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

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Reaction Steps

Ethyl 5-(4,5-dimethoxy-2-nitrobenzoyl)-1H-1,2,3-triazole-4-carboxylate (Synthesis Example 2) (1.07 g) and p-toluenesulfonic acid monohydrate (53 mg) were suspended in methylene chloride (10 ml) under an argon atmosphere. Isobutyl aldehyde (330 mg) was added to the suspension. The mixture was stirred at room temperature for 25 min. 1,1′-carbonyldiimidazole (744 mg) and methylene chloride (5.0 ml) were added thereto, and the mixture was stirred at room temperature for 25 min. Isopropyl alcohol (920 mg) was added thereto, and the mixture was stirred at room temperature for 3 hr and then refluxed for 21 hr. The mixture was post-treated by a conventional method and subjected to separation and purification to give ethyl 2-(1-isopropoxycarbonyloxy-2-methylpropyl)-5-(4,5-dimethoxy-2-nitrobenzoyl)-2H-1,2,3-triazole-4-carboxylate as a light yellow foam (520 mg, 34%).

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