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 1.6M solution of n-butyllithium in hexane are added dropwise and the mixture is then stirred 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 quickly and the mixture is stirred 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 by settling, 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 2400 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. customto return to RT
2. temperatureThe reaction mixture is cooled to −20° C.
3. stirringthe mixture is stirred
4. customto return to RT
5. stirringAfter stirring for 30 minutes at RT
6. customthe phases are separated
7. extractionthe aqueous phase is extracted with ether
8. washthe combined organic phases are washed twice with water
9. dry with materialdried over Na2SO4
10. customthe solvents are evaporated off under vacuum
11. customThe excess diethyl oxalate is removed by distillation under vacuum (b.p.=90° C. at 2400 Pa)
12. customThe resulting crude product is chromatographed on silica gel
13. washeluting with a heptane/iso ether mixture (90/10; v/v)