Hydrochloric Acid → (2R,4R,5R)-4-(4-Methoxy-phenyl)-5-[4-(3-methoxy-propyl)-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethoxy]-piperidine-1,2-dicarboxylic acid 1-benzyl ester

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Reaction Steps

A solution of 0.370 g (2R,4R,5R)-4-(4-methoxy-phenyl)-5-[4-(3-methoxy-propyl)-3,4-dihydro-2H-benzo[1,4]oxazin-6-ylmethoxy]-piperidine-1,2-dicarboxylic acid 1-benzyl ester 2-ethyl ester in 18 ml methanol-tetrahydrofuran-water 1:1:1 is cooled to 0° C. Lithiumhydroxide (0.050 g) is added and the mixture is left to warm to room temperature and stirred for 16 hours at this temperature. The mixture is acidified with 1M hydrochloric acid and extracted with dichloro-methane (2×). The combined organic phases are dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue is purified via flash chromatography (SiO2 60 F) to provide the product as a light red wax. Rf=0.25 (EtOAc-heptane-acetic acid 20:10:1); Rt=4.95.

Provenance & Evidence