Reacción #4552

Ecuación de reacción

4-chloro-2-fluorophenol

2-chloro-6-fluorophenol

2-chloro-6-fluorophenol

4-fluoronitrobenzene

dichlorofluorophenol

4-chloro-2-fluorophenol

NaCl

NaOH

potassium carbonate

→

desired product

2-[4-(4-chloro-2-fluorophenoxy)phenoxy]propionic acid methyl ester

Disolventes

DMSO

Condiciones de reacción

Tratamiento posterior

1. 1
   Extracciónthe resulting mixture extracted with ether (2×300 ml)
2. 2
   Lavadowashed with water (an emulsion
3. 3
   Otroformed which
4. 4
   Secadodried (MgSO4)
5. 5
   Otrothe solvent removed
6. 6
   workup.DISTILLATIONThe material was subjected to Kugelrohr distillation (oven temp.=135°-145°)

Procedimiento

To a stirred mixture of potassium carbonate (25.04 g; 0.18 mol) in DMSO (200 ml) under argon atmosphere was added an 8:2 mixture (25 g; 0.171 mol) (from Step 2A) of 4-chloro-2-fluorophenol (~20 g; 0.136 mol) and 2-chloro-6-fluorophenol (~5 g; 0.034 mol). To this mixture was added 4-fluoronitrobenzene (18.05 g; 0.128 mol) and the resulting mixture stirred at 100° C. for 30 minutes. At the end of this time, g.c. showed that the mixture contained (peak areas) ~10% of 2-chloro-6-fluorophenol, ~3% of a dichlorofluorophenol, a trace of 4-chloro-2-fluorophenol, and a single product peak. This mixture was poured into aqueous base (~1% NaOH) and the resulting mixture extracted with ether (2×300 ml). The ether extracts were combined, washed with water (an emulsion formed which required a little saturated aqueous NaCl to break), dried (MgSO4) and the solvent removed to given an orange-red oil (34 g). 19F NMR (CDCl3) showed that essentially a single isomer to be present. The material was subjected to Kugelrohr distillation (oven temp.=135°-145°) to give the desired product as a light yellow oil (32 g): RI=1.6038 @ 25° C. Recrystallization from hexane (freezer) gave the product as a white solid: m.p.=55°-57° C.

Fuente