Tetrabutylammonium tribromide: an effective green reagent for the one-pot reaction of 3-acetyl-2H-chromen-2-ones with o-phenylenediamines

An efficient and completely greener approach has been outlined for the reaction of 3-acetyl-2H-chromen-2-ones with o-phenylenediamines using tetrabutylammonium tribromide (TBATB) to obtain 3-(quinoxalin-2-yl)2H-chromen-2-ones in one-pot. Alternatively, a step-wise method has also been demonstrated for the synthesis of 3-(quinoxalin-2-yl)-2H-chromen-2-ones, where 3-acetyl-2H-chromen-2-ones has first treated with TBATB to give 3-(2-bromoacetyl)-2H-chromen-2-one followed by its nucleophilic substitution reaction with ophenylenediamines. Use of polyethylene glycol-600 (PEG-600) as the solvent media, mild reaction conditions and easy isolation procedure of products are the added advantages for this synthesis. Both the one-pot and step-wise methods have been compared in terms of their reaction yields and one-pot synthesis was found to be superior. All the synthesized compounds were confirmed by characterization with (HNMR)-H-1,(CNMR)-C-13, HRMS, IR spectroscopy. [GRAPHICS] .