Direct Solvent-Free Regioselective Construction of Pyrrolo[1,2-a][1,10]phenanthrolines Based on Isocyanide-Based Multicomponent Reactions

A novel efficient one-pot four-component regioselective synthesis of pyrrolo[1,2-a][1,10]phenanthrolines in excellent yields has been developed by 1,3-dipolar cycloaddition of aldehydes, malononitrile, and isocyanides with 1,10-phenanthroline under solvent-free conditions within 3 min without using any catalyst or activation. The products were preliminarily investigated as chromogenic and fluorescent sensors for Cu2+ ions.