反应详情

110 g of pyrocatechol, 276 g of potassium carbonate and 303 g of 1,3-dibromopropane were stirred at 120° C. for 48 hours in 800 ml of absolute dimethylformamide. The cooled suspension was filtered under suction, the residue was back-washed with ether and the filtrate was poured into 4 l of water. This was extracted with ether. The ether extract was washed twice with 3N sodium hydroxide and then neutral with water, dried over sodium sulfate and evaporated in vacuo. The residue (146.6 g) was distilled at 11 mm/118°-120° C. 61.9 g (41.2% of theory) of 3,4-dihydro-2H-1,5-benzodioxepine were obtained.

1. filtrationThe cooled suspension was filtered under suction
2. washthe residue was back-washed with ether
3. additionthe filtrate was poured into 4 l of water
4. extractionThis was extracted with ether
5. extractionThe ether extract
6. washwas washed twice with 3N sodium hydroxide
7. dry with materialneutral with water, dried over sodium sulfate
8. customevaporated in vacuo
9. distillationThe residue (146.6 g) was distilled at 11 mm/118°-120° C