19-Nor and Aromatic Steroids. III. The Conversion of 3β-Acetoxy-5α-lanost-8-en-7-one into Steroids with A and B Rings Aromatic

Abstract

Benzylic oxidation of 3,β,7-diacetoxy-19-norlanosta-5(10),6,8-trine (6b) resulted in a mixture of the 11-one (7) and the 1,11-dione (8a) whilst similar oxidation of 3β-acetoxy-7-methoxy-19-norlanosta-5(10),6,8-triene (6c) gave a mixture of the 1-one (9) and the 1,11-dione (8b). The 3β-acetoxy 1-ones (8a), (8b) and (9) readily eliminated acetic acid to give the 2-en-1-ones (11a), (11b) and (10) respectively. Attempts to aromatize the A ring in the three ketones (11a), (11b) and (10) with loss of one of the methyl groups at C4, failed since zinc in either acetic acid or aqueous dimethylformamide gave the reduced ketones (13a), (13c) and (13b). Under acidic conditions the same ketones (11a), (11b) and (10) underwent the dienone-phenol rearrangement to give the 1-acetates (17a), (17c) and (17b). The 2-en-1-one (10) when reduced with lithium aluminium hydride gave the 1-ols (15) and 3,4,14α- trimethyl-19-norcholesta-1,3,5(10),6,8-pentaene (16), probably arising by dehydration of the dienols (14). Reduction of 4,4-dimethylnaphthalen-1(4H)-one (23) with zinc in acetic acid gave 4,4,dimethyl-3,4-dihydronaphthalen-1(2H)-one (21) and 1,2-dimethylnaphthalene (25) and none of the phenol (26).