Reacción #79340

Ecuación de reacción

Ethylene glycol

p-toluenesulfonic acid

1-(2-bromo-5-fluorophenyl)ethanone

NaHCO3

→

2-(2-bromo-5-fluorophenyl)-2-methyl-1,3-dioxolane

Rendimiento 60.2%

Disolventes

benzene

H2O

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroThe reaction mixture was equipped with a Dean Stark trap
2. 2
   workup.ADDITIONcontaining 4.0 angstrom molecular sieves
3. 3
   Temperaturarefluxed for 16 h
4. 4
   OtroThe reaction was transferred to a separatory funnel
5. 5
   workup.ADDITIONcontaining
6. 6
   Extracciónextracted with EtOAc (3×100 mL)
7. 7
   LavadoThe combined organics were washed with H2O, brine
8. 8
   Secadodried over Na2SO4
9. 9
   Concentraciónconcentrated
10. 10
    OtroThe resulting oil was purified by column chromatography

Procedimiento

Ethylene glycol (25.6 mL, 458 mmol) and p-toluenesulfonic acid (4.36 g, 22.9 g) were added to a solution of 1-(2-bromo-5-fluorophenyl)ethanone (10.5 g, 45.8 mmol) stirring in benzene (250 mL). The reaction mixture was equipped with a Dean Stark trap containing 4.0 angstrom molecular sieves and refluxed for 16 h. The reaction was transferred to a separatory funnel containing a 1:1 mixture of H2O and sat. NaHCO3 (aq) and extracted with EtOAc (3×100 mL). The combined organics were washed with H2O, brine, dried over Na2SO4 and concentrated. The resulting oil was purified by column chromatography to give 2-(2-bromo-5-fluorophenyl)-2-methyl-1,3-dioxolane (7.20 g) in 58% yield. 1H NMR (CDCl3, 300 MHz) δ2.60 (s, 3 H) 4.02-4.20 (m, 4H), 6.85-6.90 (m, 1H), 7.29-7.33 (m, 1H), 7.48-7.56 (m, 1H).

Fuente