Deoxygenation of steroidal ring-D 16,17-ketols with trimethylsilyl iodide

Reaction of various steroidal 16,17-ketols, 16 alpha-hydroxy-17-ketones 1-3 , and 15, 16 beta-hydroxy-17-ketone 4, and 17 beta-hydroxy-16-ketones 5-7, and 17, along with methyl ethers of 16 alpha- and 17 beta-ketols 1 and 5, w ith an excess of trimethylsilyl iodide (TMSI) or with HI in CHCI3, produced the deoxygenated products, a mixture of the corresponding 17- and 16-keton es, In low to quantitative yields, in which the 17-ketone was the major pro duct in each case. When the 16 beta-deuterated 16 alpha-ketol 3 and the 17 alpha-deuterated 17 beta-ketol 7 were reacted with TMSI for a brief period (15 min), the deuterium content at C-16 beta and C-17 alpha of the recovere d steroids 3 and 7 was reduced by 17 and 35%, respectively. The present res ults indicate that the deoxygenation proceeds not only through a direct iod ination pathway producing alpha-iodoketone but also through other reaction pathways.