Organocatalytic Multicomponent Reactions Using 1,1-Diaminobenzalazine: Synthesis of Pyrano[2,3-c]pyrazoles and Pyranochromenes.

An efficient organocatalytic multicomponent reaction (OMCR) for the synthesis of pyrano[2,3-c]pyrazole and pyranochromene derivatives utilizing 1,1-diaminobenzalazine as an organocatalyst has been reported. The uniqueness of this protocol lies in its broad functional-group tolerance, showcasing the use of activated ketones bearing a trifluoromethyl group and prefunctionalized sulfonamide-based pyrazolones as key substrates. The catalyst could be recycled up to 5 cycles with only a minimal loss of yield. Mechanistic insights provided by DFT studies confirmed the importance and bifunctional character of the organocatalyst. Green chemistry metrics benchmark this process as a step forward in the development of environmentally friendly and scalable methodologies, contributing to the broader goal of sustainable pharmaceutical synthesis.