Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5214911 | Tetrahedron | 2015 | 6 Pages |
Three-component coupling reactions of 2-(cyanomethyl)phenol, aryl halides, and carbon monoxide (CO) in orthogonal-tandem catalysis were investigated. In the reactions, 2-(cyanomethyl)phenyl esters, which are produced through Pd(PPh3)4-catalyzed alkoxycarbonylation of aryl halides with 2-(cyanomethyl)phenol, undergo cycloisomerization in situ catalyzed by Pd(PCy3)2 as a co-catalyst to give 3-acyl-2-aminobenzofurans. Palladium species with homoleptic tertiary phosphines, such as Pd(PPh3)4 and Pd(PCy3)2, can catalyze the mechanistically distinct reactions in an orthogonal-tandem manner without interference. By switching the base used in this reaction, 3-acyl-2-(N-acylamino)benzofurans were obtained as major products instead of 3-acyl-2-aminobenzofurans. Given that 2-(cyanomethyl)phenols can be synthesized from commercially available salicylic acid derivatives in two steps, the present method thus provides facile access to synthetically useful 3-acyl-2-aminobenzofurans.
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