An efficient approach to azolyl-substituted steroids through copper-catalyzed Ullmann C-N coupling

Ullmann-type C–N coupling of vinyliodides and nitrogen heterocycles has been shown to be a straightforward and highly efficient approach to azolyl-substituted steroids. The amination reaction proved sensitive to steric effects exerted by the substituents in both iodide and heterocycle. The influence of reaction conditions (catalyst, base, solvent, and temperature) on conversion of the iodosteroid and the selectivity was investigated. The catalytic system comprising 10 mol-% CuI and 20 mol-% dipivaloylmethane with K2CO3 in dimethyl sulfoxide at 100 °C delivered the best result. The elaborated protocol has permitted iodosteroids with various substituted indoles, imidazoles, carbazole, indazole, and sec-amides to be coupled, affording the corresponding azolyl-substituted steroids in good to excellent yields.