Accessing Furan-Linked Methylene Oxindoles/Benzofurans via Stereoselective Palladium-Catalyzed Domino Cyclization/Cycloisomerization.

ABSTRACT

A palladium-catalyzed domino cyclization/cycloisomerization reaction of alkyne-tethered carbamoyl chlorides with (E)-ß-chloroenones is reported. This reaction proceeds via a syn-carbopalladation of the alkyne, followed by a vinyl-PdII-catalyzed cycloisomerization of the (E)-ß-chloroenone cascade, which provides an efficient method to synthesize furan-linked methylene oxindoles. The reaction features stereodefined vinyl-PdII species, high to excellent 5-exo/6-endo selectivity, excellent Z/E selectivity, and the sequential formation of three bonds and bis-heterocycles. The strategy for the synthesis of furan-containing benzofurans has also been demonstrated.