A paradigm for predicting selective oxidation on noble metals: oxidative catalytic coupling of amines and aldehydes on metallic gold.
A paradigm for predicting selective oxidation on noble metals: oxidative catalytic coupling of amines and aldehydes on metallic gold.
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DOI：
10.1039/c1fd00012h
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发表时间：
2011-10
影响因子：
3.4
通讯作者：
Bingjun Xu;C. Friend;R. Madix
中科院分区：
文献类型：
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作者：
Bingjun Xu;C. Friend;R. Madix
我们在目前的工作中表明，相对简单的酸/碱的表面反应性的原则预测氧辅助胺-醛偶联金属金。通过二甲胺的氧辅助（布朗斯特酸）N-H键活化形成，（CH 3）2N（a）作为亲核试剂与各种醛偶联，形成相应的酰胺。在表面上的氧的低初始覆盖率下，实现了非常高的选择性。反应通过表面结合的半缩醛胺中间体进行，β-氢化物在室温以下消除该中间体以形成酰胺产物。在金属金上，酰胺的解吸似乎是限速步骤。在本工作中采用的瞬态条件下，胺与醇的氧辅助偶联是有限的，这表明这种反应必须在稳态下进行，以便同时存在醛和吸附的（CH 3）2N（a）。
We demonstrate in the present work that relatively straightforward acid/base principles of surface reactivity predict oxygen-assisted amine-aldehyde coupling on metallic gold. Formed via the oxygen-assisted (Brønsted acid) N-H bond activation of dimethylamine, (CH3)2N(a) acts as a nucleophile to couple with various aldehydes, forming the corresponding amides. At low initial coverages of oxygen on the surface very high selectivities are achieved. The reaction proceeds via the surface-bound hemiaminal intermediate, which beta-hydride eliminates well below room temperature to form the amide product. On metallic gold desorption of the amide appears to be the rate-limiting step. Under the transient conditions employed in this work oxygen-assisted coupling of the amine with alcohols is limited, suggesting that such reactions must be conducted in the steady state in order to have both the aldehyde and adsorbed (CH3)2N(a) present simultaneously.