Utilization of caffeine carbon supported cobalt catalyst in the tandem synthesis of pyrroles from nitroarenes and alkenyl diols

Abstract Employing bio-waste caffeine carbon-supported heterogeneous cobalt catalyst, synthesis of various substituted pyrrole derivatives is reported. In this methodology, pyrroles were synthesized through coupling between nitroarenes and alkenyl diols in a tandem manner. Among all the heterogeneous catalysts Co(OAc)2-CC-800 displayed the highest catalytic activity. Preparative scale synthesis of pyrroles and synthesis of anti-tubercular agent 5-(4-(1H-pyrrol-1-yl)phenyl)-1,3,4-oxadiazole-2-thiol revealed the practical applicability of this protocol. Several kinetic experiments and Hammett studies were conducted to understand the probable mechanism and electronic effects on this transformation.