Carbon tetrabromide → ethyl 1-({5-[3-(trifluoromethyl)phenyl]-1,3,4-oxadiazol-2-yl}methyl)-1H-pyrazole-4-carboxylate

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Reaction Steps

A solution of the compound (1.0 g) obtained in Example 115b in dichloromethane (15 ml) was cooled in an ice bath, N,N′-carbonyldiimidazole (0.81 g) was added and the mixture was stirred for 30 min. 3-(Trifluoromethyl)benzohydrazide hydrochloride (1.2 g) was added, and the mixture was stirred at the same temperature for 45 min. Then, carbon tetrabromide (3.32 g) and triphenylphosphine (2.6 g) were added, and the mixture was further stirred at the same temperature for 2 hr. The solvent was evaporated under reduced pressure, and the residue was purified by column chromatography (carrier: silica gel, eluent: petroleum ether-ethyl acetate) to give the title compound (0.64 g) as a colorless oil.

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