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

• Caifei Tang,
• Zhiming Li and
• Quanrui Wang

Beilstein J. Org. Chem. 2013, 9, 2629–2634, doi:10.3762/bjoc.9.298

• 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. Keywords: cyclization; hydrazones; hypervalent iodine; oxidation; rearrangement; [1,2,4]triazolo[1,5-c]pyrimidines; Introduction The

• for the efficient preparation of novel triazolopyrimidines is needed. Recently, we have reported the synthesis of 8-bromo-7-chloro-[1,2,4]triazolo[1,5-c]pyrimidines from the reaction of pyrimidinylhydrazones with bromine followed by Dimroth rearrangement [15]. In the present paper, we wish to report

• pyrimidinylhydrazones 4 with different R1 and R2 groups were examined under optimal conditions. As shown in Table 3, the protocol appeared to be quite general. In all cases studied, the respective [1,2,4]triazolo[1,5-c]pyrimidines 6 could be obtained. Various aryl substituents on the triazole ring (R2), including