Highly efficient synthesis of steroid-17-spiro-5’-oxazolidine-2’,4’-diones from 17-keto steroids

Spiro{androst-4-en-17alpha,5' -oxazolidinej-2' ,3,4'-trione 8a and spiro{androst-4-en-17alpha,5' -oxazolidinej2' ,3,4' ,ll-tetraone 8b, two potentially bioactive spiranes, were prepared from the parent 17-ketones in four steps (64% and 49.5% yield, respectively). The key intermediates were the hydroxyimidates Sa and Sb, which easily underwent cyclization to the corresponding spirooxazolinone 4' -enol ethers when treated with alkylchlorocarbonates. The respective N-amyl derivatives ofthe spiranes Sa and 8b were obtained with n-pentyl bromide in the presence of KF. A new method for the synthesis of steroid 17ahydroxy- 17-carboxyesters and 17alpha-hydroxy-I7-carboxamides is described. Attempts to synthesize the title compounds from these products were unsuccessful.