Reacción #1815

Ecuación de reacción

Ethanol

toluene

diethyl carbonate

sodium hydride

toluene

water

→

7-Benzyloxy-4-hydroxy-coumarin

Rendimiento 84.0%

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturawas heated
2. 2
   workup.DISSOLUTIONto dissolve the starting material
3. 3
   OtroThis solution was then taken in an addition funnel
4. 4
   Otroequipped with a mechanical stirrer
5. 5
   Otroa distillation apparatus (double jacketed-splitter heads) with a condenser, a thermocouple, and a thermometer to read
6. 6
   TemperaturaThe reaction flask was heated to 110°-115° C. with a heating mantle during the addition
7. 7
   Otrois removed as an azeotrope with toluene
8. 8
   workup.ADDITIONAdditional toluene was added through the addition funnel
9. 9
   TemperaturaThe reaction mixture was refluxed for ~5 hrs
10. 10
    Otrothe reaction
11. 11
    OtroThe contents of the reaction flask were transferred to a separatory funnel
12. 12
    Otroto separate into two phases
13. 13
    Filtraciónfiltered under vacuum
14. 14
    OtroThe crude product was recrystallized from hot methanol

Procedimiento

4-Benzyloxy-2-hydroxy-acetophenone (20 g, 0.0825 mol), prepared in accordance with Example 4, was dissolved in 150 mL of toluene. To this solution was added diethyl carbonate (25.3 g, 0.21 mol) and the entire contents taken in a beaker was heated while stirring to dissolve the starting material. This solution was then taken in an addition funnel and was added at a rate of 7-8 mL/min (addition time=1.5 hrs) to a suspension of sodium hydride (4.3 g, 10.1 mol) in toluene (100 mL) taken in a 500 mL 4-neck flask equipped with a mechanical stirrer, a distillation apparatus (double jacketed-splitter heads) with a condenser, a thermocouple, and a thermometer to read the temperature of the distillate under N2 atmosphere. The reaction flask was heated to 110°-115° C. with a heating mantle during the addition. Ethanol produced during this reaction is removed as an azeotrope with toluene. Additional toluene was added through the addition funnel to have enough of toluene in the reaction flask. The reaction mixture was refluxed for ~5 hrs to complete the reaction. The contents of the reaction flask were transferred to a separatory funnel and 400 mL of distilled water was added to separate into two phases. The aqueous layer was acidified to pH 2.0 with 1:1 dil. HCl and filtered under vacuum. The crude product was recrystallized from hot methanol; yield 84%.

Fuente