Oximation of 2-azido-4,4-dimethyl-3-oxo steroids: formation of α-keto oximes and dioximes

Treatment of 2-azido-4,4-dimethyl-3-oxo steroids (1a, b) with an excess of hydroxylamine hydrochloride in the presence of sodium acetate give the corresponding 2α-azido-3-hydroxyimino (2a, b) and 2,3-bishydroxyimino derivatives (3a, b). In the case of the Δ5-analogue (1c), the 2-hydroxyimino-3-oxo compound (4c) is formed in addition to the 2-azido-3-hydroxyimino (2c) and 2,3-bishydroxyimino (3c) derivatives. The bishydroxyimino compounds (3) were converted into the oxadiazole (furazan) derivatives (6).