The reaction of pregnenolone (I) with I2 and pyridine at 90 C gives (3beta-hydroxypregn-5-en-20-one-21-yl)pyridinium iodide (II), which by treatment with sodium methoxide in refluxing methanol is converted into methyl 5-androsten-3beta-ol-17beta-carboxylate (III). The Meerwein-Poundorf oxidation of (III) with cyclohexanone (A) and aluminum isopropoxide in refluxing toluene yields methyl 4-androsten-3-one-17beta-carboxylate (IV), which is hydrolyzed with KOH in refluxing methanol - water to the corresponding free acid (3-oxo-4-etienic acid) (V). The reaction of (V) with oxalyl chloride (B) and diethylamine in refluxing toluene affords 17beta-(N,N-diethylcarbamoyl)-4-androstene-3-one (VI), which is oxidized with O3 or with NaIO4 and KMnO4 giving 17beta-(N,N-diethylcarbamoyl)-5-oxo-3,5-secoandrostan-3-oic acid (VII). The cyclization of (VII) with methylamine ethylene glycol at 180 C in a pressure vessel affords 17beta-(N,N-diethylcarbamoyl)-4-methyl-4-aza-5-androsten-3-one (VIII), which is finally reduced with H2 over Pt in acetic acid. The cyclization of the acid (VII) with NH3 in ethanol at 180 C in a pressure vessel gives 17beta-(N,N-diethylcarbamoyl)-4-aza-5-androsten-3-one (IX), which is reduced with H2 over Pt in acetic acid yielding 17beta-(N,N-diethylcarbamoyl)-4-aza-5alpha-androstan-3-one (X). Finally, this compound is methylated with CH3I by means of NaH in toluene.
The oxidation of 3-oxo-4-etienic acid (V) with NaIO4 and KMnO4 in tert-butanol - water gives 5-oxo-3,5-secoandrostane-3,17beta-dioic acid (XI), which is cyclized with methylamine in ethanol at 180 C in a pressure vessel yielding 17beta-carboxy-4-methyl-4-aza-5-androsten-3-one (XII). The hydrogenation of (XII) with H2 over Pt in acetic acid affords 17beta-carboxy-4-methyl-4-azaandrostan-3-one (XIII), which is finally treated with oxalyl chloride (B) and diethylamine in toluene-THF. The amidation of (XIII) with oxalyl chloride (B) and NH3 in toluene-THF gives 17beta-carboxamide-4-methyl-4-azaandrostanone (XIV), which is alkylated with ethyl bromide and NaH in toluene. The amidation of (XIII) with ethylamine and oxalyl chloride (B) in toluene-THF gives 17beta-(N-ethylcarbamoyl)-4-methyl-4-azaandrostan-3-one (XV), which is finally alkylated with ethyl bromide and NaH in toluene.