Branched-Selective Hydroformylation of Nonactivated Olefins Using an N-Triphos/Rh Catalyst
Branched-Selective Hydroformylation of Nonactivated Olefins Using an N-Triphos/Rh Catalyst
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DOI：
10.1021/acscatal.8b00566
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发表时间：
2018-05
期刊：
影响因子：
12.9
通讯作者：
A. Phanopoulos;K. Nozaki
中科院分区：
文献类型：
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作者：
A. Phanopoulos;K. Nozaki
我们报道了一种催化体系，该体系由氮为中心的二膦或三膦配体与铑结合组成，所述铑能够从末端烯烃底物递送支链醛，所述末端烯烃底物通常给出比支链醛更多的直链醛。将顶端氮原子并入配体骨架中显著提高了反应速率。机制和标记的研究表明，不寻常的选择性是由于Rh-烷基物种的不可逆捕获沿着的分支途径，相比更可逆的线性途径。通过高压原位NMR光谱法观察到铑物种的预催化平衡混合物，这表明该平衡是催化静止状态。
We report a catalytic system comprised of nitrogen-centered di- or triphosphine ligands in conjunction with rhodium that is capable of delivering branched aldehydes from terminal olefin substrates which commonly give more linear aldehydes than branched. The incorporation of an apical nitrogen atom into the ligand backbone dramatically improves the reaction rate. Mechanistic and labeling studies suggest the unusual selectivity is due to the irreversible trapping of the Rh–alkyl species along the branched pathway, in comparison to the more reversible linear pathway. A precatalytic equilibrium mixture of rhodium species was observed by high-pressure in situ NMR spectroscopy, suggesting this equilibrium is the catalytic resting state.