The general procedure for the synthesis of ethyl 3-amidinopropionate hydrochloride from ethyl 3-ethoxy-3-iminopropionate was as follows: ethyl 3-amino-3-ethoxyacrylate (760 mg, 4.78 mmol) and ammonium chloride (270 mg, 5.0 mmol) were dissolved in ethanol (4.0 mL) in a glass tube rated for 10 mL pressure. The reaction was carried out using a CEM Discover microwave synthesizer at an initial magnetron power of 200 W for 1 h at 120°C (hold time). Upon completion of the reaction, the reaction mixture was cooled in a stream of compressed air and subsequently filtered. The filtrate was concentrated by vacuum evaporation and the residue was ground with diethyl ether to afford ethyl 3-amidinopropionate hydrochloride (923 mg, 78% yield) as a colorless solid, which was ready for use without further purification. The product characterization data were as follows: νmax (neat)/ cm-1 3300, 3095, 1738, 1687; δH (500 MHz; d6-DMSO)/ ppm 9.16 (2H, broad single peak, NH2), 8.88 (2H, broad single peak, NH2), 4.15 (2H, quartet peak, J = 7.1 Hz, OCH2), 3.63 (2H, single peak, CH2), 1.22 (3H, triple peak, J = 7.1 Hz, CH3); δC (125 MHz, d6-DMSO)/ ppm 166.7 (C=O), 163.6 (C=N), 61.9 (OCH2), 38.2 (CH2), 14.4 (CH3); m/z (EI) 130 (M-+).
