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DOI: 10.1055/s-0030-1258009
Palladium-Catalyzed Three-Component Synthesis of Pyrroles
S. Lamandé-Langle, M. Abarbri, J. Thibonnet, A. Duchêne*, J.-L. Parrain*
Nancy Université, Faculté des Sciences de Tours and Aix-Marseille Université, France
Publication History
Publication Date:
23 August 2010 (online)
Significance
The palladium-catalyzed synthesis of pyrrole acetic acid derivatives 4 via the three-component coupling of diiodide 1, amines 2, and acetylenes 3 is reported. A wide range of functional groups on the acetylene are tolerated, although the yields are only moderate due to competing formation of lactone by-products arising from intramolecular cyclization of the iodo acid 1. The silyl and germyl alkynes were found to be good substitutes for acetylene, giving the disubstituted pyrroles after protonolysis of the carbon-metal bond on acidic work-up. The scope with respect to the amine component was found to be narrower. Although simple alkyl and aryl amines are tolerated, α-substituted alkyl amines and electron-poor amines are not competent in the reaction. The acid in 1 may also be replaced by an ester as demonstrated in the synthesis of retinoid 5.