Yield: 48%

Reaction Conditions:

with hydrogenchloride;sodium nitrite;copper in water at 20; for 3 h;

Steps:

1.G132.2
Step 2: 2-Bromo-5-nitro- 1 ,3 ,4-thiadiazole[0689] To a stirred solution OfNaNO₂ (116 g, 1.68 mol) in water (1200 mL) was added copper metal powder (72 g, 1.12 mol) and 1.2 mL cone. HCl. Thereafter, 5- bromo-l,3,4-thiadiazol-2-amine (100 g, 0.56 mol) was warmed to dissolve in 4 M aq. HCl (120 mL) and added potionwise. The mixture was stirred at r.t. for 3 hrs. The precipitated yellow solid was filtered and washed with water. The solid was dissolved in ether, filtered and the filtrate concentrated in vacuo to give 2-bromo-5-nitro- [l,3,4]thiadiazole (57 g, 88% purity in HPLC, 48% yield).

References:

ANACOR PHARMACEUTICALS, INC.;GLAXOSMITHKINE LLC;XIA, Yi;ALLEY, Michael, Richard Kevin;ZHOU, Yasheen;SINGH, Rajeshwar;DING, Charles;CAO, Kathy;PLATTNER, Jacob, J.;OU, Ligong;JIA, Guofeng;SARASWAT, Neerja;RAMACHANDRAN, Sreekanth;ZHOU, Ding WO2011/17125, 2011, A1 Location in patent:Page/Page column 276