Reaction #1833222

Reaction equation

5-Bromo-2,2,4-trifluorobenzo[d][1,3]dioxole

isopropylmagnesium chloride lithium chloride

2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

→

title compound

Yield 72.4%

4,4,5,5-Tetramethyl-2-(2,2,4-trifluorobenzo[d][1,3]dioxol-5-yl)-1,3,2-dioxaborolane

Yield 72.4%

Solvents

tetrahydrofuran

NH4Cl

ethyl acetate

Conditions

Workup

1. 1
   workup.STIRRINGstirring
2. 2
   workup.WAITwas continued for 1 h at 10-15° C
3. 3
   WashThe organic phase was washed with saturated NaCl (15 mL)
4. 4
   Dryingdried (Na2SO4)
5. 5
   Otherevaporated

Procedure

5-Bromo-2,2,4-trifluorobenzo[d][1,3]dioxole (4.0 g, 16 mmol) was dissolved in 20 mL dry tetrahydrofuran, cooled to −20° C. and treated with isopropylmagnesium chloride-lithium chloride complex (1.3 M in tetrahydrofuran; 13 mL, 17 mmol) in portions over 10 min. After stirring for 30 min at −20 to 0° C., 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (3.1 g, 17 mmol) was added, and stirring was continued for 1 h at 10-15° C. After treatment with saturated NH4Cl solution (10 mL), the mixture was diluted with ethyl acetate (50 mL). The organic phase was washed with saturated NaCl (15 mL), dried (Na2SO4) and evaporated to give the title compound as a brown solid (3.5 g, 72%): 1H NMR (400 MHz, CDCl3) δ 7.46 (d, J=26.5 Hz, 1H), 6.90 (dd, J=18.5, 4.5 Hz, 1H), 1.35 (s, 12H); 19F NMR (376 MHz, CDCl3) δ −49.70 (s), −126.00 (s); EIMS m/z 302.

Source