3-Ethyl-11-methylidene-18,19-dinor-5α,17α-pregn-3-en-20-yn-17-ol (as per EP); 13-Ethyl-11-methylene-18,19-dinor-5α,17α-pregn-3-en-20-yn-17-ol (as per USP); Related compound A to desogestrel USP; Desogestrel Δ3-Isomer