Reaction #1833252

Reaction equation

1,2,2-trifluorotrichloroethane

n-Butyllithium

2,2-Difluorobenzo[d][1,3]dioxole

1,2,2-Trifluorotrichloroethane

→

title compound

Yield 74.9%

4-Chloro-2,2-difluorobenzo[d][1,3]dioxole

Yield 74.9%

Solvents

tetrahydrofuran

tetrahydrofuran

Conditions

Workup

1. 1
   workup.ADDITIONwas added dropwise
2. 2
   Otherthe temperature below −70° C
3. 3
   Temperaturecooled to −65° C
4. 4
   workup.ADDITIONto remain between −60° C. and −65° C. during the addition
5. 5
   Temperatureto warm to room temperature
6. 6
   Otherpartitioned between diethyl ether and water
7. 7
   ConcentrationThe organic phase was concentrated

Procedure

2,2-Difluorobenzo[d][1,3]dioxole (6.3 g, 39.8 mmol) was dissolved in tetrahydrofuran (66 mL) and cooled to −78° C. n-Butyllithium (2.5 M solution in hexanes; 16.74 mL, 41.8 mmol) was added dropwise, keeping the temperature below −70° C. The reaction mixture was then stirred at −78° C. for 1 h to ensure complete deprotonation. 1,2,2-Trifluorotrichloroethane (14.93 g, 80 mmol) was dissolved in tetrahydrofuran (33 mL) and cooled to −65° C. The lithiate was transferred via cannula into the solution of 1,2,2-trifluorotrichloroethane at a rate that allowed the temperature to remain between −60° C. and −65° C. during the addition. The reaction mixture was then allowed to warm to room temperature and partitioned between diethyl ether and water. The organic phase was concentrated and the product was flashed through 100 g of silica gel using hexane as a solvent to provide the title compound as a clear oil (5.74 g, 74.8%): 1H NMR (400 MHz, CDCl3) δ 7.08 (dd, J=8.2, 1.4 Hz, 1H), 7.03 (t, J=8.0 Hz, 1H), 6.97 (dd, J=7.9, 1.5 Hz, 1H); EIMS m/z 192.

Source