油菜甾醇内酯中A/B环合成法

The Synthesis of A/B Rings in Brassinolide Analogue

合成了油菜甾醇内酯A/B环类似物2α,3α-二羟基-6-胆甾醇(7)。以胆甾醇为起始物,经硝化和还原水解等步骤,得3-羟基-6-羰基胆甾烷(4),按常规法苯磺酰化,消?苯磺酸得6-羰基-2-胆甾烯(6),用OsO_4氧化后得目的物(7)。总产率43.6％。该方法具有总产率高,步骤少和后处理简便等优点。

This paper presents the synthesis of A/B rings of Brassinolide analogue. Taking cholesterol as starting material, nitration and reduction-hydrolysis as key steps, 3-hydroxy-6-cholesterone (4) was obtained in good yield. (4) was then sulphonylated and desulphonated by the usual ways to 2-steroidal alkene (6) which was oxidized by OsO4 giving the target product 2α, 3α-dihyd-roxy-6-cholesterone (7) with a total yield of 43.6%. Compared to the previous metnods, the present synthesis has several advantages such as higher total yield, fewer reaction steps, aad pure products more easily obtained