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Alternative tandem cyclisation pathways in the reaction between imines and enones,

Girling, P.R.; Batsanov, A.S.; Calow, A.D.J.; Shen, H.C.; Whiting, A.

Alternative tandem cyclisation pathways in the reaction between imines and enones, Thumbnail


Authors

P.R. Girling

A.S. Batsanov

A.D.J. Calow

H.C. Shen



Abstract

Dihydroisoquinoline reacts with Danishefsky's diene under Lewis acidic conditions or neat, to give low to moderate yields of the formal aza-Diels-Alder, [4+2]-cycloadduct. However, using methoxyvinyl methylketone with Lewis acid catalysis does not give the aza-Diels-Alder adduct, rather a formal [2+2+2]-cycloaddition occurs to provide access to a diacetyl dihydropyridine. Increased Lewis acid loading results in reduced dihydropyridine formation, and instead, a trimerisation reaction of the methoxyvinyl methyl ketone, to give 1,3,5-triacetylbenzene from a different formal [2+2+2]-cycloaddition. The formal [4+2]-cycloaddition reaction of methoxyvinyl methylketone requires a cyclic imine in order to form the dihydropyridine because the reaction with acyclic imines produced a dihydropyridine from a formal [1+2+1+2]-cycloaddition. Evidence resulting from the isolation of reaction intermediates and in situ spectroscopic studies, shows that the reaction between 3,4-dihydroisoquinoline and methyl vinyl ketone, catalysed by oxy-philic Lewis acids, proceeds via a Mannich-Michael pathway and an imminium ion species. All reactions occur by one-pot cascade routes.

Citation

Girling, P., Batsanov, A., Calow, A., Shen, H., & Whiting, A. (2016). Alternative tandem cyclisation pathways in the reaction between imines and enones,. Tetrahedron, 72(8), 1105-1113. https://doi.org/10.1016/j.tet.2016.01.006

Journal Article Type Article
Acceptance Date Jan 5, 2016
Online Publication Date Jan 7, 2016
Publication Date Feb 25, 2016
Deposit Date Jan 13, 2016
Publicly Available Date Jan 7, 2017
Journal Tetrahedron
Print ISSN 0040-4020
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 72
Issue 8
Pages 1105-1113
DOI https://doi.org/10.1016/j.tet.2016.01.006
Keywords Aza-Diels-Alder, Lewis-acid, Homogeneous catalysis, Cycloaddition, Dihydropyridine, Piperidenone.
Public URL https://durham-repository.worktribe.com/output/1394826

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