3-Aminophenol → N-(3-hydroxyphenyl)-N-(1-phenethylpiperidin-4-yl)propionamide

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Reaction Steps

As indicated in Scheme 11-D above, the desired mPEGn-O-fentanyl conjugates were prepared by first reacting 1-phenethylpiperidin-4-one with 3-aminophenol under reducing conditions to thereby convert the keto functionality into an amine, i.e., by reaction with the amino group of 3-aminophenol. The product, 3-(1-phenethylpiperidin-4-ylamino)phenol, was then reacted with propionic anhydride in the presence of base (e.g., triethyl amine) and dimethylaminopyridine (DMAP) under conditions effective to form N-(3-hydroxyphenyl)-N-(1-phenethylpiperidin-4-yl)propionamide. Finally, introduction of the oligomeric PEG functionality was carried out by reacting the precursor, N-(3-hydroxyphenyl)-N-(1-phenethylpiperidin-4-yl-propionamide, with a molar excess of mPEGoligotosylate under coupling conditions effective to form the desired conjugates. Ratios of reactants and reaction conditions generally employed are provided in the reaction schemes above.

Provenance & Evidence