415698-42-9

Upstream product

• 89-98-5 2-chloro-benzaldehyde 
• 52476-88-7 1-(6-chloro-2-methyl-pyrimidin-4-yl)hydrazine 
• 1194-22-5 2-methyl-4,6-dihydroxypyrimidine 
• 1780-26-3 2,4-dichloro-2-methylpyrimidine 

Downstream Products

• 1466918-10-4 C₁₂H₈Cl₂N₄ 
• 1598383-98-2 7-chloro-2-(2-chlorophenyl)-5-methyl-[1,2,4]triazolo[1,5-c]pyrimidine 

Relevant academic research and scientific papers

Synthesis of 8-Bromo-7-chloro[1,2,4]triazolo[4,3- C ]pyrimidines, Their Ring Rearrangement to [1,5- C ] Analogues, and Further Diversification

8-Bromo-7-chloro[1,2,4]triazolo[4,3-c]pyrimidines were prepared by bromine-mediated oxidative cyclization of the aldehyde-derived hydrazones. The structure of one such product was unambiguously confirmed by single-crystal X-ray analysis. While the C-5 unsubstituted 1,2,4-triazolo[4,3-c]pyrimidine chemotype is extremely susceptible to ring isomerization at ambient conditions, the C-5-substituted analogues were found to be quite stable, permitting isolation in pure form. Nevertheless, they can still be converted into the 1,2,4-triazolo[1,5-c]pyrimidines by base- or acid-promoted Dimroth rearrangement. The presence of halogen functionalities on the pyrimidine nucleus renders the products useful as versatile synthetic intermediates for the easy diversification, as evidenced by palladium-catalyzed Kumada cross-couplings and Buchwald-Hartwig amination, as well as direct aromatic substitution.

IBD-mediated oxidative cyclization of pyrimidinylhydrazones and concurrent Dimroth rearrangement: Synthesis of [1,2,4]triazolo[1,5-c]pyrimidine derivatives

Oxidative cyclization of 6-chloro-4-pyrimidinylhydrazones 4 with iodobenzene diacetate (IBD) in dichloromethane gives rise to [1,2,4]triazolo[4,3-c]pyrimidine derivatives 5a-o. These incipient products undergo feasible Dimroth rearrangement to furnish the isolated [1,2,4]triazolo[1,5-c]pyrimidines 6a-o in moderate to high yields.