Treatment of 2-(2-formyl-1H-pyrrol-1-yl)-3-thiophenecarbonitrile by sodium percarbonate afforded, in a one-pot sequence and on a multigram scale, 5,6-dihydro-6-hydroxy-4H-pyrrolo[1,2-a]thieno-[3,2-f][1,4]diazepin-4-one whose reactivity towards various nucleophiles like amines, hydrazines and thiols was evaluated.