Reaction between Nitrogen–Containing Heterocycles and Dialkyl Acetylenedicarboxylate with Strong Ch-Acid: Synthesis of Stable Highly Functionalised 1,4-Diionic Nitrogen Betaines
Free accessResearch articleFirst published online February, 2004
Reaction between Nitrogen–Containing Heterocycles and Dialkyl Acetylenedicarboxylate with Strong Ch-Acid: Synthesis of Stable Highly Functionalised 1,4-Diionic Nitrogen Betaines
Protonation of highly reactive 1,4-zwitterionic intermediate generated in the reaction between pyridine or isoquinoline and dialkyl acetylenedicarboxylates by strong CH-acid such as 1,1,1,5,5,5-hexafluoropentane-2,4-dione, leads to a vinyl pyridinium cation derivatives, which undergo carbon centred Michael type addition with the conjugate base of the CH-acid to produce highly functionalised stable 1,4-diionic nitrogen betaines.
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