TY - JOUR
AU - Tadevosyan, D.
AB - Chemistry of Heterocyclic Compounds, Vol. 42, No. 3, 2006 RECYCLIZATION OF INTERMEDIATES IN AN ENAMINE REARRANGEMENT OF A PYRIMIDINIUM SALT WHEN TREATED WITH ISONIAZIDE G. G. Danagulyan and D. A. Tadevosyan Keywords: 2-hydrazinopyridine, isoniazide, pyrimidinium iodide, rearrangement intermediates, Kost–Sagitullin rearrangement. In a paper devoted to study of the reaction of 2-(ethoxycarbonylmethyl)-1,4,6-trimethylpyrimidinium iodide (1) with carboxylic acid hydrazides, we reported on synthesis of derivatives of 1,2,4-triazolo[4,3-a]pyridine [1]. In particular, in that paper we discussed the hypothesis that when salt 1 was treated with isonicotinic acid hydrazide (2) (isoniazide), cyclization to form triazolopyridine 4 occurs through a step involving formation of the intermediate 2-hydrazidopyridine 3 (the product of a Kost–Sagitullin rearrangement). However, as shown by later X-ray diffraction studies, during the reaction we do not obtain triazolo[4,3-a]pyridines 4 but rather their isomers: derivatives of pyrazolo[1,5-a]pyrimidine 5 [2] (Scheme 1). In studying the reaction of the intermediates for recyclization 6 and 7 with isoniazide 2, we obtained a compound with a structure matching that of the initially proposed structure for the intermediate product of "rearrangement with transamination" (compound 3). Probably during the reaction, the pseudobase 6, by eliminating a water molecule, is converted to the anhydro base 7, which also undergoes the 
TI - Recyclization of intermediates in an enamine rearrangement of a pyrimidinium salt when treated with isoniazide
JF - Chemistry of Heterocyclic Compounds
DO - 10.1007/s10593-006-0104-4
DA - 2006-06-14
UR - https://www.deepdyve.com/lp/springer-journals/recyclization-of-intermediates-in-an-enamine-rearrangement-of-a-YRfGXoT8GM
SP - 414
EP - 416
VL - 42
IS - 3
DP - DeepDyve
ER -