16-Methylene-17-keto-steroids are transformed to the corresponding 16-methylene-17a-hydroxyprogesterones which are intermediates useful in the production of betamethasone, diflorasone diacetate and melengesterol acetate. 17a-Hydroxy-6, 16-dimethylene-pregn-4-ene-3, 20-dione is simultaneously isomerized and acylated to 17a-hydroxy-6-methyl-16-methylenepregna-4, 6-diene-3, 20-dione 17-acetate.