Solvent free-synthesis of highly functionalized 4H-chromene-3-carboxamide derivatives using cerium ammonium nitrate and their antioxidant, antibacterial and solvatochromism studies

Abstract

A novel 4H-chromene-3-carboxamide derivatives were synthesized from a multicomponent reaction between 2-hydroxybenzaldehyde, acetoacetanilide, and 4-hydroxycoumarin under solvent free conditions in the presence of ceric ammonium nitrate (CAN) via Knoevenagel-Michael reaction. In this work, we attempted and developed several amendments under solvent-free conditions to obtain the biologically important 4H-chromene-3-carboxamides and characterized by NMR, HR-MS and UV–Vis spectroscopy analysis. The solvatochromic properties of compounds 4a–l was studied with solvents of increasing order of polarity. A series of 4H-chromene-3-carboxamides 4(a–l) and their antibacterial activities against Gram positive and Gram negative organisms was investigated using agar well technique. In the in vitro assay, the compounds 4k and 4l (9.3μg/mL) showed promising antibacterial activity compared to ampicillin (standard). The compounds 4(a–l) were studied for their in vitro antioxidant (DPPH method) activity, 4d, 4h, 4k, and 4l compounds showed strong antioxidant activity with IC50 values of 1.39, 1.33, 1.26 and 1.10μg/mL when compared to ascorbic acid (standard).