Microwave assisted regioselective synthesis of novel pyrazoles and pyrazolopyridazines via fluorine containing building blocks

A facile regioselective synthesis of novel pyrazole derivatives containing a fluorophenyl moiety via the 1,3-dipolar cycloaddition of nitrileimines and enamines using conventional as well as microwave irradiation conditions have been achieved. Fluorine-containing building blocks methodology was used in order to access the targeted fluorinated compounds. The structures of the synthesized products were confirmed by H-1 NMR, FT-IR, mass spectrometry, and elemental analyses. Furthermore, the synthesized pyrazoles have been used in the synthesis of some new pyrazolo pyidazines containing pendent to fluorophenyl moiety. An unambiguous structural assignment of the obtained pyrazole regioisomers was determined using the H-1 NMR analysis as a valuable tool. (C) 2017 Elsevier B.V. All rights reserved.