Methanol → 5-(2-{tert-Butoxycarbonyl-[2-(3-chloro-phenyl)-2-hydroxy-ethyl]-amino}-propyl)-benzo[1,3]dioxole-2,2-dicarboxylic acid

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To a stirred solution of 5-(2-{tert-butoxycarbonyl-[2-(3-chloro-phenyl)-2-hydroxy-ethyl]-amino}-propyl)-benzo[1,3]dioxole-2,2-dicarboxylic acid bis-ethyl ester (4.42 g, 7.65 mmol), MeOH (100 mL) and H2O (25 mL) was added 5 N NaOH (7.64 mL, 38.2 mmol). After 19 h, the solution was concentrated to an aqueous mixture and acidified to pH=1 with 1 N aq. HCl which turns the solution milky-white. Extraction with 3×100 mL EtOAc, washing the combined organics with 1×200 mL brine, drying over Na2SO4, filtration and concentration gave 3.96 g (99%) of product as a white solid; 1H NMR (300 MHz, DMSO-d6): δ 1.16 (d, J=6.7 Hz, 3H), 1.31 (s, 9H), 2.55-2.70 (m, 1H), 2.80-2.92 (m, 1H), 3.05-3.23 (m, 2H), 3.71-3.93 (m, 2H), 4.62-4.87 (m, 2H), 5.30-5.90 (brs, 1H), 6.59-6.99 (complexm, 4H), 7.14-7.47 (complexm, 3H), 8.60-8.80 (brs, 1H); MS (ES) m/z (relative intensity): 522. (M+ +H, 50).

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