Reactions based on transition-metal-catalyzed C–O bond cleavage have attracted much attention as a new synthetic method. Until now, several intermolecular reactions via C–O bond cleavage of aryl ethers, alkenyl ethers, esters, and others have been reported. Here we report an unprecedented C–O bond cleavage of 3-phenoxy acrylic acid derivatives, followed by intramolecular C–O bond formation with alkynes. This reaction gave 2,3-disubstituted benzofurans having useful functional groupssilyl substituents and acrylic acid derivativesat the 2- and 3-positions, respectively. This report also described theoretical (DFT) insights into the mechanism.

We have developed cycloisomerization between an aryl vinyl ether and a functionalized alkyne, such as silylalkyne, to give 2,3-disubstituted benzofuran derivatives using [IrCl­(cod)]2, PCy3, and NaBArF 4. This catalyst system not only catalyzes the above cycloisomerization but also isomerize a terminal olefin to give an aryl vinyl ether.

We have developed a one-iridium-catalyst system that transforms Nallyl-N-sulfonyl-2-(silylalkynyl)aniline derivatives, which are 1,7-enynes in which both multiple bonds have a heteroatom, to the corresponding substituted indole derivatives via isomerization/cycloisomerization/aromatization. This strategy provides an atom-economical and straightforward synthetic approach to a series of valuable indoles having vinyl and silylmethyl groups at the 2-and 3-positions.