A general six-step approach to 6-tosyl-2, 3, 4, 5-tetrahydro-1H-1, 3-diazepin-2-ones has been developed. The key step involves a ring expansion reaction of 4-mesyloxymethyl-or 4- tosyloxymethyl-5-tosyl-1, 2, 3, 4-tetrahydropyrimidin-2-one mediated by nucleophilic reagents.