Design, Synthesis of 5-(2-Methylbenzofuran)-2-aryl-2H-tetrazole Derivatives via Cross-Coupling of N-H Free Tetrazoles with Boronic Acids

Chemical intermediates derived from 1,3-dipolar cycloaddition reactions, such as 5-substituted 1H-tetrazole, are commonly utilized to synthesize 1,5-disubstituted tetrazoles. In this work, a highly effective and useful strategy for the synthesis of 5-(2-methylbenzofuran-3-yl)-2-phenyl-2H-tetrazoles using environmentally safe 1 atm. O2 as oxidizer is reported. Moreover, the N-H unbound tetrazoles and low hazardous boronic acids are directly coupled with the catalytic amount (5 mol%) of Cu2O to form C-N bond without any formation of the additives. The proposed method is simple for the Cu-catalyzed reactions, which require only mild conditions and green, atom-efficient chemistry for the regioselective synthesis of 2,5-disubstituted 2H-tetrazoles.