反应详情

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).

1. temperaturerefluxed for 20 hours
2. filtrationfiltered hot
3. customthe filtrate was evaporated
4. customThe residue was purified by column chromatography over silica gel (eluent: DCM)
5. customThe desired fractions were collected
6. customthe solvent was evaporated
7. additionToluene was added
8. customazeotroped on the rotary evaporator