Yield: 52.9%

Reaction Conditions:

Stage #1:ethyl cyanoformate with hydrogenchloride in ethanol;dichloromethane;water at -3 - 0;Inert atmosphere;
Stage #2: with triethylamine in ethanol;dichloromethane;water at 0; for 1 h;Inert atmosphere;

Steps:

4.1 Ethyl 2-ethoxy-2-iminoacetate
To a solution of ethyl carbonocyanidate (40 g, 404 mmol) in DCM (200 mL) stirred under nitrogen at 0 °C was added a solution of HC1 (45 wt. %, 27.3 mL, 404 mmol) in EtOH dropwise over 15 min. The reaction mixture was stirred at 0 °C for 3 hr and allowed to stand overnight at -5 °C to -3 °C. To the resulting mixture was added DCM (250 mL) at 0 °C. TEA (113 mL, 807 mmol) in DCM (50 mL) was added dropwise over 30 min at 0 °C. The mixture was stirred for 30 min at 0 °C, and water (100 mL) was added at 0 °C. The resulting mixture was stirred for 5 min. The organic layer was separated, dried over sodium sulfate, and evaporated. Diethyl ether (50 mL) was added to the residue and the solid was filtered. The filtrate was dried to afford ethyl 2-ethoxy-2-iminoacetate as a pale yellow liquid (31.0 g, 214 mmol, 52.9 % yield). 'HNMR (400 MHz, CDCb) d 8.78 (s, 1H), 4.36-4.28 (m, 4H), 1.40-1.35 (m, 6H).

References:

GLAXOSMITHKLINE INTELLECTUAL PROPERTY DEVELOPMENT LIMITED;ANBARI, Jill Marinis;REILLY, Michael;MAHAJAN, Mukesh K.;RATHI, Chetan WO2020/44206, 2020, A1 Location in patent:Page/Page column 82; 100