A simple protocol for the synthesis of 3-amino-[1,2,4]triazolo[4,3-a]pyridines is reported. The newly developed one-pot methodology involves the reaction of hydrazinopyridine with isothiocyanates to give the corresponding thiosemicarbazides, which are further desulfurized in situ using polymer-supported Mukaiyama's reagent to promote the final cyclization and formation of the central core. Aryl isothiocyanates bearing both electron-donating and electron-withdrawing groups are well tolerated, and the expected compounds were obtained in excellent purities and yields after removal of salts with a SPE-NH2 column. This methodology proved to be robust in the extension to 3-amino-[1,2,4]triazolo[4,3-a]-pyrazines and 3-amino-[1,2,4]triazolo[4,3-c]-pyrimidines, and no significant differences were noticed in terms of purities and yields. The straightforward protocol developed, mix,filler, and evaporate, is appropriate for performing multiple reactions in parallel fashion without need of purification.
Synthesis of fused 3-amino-1,2,4-triazoles via sequential addition of aryl hydrazines to isothiocyanates and I 2 -mediated cyclodesulfurization
A variety of fused 3-amino-1,2,4-triazole derivatives were synthesized via addition of aryl hydrazines to isothiocyanates followed by I2-mediated oxidative cyclodesulfurization. This transition-metal-free synthetic process provides facile access to 1,2,4-triazolo[4,3-a]pyridines and related heterocyclic frameworks bearing a 3-amino substituent from readily accessible substrates in an efficient and
通过将芳基肼加到异硫氰酸酯中,然后进行I 2介导的氧化环脱硫,合成了多种稠合的3-氨基-1,2,4-三唑衍生物。这种无过渡金属的合成方法可轻松,高效地从容易获得的底物中轻松获得1,2,4-三唑并[4,3- a ]吡啶和带有3-氨基取代基的相关杂环骨架。