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Iron(III)-Catalyzed Consecutive Aza-Cope-Mannich Cyclization: Synthesis of trans-3,5-Dialkyl Pyrrolidines and 3,5-Dialkyl-2,5-dihydro-1H-pyrroles

Rubén M. Carballo, Martín Purino, Miguel A. Ramírez, Víctor S. Martín* and Juan I. Padrón*

*Instituto Universitario de Bio-Orgnica “Antonio Gonzlez”, Departamento de Qumica Orgnica, Universidad de La Laguna, C/Astrofsico Francisco Snchez 2, 38206 La Laguna, Tenerife, Spain, Email:,

R. M. Carballo, M. Purino, M. A. Ramírez, V. S. Martín, J. I. Padrón, Org. Lett., 2010, 12, 5334-5337.

DOI: 10.1021/ol102372c

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An efficient alkene aza-Cope-Mannich cyclization between 2-hydroxy homoallyl tosylamine and aldehydes in the presence of iron(III) salts gives 3-alkyl-1-tosyl pyrrolidines in good yields via a γ-unsaturated iminium ion, 2-azonia-[3,3]-sigmatropic rearrangement, and intramolecular Mannich reaction. The cyclization of 2-hydroxy homopropargyl tosylamines gives dihydro-1H-pyrroles.

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The process works with a stoichiometric or catalytic version at iron (III). The catalytic version relies on an iron catalyst system formed from iron(III) salts and trimethylsilyl halide.

Juan I. Padrón, June 23, 2011

Key Words

3-Pyrrolines, Pyrrolidines

ID: J54-Y2010-3270