Bifunctional activation and racemization in the catalytic asymmetric Aza-Baylis-Hillman reaction.

Bifunctional activation and racemization in the catalytic asymmetric Aza-Baylis-Hillman reaction. Research Abstract Details 

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Bifunctional activation and racemization in the catalytic asymmetric Aza-Baylis-Hillman reaction. Abstract Text:

Pascal Buskens, Klankermayer,Walter Leitner,

The mechanism of bifunctional activation in the asymmetric aza-Baylis-Hillman (aza-BH) reaction was studied using NMR spectroscopic techniques. The reaction involves rate-limiting proton transfer in the absence of added protic species, but exhibits no autocatalysis. Brønsted acidic additives lead to substantial rate enhancements through acceleration of the elimination step. Furthermore, it was found that phosphine catalysts either alone or in combination with protic additives can cause racemization of the aza-BH product by proton exchange at the stereogenic center. This indicates that the spatial arrangement of a bifunctional chiral catalyst for the asymmetric aza-BH reaction is crucial not only for the stereodifferentiation within the catalytic cycle but also for the prevention of subsequent racemization.

Bifunctional activation and racemization in the catalytic asymmetric Aza-Baylis-Hillman reaction. Publishing Authors By Initials

P Buskens,J Klankermayer,W Leitner,

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Bifunctional activation and racemization in the catalytic asymmetric Aza-Baylis-Hillman reaction. Journal Published:

PUBLICATION TYPE: Journal Article

Journal: Journal of the American Chemical Society

VOLUME: 127

Page Numbers: 16762-3

Journal Abbreviation: J. Am. Chem. Soc.

ISSN: 0002-7863

DAY: 7

MONTH: Dec

YEAR: 2005

Bifunctional activation and racemization in the catalytic asymmetric Aza-Baylis-Hillman reaction. Information

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LANGUAGE: eng

NlmUniqueID: 7503056

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Grant and Affiliation Information for Bifunctional activation and racemization in the catalytic asymmetric Aza-Baylis-Hillman reaction.

AFFILIATION: Institute of Technical and Macromolecular Chemistry, RWTH Aachen, Germany.

Country: United States

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MEDLINETA: J Am Chem Soc

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