Preparation of 16-formylestradiol and the 16-(α-methylenebutanolide) derivative

Article abstract of DOI:10.1016/0039-128X(93)90025-I

Route tot he preparation of 16-formylestradiol are described. Estronen was converted to (E)-16-methoxy-methylene estrone via the 16-hydroxymethylene estrone. Reduction of themethoxymethylene estrone with NaBH4 in the presence of CeCl₃ gave 16-methoxymethylene estradiol. Deprotection by acid afforded the desired 16-formylestradiol. Attempts to prepare the 16-formylestradiol via the 16-butythio-methylene derivative gave only 16-formylestra-1,3,5(10),16-tetraen-3-ol, and a route through the 16-dimethoxymethyl derivative gave a mixture of the 16-formyltetraen-3-ol and the 16-formlestradiol in low yield. The 16-formylestradiol was subsequently converted tot he α-methylene lactone conjugate, 4-(3,17β-dihydroxyestra-1,3,5(10)trien-16-yl)-2-methylene-4-butanolide by reaction with methyl α-(bromomethyl) acrylate and zinc. (Steroids 58: 234-238, 1993).