Diels–Alder reactions of pyridinone o-quinodimethanes generated from substituted sulfolene[3,4-c]pyridin-4(1H)-ones

1-Benzyl-3-(bromomethyl)-2(1H)-pyrazinone was converted to [3,4-c] sulfolene pyridinone and further (1- or 3-) substituted derivatives having a dienophilic side chain on the sulfolene ring. Thermolytic extrusion of sulfur dioxide from o-QDM precursor led to generation of 3,4-dimethylene-2(1H)-pyrazinone , which was reacted in situ with various dienophiles. Thermolysis of the substituted precursors resulted in intramolecular cycloaddition of the corresponding o-QDM intermediates