Steroids and related products. XLII. (1) The synthesis of 11-oxa steroids. IV. (2) The synthesis of 17,21-dihydroxy-11-oxa-4-pregnene-3,20-dione, an 11-oxa analogue of the 17-hydroxylated glucocorticoids

The synthesis, from 11-oxa-5α-pregnane-3,20-dione, available from hecogenin, of 17,21-dihydroxy-11-oxa-4-pregnene-3,20-dione, the first 11-oxa analogue of corticoid hormones, is described. The acetate of its 1-dehydro derivative, 17-hydroxy-21-acetoxy-1,4-pregnadiene-3,20-dione, analogous in structure to the acetates of prednisone and prednisolone, is an intermediate in the synthesis.