2-ethoxycarbonylcyclopropane-1,1-dicarboxylic acid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: TFA (4.5 g, 39.7 mmol) was added into a solution of 1,1-di-tert-butyl 2-ethyl cyclopropane-1,1,2-tricarboxylate (4.9 g, 13.2 mmol) in dichloromethane (20 mL) and the mixture was stirred at room temperature for 48 h. The solvent was evaporated in vacuo and the excess TFA was lyophilized to afford 2-(ethoxycarbonyl)cyclopropane-1,1-dicarboxylic acid (3.3 g, 100%). 1H NMR (300 MHz, CD3OD): δ 1.23-1.29 (t, J=6.9 Hz, 3H), 1.60-1.64 (m, 1H), 1.85-1.88 (m, 1H), 2.48-2.53 (m, 1H), 4.10-4.18 (m, 1H). The solvent was evaporated in vacuo