One-pot synthesis of pyrimido[1,2-a]benzimidazoles using calcium carbide as an acetylene source

Abstract

Herein, we report a highly pot-, atom-, and step-economical (PASE) strategy for the synthesis of pyrimido[1,2-a]benzimidazoles using commercially available calcium carbide, 2-aminobenzimidazoles, and aldehydes as starting reagents. Calcium carbide serves as a safe and easy-to-handle acetylene source, thereby avoiding the use of gaseous acetylene, which is poorly compatible, highly flammable and explosive, and difficult to store and transport. The protocol is operationally simple and readily scalable, demonstrating strong potential for commercial bulk synthesis. In addition, the resulting products exhibit intense yellow photoluminescence, making them promising candidates for organic light-emitting materials.