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

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-1 was studied with solvents of increasing order of polarity. A series of 4H-chromene-3-carboxamides 4(a-1) 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 41(9.3 mu g/mL) showed promising antibacterial activity compared to ampicillin (standard). The compounds 4(a-1) were studied for their in vitro antioxidant (DPPH method) activity, 4d, 4h, 4k, and 41 compounds showed strong antioxidant activity with IC50 values of 1.39, 133, 126 and 1.10 mu g/mL when compared to ascorbic acid (standard). (C) 2017 Elsevier B.V. All rights reserved.