3-Carbethoxy-2-piperidone → Ethyl 3-[3-methoxy-4-(2-methyl-1,3-oxazol-5-yl)phenyl]-5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyridine-8-carboxylate

Participants

Reaction Steps

A mixture of ethyl 2-oxo-3-piperidinecarboxylate (34.6 g), trimethyloxonium tetrafluoroborate (95%, 31.5 g) and acetonitrile (600 mL) was stirred at room temperature for 16 hr. 3-Methoxy-4-(2-methyl-1,3-oxazol-5-yl)benzohydrazide (50.0 g) was added to the reaction mixture at room temperature, and the mixture was heated under reflux for 24 hr, allowed to cool to room temperature and concentrated under reduced pressure. Saturated aqueous sodium hydrogen carbonate solution was added to the residue, the insoluble material was filtered off through celite, and the filtrate was extracted with ethyl acetate. The extract was washed with saturated brine, and dried over anhydrous sodium sulfate, and the solvent was evaporated under reduced pressure. The residue was crystallized from methanol/ethyl acetate to give the title compound (29.0 g).

Provenance & Evidence