Fig. 4: Substrate scope of Ru-catalyzed hydrogenation reactions.
From: Asymmetric hydrogenation of 1,1-diarylethylenes and benzophenones through a relay strategy
Synthesis of compounds bearing a chiral gem-diaryl motif from either 1,1-diarylethylenes or benzophenones by a sequence involving selective arene exchange and stereoselective asymmetric hydrogenation. Reaction conditions, unless otherwise stated: (1) 1 (0.2 mmol), 2 (0.3 mmol), dioxane (2 mL), 80 °C, 24 h. (2) Ru-1 (3 mol%), NaOtBu (15 mol%), toluene (1.5 mL), H2 (5 atm), 0 °C, 36 h; then irradiation with 440 nm LEDs for 2 h in air at room temperature. a(1) 2 (0.22 mmol). b(2) Room temperature. c(2) Hexane (1.5 mL), H2 (50 atm). Isolated yields were reported. The absolute configurations of 4a, 4e, 4 h, and 4 m were S, as determined by comparison of their optical rotations with reported data.
