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

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Reaction Steps

Reaction of benzaldehyde with diethylzinc in the presence of the polymer of Example 2 to give (R)-1-phenyl-1-propanol. The polymer of Example 2 (28.6 mg, 0.1 mmol based on the 2,2'-substituted biphenyl subunit) and diethylzinc (0.42 mL, 4 mmol) were added to a Schlenk flask containing degassed dry dichloromethane (10 mL), to form an organozinc species. The resulting mixture was stirred at r.t. for 2.5 h. Benzaldehyde (0.2 mL, 2 mmol) was then added and the reaction mixture was stirred at r.t. for 112 h. Water (5 mL) and 1N HCl (5 mL) were added to quench the reaction. The polymer catalyst was filtered off and recovered. The organic layer in the filtrate was separated and the aqueous layer was extracted with dichloromethane. The combined organic extracts were dried over Na2SO4 and concentrated under reduced pressure. 1H NMR spectroscopic analysis of this crude product indicated a complete conversion and the ratio of 1-phenyl-1-propanol to benzyl alcohol (a side product) was 53:47. Column chromatography on silica gel (eluent: EtOAc/hexanes=1/4) gave 1-phenyl-1-propanol as a colorless liquid (117 mg, 43%). GC analysis on a chiral column (β-Dex capillary column, Supelco Company) showed an ee of 13%.

Provenance & Evidence