L-Proline → (S)-6,7-difluoro-2,3,5,10,11,11a-hexahydro-1H-pyrrolo[2,1-c][1,4]benzodiazepine-5,11-dione

Participants

Reaction Steps

A solution of 28.8 g (144.6 mmol) of 5,6-difluoro-2,4-dihydro-1H-3,1-benzoxazine-2,4-dione and 16.7 g (144.6 mmol) of L-proline in 110 ml of dimethylformamide and 20 ml of acetic acid was stirred at 120° for 16 hours. The brown solution was evaporated and the brown residue obtained was crystallized from ethanol. There were obtained 30 g (82%) of (S)-6,7-difluoro-2,3,5,10,11,11a-hexahydro-1H-pyrrolo[2,1-c][1,4]benzodiazepine-5,11-dione as colourless crystals of m.p. >250°.

Provenance & Evidence