A new route for the preparation of the 22,23-dioxocholestane side chain from diosgenin and its application to the stereocontrolled construction of the 22R,23S-diol function
作者:Susana Rincón、Rosa E. del Río、Jesús Sandoval-Ramírez、Socorro Meza-Reyes、Sara Montiel-Smith、Ma. Antonieta Fernández、Norberto Farfán、Rosa Santillan
DOI:10.1016/j.tet.2005.12.036
日期:2006.3
The new (22R,23S,25R)-3β,16β,26-triacetoxy-cholest-5-ene-22,23-diol (11a) was synthesized from diosgenin (3) through a synthetic route based on chemoselective RuO4 oxidation of (25R)-3β,16β-diacetoxy-23-ethyl-231,26-epoxycholesta-5,23(231)-dien-22-one (9) that afforded (20S,25R)-3β,16β,26-triacetoxycholest-5-ene-22,23-dione (10) which was stereoselectively reduced using NaBH4. Compound 9 was obtained
由薯os皂苷元(3)通过基于化学选择性RuO的合成路线合成了新的(22 R,23 S,25 R)-3β,16β,26-三乙酰氧基-胆甾-5-烯-22,23-二醇(11a)4氧化(25 - [R)-3β,16β二乙酰氧基23乙基23 1,26 epoxycholesta-5,23(23 1) -二烯-22-酮(9即得到)(20小号,25 - [R )-3β,16β,26-triacetoxycholest-5-ene-22,23-dione(10)使用NaBH 4进行了立体选择性还原。化合物9通过在甲苯,amberlyst-15中用对-TsOH处理,或直接从薯os皂素中用BF 3 ·OEt 2 / Ac 2 O处理,从已知的异构体22,26-epoxycholest-5-ene类固醇骨架8b中获得。在-70℃下使用NaBH 4 / ZnCl 2,得到23酮基的10个基团,得到23 S- 14