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
PDF
Graphical Abstract
Figure 1:
The structure of two representatives of [1,2,4]triazolopyrimidines.