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DOI: 10.1055/s-2007-968477
Four-Component Synthesis of Highly Substituted Pyrroles
Contributor(s):Victor Snieckus, Yigang ZhaoMcGill University, Montreal, Canada
Directed Synthesis of Pyrroles from Imines, Alkynes, and Acid Chorides: An Isocyanide-Mediated Reaction
Org. Lett. 2007, 9: 449-452
Publication History
Publication Date:
24 April 2007 (online)
Key words
pyrroles - imines - alkynes - isocyanides - multicomponent reaction
Significance
A synthesis of 1,2,3,4-tetrasubstituted pyrroles from simple commercially available materials is reported. The 4-CR involves the combination of imines, acid chlorides and acetylenes in the presence of cyclohexyl isocyanide which removes molecular oxygen by being oxidized to cyclohexyl isocyanate. Significantly, the reaction proceeds under mild conditions and without metal catalysis. The scope and limitations were not well investigated.
Comment
Highly substituted pyrroles are often structural entities in biologically active compounds (see review below). Many previous methods for their synthesis involve multistep or metal-catalyzed routes (e.g., G. Balme Angew. Chem. Int. Ed. 2004, 43, 6238-6241). The present metal-free methodology represents a competitive alternative for the introduction of diverse substitution patterns on the pyrrole nucleus in an efficient, economic, and environmentally friendly way.
Review
R. Rossi, F. Bellina Tetrahedron 2006, 62, 7213-7256.