Trifluoroacetic acid → 3,6-Dihydro-4-[4-[[(phenylmethoxy)carbonyl]amino]phenyl]-1(2H)-pyridinecarboxylic acid phenylmethyl ester

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Reaction Steps

A solution of 4-hydroxy-4-[4-[[(phenylmethoxy)carbonyl]amino]phenyl]-1-piperdinecarboxylic acid phenylmethyl ester (EXAMPLE 17, Step 1, 2.50 g) in dry methylene chloride under N2 is treated with trifluoroacetic acid (0.84 mL), stirred at ambient temperature for three hours, diluted with saturated aqueous potassium carbonate (25 mL) to neutralize excess trifluoroacetic acid, and the layers are separated. The organic phase is washed with water (20 mL) and saline (20 mL), dried over anhydrous sodium sulfate and concentrated under reduced pressure, and the residue is chromatographed on silica gel (230-400 mesh, 300 g), eluting with a gradient of ethyl acetate/hexane (20/80-50/50). Pooling of fractions with an Rf =0.69 by TLC (ethyl acetate/hexane, 50/50) and removal of solvent under reduced pressure gives the title compound, mp 146-148° C.

Provenance & Evidence