Improved synthetic routes to (±)-pentalenene (1) and (±)-9-epipentalenene (6) were developed. Intramolecular alkylation of a tricyclic halo ester (7), obtained from 3, by treatment with lithium hexamethyldisilazide in tetrahydrofuran gave 14 and 15 in a ratio of 74 : 26. Compound 14 was successfully converted into the key intermediate (16) for (±)-1. On the other hand, catalytic hydrogenation of 8 afforded 20, a key intermediate for (±)-6, along with 16 (20 : 16=86 : 14).
开发了改进的合成路线,以制备(±)-五桠烯(1)和(±)-9-epi五桠烯(6)。通过用六甲基二
硅氮化锂在
四氢呋喃中的处理,从3得到的
三环卤代酯(7)进行了分子内烷基化,得到了化合物14和15,比例为74:26。化合物14成功转换为(±)-1的关键中间体(16)。另一方面,8的催化氢化反应得到20,这是(±)-6的关键中间体,同时还得到16(20:16=86:14)。