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Paper | Regular issue | Vol 43, No. 6, 1996, pp.1257-1266
Published online, 1st January, 1970
DOI: 10.3987/COM-96-7447
■ Simple and Efficient One-Pot Preparation of 3-Substituted Coumarins in Water

Gianluca Brufola, Francesco Fringuelli,* Oriana Piermatti, and Ferdinando Pizzo

*Dipartimento di Chimica, Università de Perugia, Via Elce di Sotto, 8 06100 Perugia, Italy

Abstract

3-Cyanocoumarin and seven derivatives [4-Me; 6-NO2; 7-OH; 7-OMe; 8-OH; 5,7-OMe; 6,7-(-CH=CH-)-2] and eight coumarins substituted at C-3 (CO2Et; NO2; Ph; p-NO2-C6H4; Ph-SO2; 2-pyridyl; 2-thienyl; 2-benzothiazolyl) were prepared, on multigram scale by a one-pot procedure in water alone, by the Knoevenagel reaction of o-hydroxyaryl aldehydes and o-hydroxyacetophenone with acetonitriles. The yields are high and the procedure does not require organic solvents. The reactions carried out in heterogeneous aqueous phase, sometimes in the presence of a surfactant, always have higher yields than the same reactions excuted in homogeneous ethanolic medium.