A Beckmann rearrangement initiated by trifluoromethanesulfonic anhydride in the synthesis of compounds containing a new pyrazolo[3',4':5,6]pyrido[3,2-b]azepine heterocyclic system
Chem. Heterocycl. Compd. 2021, 57 (2), 199-206
N-Boc-5-formylpyrazol-4-amines reacted with 1,3-cyclohexanediones in AcOH–1,4-dioxane medium in the presence of pyrrolidine, resulting in the formation of pyrazolo[4,3-b]quinolin-8-one derivatives that were converted into the respective oximes. A reaction of the latter with trifluoromethanesulfonic anhydride under mild conditions was used to synthesize hexahydropyrazolo[3',4':5,6]pyrido[3,2-b]-azepin-4-ium trifluoromethanesulfonates.