5-(Cyclopropylmethyl)-1,3,4-thiadiazol-2-amine

5-(Cyclopropylmethyl)-1,3,4-thiadiazol-2-amine

Oxalyl chloride (3.13 ml, 35.9 mmol) and N,N-dimethylformamide (1 drop) were added to a solution of cyclopropylacetic acid (3 g, 29.9 mmol) in dichloromethane (30 ml), and the reaction stirred at room temperature for 18 hours. The mixture was concentrated under reduced pressure and azeotroped with dichloromethane to give a brown oil. A mixture of this intermediate acid chloride (887 mg, 7.48 mmol) and thiosemicarbazide (455 mg, 4.99 mmol) were heated at 70° C. for 18 hours, then cooled. Water was added, the mixture basified to pH 9 using 50% aqueous sodium hydroxide solution, and the resulting precipitate filtered and dried, to give the title product, 410 mg, 53%; 

¹H NMR (CD₃OD, 400 MHz) δ: 0.28 (m, 2H), 0.60 (m, 2H), 1.02 (m, 1H), 2.77 (d, 2H); 

LRMS: m/z 155.2 (MH⁺).