4‐(1,1‐Dimethylethyl)‐1,2,3‐thiadiazole

image [40753‐16‐0] C 6 H 10 N 2 S (MW 142.2200) InChI = 1S/C6H10N2S/c1‐6(2,3)5‐4‐9‐8‐7‐5/h4H,1‐3H3 InChIKey = OEPVZAPYTAHXAB‐UHFFFAOYSA‐N (reagent widely used as the precursor of tert ‐butylthioketene and 3,3‐dimethylbut‐1‐yne‐1‐thiolate in a wide array of reactions) Physical Data: mp 23 °C. Solubility: soluble in most organic solvents. Form Supplied in: beige powder or yellow oil, depending on the ambient temperature; not commercially available. Analysis of Reagent Purity: 1 H NMR; GC‐MS. Preparative Methods: two widely used methods are listed as follows (eqs 1 and 2). Method 1: the mixture of ethyl hydrazinecarboxylate (1.56 g, 15 mmol), 3,3‐dimethylbutan‐2‐one (1.5 g, 15 mmol), acetic acid (0.2 mL), and ethanol (10 mL) was refluxed for 3 h. Afterward, the removal of ethanol gave white solids, which were directly dissolved in 1,2‐dichloroethane. Thionyl chloride (5 mL) was added to the solution dropwise at 0 °C and the reaction mixture was stirred overnight at room temperature to obtain the corresponding product (89% yield) (eq ). 1–5 image Method 2: the mixture of 3,3‐dimethylbutan‐2‐one (500 mg, 5 mmol), p ‐toluenesulfonylhydrazide (931 mg, 5 mmol), potassium thiocyanate (486 mg, 5 mmol), iodine (2.54 g, 10 mmol), and CuCl 2 (335 mg, 2.5 mmol, 50 mol %) in DMSO (15 mL) was stirred at 100 °C for 1 h. After the reaction was complete, the mixture was quenched with saturated Na 2 S 2 O 3 solution and extracted with EtOAc. The combined organic layers were washed with brine, dried over anhydrous Na 2 SO 4 , and concentrated under reduced pressure. The residue was purified by column chromatography on silica gel to give the product in 55% yield (390 mg) (eq ). 6 image Handling, Storage, and Precautions: stored in glass or plastic bottles at ambient temperature; it may slowly decompose and turn brown when exposed to air and light for a long time.