The general procedure for the synthesis of 2,2-diethoxy-1-methoxyethanimidamide from diethoxyacetonitrile and sodium methanol was as follows: first, diethoxyethanimidamide hydrochloride was synthesized according to the literature method. This was done as follows: to a solution of methanol (8.4 mL) containing sodium methanolate (0.09 g, 1.6 mmol) was added diethoxyacetonitrile (2.00 g, 15.5 mmol), and the reaction mixture was stirred at 0 °C for 4 h, and then returned to room temperature. Solid carbon dioxide (0.5 g) was added, followed by evaporation of most of the methanol. Ether was added to the residue and filtered to remove the resulting sodium carbonate. Concentration of the filtrate gave methyl diethoxyacetimidate as a colorless oil (2.47 g, 99% yield), which could be used in the next reaction without further purification. The resulting oil was dissolved in methanol (4 mL), ammonium chloride (0.82 g, 15.3 mmol) was added and the resulting mixture was stirred at room temperature overnight. Upon completion of the reaction, the mixture was filtered and the methanol was removed under vacuum. The residual oily substance was cooled to -78 °C, allowed to solidify and subsequently washed with ether (3 mL). The solid product was collected by filtration, recovered to room temperature and dried under vacuum to give the final diethoxyacetamidine hydrochloride (1.64 g, 58% overall yield in two steps) as a white solid. Its 1H NMR (400 MHz, DMSO-d6) data were as follows: 9.15 (br, 4H), 5.29 (s, 1H), 3.61 (q, 4H, J = 6.8 Hz), 1.18 (t, 6H, J = 6.8 Hz).
