One-step process for preparation of N-(4-substituted pyrazolyl) amidines as intermediates in PT-coupler synthesis

摘要

In the production of 1H-pyrazolo[1,5-b] [1,2,4]triazole couplers, substituted 3-amino-pyrazole compounds add to suitable organic nitriles in the presence of an acidic condensing agent such as aluminum chloride, stannic chloride or boron trifluoride to directly produce desired amidine intermediates in good yields, avoiding the generation of moisture sensitive intermediate imidate esters. Moreover, the availability of oxidation techniques to convert amidines to 1H-pyrazolo[1,5-b] [1,2,4]triazole couplers in a single step makes it possible to produce these couplers in a total of two steps compared to conventional multi-step synthetic schemes.