The alpha-effect in cyclic secondary amines: new scaffolds for iminium ion accelerated transformations

Nick Tomkinson; Achim Porzelle; Julie L. Cavill; Richard L. Elliott; Gareth Evans; Timothy J. K. Gibbs; Ian L. Jones; James A Platts

doi:10.1016/j.tet.2009.10.009

The alpha-effect in cyclic secondary amines: new scaffolds for iminium ion accelerated transformations

Nick Tomkinson, Achim Porzelle, Julie L. Cavill, Richard L. Elliott, Gareth Evans, Timothy J. K. Gibbs, Ian L. Jones, James A Platts

Pure And Applied Chemistry

Research output: Contribution to journal › Article

25 Citations (Scopus)

78 Downloads (Pure)

Abstract

Five-membered secondary amine heterocycles containing an α-heteroatom were prepared and shown to be ineffective as catalysts for the iminium ion catalysed Diels–Alder reaction between cinnamaldehyde and cyclopentadiene. Their six-membered counterparts proved to be highly active catalysts. In stark contrast, the catalytic activity observed when comparing the non α-heteroatom cyclic amines proline methyl ester and methyl pipecolinate showed the five-membered ring amine was significantly more active. Concurrent density functional theoretical calculations suggest a rationale for the observed trends in reactivity, highlighting that LUMO activation through an iminium ion intermediate plays a key role in catalytic activity.

Original language	English
Pages (from-to)	9961
Number of pages	9966
Journal	Tetrahedron
Volume	65
DOIs	https://doi.org/10.1016/j.tet.2009.10.009
Publication status	Published - 2009

Keywords

cyclic secondary amines
iminium ions
accelerated transformations

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10.1016/j.tet.2009.10.009

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Research Output

25 Citations
1 Chapter

Organocatalysed transformations of alpha,beta-unsaturated carbonyl compoundsthrough iminium ion intermediates

Tomkinson, N. & Rowley, J., 14 Nov 2012, Asymmetric Synthesis : More Methods and Applications. Christmann, M. & Brase, S. (eds.). Weinheim, p. 29-34 6 p.

Research output: Chapter in Book/Report/Conference proceeding › Chapter

Cite this

Tomkinson, N., Porzelle, A., Cavill, J. L., Elliott, R. L., Evans, G., Gibbs, T. J. K., Jones, I. L., & Platts, J. A. (2009). The alpha-effect in cyclic secondary amines: new scaffolds for iminium ion accelerated transformations. Tetrahedron, 65, 9961. https://doi.org/10.1016/j.tet.2009.10.009

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abstract = "Five-membered secondary amine heterocycles containing an α-heteroatom were prepared and shown to be ineffective as catalysts for the iminium ion catalysed Diels–Alder reaction between cinnamaldehyde and cyclopentadiene. Their six-membered counterparts proved to be highly active catalysts. In stark contrast, the catalytic activity observed when comparing the non α-heteroatom cyclic amines proline methyl ester and methyl pipecolinate showed the five-membered ring amine was significantly more active. Concurrent density functional theoretical calculations suggest a rationale for the observed trends in reactivity, highlighting that LUMO activation through an iminium ion intermediate plays a key role in catalytic activity.",

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AU - Cavill, Julie L.

AU - Elliott, Richard L.

AU - Evans, Gareth

AU - Gibbs, Timothy J. K.

AU - Jones, Ian L.

AU - Platts, James A

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AB - Five-membered secondary amine heterocycles containing an α-heteroatom were prepared and shown to be ineffective as catalysts for the iminium ion catalysed Diels–Alder reaction between cinnamaldehyde and cyclopentadiene. Their six-membered counterparts proved to be highly active catalysts. In stark contrast, the catalytic activity observed when comparing the non α-heteroatom cyclic amines proline methyl ester and methyl pipecolinate showed the five-membered ring amine was significantly more active. Concurrent density functional theoretical calculations suggest a rationale for the observed trends in reactivity, highlighting that LUMO activation through an iminium ion intermediate plays a key role in catalytic activity.

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KW - iminium ions

KW - accelerated transformations

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