反应详情

温度

0 °C

To a stirred solution of (R)-MeCBS oxazaborolidine (2.9 ml, 1M solution in toluene) in dry tetrahydrofuran (5 ml) was added dropwise borane-THF complex (17.4 ml, 1M solution in tetrahydrofuran) under an argon atmosphere. The solution was cooled to 0° C. and 3′-chloro-5′-fluoroacetophenone (5.0 g) dissolved in dry tetrahydrofuran (5 ml) was added dropwise to the reaction mixture in 40 min. The reaction mixture was stirred for 1 h at 0° C. and was slowly quenched with methanol (5 ml) followed by addition of HCl 4M in ethanol (1 ml). After stirring the mixture for 5 min at 0° C., the cooling bath was removed and the white suspension was stirred at room temperature for 30 min. The suspension was filtered over celite and the filtrate was evaporated over silica gel for purification. Column chromatography (SiO2; heptane/EtOAc) afforded (S)-1-(3-chloro-5-fluoro-phenyl)-ethanol (4.50 g, 89%) as a colourless liquid. 1H NMR (300 MHz, CDCl3, δ): 1.48 (d, J=6.3 Hz, 3H), 1.92 (bs, 1H), 4.87 (q, J=6.6 Hz), 6.98 (m, 2H), 7.16 (s, 1H).

1. additionwas added dropwise to the reaction mixture in 40 min
2. customwas slowly quenched with methanol (5 ml)
3. additionfollowed by addition of HCl 4M in ethanol (1 ml)
4. stirringAfter stirring the mixture for 5 min at 0° C.
5. customthe cooling bath was removed
6. stirringthe white suspension was stirred at room temperature for 30 min
7. filtrationThe suspension was filtered over celite
8. customthe filtrate was evaporated over silica gel for purification