An Unusual Occurrence in the Reaction of 4-Azasteroid Derivatives with N-Fluorodibenzenesulfonimide and Lithium Diisopropylamide

The reaction of N,N-diethyl-3-oxo-4-methyl-4-aza-5-androstane-17β-carboxamide (1) with N-fluorodibenzenesulfonimide (NFA) and lithium diisopropylamide (LDA) was studied.Under absolute anhydrous and anaerobic conditions, the formation of 5 (2α-fluoro-4-methyl-3-oxo-4-aza-5α-androstane- 17β-carboxylic acid methyl ester) can be rationalized by participating in the expected nucleophilic substitution reaction. Not in absolute anhydrous and anaerobic conditions, the formation of 10 (N-di-isopropyl-N'-aryl- sulfonamides (C12H20N2O2S) and 11 (N-diethyl-3-oxo-4-methyl-4-aza-5-androstene-17β-carboxamide) can be rationalized by assuming that the situ generated carbanion 2 followed by a single electron transfer mechanism. 5, 10 and 11 were characterized.10 was a new compound and determined by X-ray single-crystal diffraction. Crystal data for 10:space group C2/c with a = 14.783(2), b = 7.6193(11), c = 24.663(3) (A),β = 98.688(3)°, V= 2746.1(7)nm3, Mr = 256.36, Z= 8, Dc = 1.240 g/cm3, μ = 0.229 mm-1, F(000) = 1104, R = 0.0511 and wR =0.1268. There exist intramolecular H-bonds which result in a supramolecular framework of the title compound. The formation mechanisms of 10 and 11 were also discussed briefly.