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Updated: Sep 18, 2025

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Influence of sp2 Nitrogen Atom Replacement on the Structure and Redox Properties of Allylic Intermediates
1Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China.
Abstract:
Heteroatom doping offers an opportunity for engineering the electronic structure of a conjugated system. Herein, we report the isolation and characterization of multiredox allyl and 2-azaallyl intermediates, including anions, radicals, and cations. The replacement of ═CH moiety with ═N at the C-2 position significantly stabilizes the 2-azaallyl cation [Ph2CNCPh2]+, resulting in reduced hydride affinity and decreased hydride abstraction reactivity, which have been proven by thermodynamic and kinetic studies. The contribution of a nitrogen lone pair to bonding and π-interactions between phenyl groups is attributed to a bent geometry of [Ph2CNCPh2]+. The substitution of electronegative nitrogen reduces the energy level of π1 (bonding) and π3 (antibonding) orbitals of allyl systems, causing a red shift in ultraviolet-visible (UV-vis) absorption for the allyl radical but a blue shift for the cation. This study reveals the distinct regulatory effects of sp2- and sp3-hybridized nitrogen on the electronic and molecular structures of multiredox intermediates, providing guidance for selecting heteroatom doping strategies based on the specific needs of conjugated materials.
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