One-Pot Sequential Approach for the Construction of Highly Functionalized Triazolo[4,3-c]pyrimidine Library

Novel [1,2,4]triazolo[4,3-c]pyrimidine-8-carboxamides were synthesized via oxidative cyclization of hydrazono-1,6-dihydropyrimidine-5-carboxamide intermediates by the application of iodobenzenediacetate as a sole cyclizing agent. Here, we report a one-pot sequential strategy to generate the corresponding triazolopyrimidines by condensation of preprepared α-acylketene dithioacetals and arylamidines. Moreover, this process describes the application of presynthesized arylamidines, which omits the Suzuki–Miyaura cross-coupling reaction and hence provides metal-free organic synthesis in an atom- and step-economical fashion.