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.
Professor Andrew Whiting email@example.com
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.
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|
|Peer Reviewed||Peer Reviewed|
|Keywords||Aza-Diels-Alder, Lewis-acid, Homogeneous catalysis, Cycloaddition, Dihydropyridine, Piperidenone.|
Accepted Journal Article
Publisher Licence URL
© 2016 This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/