1,1-Dibromoethane → 5-Methyl-1,4-benzodioxane

Dry potassium carbonate (0.93 eq.) is added to a solution of ortho-methylcatechol (10 g) dissolved in 150 ml of acetone under an argon atmosphere; the reaction mixture is heated to a gentle reflux and dibromoethane (0.4 eq.) is then added. Those operations are repeated twice at 15 minute intervals and in identical proportions (that is to say, in total 2.8 eq. of K2CO3 and 1.2 eq. of dibromoethane are added). After 12 hours' reflux, the latter is again introduced into the reaction mixture in an altogether identical amount (that is, 1.2 eq.). Heating is continued for 72 hours. The solution obtained is cooled, the salts are then filtered off over Celite and the filtrate is concentrated, hydrolysed with 60 ml of water and then extracted with dichloromethane. The recovered organic phase is washed with a 5% sodium hydroxide solution, dried over magnesium sulphate and evaporated. The cyclised product is purified over a flash silica column eluted with a 2:8 AcOEt/PE mixture (PE=petroleum ether). Yellow oil.

1. temperaturethe reaction mixture is heated to
2. temperaturea gentle reflux
3. temperatureAfter 12 hours' reflux
4. additionthe latter is again introduced into the reaction mixture in an altogether identical amount (
5. temperatureHeating
6. waitis continued for 72 hours
7. customThe solution obtained
8. temperatureis cooled
9. filtrationthe salts are then filtered off over Celite
10. concentrationthe filtrate is concentrated, hydrolysed with 60 ml of water
11. extractionextracted with dichloromethane
12. washThe recovered organic phase is washed with a 5% sodium hydroxide solution
13. dry with materialdried over magnesium sulphate
14. customevaporated
15. customThe cyclised product is purified over a flash silica column
16. washeluted with a 2:8 AcOEt/PE mixture (PE=petroleum ether)

ORD record

ord-3861b55684ca4b97b8f28eabafea90ef

Source dataset

uspto-grants-1999_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05919814