115852-29-4Relevant academic research and scientific papers
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.
Synthesis, Molecular Structure, and Reactions of 1H-1,2,4-Triazolopyrimidinium Betaines
Marley, Hugh,McCullough, Kevin J.,Preston, Peter M.,Wright, Stanley H. B.
, p. 351 - 358 (2007/10/02)
Novel 1-substituted 1,2,4-triazolopyrimidinium betaines have been prepared and characterised.Treatment of 1-alkyl-1-(4,6-dimethylpyrimidin-2-yl)hydrazines (2f-j) with phosgene gave a series of 1,2,4-triazolopyrimidinium chlorides (3a-e) which were subsequently converted by ammonia into 1,2,4-triazolopyrimidinium-3-olates (5a-e).Analogous 3-thiolates (5g-k) were best synthsized by treating the appropriate hydrazines (2f-j) with carbon disulphide.The 1-(3-hydroxypropyl) derivatives (5f) and (5l) were obtained by deprotection of benzyl derivatives (5e) and (5k) using BCl3 in dichloromethane at -10 deg C.Methylation of the 3-thiolate derivative (5g) with iodomethane gave the salt (9) which was subsequently transformed by methylamine into the triazole derivative (10). 1,5,7-Trimethyl-1H-1,2,4-triazolopyrimidinium-3-thiolate gave 5-amino-1-methyl-1H-1,2,4-triazole-3-thiol (11) on treatment with hydrazine hydrate.The molecular structure of 1-benzyl-5,7-dimethyl-1H-1,2,4-triazolopyrimidinium-3-olate (5b) has been determined by X-ray crystallography.
