General procedure: synthesis of intermediate 3: cyclopropane carboxamide
Ammonia was passed into a well-stirred solution of cyclopropanecarbonyl chloride (1 g, 9.61 mmol) in dichloromethane (10 mL) at room temperature and purged continuously for 2 hours. Upon completion of the reaction, the solvent was removed by vacuum distillation. The residue was dissolved in ethyl acetate and filtered to remove insoluble matter. Subsequently, the filtrate was concentrated to give pure cyclopropanecarboxamide as a crystalline solid (0.81 g, 100% yield).
1H NMR (400 MHz, CHCl3-d): δ 5.63-5.91 (broad single peak, 2H, NH2), 1.43 (multiple peaks, 1H, cyclopropane-CH), 0.98 (double peaks, J = 4.42,2.98 Hz, 2H, cyclopropane-CH2), 0.79 (double peaks, J = 7.91,2.95 Hz, 2H, cyclopropane- CH2).
MS (mass spectrum): 85.91 (M + 1).
