Inter- and intra-molecular N-alkylation of α-halocarboxamides and dihalocarboxamides in the presence of solid phase transfer catalyst led to the corresponding piperazine-2,5-diones (2) and lactams (4) in the yields of 64–88 and 63–99%, respectively. A one-pot synthesis of β-lactams (7) from α-methyl-α,β-dibromopropionyl chloride (5) and α-amino acid using phase transfer catalyst was also successfully achieved.
Substituted and unsubstituted 2,5-diketopiperazines can be prepared by a process which comprises bringing together a substituted or unsubstituted glycinamide and a haloacetyl halide, optionally in the presence of a non-nucleophilic base, and thereafter adding a stronger base.