烯虫酯的立体选择性全合成

Stereoselective Total Synthesis of Methoprene

以香茅醛为起始原料,通过羟醛缩合反应和Reformatskii反应得到3,7,11-三甲基-2,4,10-十二碳三烯酸异丙酯的双键顺反异构体混合物,经苯硫酚两次催化双键顺反异构化,(2E,4E)-异构体3a的含量由原来的26%提高到85%.再通过醚化反应,立体选择性地全合成了具有保幼激素活性的昆虫生长调节剂烯虫酯及其异构体,即11-甲氧基-3,7,11-三甲基-2,4-十二碳二烯酸异丙酯.其中具有较高生物活性的(2E,4E)-异构体的含量达85%.各步所合成的化合物的结构经IR,MS和NMR证实.

The cis- and trans-isomers of isopropyl 3,7,1 1-trimethy1-2,4,10-dodecatrienoate were prepared from citronellal by aldol condensation and Reformatskii reaction. After the isomeric mixture was subjected twice to the Z-E isometrization of the double bond using benzenethiol as a catalyst, the content of 2E,4E-isomer 3a was increased from 26% to 85%. The mixture of 3a and 3b was etherified to give methoprene and its isomers possess somewhat juvenile hormone activity. Among them the content of 2E,4E-stereoisomer with quite higher activity can reach 85%. The structures of all the compounds were confirmed by IR, NMR and MS spectra.