Manganese(I)-Catalyzed β-Methylation of Alcohols using Methanol as C1 Source
Manganese(I)-Catalyzed β-Methylation of Alcohols using Methanol as C1 Source
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DOI：
10.1002/anie.201909035
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发表时间：
2019-11-28
影响因子：
16.6
通讯作者：
Leitner, Walter
中科院分区：
文献类型：
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作者：
Kaithal, Akash;van Bonn, Pit;Leitner, Walter
在空气稳定的分子锰配合物[Mn（CO）（2）Br[HN（（C2 H4 PPr 2）-Pr-i）（2）]] 1（[HN（（C2 H4 PPr 2）-Pr-i）（2）]=MACHO-Pr-i）中使用地球上丰富的第一行过渡金属实现了醇的高度选择性β-甲基化。该反应仅需要低负载量的1（0.5mol%），甲醇盐作为碱和MeOH作为甲基化试剂以及溶剂。各种醇的β-甲基化具有非常好的选择性（> 99%）和优异的产率（高达94%）。生物质衍生的脂肪醇和二醇也在β-位上选择性甲基化，从而打开了完全由非化石碳构建的“生物杂交”分子的途径。机理研究表明，该反应通过涉及在锰钳配合物的金属-配体合作的借氢途径进行。这种转化为C-C键的选择性形成提供了一种方便、经济和环境友好的途径，在制备先进的生物燃料、精细化学品和生物活性分子方面具有潜在的应用前景
Highly selective beta-methylation of alcohols was achieved using an earth-abundant first row transition metal in the air stable molecular manganese complex [Mn(CO)(2)Br[HN((C2H4PPr2)-Pr-i)(2)]] 1 ([HN((C2H4PPr2)-Pr-i)(2)]=MACHO-Pr-i). The reaction requires only low loadings of 1 (0.5 mol %), methanolate as base and MeOH as methylation reagent as well as solvent. Various alcohols were beta-methylated with very good selectivity (>99 %) and excellent yield (up to 94 %). Biomass derived aliphatic alcohols and diols were also selectively methylated on the beta-position, opening a pathway to "biohybrid" molecules constructed entirely from non-fossil carbon. Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal-ligand cooperation at the Mn-pincer complex. This transformation provides a convenient, economical, and environmentally benign pathway for the selective C-C bond formation with potential applications for the preparation of advanced biofuels, fine chemicals, and biologically active molecules