Enzyme-Like Catalysis via Ternary Complex Mechanism: Alkoxy-Bridged Dinuclear Cobalt Complex Mediates Chemoselective O-Esterification over N-Amidation
2013 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 135, no 16, 6192-6199 p.Article in journal (Refereed) Published
Hydroxy group-selective acylation in the presence of more nucleophilic amines was achieved using acetates of first-row late transition metals, such as Mn, Fe, Co, Cu, and Zn. Among them, cobalt(II) acetate was the best catalyst in terms of reactivity and selectivity. The combination of an octanuclear cobalt carboxylate cluster [Co-4(OCOR)(6)O](2) (2a: R = CF3, 2b: R = CH3, 2c: R = Bu-t) with nitrogen-containing ligands, such as 2,2'-bipyridine, provided an efficient catalytic system for transesterification, in which an alkoxide-bridged dinuclear complex, Co-2((OCOBu)-Bu-t)(2)-(bpy)(2)(mu(2)-OCH2-C6H4-4-CH3)(2) (10), was successfully isolated as a key intermediate. Kinetic studies and density functional theory calculations revealed Michaelis-Menten behavior of the complex 10 through an ordered ternary complex mechanism similar to dinuclear metallo-enzymes, suggesting the formation of alkoxides followed by coordination of the ester.
Place, publisher, year, edition, pages
2013. Vol. 135, no 16, 6192-6199 p.
IdentifiersURN: urn:nbn:se:su:diva-90362DOI: 10.1021/ja400367hISI: 000318204800044OAI: oai:DiVA.org:su-90362DiVA: diva2:628179
FunderSwedish Research CouncilKnut and Alice Wallenberg Foundation