Alternatively, a solution of 17β-carboxy-6-t-butylcarboxy-6-azaandrost-4-en-3-one (260 mg, 0.62 mmol), example 3, Part F, is dissolved in toluene (10 mL) and treated with pyridine (3 eq) and catalytic dimethylformamide, cooled to 0° C., and thionyl chloride added (80 μL, 1.10 mmol). The reaction is then allowed to warm to room temperature and is stirred for 1 hr. The solids are then removed by filtration, the solution concentrated, the resulting crude acid chloride dissolved in THF (6 mL), CuL added (120 mg, 0.62 mmol), cooled to -78° C. and treated with isobutylmagnesium bromide (2.0M in diethyl ether, 0.5 mL, 1 mmol). The reaction is allowed to warm to room temperature, stirred for 30 min and is worked up as in Part C above to give 17β-(1-oxo-3-methylbutyl)-6-azaandrost-4-en-3-one.
