The Aza-Morita-Baylis-Hillman Reaction: A Mechanistic and Kinetic Study

• Published in: Chemistry : a European journal Vol. 19; no. 20; pp. 6429 - 6434
• Main Authors: Lindner, Christoph, Liu, Yinghao, Karaghiosoff, Konstantin, Maryasin, Boris, Zipse, Hendrik
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 10-05-2013; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: Catalysis; Catalysts; Chemistry; Imines; Kinetics; Lewis bases; NMR spectroscopy; Protonation; Quantum chemistry; Reaction kinetics; reaction mechanisms; solvent effects; Solvents; Spectroscopy; synthetic methods
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201204006

The aza‐Morita‐Baylis–Hillman (aza‐MBH) reaction has been studied in a variety of solvents, a selection of imine substrates and with various combinations of PPh3 and para‐nitrophenol as the catalyst system. The measured kinetic data indicates that the effects of solvent and protic co‐catalyst are strongly interdependent. These results are most easily reconciled with a mechanistic model involving the reversible protonation of zwitterionic intermediates in the catalytic cycle, which is also supported by 31P NMR spectroscopy and quantum chemical studies.
Examining the aza‐MBH: The aza‐Morita–Baylis–Hillman (aza‐MBH) reaction has been studied in a variety of solvents, with a selection of imine substrates, and with various combinations of PPh3 and para‐nitrophenol as the catalyst system (see scheme). The measured kinetic data indicates that the effects of solvent and protic co‐catalyst are strongly interdependent. 31P NMR spectroscopy and quantum chemical studies support a mechanistic model that involves the reversible protonation of zwitterionic intermediates in the catalytic cycle.