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Updated: Apr 18, 2026

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Catalytic enantioselective [5+2] cycloaddition between oxidopyrylium ylides and enals under dienamine activation
Ane Orue1, Uxue Uria, Efraim Reyes
1Department of Organic Chemistry II, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao (Spain) http://www.ehu.es/GSA.
Abstract:
Benzopyrylium ylides generated in situ from 1-acetoxyisochroman-4-ones reacted with α,β-unsaturated aldehydes in the presence of a bifunctional secondary-amine/squaramide catalyst to furnish [5+2] cycloaddition products in good yield with high diastereo- and enantioselectivity. The reaction proceeds by dienamine activation and involves β,γ-functionalization of the enal. The dienamine intermediates showed exclusive β,γ-reactivity and provided direct access to compounds with the 8-oxabicyclo[3.2.1]octane framework. The ability of the bifunctional secondary-amine/squaramide catalyst to engage in hydrogen-bonding interactions with the ylide made it particularly effective in terms of both the yield and the stereoselectivity of the transformation.
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