Isopropanol → Ethyl 5-(3,4-dimethoxybenzoyl)-2-(1-isopropoxycarbonyloxy-2-methylpropyl)-2H-1,2,3-triazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

p-Toluenesulfonic acid monohydrate (482 mg, 2.5 mmol) and isobutylaldehyde (3.4 ml, 37 mmol) were added to a solution of ethyl 5-(3,4-dimethoxybenzoyl)-1H-1,2,3-triazole-4-carboxylate (7.7 g, 25 mmol), prepared in the same manner as described above in connection with Intermediate 5, in methylene chloride (115 ml) under an argon atmosphere at −20° C. The mixture was stirred at −20° C. for one hr. Carbonyldiimidazole (6.2 g, 38 mmol) was added thereto, followed by stirred at −20° C. for additional one hr. Isopropyl alcohol (20 ml) was added thereto. The mixture was cooled to −30° C. Trifluoroacetic acid (5.8 ml, 75 mmol) was added thereto. The mixture was stirred at room temperature for 18 hr. The reaction solution was treated by a conventional method and purified by column chromatography on silica gel (hexane/ethyl acetate) to give the title compound as a colorless liquid (10.9 g, 93.4%).

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