13-Ethyl-11-methylidenegon-4-en-17-one; 13-Ethyl-11-methylene-gon-4-en-17-one; 13β-Ethyl-11-methylenegon-4-en-17-one;13-Ethyl-11-methylenegon-4-en-17-one; Compound related to desogestrel D (USP);