Derivatives of α,β-dehydro amino acids: II. New synthesis of 2,4-disubstituted 1-aminoimidazol-5-ones from N-substituted α,β-unsaturated α-amino acid hydrazides

10.1007/s11178-008-3029-9

“…

SHORT COMMUNICATIONS

The synthesis of 4-arylmethylidene-1-(arylmethylideneamino)imidazol-5-ones via cyclization of N-benzoyl α,β-dehydro amino acid arylmethylidenehydrazides by the action of acid reagents was reported in [1,2]. We recently showed that primary amides [3], arylamides [4], and hydrazides derived from N-substituted α,β-dehydro amino acids [5] in the presence of silylating agents (chlorotrimethylsilane, hexamethyldisilazane) undergo dehydration to give 2,4-di-or 1,2,4trisubstituted imidazol-5-ones.In the present communication we describe the synthesis of 2-aryl-4-arylmethylidene-1-arylmethylideneamino-4,5-dihydro-1H-imidazol-5-ones II by cyclization of N-substituted α,β-unsaturated amino acid arylmethylenehydrazides I in the presence of hexamethyldisilazane (HMDS). The reactions were carried out by heating the reactants in boiling DMF for 15-30 min.

…”