Reacción #1687648

Ecuación de reacción

acetyl chloride

pyridine

THF

sodium hydrogen carbonate

3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-1-benzopyran-2-carboxylate

→

3,4-dihydro-6-acetyl-2,5,7,8-tetramethyl-1-benzopyran-2-carbonyl chloride

Disolventes

water

Condiciones de reacción

Tratamiento posterior

1. 1
   Otrowas reduced to 0° C.
2. 2
   Temperaturarefluxed for 1 hour
3. 3
   TemperaturaThe solution was cooled
4. 4
   ExtracciónThe solution was extracted three times with DCM
5. 5
   Secadothe DCM dried (sodium sulphate)
6. 6
   Otroevaporated to dryness
7. 7
   workup.DISSOLUTIONThe hydroxy acetyl was redissolved in dry THF (100 ml)
8. 8
   workup.ADDITIONoxalyl chloride (10% solution 50 ml, excess) was slowly added at 10° C. under an atmosphere of di-nitrogen
9. 9
   Temperaturato warm to ambient temperature
10. 10
    OtroThe clear solution was evaporated to dryness at 50° C.

Procedimiento

To a 1 liter round bottom flask with an atmosphere of di-nitrogen was added dry pyridine (10.00 g, excess mole) and dry THF solvent to dissolve 3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-1-benzopyran-2-carboxylate (24.9 g). The temperature was reduced to 0° C. and acetyl chloride (15 ml) slowly added with agitation. The solution was observed to be yellow. The solution was allowed to warm up to ambient temperature and then refluxed for 1 hour. The solution was cooled, reduced in volume (100 ml) and water added with a sodium hydrogen carbonate (1 g). The solution was extracted three times with DCM, the DCM dried (sodium sulphate) and evaporated to dryness. The hydroxy acetyl was redissolved in dry THF (100 ml) and oxalyl chloride (10% solution 50 ml, excess) was slowly added at 10° C. under an atmosphere of di-nitrogen. The solution was allowed to warm to ambient temperature and stirred for 12 hours. The clear solution was evaporated to dryness at 50° C. and 10 mbar to give 3,4-dihydro-6-acetyl-2,5,7,8-tetramethyl-1-benzopyran-2-carbonyl chloride. The solid was washed with saturated sodium bicarbonate and vacuum dried. A carbon 13 NMR clearly showed the aromatic ring and the acetyl functionality.

Fuente