A green four-component synthesis of zwitterionic alkyl/benzyl pyrazolyl barbiturates and their photophysical studies.

A novel series of unsymmetrically substituted alkyl/benzyl pyrazolyl barbiturates incorporating highly biologically active pyrazolone and barbiturate moieties was synthesized by four-component reactions of a mixture of ethyl acetoacetate, hydrazine hydrate, aldehydes and barbituric acid/thiobarbituric acid in ethanol without using a catalyst. The photophysical properties of the newly designed alkyl/benzyl pyrazolyl barbiturates were studied, and good quantum yield of some products indicated a definitive scope in the field of biochemical applications. Single-crystal X-ray crystallographic studies revealed that the newly synthesized compounds exist in zwitterionic form. The zwitterionic nature of the new chimera makes them interesting candidates for drug delivery as zwitterionic drugs are known to have highly water soluble properties, specific protein absorption, slow recognition by immune system, slow blood clearance from body and can constantly diffuse and deposit throughout the physiological pH.