Three compounent reaction of isoquinoline with strong cyclic CH-acids in presence of dimethylacetylene dicarboxylate

Protonation of highly reactive 1, 4-zwitterionic intermediate produced in the reaction between Isoquinoline or 2, 4- dimethyl pyridine and dimethylacetylene dicarboxylate by strong cyclic CH-acids such as N,Nʹ-dimethylbarbitoric acid, meldrum,s acid or 1,3-indanedione leads to a vinyl cation which undergoes an addition reaction with the enolate anion of the CH-acid to produce stable 1, 4-diionic betaines in good yields.