148319-55-5Relevant articles and documents
Synthesis and Reactions of Triazolopyridinium-3-aminides and Triazolopyrimidinium-3-aminides: Evaluation of the Scope and Mechanism of a New Type of Heterocyclic Rearrangement
Bishop, Brian C.,Marley, Hugh,McCullough, Kevin J.,Preston, Peter N.,Wright, Stanley H. B.
, p. 705 - 714 (2007/10/02)
1,2,4-Triazolopyridinium betaines 6a, b have been prepared by treating 2-pyridyl-4-phenylthiosemicarbazides 4a, b with dicyclohexylcarbodiimide, and related compounds 6c-f have been prepared through the intermediate S-methyl thiosemicarbazides 5c-f.Reaction of the pyrimidin-2-yl thiosemicarbazide derivatives 8a-c with dicyclohexylcarbodiimide (DCC) gave the 1,2,4-triazolopyrimidinium betaines 7a-c, but attempted thermal cyclization of the free bases derived from methiodides 8j-o gave a series of enamines 11.The structure of one such enamine 11a was elucidated by degradation with 2 mol dm-3 HCl which afforded a mixture o f the amine 9 and the ketone 10.Treatment of the thiosemicarbazide 8d with dicyclohexylcarbodiimide gave the pyridinium betaine 14a, and a related compound 14b was prepared by reaction of the salt 12b with diazabicycloundec-7-ene (DBU).The crystal and molecular structure of the maleate salt of 14b was determined by X-ray crystallography.It was established that the betaine 14a could be converted into an enamine derivative 11a by heating it in toluene.
