Thermolysis and photolysis of two steroidal hydroxamic acid methanesulfonates

Article abstract of DOI:10.1139/v97-104

Thermolysis or photolysis of N-methanesulfonyloxy-4-aza-5α-cholestan- 3-one gave derivatives of 4-azacholestan-3-one, 4-aza-A-nor-B-homocholestan- 3-one, 3-aza-A-norcholestane, bis (4-aza-3-oxocholest-5-en-6-yl) methane, and bis(3-aza-A-norcholestan-3-yl) urea. The corresponding 5β-methanesulfonate gave the 5β (coprostane) analogues. Evidence for the mechanism of formation of these products, including a Favorski-like ring contraction and amide oxidation by methanesulfonic acid, is presented. Detailed ¹H and ¹³C assignments are made for many of the products, and ultraviolet absorption for seven steroidal enamides is tabled. Long-range homo- and heteronuclear NMR connectivities were used to confirm the structure of three dimeric compounds and to assign the configuration of the methoxy function of 4-aza-5-methoxy- A-nor-β-homocholestan-3-one to be 5α. Thermolysis or photolysis of N-methanesulfonyloxy-4-aza-5α-cholestan-3-one gave derivatives of 4-azacholestan-3-one, 4-aza-A-nor-B-homocholestan-3-one, 3-aza-A-norcholestane, bis (4-aza-3-oxocholest-5-en-6-yl) methane, and bis(3-aza-A-norcholestan-3-yl) urea. The corresponding 5β-methanesulfonate gave the 5β (coprostane) analogues. Evidence for the mechanism of formation of these products, including a Favorski-like ring contraction and amide oxidation by methanesulfonic acid, is presented. Detailed ¹H and ¹³C assignments are made for many of the products, and ultraviolet absorption for seven steroidal enamides is tabled. Long-range homo- and heteronuclear NMR connectivities were used to confirm the structure of three dimeric compounds and to assign the configuration of the methoxy function of 4-aza-5-methoxy-A-nor-β-homocholestan-3-one to be 5α.