Reaction #1833241

Reaction equation

HCl

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

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

NH4Cl

→

title compound

4,4,5,5-Tetramethyl-2-(2,2,7-trifluorobenzo[d][1,3]dioxol-5-yl)-1,3,2-dioxaborolane

Solvents

ethyl acetate

NaCl

tetrahydrofuran

Conditions

Workup

1. 1
   workup.ADDITIONtreated in portions with isopropylmagnesium lithium chloride complex (1.3 M; 6.3 mL, 8.2 mmol)
2. 2
   OtherThe cooling bath was removed
3. 3
   workup.STIRRINGthe mixture was stirred for 1 h
4. 4
   WashThe organic phase was washed with saturated NaCl (5 mL)
5. 5
   Dryingdried (Na2SO4)
6. 6
   Otherevaporated

Procedure

6-Bromo-2,2,4-trifluorobenzo[d][1,3]dioxole (2.0 g, 7.8 mmol) was dissolved in dry tetrahydrofuran (10 mL), cooled to −5 to 0° C. and treated in portions with isopropylmagnesium lithium chloride complex (1.3 M; 6.3 mL, 8.2 mmol). The cooling bath was removed and the mixture was stirred for 30 min. 2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1.6 g, 8.4 mmol) was added, the mixture was stirred for 1 h and then treated with saturated NH4Cl (5 mL). The mixture was diluted with ethyl acetate (40 mL) and saturated NaCl (10 mL) and the pH was adjusted to 2 by addition of HCl. The organic phase was washed with saturated NaCl (5 mL), dried (Na2SO4) and evaporated to give the title compound which was used without further purification (2 g, 85%): 1H NMR (400 MHz, CDCl3) δ 7.36 (d, J=9.8 Hz, 1H), 7.29 (d, J=6.5 Hz, 1H), 1.33 (s, 12H); 19F NMR (376 MHz, CDCl3) δ −49.79, −136.26; EIMS m/z 302.

Source