General procedure for the synthesis of [1,1'-bicyclopropane]-1-carboxylic acid from the compound (CAS: 1447944-40-2): to a mixture of ester B-41a (100 mg, 0.462 mmol) dissolved in methanol (2.5 mL) and water (0.5 mL) at 0 °C was added an aqueous solution of 1 N NaOH (1 mL, 0.247 mmol ) and stirred at 0 °C for 10 min. The reaction mixture was then warmed to 25 °C and stirring was continued for 12 hours. After completion of the reaction, the volatile components were completely removed under reduced pressure. Water (5 mL) was added to the residue and extracted with ether (2 x 10 mL). The aqueous layer was adjusted to pH ~2 with 1.5 N HCl and then extracted with a 10% MeOH/DCM (3 × 10 mL) mixture. The organic layers were combined, washed with brine solution (10 mL) and dried with anhydrous sodium sulfate. The solvent was removed under reduced pressure to afford [1,1'-bicyclopropane]-1-carboxylic acid (CapB-41) (60 mg, 0.476 mmol, 93% yield) as an off-white solid.1H NMR (CDCl3, δ=7.26 ppm, 400 MHz): δ1.49-1.46 (m, 1H), 1.15 (app. q J=3.6 Hz. 2H), 0.62 (app.q J=3.6 Hz, 2H), 0.49-0.44 (m, 2H), 0.04--0.008 (m, 2H).
