反応 #65865

反応方程式

n-butyllithium

TMEDA

2,2-difluoro-1,3-benzodioxole

tetrahydrofuran

→

ethoxymethylenecyanoacetic acid ethyl ester

溶媒

hexane

反応条件

後処理

1. 1
   その他To the 2,2-difluoro-1,3-benzodioxol-4-yllithium which precipitates there
2. 2
   workup.ADDITIONis added at -20° C., over a period of 30 minutes

実験手順

7.9 g (50 mmol) of 2,2-difluoro-1,3-benzodioxole are metallated according to Example 2 at -15° C. with 35 ml (55 mmol) of n-butyllithium (1.60M in hexane) and 6.5 g (55 mmol) of TMEDA in 60 ml of hexane. To the 2,2-difluoro-1,3-benzodioxol-4-yllithium which precipitates there is added at -20° C., over a period of 30 minutes, a solution of 9.3 g (55 mmol) of ethoxymethylenecyanoacetic acid ethyl ester in 30 ml of tetrahydrofuran, an orange-red turbid solution being formed during the reaction, which is exothermic. After stirring for 20 minutes at -15° C., the solution is hydrolysed with 50 ml of 2N hydrochloric acid. The aqueous phase is extracted twice with 80 ml of diethyl ether each time. The organic solutions are washed twice with 50 ml of water each time, dried over MgSO4 and concentrated to dryness by evaporation in a vacuum rotary evaporator. The residue is crystallised from ethanol/water 4:1, affording 10.1 g (72%) of colourless platelets of m.p. 87°-88° C.

出典