Diethyl Oxalate → HCID 178527201, compound

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).

1. customThe compound was prepared
2. temperatureThe resulting mixture was heated
3. temperatureat reflux for 18 hours
4. temperatureThe mixture was cooled
5. filtrationfiltered
6. washthe solid was washed with methanol
7. customdried

ORD record

ord-5bad63886c5d41d5a1990c03f7c824cb

Source dataset

uspto-grants-1993_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05206252