Dihydrooxazine oxides as key intermediates in organocatalytic michael additions of aldehydes to nitroalkenes

Gokarneswar Sahoo, Hasibur Rahaman, Ádám Madarász, Imre Pápai, Mikko Melarto, Arto Valkonen, Petri M. Pihko

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71 Citations (Scopus)


The organocatalytic enantioselective Michael addition of aldehydes to nitroalkenes through enamine catalysis has been studied intensively in recent years. Pioneering mechanistic studies by Seebach and Hayashi and co-workers, as well as by the Blackmond group, on reactions catalyzed by diaryl prolinol ethers have identified cyclobutane (CB) species 6a (Scheme 1) as a key intermediate and the resting state of the amine catalyst. Although these studies clearly demonstrated that the rate-determining step in the catalytic cycle takes place after the formation of 6a, and possibly involves the protonation of the iminium nitronate 5a, the detailed mechanism of the rate-determining step was not addressed. More recently, the Blackmond group suggested a modified catalytic cycle where the cyclobutane species 6a is first deprotonated to give the anion 10 a, followed by protonation to form the enamine 8a.

Original languageEnglish
Pages (from-to)13144-13148
Number of pages5
JournalAngewandte Chemie - International Edition
Issue number52
Publication statusPublished - Dec 21 2012



  • Aminocatalysis
  • Computational chemistry
  • Heterocycles
  • Intermediate characterization
  • NMR spectroscopy

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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