An efficient synthesis of pyrido-imidazodiazepinediones

We herein report the synthesis of a series of 12 optically pure 3,4-dihydro-1H-pyrido-[1′,2′:1,2]-imidazo[4,5-d][1,3]diazepine-2,5-diones, which form a new family of azaheterocycle-fused [1,3]diazepines. The key step of the synthesis consists in a selective C-acylation of 2-amino-imidazo[1,2-a]pyridine by various natural amino-acids, followed by an intracarbonylation reaction.