Réaction #45672

Équation de réaction

6-bromo-4-cyano-7-fluoro-N,N,5-trimethyl-1,3-benzoxazole-2-carboxamide

tributyl(1-ethoxyvinyl)tin

2,6-di-tert-butyl-p-cresol

→

4-cyano-6-[1-(ethoxy)ethenyl]-7-fluoro-N,N,5-trimethyl-1,3-benzoxazole-2-carboxamide

Rendement 81.3%

Solvants

toluene

Conditions de réaction

Traitement

1. 1
   Températureheated
2. 2
   Températureunder reflux for 20 hours
3. 3
   TempératureAfter cooling
4. 4
   Autrethe solvent was evaporated away under reduced pressure
5. 5
   workup.ADDITIONn-hexane was added to the resulting residue
6. 6
   FiltrationNext, the precipitated solid was collected by filtration

Mode opératoire

Under nitrogen atmosphere, bis(triphenylphosphine)palladium chloride (435 mg, 620 μmol) was added to a toluene (125 ml) solution of 6-bromo-4-cyano-7-fluoro-N,N,5-trimethyl-1,3-benzoxazole-2-carboxamide (I-127) (4.04 g, 12.4 mmol), tributyl(1-ethoxyvinyl)tin (5.37 g, 14.9 mmol) and 2,6-di-tert-butyl-p-cresol (about 20 grains), and heated under reflux for 20 hours. After cooling, the solvent was evaporated away under reduced pressure, then n-hexane was added to the resulting residue and stirred at room temperature for 1 hour. Next, the precipitated solid was collected by filtration and subjected to silica gel column chromatography, and the eluate with n-hexane/ethyl acetate (1:1, v/v) gave 4-cyano-6-[1-(ethoxy)ethenyl]-7-fluoro-N,N,5-trimethyl-1,3-benzoxazole-2-carboxamide (3.20 g, 81%) as a yellow solid. The fraction containing impurities was recovered and purified in the same manner, and 3.57 g (91%) of 4-cyano-6-[1-(ethoxy)ethenyl]-7-fluoro-N,N,5-trimethyl-1,3-benzoxazole-2-carboxamide was obtained in total. The analytical data are shown below.

Source