Benzaldehyde → 1-Phenyl-1-propanol

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Reaction Steps

A dry Schlenk flask under argon was charged with 0.05 equiv. of the pyridinyl alcohol. The flask was evacuated twice and flushed with argon. Then, 5 mL of freshly distilled toluene were added followed by 1.5 equiv. of neat diethylzinc while stirred. After stirring for 20 min at room temperature, 1.0 equiv. of benzaldehyde (10) was added at the given temperature (see Table). The proceeding of the reaction was monitored by thin layer chromatograpy. After full conversion of the aldehyde, the reaction was quenched by careful addition of 10 mL of 2 M HCl, and the resulting mixture was extracted three times with 25 mL of dichloromethane. The combined organic phases were washed with brine, dried over MgSO4, and the solvent was removed under reduced pressure. The crude product was purified by column chromatography (silica gel, hexane/methyl tert-butylether=10:1) followed by Kugelrohr distillation to give 1-phenylpropanol (11) as a colorless oil. The enantiomeric excess of 11 was determined by HPLC on a stationary phase [CHIRALCEL OD, n-heptane/iso-propanol=98:2, 1 0 mL/min; tR=17.2 min (R); 21.5 min (S)], and the absolute configuration was determined by correlation of the optical rotation with the values reported in the literature (Soai, K.; Ookawa.; Kaba, T.; Ogawa, K.; J. Arn. Chem. Soc. 1987, 109, 7111).

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