Microwave assisted synthesis and photophysical properties of blue emissive 2-amino-3-carboxamide-1,1′-biaryls and 4-(arylamino)-[1,1′-biphenyl]-3-carboxamides via Suzuki and Chan-Evans-Lam coupling

Abstract

An efficient microwave assisted synthesis of 2-amino-3-carboxamide-1,1′-biaryls derivatives 4a-p and terphenyl derivative 5a from 2-amino-5-iodobenzamide 2a, 2-amino-3,5-diiodobenzamide 2b and (het)aryl boronic acids via Suzuki coupling has been achieved. Synthetic utility of the product 4-amino-4′-cyano-[1,1′-biphenyl]-3-carboxamide 4j has been demonstrated for the synthesis of 4-(aryl amino)-[1,1′-biphenyl]-3-carboxamide derivatives 10a-c via Chan-Evans-Lam coupling reaction. Furthermore, 4-(4′-oxo-3′, 4′-dihydro-1′H-spiro[fluorene-9,2′-quinazolin]-6′-yl)benzonitrile 12a was obtained from biaryl derivative 4j and fluorenone 11a and 6(4- methoxyphenyl)2-(ferrocenyl) quinazolin-4(3H)-one 12b from biaryl derivative 4k and ferrocenealdehyde 11b using phosphotungstic acid as green catalyst and solvent free microwave irradiation condition. Remarkably, all the synthesized 2-amino-3-carboxamide-1,1′-biaryls and 4-(aryl amino)-[1,1′-biphenyl]-3-carboxamide derivatives 4a-p showed luminescence in the blue region with large Stokes shift. Significantly, 2-amino-3-carboxamide-1,1′-biaryls 4d and 4j showed high fluorescence quantum yields (Φf) 0.54 and 0.84, respectively.