反应详情

温度

-40 °C

A mixture of 27.6 g of 1,2-dimethoxybenzene in 160 ml of ether is cooled to −40° C., 250 ml of a 1.6 M solution of n-butyllithium in hexane are added dropwise and the mixture is then left stirring for 24 hours while allowing the temperature to return to RT. The reaction mixture is cooled to −20° C., 136 ml of diethyl oxalate are added rapidly and the mixture is left stirring while allowing the temperature to return to RT. After stirring for 30 minutes at RT, the reaction mixture is poured into saturated NH4Cl solution, the phases are separated after settling has taken place, the aqueous phase is extracted with ether, the combined organic phases are washed twice with water and dried over Na2SO4, and the solvents are evaporated off under vacuum. The excess diethyl oxalate is removed by distillation under vacuum (b.p.=90° C. at 2 400 Pa). The resulting crude product is chromatographed on silica gel, eluting with a heptane/iso ether mixture (90/10; v/v). 25 g of the expected product are obtained and are used without further purification in the following step.

1. waitthe mixture is then left
2. customto return to RT
3. temperatureThe reaction mixture is cooled to −20° C.
4. waitthe mixture is left
5. stirringstirring
6. customto return to RT
7. stirringAfter stirring for 30 minutes at RT
8. customthe phases are separated after settling
9. extractionthe aqueous phase is extracted with ether
10. washthe combined organic phases are washed twice with water
11. dry with materialdried over Na2SO4
12. customthe solvents are evaporated off under vacuum
13. customThe excess diethyl oxalate is removed by distillation under vacuum (b.p.=90° C. at 2 400 Pa)
14. customThe resulting crude product is chromatographed on silica gel
15. washeluting with a heptane/iso ether mixture (90/10; v/v)