ethyl 4-(3,5-dimethylphenyl)-4-oxobutanoate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of ethyl-4-(3,5-dimethylphenyl)-4-oxobutyrate (0.5 g; 2.14 mmol) in THF (5 mL) was added a solution of (−)-chlorodiisopinocampheylborane (1.71 g; 5.34 mmol) in THF (1 mL). The resultant solution stirred at room temperature for 4 days. The reaction was concentrated in vacuo and dried under high vacuo for 1 h. The residue was dissolved in ethyl acetate (10 mL) and diethanolamine (470 mL) was added. A white precipitate formed and the resultant mixture was stirred for 2 h, after which the solid was filtered off and washed with pentane. The filtrate was concentrated in vacuo and purified by flash silica gel chromatography (0-20% EtOAc/hexanes gradient) to afford ethyl (4S)-4-(3,5-dimethylphenyl)-4-hydroxybutanoate as a clear oil. LCMS=219.3 (M+1−18)+. 1H NMR (CDCl3, 500 MHz): δ 6.99 (s, 2H), 6.95 (s, 1H), 4.72-4.69 (m, 1H), 4.16 (q, J=7.1 Hz, 2H), 2.45 (t, J=7.3 Hz, 2H), 2.34 (s, 6H), 2.11-2.06 (m, 2H), 1.29 (t, J=7.2 Hz, 3H). The reaction was concentrated in vacuo dried under high vacuo for 1 h The residue was dissolved in ethyl acetate (10 mL) diethanolamine (470 mL) was added A white precipitate formed after which the solid was filtered off washed with pentane The filtrate was concentrated in vacuo purified by flash silica gel chromatography (0-20% EtOAc/hexanes gradient)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a stirred solution of ethyl-4-(3,5-dimethylphenyl)-4-oxobutyrate (0.5 g; 2.14 mmol) in THF (5 mL) was added a solution of (−)-chlorodiisopinocampheylborane (1.71 g; 5.34 mmol) in THF (1 mL). The resultant solution stirred at room temperature for 4 days. The reaction was concentrated in vacuo and dried under high vacuo for 1 h. The residue was dissolved in ethyl acetate (10 mL) and diethanolamine (470 mL) was added. A white precipitate formed and the resultant mixture was stirred for 2 h, after which the solid was filtered off and washed with pentane. The filtrate was concentrated in vacuo and purified by flash silica gel chromatography (0-20% EtOAc/hexanes gradient) to afford ethyl (4S)-4-(3,5-dimethylphenyl)-4-hydroxybutanoate as a clear oil. LCMS=219.3 (M+1−18)+. 1H NMR (CDCl3, 500 MHz): δ 6.99 (s, 2H), 6.95 (s, 1H), 4.72-4.69 (m, 1H), 4.16 (q, J=7.1 Hz, 2H), 2.45 (t, J=7.3 Hz, 2H), 2.34 (s, 6H), 2.11-2.06 (m, 2H), 1.29 (t, J=7.2 Hz, 3H). The reaction was concentrated in vacuo dried under high vacuo for 1 h The residue was dissolved in ethyl acetate (10 mL) diethanolamine (470 mL) was added A white precipitate formed after which the solid was filtered off washed with pentane The filtrate was concentrated in vacuo purified by flash silica gel chromatography (0-20% EtOAc/hexanes gradient)