STUDIES ON THE MECHANISMS OF CYCLIZATION OF RING A OF STEROIDS DURING THE REFORMATSKY REACTION

The Reformatsky reaction of 3,5-seco-5-ketocholestan-3-oic acid methyl ester with methyl bromoacetate yielded 2-carbohydroxycholestenone, cholestenone, and 4-carbomethoxycholestenone. The appearance of these products indicated that cyclization of ring A proceeded along two different paths; this conclusion was confirmed by the use of methyl bromoacetate-1-C14 and -2-C14.