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  • Structural Investigations o...
    Fernández‐Pérez, Héctor; Balakrishna, Bugga; Vidal‐Ferran, Anton

    European journal of organic chemistry, April 9, 2018, Letnik: 2018, Številka: 13
    Journal Article

    A second generation of phosphine–phosphite (P–OP) ligands, incorporating a more sterically bulky phosphite group than previous P–OP ligand designs, gave very efficient catalysts for the Rh‐catalysed asymmetric hydrogenation of a diverse array of substrates (11 examples, 93–99 % ee) containing structurally diverse substituents and chelating groups at the C=C double bond. The presence of the sterically bulky (Sa)‐3,3′‐diphenyl‐5,5′,6,6′,7,7′,8,8′‐octahydro‐1,1′‐binaphthalene‐2,2′‐diol‐derived phosphite fragment caused significant increases in enantioselectivity (up to Δee = 58 %), and provided improved results compared to those obtained with the first generation of P–OP‐derived rhodium catalysts {i.e., rhodium complexes incorporating phosphine–phosphite ligands with (Ra)‐ and (Sa)‐BINOL‐derived phosphite groups; BINOL = 1,1′‐binaphthalene‐2,2′‐diol}. Overall, the optimal ligand L8 provided very high enantioselectivities for a range of structurally diverse olefins (up to 99 % ee). A second generation of phosphine–phosphite (P–OP) ligands, incorporating a larger phosphite group than previous P–OP ligand designs, led to very efficient catalysts for the Rh‐catalyzed enantioselective hydrogenation of a diverse array of substrates (11 examples, 93–99 % ee, mean value of 98 % ee).