Cfc 113 → 5-chloro-1-isopropyl-1H-[1,2,4]triazole

Under an atmosphere of nitrogen a solution of 1-isopropyl-1H-[1,2,4]triazole (19 mmol) in THF (50 mL) at −78° C. was treated with n-butyllithium (11.4 mL, 2.5 M, 28.5 mmol) dropwise giving a cream yellow suspension. Further n-butyllithium (3.8 mL, 2.5 M, 9.5 mmol) was added after 1 h and stirring continued for a further 1.5 h. 1,1,2-trichlorotrifluoroethane (4.57 mL, 38 mmol) was added dropwise giving a dark brown solution. The resultant reaction mixture was stirred for 15 min before being quenched by the addition of saturated aqueous NaHCO3 (20 mL) then allowed to warm to RT. The resultant mixture was extracted twice with diethyl ether, the combined organic extracts dried (Na2SO4), filtered and concentrated in vacuo to give 5-Chloro-1-isopropyl-1H-[1,2,4]triazole as a dark oil (3.9 g) which was used in the subsequent step without further purification. 1H NMR δ (ppm) (CDCl3): 7.85 (1H, s), 4.73-4.63 (1H, m), 1.54-1.46 (6H, m).