To a solution of p-nitrobenzyl 4-carboxy-4-methylvalerate (17.26 g) in dry dimethylformamide (100 ml), prepared by the procedure similar to that described in Example 174 from 2,2-dimethylglutaric anhydride and p-nitrobenzyl alcohol, was added p-methoxybenzyl chloride (9.16 g) and triethylamine (5.91 g). The reaction mixture was stirred at 80° C. for 9.5 hours, diluted with water and extracted with diethyl ether. The extract was washed successively with aqueous potassium carbonate, water, dilute hydrochloric acid and again water, dried over anhydrous sodium sulfate and evaporated to give p-nitrobenzyl 4-p-methoxybenzyloxycarbonyl-4-methylvalerate.
