D. I. Brahmbhatt

Synthesis of a new series of 2-(2-oxo-2H-chromen-3-yl)-5H-chromeno[4,3-b]pyridin-5-ones by two facile methods and evaluation of their antimicrobial activity

A series of novel 2-(2-oxo-2H-chromen-3-yl)-5H-chromeno[4,3-b]pyridin-5-ones 4a–4l have been synthesized using two methodologies (using Mannich base of 4-hydroxy coumarin and 4-chloro-3-formyl coumarin) (Patel et al., 2012) and assayed for their antibacterial activity against gram-positive bacteria viz. Bacillus subtilis (MTCC 441), Staphylococcus aureus (MTCC 96) and gram-negative bacteria viz. Escherichia coli (MTCC 443), Salmonella typhimurium (MTCC 98). The compounds 4a–4l were also assayed for their antifungal activity against Aspergillus niger (MTCC 282) and Candida albicans (MTCC 227). All the compounds 4a–4l exhibited potent inhibitory activity against gram-positive bacteria compared to standard drugs at the tested concentrations. The compounds also showed appreciable activity against gram-negative bacteria as well as fungi. The compounds 4e, 4f, 4i, 4k, and 4l are found to be the most proficient members of the series and emerged as potential molecules for further development.Graphical Abstract

An efficient synthesis and antimicrobial screening of new hybrid molecules containing coumarin and indenopyridine moiety

A novel series of hitherto unknown 3-(4-aryl-5H-indeno[1,2-b]pyridin-2-yl)coumarin derivatives 3a–r have been synthesized by the reaction of 3-coumarinyl methyl pyridinium salts 1a-c with appropriate 2-arylidene-1-indanones 2a–f under Krohnke’s reaction condition so as to investigate their in vitro antimicrobial activity. Structures of the target compounds 3a–r were characterized by their spectral and elemental analyses. Among the series, compound 3l displayed an encouraging antibacterial activity profile as compared to the reference drug ampicillin against tested bacterial strains.Graphical Abstract

One pot synthesis of some novel coumarins containing 5-(substituted-2-hydroxybenzoyl) pyridine as a new class of antimicrobial and antituberculosis agents

A novel class of substituted pyridyl coumarin derivatives has been synthesized starting from 3-acetyl coumarin and chromone-3-carbaldehyde via one pot reaction and fully characterized by spectral and elemental analysis. All these derivatives 3a–l were screened in vitro for antimicrobial activity against a representative panel of pathogenic strains. Compounds demonstrated good to excellent antibacterial activity, while some compounds exhibited equipotent antifungal activity as compared to that of first line standard drug. As a part of investigation of new antitubercular agents, in vitro screening of synthesized compounds against Mycobacterium tuberculosis H37Rv has been done. Among the designed molecules, three compounds showed relatively better activity. From the entire study, it has been revealed that compounds appear to be better antimicrobials but relatively poor antituberculars.

Reductive Formation of 1,5-Benzothiazepines

An unprecedented formation of a new type of 1,5-benzothiazepines with exocyclic double bond at position 4 has been achieved by the reaction of 3-aryl-1-(3-coumarinyl)propen-1-ones with 2-aminothiophenol.