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DOI: 10.1055/s-2007-992452
Samarium(II) Iodide Catalyzed One-Pot Aza-Diels-Alder Reactions
Contributor(s):Hisashi Yamamoto, Matthew B. BoxerSuzhou University, P. R. of China
Stereoselective Synthesis of Pyrano[3,2-c]- and Furano[3,2-c]quinolines: Samarium Diiodide-Catalyzed One-Pot Aza-Diels-Alder Reactions
Eur. J. Org. Chem. 2007, 5265-5269
Publication History
Publication Date:
23 January 2008 (online)
Key words
samarium(II) iodide - aza-Diels-Alder reaction - quinolines
Significance
The authors describe a three-component aza-Diels-Alder reaction that is catalyzed by samarium(II) iodide. Interestingly, the cis/trans isomer issue can be controlled by the reaction conditions. When the reaction is conducted in organic solvents, the trans isomer is favored. Under solvent-less conditions, the cis isomer predominates. Higher temperatures were also found to give high yields of the trans product, while lower temperatures increased the cis selectivity.
Comment
This is a nice paper for the synthesis of biologically important quinoline-type products. The reaction works well with aromatic amines and aldehydes. The failure of aliphatic aldehydes in this reaction is believed to be due to the instability issues of the in situ formed imines. The selectivity issues associated with the solvent, temperature, and substrate concentration are of particular note. If the scope of the reaction can be expanded, this will become a very useful three-component coupling in heterocyclic synthesis.