Hydridotetrakis(triphenylphosphine)rhodium(I)

Typical Procedure: (1,2-Reduction) (Ph3P)4RhH (ca. 5 mg) is placed in a 10 mL flask furnished with a magnetic stirring bar and sealed with a rubber septum under argon. Dried CH2Cl2 (1 mL) is added via a syringe followed by the alpha,beta-unsaturated ketone (1 mmol). After 10 min, diphenylsilane (1.3 mmol) is added dropwise. The reaction mixture is stirred at room temperature for 4 h and then transferred to a 25 mL flask with a solution of HCl (2 N, 3 mL)―acetone (3 mL). The mixture is stirred at room temperature for 2 h. Acetone is removed via rotary evaporation. The aqueous residue is then extracted with dichloromethane (4 × 3 mL). The combined organic layers are dried over Na2SO4. Removed of solvent gives the crude product, which is purified by flash column chromatography separation or Kugelrohr distillation. (1,4-Reduction) In a 5 mL flask furnished with a magnetic stirring bar and sealed with a rubber septum, (Ph3P)4RhH (ca. 5 mg) is placed under argon. The alpha,beta-unsaturated ketone (1 mmol) is introduced to the flask via a syringe followed by the dimethylphenylsilane (1.1 mmol). The reaction mixture is stirred at room temperature for 12 h, and then hexane (1 mL) are added. The mixture is filtered and the solvent is removed to get the crude product, which is purified by Kugelrohr distillation.