3-(1,3-dioxobutan-1-yl)-2H-chromen-2-one in reactions with electrophilic and nucleophilic reagents

Reactions of 3-(1,3-dioxobut-1-yl)-2H-chromen-2-one with electrophilic (boron trifluoride diethyl etherate and phosphorus pentachloride) and nucleophilic (phosphorus pentasulfide and hydrogen sulfide) compounds have been studied. The reactions proceed mainly with the enol form of the substrate which is more stable both in polar and nonpolar solvents. The substrate ability to undergo aromatization into 4-oxopyranochromolium salts under action of electrophilic reagents and thionation at the oxo groups have been demonstrated. The suggested schemes of heterocyclization have been described. Possibility of in situ competitive formation of the hemiketal at the interaction with hydrogen sulfide in acidic medium has been found.