to be 10, 14-dimethylpentadecyl isobutyrate. It is also reported that its R, S enantiomers and their racemic mixture are bioactive. However, papers on its synthesis are rarely reported.1. With elaborate retrosynthetic analysis, this molecular can be dissembled into three synthons, namely, fragment A, B and C. Through Grignard coupling, the skeleton of 10,14-dimethylpentadecyl isobutyrate can be formed by these three fragments. So, The key step is how to synthesize fragment A, which processes a chiral side chain of methyl.2. In this thesis, the cheap, commercially available γ-butyrolactone was adopted as starting material. It was subjected to the treatment of KOH and BnCl, then, through the construction of Evans chiral auxiliary, asymmetric methylation, reduction, sulfonylation, and bromization, three key intermediates, i.e.,(S)-4-benzyloxy-2-methylbutanol,(S)-4-(benzyloxy)-2-methylbutyl 4-methylbenzenesulfonate and(S)-((4-bromo-3-methylbutoxy)methyl)benzene were prepared. The most difficult part is the connection of Evans auxiliary group. For this purpose, we have tried three methods which are acyl chloride activation, DCC/HOSu condensation and mixed anhydride activation. At last, under the condition of ethyl chlorocarbonate, a mixed anhydride was prepared firstly, and then treated with lithium(R)-5-benzyl-2-oxooxazolidin-3-ide, the desired intermediate was synthesized.3. The synthesis of fragment B is relatively easier. The single bromization of 1,8-octandiol was achieved at the presence of 40% HBr(aq) at a Dean-Stark trap. After the rest hydroxyl group was protected with –OTBS, fragment B was synthesized with high yield.The Grignard Coupling reaction trial of fragment A and B was undertaken several times, but ended up with failure. Due to time constraints, we have just tried a new method, TosMIC as a coupling alkylated agent and all of the synthesis is in progress.