Synthesis of pyrrolo[1,3]diazepines by a dipolar cycloaddition-retro-Mannich domino reaction

Microwave irradiation facilitated the synthesis of 4-arylthio-3-oxazolin-5-ones from ethyl cyanoformate, thiophenol, and cyclic ketones. Subsequent decarboxylation and in situ [3+2] cycloaddition provided novel 2,3,4,5-tetrahydro-1H-pyrrolo[1,2-c][1,3]diazepine scaffolds after a spontaneous retro-Mannich domino reaction.