Diethyl Malonate → 1,1-Diethyl cyclopent-3-ene-1,1-dicarboxylate

Participants

Reaction Steps

To a stirred solution of 160 g of diethyl malonate in 1.5 1 of dry dimethylformamide at 0° C. under nitrogen was slowly added 30 g of lithium hydride. After the evolution of hydrogen ceased (2 hours) 143 g of cis-1,4-dichloro-2-butene was slowly added and the mixture allowed to come to room temperature. After 72 hours, the mixture was diluted with a mixture of ether and hexane (1:4) and poured into water. The organic layer was washed with water and brine before drying over magnesium sulfate. Distillation gave diethyl 3-cyclopentene-1,1-dicarboxylate, bp 70-80° C./0.1 mm, containing a small amount (~10%) of diethyl 2-vinylcyclo- propane-1,1-dicarboxylate.

Provenance & Evidence