Studies of the Electronic Effects of Zinc Cluster Catalysts and Their Application to the Transesterification of β‐Keto Esters |
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| Authors: | Dr Kazushi Agura Dr Yukiko Hayashi Mari Wada Daiki Nakatake Prof Dr Kazushi Mashima Prof Dr Takashi Ohshima |
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| Affiliation: | 1. Graduate School of Pharmaceutical Sciences, Kyushu University, CREST, Higashi-ku, Fukuoka, Japan;2. Department of Chemistry, Graduate School of Engineering Science, Osaka University, CREST, Toyonaka, Osaka, Japan |
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| Abstract: | The electronic effects of tetranuclear zinc cluster catalysts on transesterification were investigated by changing the carboxylate ligands in the clusters. High catalyst activity crucially depended on the balance between Lewis acidity and Brønsted basicity of the catalyst; this was consistent with the dual activation of both the electrophile and nucleophile by the cooperative zinc centers. In addition, tetranuclear zinc cluster catalysts achieved the transesterification of β‐keto esters with unprecedented levels of broad substrate generality, in which a newly developed pentafluoropropionate‐bridged zinc cluster and 4‐dimethylaminopyridine additive greatly improved the reactivity of sterically congested α‐ and α,α‐disubstituted β‐keto esters. |
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| Keywords: | beta-keto esters electronic effects synthesis design transesterification zinc |
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