Ethanol → Z-Phe-His-Leu-Val 7-(pivaloyloxymethoxycarbonyl)-heptyl amide

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Reaction Steps

40 mg of Z-Phe-His-Leu-Val-7-carboxyheptyl amide (Example 29) are made into a slurry in 1 ml of ethanol and 100 μl of 1N NaOH are added. The solution is concentrated by evaporation and dried by twice making into a slurry in toluene/ethanol and concentrating by evaporation. The residue is dissolved in 0.5 ml of DMF; at 0° while stirring 12 mg of pivalic acid iodomethyl ester in 0.2 ml of DMF are added twice at an interval of 1 hour, the whole is further stirred for 16 hours at 0° and for 1 hour at room temperature and then evaporated to dryness in a high vacuum. The title compound is obtained by flash chromatography (5.5 g of silica gel, eluant methylene chloride/methanol/conecentrated ammonia 700:50:1) of the residue. Rf (B11)=0.81 Rf (methylene chloride/methanol/concentrated ammonia 700:50:1)=0.23.

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