Acetophenone → 1-Phenylethanol, (R)-

Participants

Reaction Steps

A ruthenium hydride complex was then prepared using the ruthenium chloride thus obtained, and this complex was used without isolation to carry out chiral hydrogenation of acetophenone. That is, trans-RuCl2[(S)-xylbinap][(S)-daipen] (1.5 mg; 0.00125 mmol) and sodium borohydride (0.9 mg; 0.025 mmol) were weighed and placed in a 100 mL glass autoclave equipped with a stirrer coated with polytetrafluoroethylene, and after depressurizing the interior of the vessel to eliminate air, argon was introduced. 2-propanol (1 mL) , which had been deaerated by argon bubbling in advance, was then added into the vessel by means of a syringe and under an argon gas flow. The procedure of performing pressure reduction and argon introduction while stirring the solution obtained was then repeated 5 times for deaeration, and then upon immersing in an oil bath for 5 minutes at 65° C., vigorous stirring was subsequently performed for 30 minutes at room temperature. Acetophenone (600 mg; 5.0 mmol) and 2-propanol (1.5 mL) were then added into the vessel by means of a syringe and under an argon gas flow. The procedure of performing pressure reduction and argon introduction while stirring the solution obtained was then repeated 5 times for deaeration. A hydrogen tank was then connected to the autoclave using a hydrogen introduction tube and the replacement of the air inside the introduction tube with hydrogen at 2 atmospheres was performed 5 times. The pressure inside the autoclave was then adjusted to 5 atmospheres and then hydrogen was released carefully until the pressure dropped to 1 atmosphere. After repeating this procedure 10 times, the hydrogen pressure was adjusted to 8 atmospheres and vigorous stirring at 25° C. was performed for 12 hours. After completion of reaction, by concentrating the solution obtained by depressurization and subjecting the same to simple distillation under reduced pressure (1 mmHg), (R)-1-phenylethanol (579 mg; 4.75 mmol; yield: 95%; enantiomeric excess: 98%) was obtained.

Provenance & Evidence