Specific features of heterocyclization of (E)-3-(2-ethoxyphenyl)-1-phenylprop-2-en-1-one with aminoazoles

A reaction of 3-(2-ethoxyphenyl)-substituted chalcone with aminoazoles was studied. The nature of aza groups in aminoazoles was found to affect the regioselectivity of β-amination in the course of the formation of isomeric pyrazolo[3,4-b]pyridine, azolo[1,5-a]- and [4,3-a]-pyrimidine systems and the depth of the reaction were determined. A regulatory role of catalysts and solvents in the direction of the cascade reactions was established. Mechanisms of the reactions were suggested. A significance of the alkoxy substituent in chalcone for stereoselective synthesis of Michael adducts, including 3-(2-ethoxyphenyl)-3-(7-(2-ethoxyphenyl)-5-phenyl-6,7-dihydroazolopyrimidin-6-yl)-1-phenylpropan-1-ones, was demonstrated. The structures of products synthesized were established by 1H and 13C NMR spectroscopy and X-ray diffraction analysis.