A novel one-pot highly diastereoselective synthesis of substituted 3-nitroazetidines via an anionic domino process is described. The synthesis involves a high yielding annulation of Baylis–Hillman alcohols and their aldehydes with either N-aryl/tosylphosphoramidates or N-aryl/tosylphosphoramidates in combination with a task-specific ionic liquid [bmim][X–Y] to afford the corresponding 1,2,3-tri- and 1,2,3,4-tetrasubstituted azetidines, respectively. Plausible mechanisms for the formation of various 3-nitroazetidines have been suggested.