Reacción #792178

Ecuación de reacción

6-chloro-8-methyl-2H-3,1-benzoxazine-2,4(1H)-dione

Oxalyl chloride

1-(3-chloro-2-pyridinyl)-3-(2,2,2-trifluoroethoxy)-1H-pyrazole-5-carboxylic acid

Pyridine

→

title product

6-Chloro-2-[1-(3-chloro-2-pyridinyl)-3-(2,2,2-trifluoroethoxy)-1H-pyrazol-5-yl]-8-methyl-4H-3,1-benzoxazin-4-one

Disolventes

dichloromethane

acetonitrile

Condiciones de reacción

Tratamiento posterior

1. 1
   Concentraciónconcentrated under vacuum
2. 2
   workup.DISSOLUTIONThe isolated acid chloride was dissolved in dry acetonitrile (10 mL)
3. 3
   Temperaturathe solution heated
4. 4
   Temperaturaat reflux 6 hours
5. 5
   TemperaturaAfter cooling
6. 6
   Otroa precipitate of white solid (9.15 g) was collected
7. 7
   OtroA small portion of the collected precipitate was recrystallized from acetonitrile

Procedimiento

To a suspension of 1-(3-chloro-2-pyridinyl)-3-(2,2,2-trifluoroethoxy)-1H-pyrazole-5-carboxylic acid (i.e. product of Step C) (7.9 g, 24 mmol) stirred in dichloromethane (100 mL) was added N,N-dimethylformamide (4 drops). Oxalyl chloride (4.45 g, 35 mmol) was added dropwise over a period of 45 minutes. The resulting solution was stirred at room temperature for 4 hours and then concentrated under vacuum. The isolated acid chloride was dissolved in dry acetonitrile (10 mL) and added to a suspension of 6-chloro-8-methyl-2H-3,1-benzoxazine-2,4(1H)-dione (i.e. product of Step D) (4.9 g, 23 mmol) stirred in dry acetonitrile (14 mL). Pyridine (10 mL) was added, and the solution heated at reflux 6 hours. After cooling using an ice bath, a precipitate of white solid (9.15 g) was collected. The 1H NMR spectrum of the collected precipitate showed peaks consistent with the title compound and residual 6-chloro-8-methyl-2H-3,1-benzoxazine-2,4(1H)-dione starting material. A small portion of the collected precipitate was recrystallized from acetonitrile to yield the pure title product melting at 178-180° C.

Fuente