Hydrochloric Acid → 1-(4-Fluorophenyl)-1-hydroxyacetone

Temperature

-78 °C

A suspension of ground LaCl3 (26 mg, 0.104 mmol) in dry THF (7.8 mL) under N2 was cooled to −78° C. and stirred for 15 min. A solution of n-BuLi (1.6 M in hexanes, 195 μL, 0.312 mmol) was added and stirring was continued for 15 min. The reaction was warmed to 0° C. and stirred for 30 min. Trimethylsilyl cyanide (31 mg, 42 μL, 0.312 mmol) was added and the reaction was stirred for 30 min at 0° C. and warmed to room temperature over 30 min. A solution of acetyltrimethylsilane (Cunico, R. F., Kuan, C.-P., J. Org. Chem., 1985, 50, 5410-5413) (121 mg, 1.04 mmol) and 4-fluorobenzaldehyde (142 mg, 1.14 mmol) in dry THF (19 mL) was added by cannula and the reaction was stirred at room temperature for 2 h. After this time 1N HCl (24 mL) was added and the reaction was stirred for 1 h. Et2O (25 mL) was added and the organic layer was separated and washed with H2O (2×25 mL). The combined aqueous layers were extracted with Et2O (3×50 mL). The combined organic extracts were dried (MgSO4) and concentrated in vacuo to give the crude product. This was purified by flash chromatography (Si, 25×160 mm, 0-50% EtOAc in hexanes gradient) to give 1-(4-fluorophenyl)-1-hydroxyacetone as a colorless solid. Rf=0.31 (20% EtOAc/hexanes). 1H NMR (CDCl3, 500 MHz) δ 7.29 (m, 2H), 7.08-7.04 (m, 2H), 5.06 (d, J=3.6 Hz, 1H), 4.35 (t, J=6.5 Hz, 1H), 2.05 (s, 3H).

1. stirringstirring
2. waitwas continued for 15 min
3. temperatureThe reaction was warmed to 0° C.
4. stirringstirred for 30 min
5. stirringthe reaction was stirred for 30 min at 0° C.
6. temperaturewarmed to room temperature over 30 min
7. stirringthe reaction was stirred at room temperature for 2 h
8. stirringthe reaction was stirred for 1 h
9. customthe organic layer was separated
10. washwashed with H2O (2×25 mL)
11. extractionThe combined aqueous layers were extracted with Et2O (3×50 mL)
12. dry with materialThe combined organic extracts were dried (MgSO4)
13. concentrationconcentrated in vacuo
14. customto give the crude product
15. customThis was purified by flash chromatography (Si, 25×160 mm, 0-50% EtOAc in hexanes gradient)

ORD record

ord-c465965d01fe44d6b8a85cdc1d3b4e4c

Source dataset

uspto-grants-2014_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08735435B2