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Updated: Jan 15, 2026

Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Carbonyl-Allene Metathesis of S-Allenyl-α-oxo-S,S/N,S-ketene Acetals: A Thermally Driven Intramolecular Tandem [2 +
Malkeet Singh1, Saurabh Singh1, Nimisha Gupta1
1Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
Abstract:
Carbonyl-allene metathesis (CAM) represents an emerging class of bond-reorganizing transformations with significant synthetic potential. Here, we report a thermally controlled, catalyst-free intramolecular CAM reaction demonstrated via a tandem [2 + 2] cycloaddition and retrocyclization of S-allenyl-α-oxo-S,S-/N,S-ketene acetals. Control experiments and kinetic and DFT studies indicate the reaction involved an asynchronous concerted cycloaddition between the carbonyl and allene moieties, forming an oxetane intermediate, which subsequently undergoes retro-cyclization to afford 2,4-disubstituted thiophene derivatives.
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