Dichloromethane as a Carbon Source for the Base Promoted Synthesis of Methylene-Bridged Bis-Enaminones and Bis-Pyrazoles

The reactions of NH-enaminones with dichloromethane (DCM) leading to the synthesis of methylene-bridged bis-enaminones have been realized under redox neutral conditions wherein the DCM acts as both the reaction medium and methylene donor. The substrates of bulk chemical DCM and easily accessible enaminones make the present method rather practical, thus enabling the efficient synthesis of methylene-bridged bis-pyrazoles via simple condensation of the methylene-bridged bis-enaminones with hydrazines under acid promotion.