Direct synthesis of 2-arylazulenes by [8+2] cycloaddition of 2<i>H</i>-cyclohepta[<i>b</i>]furan-2-ones with silyl enol ethers

Abstract

We developed a procedure for the direct synthesis of 2-arylazulenes, which were obtained in moderate to excellent yields, by [8+2] cycloaddition of 2H-cyclohepta[b]furan-2-ones with aryl-substituted silyl enol ethers. The structures of some 2-arylazulenes were clarified by single-crystal X-ray analysis. The 2-phenylazulene derivatives obtained by this study showed noticeable fluorescence in acidic media.