Rhodium(I)-Catalyzed [2+2+1]-Carbonylative Cycloaddition of Diynes with Anthracene α-Diketone as the Source of CO

Abstract

We report on the use of anthracene α-diketone as a source of carbon monoxide (CO) in carbonylation reactions. Photoirradiation of a reaction of diynes with anthracene α-diketone in the presence of a rhodium(I) catalyst with a 5W Blue LED resulted in the [2+2+1] carbonylative cycloaddition of 2 with CO from anthracene α-diketone to give high yields (up to 99%) of cyclopentadienones (CPDs). This represents the first demonstration of a CO gas-free carbonylation reaction using anthracene α-diketone. The light irradiation was a major factor in both the generation of CO from anthracene α-diketone and for catalytic activity. A halogen lamp, a fluorescent light, and sunlight were also applicable as a light source in this reaction. Using this system, there is no need for an additional reagent for generating CO.