Transient zwitterions generated from dimethyl allenedi-carboxylate and isoquinoline were successfully intercepted with 2oxo-IH-indol-3-ylidenes to result in a facile multicomponent reaction under mild conditions.
R. Rejithamol, Beneesh Pattoorpad Babu, and Vijay Nair, “A facile Multicomponent Reaction Involving Isoquinoline, Dimethylallene Dicarboxylate and 2-oxo-1H-Indole-3-Ylidenes”, Synthesis, 2011.