Yield:-

Reaction Conditions:

with trichlorophosphate in Triethyl orthoacetate;

Steps:

2- Methyl-5-(4-trifluoromethyl-3-pyridyl)-1,3,4-oxadiazole (Table 3, No.549)

2- Methyl-5-(4-trifluoromethyl-3-pyridyl)-1,3,4-oxadiazole (Table 3, No.549) 500 mg of 4-trifluoromethylnicotinic hydrazide were heated under reflux in 3.5 ml of triethyl orthoacetate for 2 hours. The reaction mixture was subsequently concentrated and the residue was carefully admixed with 2 ml of phosphorus oxychloride. The mixture was stirred at room temperature for 1 hour and then poured on ice and extracted with ethyl acetate. Chromatographic purification of the crude product obtained after drying and concentrating gave the desired compound as a yellowish oil. ¹H-NMR (CDCl₃, 300 MHz): d=2.67 (s, 3H), 7.75 (d, J=5 Hz, 1H), 8.99 (d, J=5 Hz, 1H), 9.34 (s, 1H) ppm.

References:

US2003/162812,2003,A1