A mixture of 1.64 g (11.1 mmol) of 4,5,6,7-tetrahydro[1,2,3]oxadiazolo[3,4-a]pyridin-8-ium 3-olate and 2.19 g (11.1 mmol) of 4-{[4-fluorophenyl]ethynyl}pyridine in 40 ml of mesitylene is stirred under argon at 165° C. for 16 h. After cooling, the reaction mixture is concentrated under reduced pressure. Purification by column chromatography on silica gel (cyclohexane/ethyl acetate) gives 888 mg (27%) of the desired product; log P(HCOOH): 1.03; 1H-NMR (CDCl3-d1): 8.52 (d, 2H), 7.38 (dd, 2H), 7.08 (d, 2H), 7.00 (dd, 2H), 4.25 (dd, 2H), 2.85 (dd, 2H), 2.12 (m, 2H), 1.92 (m, 2H).
