Efficient Syntheses of New Chromone- and Chromanequinoline Hybrids and their Aza-analogs

Some novel chromone- and chromanequinoline hybrids and their aza-analogs were synthesized from 2-chloro- 3-quinolinecarboxaldehydes as starting materials. The cyclization of 2-hydroxychalcones in the presence of AcONa yielded chroman-4-ones, while, in the typical AFO conditions, the 2-corresponding quinolyl-3-hydroxyflavonols were obtained. These approaches were extended to 2-aminochalcones, which delivered the 3-hydroxy-2,3-dihydroquinolin- 4(1H)-one via an epoxy-ketone and 2-quinolyl-2,3-dihydroquinoline-4(1H)-one under microwave irradiation in the presence of silica gel impregnated with indium (III) chloride.