反应详情

Diethyl 2-vinylcyclopropane-1,1-dicarboxylate was prepared as follows: Fifty percent aqueous potassium hydroxide solutin (168 g) was added dropwise to a vigorously stirred solution of 125 g (1.0 mol) trans 1,4-dichlorobutene-2, 80 g (0.50 mol) diethyl malonate and 3.2 g tricaprylymethylammonium chloride while the temperature was maintained at 25°-30° C. When the addition was complete, the reaction mixture was stirred at ambient temperature for an additional five hours. Water was then added to the reaction mixture to completely dissolve the suspended salts in the aqueous phase. The phase layers were separated and the aqueous portion extracted three times with ethyl ether. Distillation of the combined organic solutions gave 21.3 g of the desired diethyl 2-vinylcyclopropane-1,1-dicarboxylate. Bp 64°-66° C. (0.15 mm); nD27° 1.4512; [lit.bp 69°-72° C. (0.5 mm); nD19° 1.4528]. Infrared and proton nmr spectra were consistent with the desired compound. Upon acidification and extraction of the aqueous phase, 19.6 g 2-vinylcyclopropane-1,1-dicarboxylic acid was recovered so that the overall yield of cyclized product was 45.3%.

1. customDiethyl 2-vinylcyclopropane-1,1-dicarboxylate was prepared
2. temperaturewas maintained at 25°-30° C
3. additionWhen the addition
4. dissolutionto completely dissolve the suspended salts in the aqueous phase
5. customThe phase layers were separated
6. extractionthe aqueous portion extracted three times with ethyl ether
7. distillationDistillation of the combined organic solutions