42726-73-8Relevant articles and documents
Studies of the Electronic Effects of Zinc Cluster Catalysts and Their Application to the Transesterification of β-Keto Esters
Agura, Kazushi,Hayashi, Yukiko,Wada, Mari,Nakatake, Daiki,Mashima, Kazushi,Ohshima, Takashi
supporting information, p. 1548 - 1554 (2016/06/01)
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 Br?nsted 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 Br?nsted: High catalyst activity of zinc clusters on transesterification crucially depend on a balance between Lewis acidity and Br?nsted 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).
Iron(iii)-salan complexes catalysed highly enantioselective fluorination and hydroxylation of β-keto esters and N-Boc oxindoles
Gu, Xin,Zhang, Yan,Xu, Zhen-Jiang,Che, Chi-Ming
supporting information, p. 7870 - 7873 (2014/07/08)
Chiral iron(iii)-salan complexes catalysed highly enantioselective α-fluorination and α-hydroxylation of β-keto esters and N-Boc oxindoles to give the corresponding products in high yields and good-to-excellent ee values under mild reaction conditions. This journal is the Partner Organisations 2014.
An efficient method for generation of α-oxoketenes: Cycloreversion of enolized Meldrum's acid derivatives
Sato, Masayuki,Ban, Hitoshi,Kaneko, Chikara
, p. 6689 - 6692 (2007/10/03)
A series of 6-methoxy- or siloxy-4H-1,3-dioxin-4-ones was synthesized from Meldrum's acids. These dioxinones underwent 4+2 cycloreversion to methoxy- or siloxycartbonylketenes and ketones quantitatively at 20-50°C. The ketenes were characterized by IR spectroscopy as well as by trapping with t-butanol. The ready cycloreversion of these enolized Meldrum's acid derivatives strongly indicates that the anomalously high susceptibility of Meldrum's acids to nucleophilic reagents is due to the participation of carboxyketenes generated through the cycloreversion of tautomeric 6-hydroxydioxinones.
