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

The Euproctis pseudoconspersa Stand, it stands for lepidoptera moth as well as a moth genera of one specie of insect, it is a kind of important pests of Chinese tea tree. It is widely distributed in all parts of China’s tea area. They not only harm the tea, but also harm camellia,citrus and so on. Tranditionally, it is the current main methods to prevent control of the pests by spreading highly-toxic pesticide. Japanese scholar Sadao Wakamura firstly discovered the main component of the pheromone of Euproctis pseudoconspersa as 10,14-dimethyl 15 carbon butyl. Ichikawa A ascertained the R isomer is the most active one in 1995. But now there are few reports of sex pheromone for Euproctis pseudoconspersa and it has confined the further application of this green pestcide.Steroidal compounds are a kind of very important natural organic compounds existing in organism. In our country every year, thousands of tons of steroidal saponins were waste, but they can be procides as raw materials for us.Thanks to our group long-standing research of the pheromone synthetic experience, we envisaged a synthesis based on the chiral molecular from steroid plants. After elaborate retrosynthetic analysis, this molecular can be dissembled into three subunits namely, fragment A, B and C. Through Grignard coupling, the skeleton of 10,14-dimethylpentadecyl isobutyrate can be formed by these three fragments.The main chain of(R)-10,14-dimethyl 15 carbon butyl can be built through "C4 + C4 +C7" strategy. The chiral starting material was extracted from abandoned residue in our experiment. Through separation and purification of steroid, benzyl protection, esterification reaction, reduction reaction, oxidation reaction to give the key chiral intermediates(R)-3-methyl-4-benzyl-butyl aldehyde, it was subjected to sodium borohydride reduction to afford(R)-3-methyl-4-benzyl-pentane-1-alcohol, the section A. We successfully coupled two pieces by Julia olefination. It’s a great pity, the we haven’t completed the total synthesis of this molecularUp to now, we have finished the synthesis of 20 compounds. The key intermediate was obtained in 1.6% overall yield. All this lay a ground the achievement of this insect pheromone.