反应详情

Ethylmagnesium bromide (1.63 mL, 1M in THF, 1.63 mmol) was added dropwise to a stirred solution of 1-iodo-3,5-bis(trifluoromethyl)benzene (608 mg, 317 μL, 1.79 mmol) in dry THF (1 mL) at room temperature under N2 and the reaction was stirred for 30 min. The resulting solution was added to a stirred solution of benzyl (1,1-dimethyl-2-oxoethyl)carbamate (163.5 mg, 0.739 mmol) in dry THF (1 mL) at −20° C. and reaction was allowed to warn to room temperature over 3 h. Saturated NH4Cl (10 mL) and water (10 mL) were added and the mixture was extracted with EtOAc (3×20 mL). The combined extracts were dried (Na2SO4) and concentrated in vacuo to give the crude product. This was purified by flash chromatography (Si, 25×160 mm, 0-40% EtOAc in hexanes gradient) to afford benzyl {2-[3,5-bis(trifluoromethyl)phenyl]-2-hydroxy-1,1-dimethylethyl}carbamate. Rf=0.40 (20% EtOAc in hexanes). LCMS calc.=436.1; found=436.0 (M+1)+. 1H NMR (600 MHz, CDCl3) δ 7.80 (s, 1H), 7.77 (s, 2H), 7.39-7.33 (m, 5H), 5.12-5.08 (m, 2H), 1.36 (s, 1H), 4.90 (d, J=4.4 Hz, 1H), 4.81 (s, 1H), 1.36 (s, 3H), 1.23 (s, 3H).

1. customreaction
2. waitto warn to room temperature over 3 h
3. extractionthe mixture was extracted with EtOAc (3×20 mL)
4. dry with materialThe combined extracts were dried (Na2SO4)
5. concentrationconcentrated in vacuo
6. customto give the crude product
7. customThis was purified by flash chromatography (Si, 25×160 mm, 0-40% EtOAc in hexanes gradient)