Transition-metal clusters as catalysts for chemoselective transesterification of alcohols in the presence of amines

Kazushi Mashima, Yukiko Hayashi, Kazushi Agura, Takashi Ohshima

研究成果: Contribution to journalArticle査読

7 被引用数 (Scopus)

抄録

Acylation is one of the most abundant organic transformations of alcohols (esterification) and amines (amidation). Because of the greater nucleophilicity of the amino group compared to the hydroxyl group and the stability of amides compared to esters, N-acylation occurs predominantly in organic synthetic reactions. We reported that the μ-oxo-tetranuclear zinc cluster Zn 4(OCOCF3)6O efficiently catalyzes highly chemoselective acylation of hydroxyl groups in the presence of primary and secondary alkyl amino groups to afford the corresponding esters in high yields. Not only zinc carboxylate complexes but also various carboxylate complexes of first-row late transition metals, such as Mn, Fe, Co, and Cu, become catalysts for such the hydroxy group-selective acylation in the presence of amines. Among these carboxylate compounds, we found that the combination of an octanuclear cobalt carboxylate cluster [Co4(OCOR)6O]2 (R = CF3, CH3, and tBu) with nitrogen-containing ligands such as 2,2′-bipyridine show sufficient catalytic activity toward O-selective transesterification. Notably, an alkoxide-bridged dinuclear complex, Co2(OCOtBu)2(bpy) 22-OCH2-C6H4-4- CH3)2, was successfully isolated as a key intermediate that proceeds with Michaelis-Menten behavior through an ordered ternary complex mechanism similar to dinuclear metallo-enzymes, suggesting that the formation of alkoxides, followed by coordination of the ester, is responsible for the unique O-selective acylation.

本文言語英語
ページ(範囲)335-343
ページ数9
ジャーナルPure and Applied Chemistry
86
3
DOI
出版ステータス出版済み - 3 20 2014

All Science Journal Classification (ASJC) codes

  • 化学 (全般)
  • 化学工学(全般)

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