10.1021/ja211649a
The research aims to develop highly efficient rhodium catalysts for the intermolecular hydroacylation of unactivated alkenes and alkynes with β-S-substituted aldehydes. The study focuses on using small-bite-angle diphosphine ligands, such as [Rh(C6H5F)(R2PCH2PR2)][BArF4] (where R, R′ = tBu or Cy), to create catalysts that are both bench-stable and highly active. The key chemicals used include various diphosphine ligands, fluorobenzene, and β-S-substituted aldehydes like 2-(methylthio)benzaldehyde. The researchers synthesized several catalyst precursors and characterized intermediates like acyl hydride complexes and decarbonylation products using NMR spectroscopy and X-ray crystallography. The study concludes that by carefully selecting solvents and optimizing catalyst/substrate concentrations, decarbonylation can be minimized, and very low catalyst loadings (0.1 mol %) with turnover frequencies exceeding 300 h?1 can be achieved. The developed catalysts are highly efficient, allowing for the hydroacylation of a broad range of substrates, including challenging ones like disubstituted alkenes and enol ethers. The findings suggest that these catalysts could be further developed for enantioselective applications and for reactions that do not require β-tethered aldehydes.
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