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Facile Preparation of (2Z,4E)-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Ruthenium Catalyzed Formal [4 + 2] C-H Annulation to Pyranone via Chemoselective Ester Demethylation/O-C Cleavage
Amar D Uike1, Dattatraya H Dethe1
1Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur208016, India.
Abstract:
In this study, we delineate a highly efficient and operationally robust Ru(II)-catalyzed chemoselective ester demethylation/O-C cleavage enabled C-H annulation protocol for the expedient construction of pyranone architectures from readily accessible acrylates and internal alkynes. The transformation is postulated to proceed via Ru(0)-complex, intricately coordinated by p-cymene and the emergent pyranone scaffold. This catalytic paradigm is distinguished by a carboxylate-assisted C-H activation, subsequent formation of a thermodynamically stabilized sandwich Ru(0) intermediate, and a mechanistically intriguing chemoselective O-Me/Et bond scission of the ester moiety, collectively orchestrating the annulation sequence. A comprehensive exposition of this protocol underscores its synthetic efficacy and broad-spectrum applicability in the streamlined synthesis of pyranone frameworks.
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