Ethyl Acetate → Pivaloyloxymethyl 1-[(2'-t-butoxycarbonylbiphenyl-4-yl)methyl]-4-(1-hydroxy-1-methylethyl)-2-propylimidazole-5-carboxylate

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Reaction Steps

2.13 ml of chloromethyl pivalate and 3.99 g of potassium carbonate were added to a solution of 6 g of 1-[(2'-t-butoxycarbonylbiphenyl-4-yl)methyl]-4-(1-hydroxy-1-methylethyl)-2-propylimidazole-5-carboxylic acid [prepared as described in step (b) above] in 70 ml of N,N-dimethylacetamide, and the resulting mixture was stirred at room temperature for 1 hour and then at 50° C. for 2 hours. At the end of this time, the reaction mixture was mixed with ethyl acetate and water. The ethyl acetate layer was separated and dried over anhydrous magnesium sulfate, after which the solvent was removed by distillation under reduced pressure. The resulting residue was purified by column chromatography through silica gel, using a 1:1 by volume mixture of ethyl acetate and hexane as the eluent, to give 6.80 g of the title compound as crystals, melting at 106°-107° C.

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