Recyclization of 4H-chromen-4-imine derivatives under the influence of dinucleophiles with the formation of functionally substituted pyrazoles

It has been established that the recyclization of 2-aryl-4H-chromen-4-imines under the influence of thiosemicarbazide as N-dinucleophile is completed by the formation of 3-aryl-5-(o-hydroxyaryl)-1H-pyrazole-1-carbothioamides by the 5-exo-trig-cyclization mechanism. Aromatic acid hydrazides (isonicotinic, benzoic, salicylic, and 4-methoxybenzoic) enter into a similar reaction with the participation of an excess of piperidine to form 1H-pyrazol-5-ylphenols. [GRAPHICS] .