Benzaldehyde → (R)-(+)-1-Phenyl-1-propanol

Participants

Reaction Steps

Reaction of benzaldehyde with diethylzinc in the presence of (R)-3,3'-bis(2",5"-dihexyloxyphenyl)-1,1'-bi-2-naphthol to give (R)-1-phenyl-1-propanol. (R)-3,3'-bis(2",5"-dihexyloxyphenyl)-1,1'-bi-2-naphthol (42 mg, 0.05 mmol) and diethylzinc (0.21 mL, 2 mmol) were added to a Schlenk flask containing toluene (10 mL, dried with Na and degassed with N2) , under nitrogen and at room temperature, to form the organozinc species. The resulting mixture was stirred at r.t. for ca. 15 min. The flask was cooled to 0° C. and benzaldehyde (0.1 mL, 1 mmol) was then added dropwise. The yellow color of the mixture faded in 4 hours, which indicated the completion of the reaction. 1N HCl was added to quench the reaction at 0° C. and the aqueous layer was extracted with ether. The combined organic extracts were washed with brine until pH=7 and then dried over anhydrous Na2SO4. The purification by column chromatography on silica gel with EtOAc/hexanes (1:5) gave (R)-1-phenylpropanol as a colorless liquid (129 mg, 95%). HPLC analysis on a Chiracel-OD column (eluent: isopropanol/hexane=1/9; 1 mL/min) indicated an ee of 99.3%. The retention time of the (R)-isomer is 7.45 min and (S)-isomer is 8.8 min. 1H NMR (270 MHz, CDCl3): 0.90 (t, J=7.5, 3H), 1.74 (m, 2H), 2.73 (s, 1H), 4.52 (t, J=6.5, 1H), 7.23-7.38 (m, 5H).

Provenance & Evidence