3-Oxo-4-aza-11aR-methoxy-5α-αndrost-1-ene-17β-carboxylic Acid Methyl Ester is an intermediate used in the synthesis of 5,6-Dehydro-17α-Dutasteride (D229570), which is 5,6-Dehydro-17α-Dutasteride (D229570), which is an epimer of 5,6-Dehydro-17β-dutasteride (D229560) an impurity in the synthesis of Dutasteride (D735000), a dual inhibitor of 5α-reductase isoenzymes type 1 and 2; structurally related to Finasteride (F342000). Dutasteride is used in the treatment of benign prostatic hyperplasia.