Diethyl Oxalate → HCID 178527201, compound

Participants

Reaction Steps

The compound was prepared according to Carmack et al. (J. Org. Chem. 1975, 40, 2743) as follows. Potassium metal (10.0 g, 0.26 mol) was dissolved in cool isopropanol (50 mL) which was then diluted with methanol (50 mL). A methanolic solution (100 mL) of sulfamide (12.32 g, 0.13 mol) was added dropwise with vigorous stirring, followed by dropwise diethyl oxalate (17.4 mL, 0.13 mol). The resulting mixture was heated at reflux for 18 hours. The mixture was cooled, filtered, and the solid was washed with methanol and dried to give 28.3 g of 3,4-dihydroxy-[1,2,5]thiadiazole-1,1-dioxide as the di-potassium salt. This was stirred with PCl5 (90.0 g, 0.43 mol) at 150° C. for 10 minutes. When enough POCl3 was generated to maintain stirring, the mixture was cooled to 60° C. and stirred for 18 hours. The reaction was cooled, diluted with diethyl ether, filtered, and washed with additional diethyl ether. The ether filtrate was added dropwise to ethanol (500 mL) at 0° C. The resulting solution was heated to reflux for 1.5 hours, cooled, and concentrated to 1/4 volume. The diethoxy derivative was collected as a white solid (4.80 g). The mother liquor afforded an additional 1.80 g. (Total yield: 26%): mp 171°-172° C. (Th. 178°-179° C.); 1H NMR (CDCl3): δ 4.59 (q, 4H), 1.50 (t, 6H).

Provenance & Evidence