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Updated: Aug 25, 2026

Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Unusual intramolecular [2 + 2] cycloaddition of allyl and vinylidene C=C bonds under mild conditions: a theoretical
Pedro Braña1, José Gimeno, José A Sordo
1Laboratorio de Química Computacional, Instituto de Química Organometálica Enrique Moles (Unidad asociada al CSIC), Facultad de Química, Universidad de Oviedo, Julián Clavería 8, 33006, Oviedo, Principado de Asturias, Spain.
Abstract:
A theoretical analysis allows for the rationalization of the recently reported unusual formation under mild conditions of a cyclobutylidene ring from a diastereoselective [2 + 2] intramolecular cycloaddition of two C=C systems. The reaction takes place by heating in dichloromethane the vinylidene complexes [Ru((eta(5),eta(3)-C(9)H(7))[=C=C(R)H][kappa(1)-(P)-PPh(2)(C(3)H(5))](PPh(3))][BF(4)] (R = Ph, p-Me-C(6)H(4)) (1) yielding the bicyclic alkylidene complexes [Ru((eta(5),eta(3)-C(9)H(7))[kappa(2)-(P,C)-(=CC(R)HCH(2)CHCH(2)-PPh(2)](PPh(3))][BF(4)] (2). The proposed mechanism represents an alternative to the classical Woodward-Hoffmann's supra-antara approach.
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