تفاعل #1687648

معادلة التفاعل

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

المذيبات

water

ظروف التفاعل

المعالجة

1. 1
   أخرىwas reduced to 0° C.
2. 2
   درجة الحرارةrefluxed for 1 hour
3. 3
   درجة الحرارةThe solution was cooled
4. 4
   استخلاصThe solution was extracted three times with DCM
5. 5
   تجفيفthe DCM dried (sodium sulphate)
6. 6
   أخرىevaporated 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
   درجة الحرارةto warm to ambient temperature
10. 10
    أخرىThe clear solution was evaporated to dryness at 50° C.

الإجراء التجريبي

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.

المصدر