Solvolysis of 14,17-etheno-bridged 16α-nitroestratrienyl acetate and lactam formation pathways studied by LC-NMR and LC-MS. Structures of minor products.

The ethanol solvolysis of 3-methoxy-14,17-etheno-16α-nitroestra-1,3,5(10)-trien-17ß-yl acetate in the presence of NaHCO3 was studied by means of real-time NMR experiments, LC-SPE-NMR, and LC-MS. The pathway to form 3-methoxy-2'-oxopyrrolidino-[4',5':14ß,15ß]-estra-1,3,5(10)-trien-17-one was disclosed. The intermediacy of nitrile oxide and alkoxynitrone was postulated based on the analysis of the reaction products. The proposed mechanism of cleaving the bridge in the nitro compound is legal for the formation of N-acetoxylactams, nitriles, isoxazoles and isoxazolines.