Bi(OTf)3-catalyzed tandem reaction of naphthols with β,γ-unsaturated α-ketoesters. Efficient synthesis of functionalized 4H-chromenes

An efficient synthesis of functionalized 4H-chromenes by the tandem reaction of β,γ-unsaturated α-ketoesters with 2-naphthols, 1-naphthols, and 1,3-dihydroxynaphthalenes has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of bismuth triflate [Bi(OTf)3, 5 mol%] under mild conditions. The functionalized 4H-chromene synthesis and our previous 2H-chromene hemiacetal synthesis could complement each other to enrich reaction diversity.

Graphical abstractAn efficient synthesis of functionalized 4H-chromenes by the tandem reaction of β,γ-unsaturated α-ketoesters with 1-naphthols, 2-naphthols, and 1,3-dihydroxynaphthalenes has been accomplished with high selectivity and excellent yields in the presence of a catalytic amount of bismuth triflate [Bi(OTf)3, 5 mol%] under mild conditions. The functionalized 4H-chromene synthesis and our previous 2H-chromene hemiacetal synthesis could complement each other to enrich reaction diversity.Figure optionsDownload full-size imageDownload as PowerPoint slide