Reacción #43295

Ecuación de reacción

5-chloro-2,3-dihydroxy-benzoic acid methyl ester

1,3-dibromopropane

K2CO3

→

methyl 8-chloro-3,4-dihydro-2H-1,5-benzodioxepin-6-carboxylate

Rendimiento 94.8%

Disolventes

2-propanone

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturarefluxed for 20 hours
2. 2
   Filtraciónfiltered hot
3. 3
   Otrothe filtrate was evaporated
4. 4
   OtroThe residue was purified by column chromatography over silica gel (eluent: DCM)
5. 5
   OtroThe desired fractions were collected
6. 6
   Otrothe solvent was evaporated
7. 7
   workup.ADDITIONToluene was added
8. 8
   Otroazeotroped on the rotary evaporator

Procedimiento

A mixture of 5-chloro-2,3-dihydroxy-benzoic acid methyl ester (0.3 mol), 1,3-dibromopropane (0.42 mol) and K2CO3 (0.66 mol) in 2-propanone (500 ml) was stirred and refluxed for 20 hours, then filtered hot and the filtrate was evaporated. The residue was purified by column chromatography over silica gel (eluent: DCM). The desired fractions were collected and the solvent was evaporated. Toluene was added and azeotroped on the rotary evaporator, yielding 69 g of methyl 8-chloro-3,4-dihydro-2H-1,5-benzodioxepin-6-carboxylate (intermediate 5).

Fuente