Highly Regio- and Enantioselective Hydroformylation of Vinyl Esters Using Bidentate Phosphine,P-Chiral Phosphorodiamidite Ligands

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• 作者：Christian Schmitz ; Katharina Holthusen ; Walter Leitner ; Giancarlo Franciò
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：March 4, 2016
• 年：2016
• 卷：6
• 期：3
• 页码：1584-1589
• 全文大小：368K
• ISSN：2155-5435

文摘

Hybrid bidentate phosphine-phosphorodiamidite ligands based on a chiral Betti base backbone and diphenylphosphinoaniline derivatives have been prepared (BettiPhos). The ligands possess a stereogenic P atom at the phosphorodiamidite moiety, whose configuration can be largely controlled by the synthetic route and the choice of base and solvent. The new ligands were applied in the rhodium-catalyzed asymmetric hydroformylation (AHF) of vinyl esters and vinyl amides. Very high enantioselectivities of up to 97% ee accompanied by excellent regioselectivities (up to b/l > 1000) were obtained using the BettiPhos ligand (S_C,S_C,R_P,S_C)-4b bearing an additional chiral group at the aniline nitrogen. The catalyst resting state [RhH(CO)₂{(S_C,S_C,R_P,S_C)-4b}] was investigated by high pressure-NMR studies, revealing an equatorial–apical coordination of the bidentate ligand where the two phosphorus donors rapidly exchange their positions through an intermediate with the ligand bound via the phosphine group only.