NNTETRAMETHYLENEUREA

1,3-Tetramethyleneurea

Hexahydro-1H-1,3-diazepin-2-one

Hexahydro-2H-1,3-diazepine-2-one

4,5,6,7-Tetrahydro-1H-1,3-diazepine-2(3H)-one