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Studies of the Electronic Effects of Zinc Cluster Catalysts and Their Application to the Transesterification of β‐Keto Esters
Author(s) -
Agura Kazushi,
Hayashi Yukiko,
Wada Mari,
Nakatake Daiki,
Mashima Kazushi,
Ohshima Takashi
Publication year - 2016
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201600062
Subject(s) - transesterification , zinc , catalysis , chemistry , steric effects , electrophile , nucleophile , substrate (aquarium) , electronic effect , reactivity (psychology) , organic chemistry , lewis acids and bases , carboxylate , medicinal chemistry , oceanography , geology , medicine , alternative medicine , pathology
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.