Synthesis
The general procedure for the synthesis of ethyl thiooxalate from ethyl cyanoformate was as follows: [(cyanocarbonyl)oxy]ethane (25 g, 0.25 mol) was dissolved with triethylamine (1 ml) in ether (200 ml) and cooled to 0°C. H2S gas was drummed into the solution for 2 hours. After completion of the reaction, the mixture was stirred at room temperature overnight, followed by replacement of the gas in the reaction system with N2. A 1N HCl solution (200 ml) was added and stirring was continued for 30 minutes. The reaction mixture was separated by extraction with ether. The organic layer was washed with brine and dried with anhydrous MgSO4. The desiccant was removed by filtration and the solvent was evaporated under reduced pressure to give ethyl thiooxalate as a yellow solid (32 g, 95% yield). The product was characterized by 1H NMR (400 MHz, chloroform-d): δ 1.37 (t, J = 7.14 Hz, 3H), 4.34 (q, J = 7.14 Hz, 2H), 7.49-8.43 (m, 2H). m/z 134 (M + H)+ was shown by LC-MS (ESI) analysis.
References
[1] Patent: US2010/196321, 2010, A1. Location in patent: Page/Page column 19
[2] Journal of Medicinal Chemistry, 2012, vol. 55, # 7, p. 3021 - 3026
[3] Zeitschrift fuer Naturforschung, Teil B: Anorganische Chemie, Organische Chemie, 1983, vol. 38, # 3, p. 335 - 340
[4] Organic Syntheses, 1988, vol. 66, p. 142 - 142
[5] Patent: WO2005/37804, 2005, A1. Location in patent: Page/Page column 10
