TY - JOUR
T1 - Studies of the Electronic Effects of Zinc Cluster Catalysts and Their Application to the Transesterification of β-Keto Esters
AU - Agura, Kazushi
AU - Hayashi, Yukiko
AU - Wada, Mari
AU - Nakatake, Daiki
AU - Mashima, Kazushi
AU - Ohshima, Takashi
PY - 2016/5/20
Y1 - 2016/5/20
N2 - 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. Lewis versus Brønsted: High catalyst activity of zinc clusters on transesterification crucially depend on a balance between Lewis acidity and Brønsted basicity of the catalyst. Zinc clusters, including a newly developed pentafluoropropionate-bridged zinc cluster, achieved the transesterification of β-keto esters with unprecedented levels of broad substrate generality (see figure).
AB - 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. Lewis versus Brønsted: High catalyst activity of zinc clusters on transesterification crucially depend on a balance between Lewis acidity and Brønsted basicity of the catalyst. Zinc clusters, including a newly developed pentafluoropropionate-bridged zinc cluster, achieved the transesterification of β-keto esters with unprecedented levels of broad substrate generality (see figure).
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U2 - 10.1002/asia.201600062
DO - 10.1002/asia.201600062
M3 - Article
AN - SCOPUS:84981765516
VL - 11
SP - 1548
EP - 1554
JO - Chemistry - An Asian Journal
JF - Chemistry - An Asian Journal
SN - 1861-4728
IS - 10
ER -