Réaction #1833219

Équation de réaction

1,1,2-Trichloro-1,2,2-trifluoroethane

2,2,6,6-Tetramethylpiperidine

n-butyllithium

NH4Cl

5-Bromo-2,2-difluorobenzo[d][1,3]dioxole

→

title compound

Rendement 28.1%

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

Rendement 28.1%

Solvants

water

diethyl ether

tetrahydrofuran

Conditions de réaction

Traitement

1. 1
   workup.STIRRINGthe mixture was stirred for 2 h at −75° C
2. 2
   workup.STIRRINGstirring
3. 3
   workup.WAITwas continued for 1.5 h
4. 4
   LavageThe ether phase was washed with saturated NaCl (10 mL)
5. 5
   Séchagedried (Na2SO4)
6. 6
   Autreevaporated under vacuum
7. 7
   AutreThe residue was purified by chromatography on silica with hexane
8. 8
   Autrerepurified by reverse-phase

Mode opératoire

2,2,6,6-Tetramethylpiperidine (2.1 mL, 1.8 g, 12 mmol) was dissolved in dry tetrahydrofuran (15 mL), cooled to −75° C. and treated with n-butyllithium (n-BuLi, 2.5 M; 4.8 mL, 12 mmol), and the mixture was stirred for 30 min at −75° C. 5-Bromo-2,2-difluorobenzo[d][1,3]dioxole (2.0 g, 8.4 mmol) was added, and the mixture was stirred for 2 h at −75° C. 1,1,2-Trichloro-1,2,2-trifluoroethane (2.4 mL, 3.8 g, 20 mmol) was added and stirring was continued for 1.5 h. Saturated NH4Cl (10 mL) was added, and the mixture was shaken with diethyl ether (30 mL) and water (20 mL). The ether phase was washed with saturated NaCl (10 mL), dried (Na2SO4) and evaporated under vacuum. The residue was purified by chromatography on silica with hexane and then repurified by reverse-phase HPLC using 75% acetonitrile to give the title compound as a clear liquid (640 mg, 28%): 1H NMR (400 MHz, CDCl3) δ 7.38 (dd, J=8.5, 5.1 Hz, 1H), 6.90 (dd, J=9.0, 4.7 Hz, 1H); EIMS m/z 332.

Source