Tschitschibabin pyridine synthesis

Galatasis, P. Chichibabin (Tschitschibabin) Pyridine Synthesis In Name Reactions in Heterocyclic Chemistry, Li, J. J. Corey, E. J., Eds. Wiley Sons Hoboken, NJ, 2005, 308-309. (Review). 

Guareschi-Thorpe pyridine synthesis Chichibabin (Tschitschibabin) pyridine synthesis Bohlmann-Rahtz pyridine synthesis Krohnke pyridine synthesis... 

In the case of pyridine, Tschitschibabin s synthesis proceeds with special ease. An intermediate addition product of NH2Na to the —N=C double bond with the grouping —NNa—C(NH2)— is doubtless formed. The net result is as follows ... 

The base-induced cyclization of Ar-(oxoethyl(pyridinium salts of 2-picolines, known as the Tschitschibabin indolizine synthesis, is a classical method of preparation of indolizines from pyridines. The ready isolation of the products by decanting or filtration has allowed for the recent development of a parallel synthesis of a wide range of 2-substituted indolizines <2003SL2086>. 

This synthesis, originally devised by Tschitschibabin,8 is still the most widely used because it can easily be modified to yield substituted indolizines. The synthesis involves the quaternization of a 2-substituted pyridine, normally using an a-halo carbonyl compound, followed by intramolecular cyclization of the quaternary salt with a mild base, usually aqueous sodium bicarbonate (Scheme 1). 

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