A Facile Synthesis of 7-Hydroxy-4-methyl-8-heteryl-2H-2-chromenones

Abstract

7-Hydroxy-4-methyl-8-(1H-3-pyrazolyl)-2H-2-chromenones and 7-hydroxy-8-(3-isoxazolyl-4-methyl-2H-2-chromenones were prepared by a two step synthetic sequence starting from 8-acetyl- 7-hydroxyl-4-methyl-2H-2-chromenones. Reaction of 8-acetyl chromenone derivatives with dimethylformamide-dimethylacetal (DMF-DMA) and subsequent condensation of the resulted enaminones with hydrazines and hydroxylamine hydrochloride furnished the desired products in high yields.