Copper(I) Complex of Dihydro Bis(2‐Mercapto Benzimidazolyl) Borate as an Efficient Homogeneous Catalyst for the Synthesis of 2 <i>H</i> ‐Indazoles and 5‐Substituted 1 <i>H</i> ‐Tetrazoles

Abstract In this work, catalytic activity of a series of copper(I) complexes containing dihydrobis(2‐mercapto‐benzimidazolyl) borate (Bb), and phosphine co‐ligands was investigated in the synthesis of N ‐heterocycle compounds including 2 H ‐indazoles and 5‐substituted 1 H ‐tetrazoles. The copper(I) complex containing tricyclohexylphosphine co‐ligand, [Cu(Bb)(PCy 3 )], displayed the highest catalytic activities for the formation of 2 H ‐indazoles and 1 H ‐tetrazoles. Apart from the nontoxicity and strong σ‐donating ability of the introduced ligands, the introduced catalyst required easy handling processes. The catalytic reactions were successfully performed at low catalyst loadings in either PEG‐200 or DMF and in relatively short reaction times. The diversity of these reactions was also explored with 20 and 12 examples. Finally, the current catalytic system is amenable to large‐scale production of these N ‐heterocycle compounds.

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