Steroids and related products. 38. 11-Aza steroids. 3. The synthesis of 11-aza 9 -steroids. I

The synthesis of 3,20-dioxygenated 11-azapregnanes, with a “normal” (a) configuration.in position 9, is described. The saturation of the 8,9-double bond of previously described unsaturated precursors can be effected not only by reduction of 9,11-iminium salts, but also catalytically, under pressure, in the presence of perchloric acid, It is shown that the 7-position of 8,9-unsaturated 11-aza steroids can be functionalized with the chromic acid-pyridine complex, the double bond of the resulting 7-ketone being prone to Birch reduction. Other, direct, pathways from saturated 11-nor 9,12-seco steroids to saturated 11-aza 9α-steroids have been explored. The crucial difficulty inherent in this approach stems from the fact that in displacement reactions involving an axial 9α-substituent, elimination competes successfully with substitution.