N,N,N',N'-Tetramethylethylenediamine → (E)-2-cyano-3-(2,2-difluoro-1,3-benzodioxol-4-yl)-2-propenoic acid ethyl ester

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Reaction Steps

40.0 g (253 mmol) of 2,2-difluoro-1,3-benzodioxole in 29.5 g (254 mmol) of TMEDA and 35 ml of toluene are metallated analogously to Example 2c) at from -15° to -10° C. with 106.2 g (307 mmol) of n-butyllithium solution (18.5% in toluene). 52.1 g (308 mmol) of ethoxymethylenecyanoacetic acid ethyl ester in 115 ml of toluene are added to the reaction mixture at from -15° to -10° C. over a period of 2 hours. The resulting suspension is poured, after 20 minutes at +10° C., into 350 ml of water, the aqueous phase is separated off and the organic phase is concentrated by evaporation in a vacuum rotary evaporator to yield the desired product.

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