Activation via trienamine intermediates is a synthetically useful protocol for performing asymmetric Diels-Alder reactions controlled by a remote chiral catalyst (a secondary or primary amine). Key features underpinning this concept are the conformation towards the trienamine formation and also the use of highly electrophilic dienophiles. This cycloaddition reaction allows the application of asymmetric organocatalysis at a remote position, and the synthesis of complex molecules short synthetic sequences is possible.
For some selected reviews in organocatalysis, see: a)
Berkessel A., Göger H., Asymmetric Organocatalysis,
WILEY-VCH, Weinheim, Germany, 2005. b) Dalko P. I.,
Enantioselective Organocatalysis, WILEY-VCH, Weinheim,
2007. c) Dalko P. I., Enantioselective Organocatalysis, Wiley-
VCH, Weinheim, 2007. d) MacMillan D. W. C., The Advent
and Development of Organocatalysis, Nature, 2008, 455,
304-308. e) Moyano A., Rios R., Asymmetric Organocatalytic
Cyclization and Cycloaddition Reactions, Chem. Rev. 2011,
111, 4703-4832. f) Bernardi L., Fochi M., Franchini M. C.,
Ricci A., Bioinspired Organocatalytic Asymmetric Reactions,
Org. Biomol. Chem. 2012, 10, 2911-2922. g) Cabrera S., Alemán J., Applications of Asymmetric Organocatalysis in
Medicinal Chemistry, Chem. Soc. Rev. 2013, 42, 774-793.
For a seminal work in HOMO activation via enamine
intermediates, see: a) List B., Lerner R. A., Barbas III C. F. J.,
Proline-Catalyzed Direct Asymmetric Aldol Reactions, J. Am.
Chem. Soc., 2000, 122, 2395-2396. For a review in enamine
activation, see: b) Mukherjee S., Yang J. W., Hoffmann S.,
List B., Asymmetric Enamine Catalysis, Chem. Rev. 2007,
107, 5471-5569. For a seminal work in HOMO-activation via
dienamine intermediates, see: c) Bertelsen S., Marigo M.,
Brandes S., Dinér P., Jørgensen K. A., Dienamine Catalysis:
Organocatalytic Asymmetric γ-Amination of α,β-Unsaturated
Aldehydes, J. Am. Chem. Soc. 2006, 128, 12973-12980.
For reviews in dienamine activation, see: d) Ramachary D. B.,
Reddy Y. V., Dienamine Catalysis: An Emerging Technology
in Organic Synthesis, Eur. J. Org. Chem., 2012, 865-887. e)
Parra A., Reboredo S., Alemán J., Asymmetric Synthesis of
Cyclobutanes by a Formal [2+2] Cycloaddition Controlled by
Dienamine Catalysis, Angew. Chem. Int. Ed. 2012, 51, 9734-
For a seminal work in LUMO activation, see: a) Ahrendt K. A.,
Borths C. J., MacMillan D. W. C., New Strategies for Organic
Catalysis: The First Highly Enantioselective Organocatalytic
Diels−Alder Reaction, J. Am. Chem. Soc. 2000, 122, 4243-
4244. For a review in LUMO activation, see: b) Erkkilä A.,
Majander I., Pihko P. M., Iminium Catalysis, Chem. Rev.
2007, 107, 5416-5470.
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