The photochemical cyclisation of 11-keto steroids to 11β, 19-cyclo-11-hydroxy compounds is strongly influenced by steric factors. The presence of a gem-dimethyl group at C-4 gives rise to a marked improvement in the yield of the cyclic product. The nature of this steric interaction is briefly discussed.
11-
酮类固醇向11β,19-cyclo-11-hydroxy化合物的光
化学环化作用受空间因素的强烈影响。在C-4处的宝石-二甲基基团的存在显着提高了环状产物的产率。简要讨论了这种空间相互作用的性质。