Regioselective CC bond cleavage in arylhydrazones of 4,4,4-trifluoro-1-(thiophen-2-yl)butane-1,3-diones

• Synthesis of (E)-2-(2-(4-substituted phenyl) hydrazono)-1-(thiophen-2-yl)ethanones.
• Regioselective carbon–carbon bond cleavage.
• Z/E isomerisation assisted by the CC bond cleavage.

New (Z)-2-(2-(para-substituted phenyl)hydrazono)-4,4,4-trifluoro-1-(thiophen-2-yl)butane-1,3-diones with chloro (1), bromo (2) and carboxy (3) substituents were synthesized and characterized by ESI-MS, IR, 1H and 13C NMR spectroscopies and elemental analysis. The regioselective carbon–carbon bond cleavage with the formation (E)-2-(2-(4-substituted phenyl) hydrazono)-1-(thiophen-2-yl)ethanones was achieved upon heating (80 °C) of 1–3 in methanol–water.

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