期刊
ACS CATALYSIS
卷 2, 期 12, 页码 2779-2786出版社
AMER CHEMICAL SOC
DOI: 10.1021/cs300541m
关键词
hydroacylation; rhodium; alkyne; alkene; diphosphine
资金
- EPSRC
- Archimedes Foundation (Estonia)
- EPSRC [EP/G056609/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/G056609/1] Funding Source: researchfish
A comparative study of seven crystallographically characterized rhodium precatalysts, which contain a variety of chelating diphosphine ligands, for the hydroacylation of 1-octyne or 1-octene with 2-(methylthio)benzaldehyde has been undertaken. These studies show that the best performing catalyst for 1-octyne, [Rh(L)(eta(6)-C6H5F)][BAr4F], L = (Pr2PNMePPr2)-Pr-i-Pr-i, delivers alkyne selective hydroacylation with high efficiencies at low loadings (1 mol %, 2.0 M aldehyde, 25 degrees C, ToN = 100, 97% conversion in 5 min), and also shows high selectivity for the linear product. Experiments suggest that the alkyne selectivity arises from the alkyne being more competitive for metal binding compared to the alkene. Labeling experiments using the [Rh((Bu2PCH2PBu2)-Bu-t-Bu-t)(eta(6)-C6H5F)][BAr4F] system, that gives the final product in a linear:branched ratio of 6:1, indicate that the pathway that produces the branched product operates via an irreversible hydride insertion. Intermediate acyl hydride complexes, [Rh(L)(H)(COC6H4SMe)(acetone)][BAr4F], have been characterized by low temperature NMR spectroscopy, as have their subsequent reductive decarbonylation products, one of which has also been crystallographically characterized: [Rh((Pr2PNMePPr2)-Pr-i-Pr-i)(SMePh)(CO)][BAr4F].
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