Reacción #1880957

Ecuación de reacción

methyl 4-allyl-2-(ethoxycarbonylmethoxy)phenoxyacetate

sodium hydride

hydrochloric acid

→

7-allylbenzo[b][1,4]dioxepin-3-one

Rendimiento 42.0%

Disolventes

tetrahydrofuran

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe reaction mixture was then refluxed for 20 h
2. 2
   Temperaturaafter cooling
3. 3
   Extracciónextracted three times
4. 4
   SecadoThe combined ether extracts were dried over sodium sulfate
5. 5
   Otrofreed from solvent on a rotary evaporator
6. 6
   workup.ADDITION400 ml of 2N hydrochloric acid were added
7. 7
   Temperaturathe mixture was refluxed for 20 h
8. 8
   workup.ADDITIONThe mixture was then poured into 1.5 l of ice water
9. 9
   Extracciónthe product was extracted four times
10. 10
    Lavadoeach time with 1.5 l of ether, and the combined ether extracts were washed with 1 l of water and 100 ml of saturated sodium chloride solution
11. 11
    SecadoAfter drying over sodium sulfate, concentration on a rotary evaporator and flash chromatography

Procedimiento

A solution of 69.0 g (234 mmol) of methyl 4-allyl-2-(ethoxycarbonylmethoxy)phenoxyacetate was added dropwise in the course of 2.5 h to a suspension of 12.0 g (500 mmol) of sodium hydride in 500 ml of tetrahydrofuran. The reaction mixture was then refluxed for 20 h and, after cooling, poured into 1.5 l of ice water. The resultant mixture was acidified to pH 2 with 2N hydrochloric acid and extracted three times, each time with 2 l of ether. The combined ether extracts were dried over sodium sulfate, freed from solvent on a rotary evaporator and taken up into 400 ml of ethanol. 400 ml of 2N hydrochloric acid were added and the mixture was refluxed for 20 h. The mixture was then poured into 1.5 l of ice water, the product was extracted four times, each time with 1.5 l of ether, and the combined ether extracts were washed with 1 l of water and 100 ml of saturated sodium chloride solution. After drying over sodium sulfate, concentration on a rotary evaporator and flash chromatography. (pentane/ether, 4:1, Rf=0.37) on silica gel, 20.0 g (42%) of 7-allylbenzo[b][1,4]dioxepin-3-one (1) were obtained as a colorless liquid.

Fuente