Iridium‐Catalyzed Condensation of Amines and Vicinal Diols to Substituted Piperazines

Linda Luise Reeh Lorentz-Petersen, Lars Ulrik Rubæk Nordstrøm, Robert Madsen

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A straightforward procedure is described for the synthesis of piperazines from amines and 1,2‐diols. The heterocyclization is catalyzed by [Cp*IrCl2]2 and sodium hydrogen carbonate and can be achieved with either toluene or water as solvent. The transformation does not require any stoichiometric additives and only produces water as the byproduct. The reaction can be performed between a 1,2‐diamine and a 1,2‐diol or by a double condensation between a primary alkylamine and a 1,2‐diol. At least one substituent is required on the piperazine ring to achieve the cyclization in good yield. The mechanism is believed to involve dehydrogenation of the 1,2‐diol to the α‐hydroxy aldehyde, which condenses with the amine to form the α‐hydroxy imine. The latter rearranges to the corresponding α‐amino carbonyl compound, which then reacts with another amine followed by reduction of the resulting imine.

Original languageEnglish
JournalEuropean Journal of Organic Chemistry
Issue number34
Pages (from-to)6752-6759
Publication statusPublished - 2012


  • Alcohols
  • Amination
  • Cyclization
  • Homogeneous catalysis
  • Nitrogen heterocycles


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