4′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-carboxylic acid: Synthetic approaches, single crystal X-ray structures and antimicrobial activity of intermediates

Abstract

Two synthetic approaches towards 4′-(2H-tetrazol-5-yl)-[1,1′-biphenyl]-4-carboxylic acid, a valuable organic ligand for the preparation of metal-organic frameworks, are reported. The first reaction sequence leading to the target compound comprises the iodination of [1,1′-biphenyl]-4-carboxylic acid, formation of the methyl ester of 4′-iodo-[1,1′-biphenyl]-4-carboxylic acid, nucleophilic substitution of iodine with cyano, ring closure of tetrazole, and hydrolysis of the ester function. The second synthetic pathway starts from 4-bromobenzonitrile, which is converted through Suzuki coupling with 4-carboxyphenylboronic acid into 4′-cyano-[1,1′-biphenyl]-4-carboxylic acid, which in turn leads to the desired compound after ring closure of tetrazole. All of the synthesized compounds have been fully characterized by IR and 1H- and 13C-NMR spectroscopy. Single crystal X-ray structures are reported for the target compound and for methyl esters of 4′-iodo-[1,1′-biphenyl]-4-carboxylic acid and 4′-cyano-[1,1′-biphenyl]-4-carboxylic acid. The target compound and the intermediates showed no antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans.