The general procedure for the synthesis of (R)-1-[3,5-bis(trifluoromethyl)phenyl]ethanol from 3,5-bis(trifluoromethyl)acetophenone and cis-1-amino-2,3-dihydro-1H-inden-2-ol is as follows:
Example 5: To 2-propanol (21 L), [RuCl2 (p-cymene)]2 (18.4 g), (1S,2R)-cis-1-amino-2,3-dihydro-1H-inden-2-ol (9.0 g), and 1-(3,5-bis(trifluoromethyl)phenyl)ethan-1-one (3 kg) were added, stirred for 30 minutes and thoroughly degassed under vacuum. Subsequently, 5M sodium hydroxide solution (28mL) was added and the mixture was aged for 4-6 hours to ensure complete conversion of the feedstock. Upon completion of the reaction, the reaction mixture was poured into 1N HCl (21 L) and extracted with heptane (2 x 10.5 L). The organic layers were combined, washed with brine, and 1,4-diazabicyclo[2.2.2]octane (740 g) was added. The solution was concentrated to nearly 4 mL/g of alcohol (KF < 200 μg/mL; 2-propanol < 5 vol%). After inoculation at 40°C, the mixture was allowed to cool to room temperature to form crystalline species, which were further cooled to 0°C. The crystalline product was obtained by filtration, washed with cold heptane and dried to give the final DABCO complex in 75-80% yield and ee value >99%.