| Popis: |
Expoxidation of cholesta-5,8-dien-3b-yl acetate (1) with peracids takes place preferentially at the more highly substituted D8-olefinic double bond to give: (a) with monoperphthalic acid, 8a,9a-epoxycholest-5-en-3b-yl acetate (2) (in 39 % yield) and 9a-hydroxy-5a,6a-epoxycholest-8(14)-en-3b-yl acetate (3) (in 30 % yield); and (b) with m-chloroperbenzoic acid, the 8a,9a-epoxide 2 (64 %) and 5a,6a-epoxy derivative 3 (20 %). Some chemical transformations of the obtained epoxides are described. |
