Hydrochloric Acid → 3-{4-[2-(4-Methoxy-2-o-tolylaminobenzoxazol-6-yl)acetylamino]phenyl}butanoic acid

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Reaction Steps

A solution of ethyl (R) 3-{4-[2-(4-methoxy-2-o-tolylaminobenzoxazol-6-yl)acetylamino]phenyl}butanoate (0.17 g, Reference Example 8) in methanol was treated with aqueous lithium hydroxide solution (5 mL, 1M) and left to stand for five hours under argon. The mixture was acidified to pH 1 by addition of dilute hydrochloric acid, then partially evaporated, then diluted with more water and then partially evaporated again. The residue was diluted with water to afford a tan solid which was filtered, then dissolved in saturated sodium bicarbonate solution. The solution was washed with ethyl acetate, then acidified to pH1 and then extracted with ethyl acetate several times. The combined ethyl acetate extracts were washed with brine and then evaporated to give the title compound (0.12 g) as a white powder. LC-MS: RT=3.29 minutes (100% by ELSD); MS (ES+), 474 (MH+).

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