1,8-Diazabicyclo(5.4.0)undec-7-ene → 2-(6-Methyl-pyridin-2-yl)-pyrazolo[1,5-a]pyridine-3-carboxylic acid ethyl ester

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Reaction Steps

A solution of (6-methyl-pyridin-2-yl)-propynoic acid ethyl ester (0.62 g, 3.3 mmol) and 1-aminopyridinium iodide (0.8 g, 3.6 mmol) in acetonitrile (15 mL) is treated with DBU (0.5 mL, 3.3 mmol) and heated to reflux for 0.5 hours. The reaction is concentrated to a dark solid and purified by silica gel column chromatography (1:1 hexane/ethyl acetate) to afford 0.224 g (24%) of desired product as a yellow solid. MS ES+ m/e 282.2 (M+1). UV (95% EtOH) λmax 275 nm (ε 13005), 234 nm (ε 26550), 225 nm (ε 26057). TOF MS ES+ exact mass calculated for C11H11NO2 (p+1): m/z=282.1243. Found: 282.1244. Anal. Calcd for C16H15N3O2: C, 68.31; H, 5.37; N, 14.94. Found: C, 68.04; H, 5.28; N, 14.65.

Provenance & Evidence