Synthesis of novel amide functionalized 2H-chromene derivatives by Ritter amidation of primary alcohol using HBF4·OEt2 as a mild and versatile reagent and evaluation of their antimicrobial and anti-biofilm activities

A series of novel amide functionalized 2H-chromene derivatives 3 were prepared starting from ethyl-2-hydroxy-2-(trifluoromethyl)-2H-chromene-3-carboxylate 1 via sodium borohydride reduction followed by Ritter amidation using HBF4·OEt2 as a mild and versatile reagent. All the products 3 were screened for antimicrobial activity against various Gram-positive, Gram-negative bacteria and fungal strain. The promising derivatives such as 3f, 3g, 3k, 3l, 3m, 3n and 3o were further screened for minimum bactericidal concentration and bio-film inhibition activity and identified the potential ones. Among all the promising, compound 3g was more potent for antimicrobial, MBC and anti bio-film activities. The structure verses activity relationship of 3g revealed that the presence of two bromine atoms at sixth and R position promotes high activity.

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