Cesium carbonate → t-butyl (R)-2-hydroxy-1-(4-((S)-2-methylbutoxy)phenyl)ethylcarbamate

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[(R)-2-Hydroxy-1-(4-hydroxy-phenyl)-ethyl]-carbamic acid t-butyl ester (10 mmol), (S)-2-methylbutyl bromide (2.60 g, 17 mmol) and Cs2CO3 (7.47 g, 23 mmol) were combined in DMF (50 ml). The reaction mixture was heated at 70° C. overnight. Saturated NH4Cl was added to quench the reaction. The aqueous layer was extracted with ethyl acetate (3×20 ml). The combined organic layers were washed with brine, then dried over MgSO4, filtered and concentrated to give a white crude solid. The crude product was purified via column chromatography on silica gel (0%-50% ethyl acetate in hexanes) to afford the title compound (2.09 g, 65% yield of 3 steps) as a white solid: 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 7.22 (d, J=8.6 Hz, 2H), 6.90 (m, 2H), 5.13 (d, J=6.6 Hz, 1H), 4.73 (br. s., 1H), 3.83 (m, 3H), 3.74 (m, 1 H), 2.39 (br. s., 1H), 1.87 (m, 1H), 1.58 (m, 1H), 1.42 (m, 9H), 1.29 (m, 1H), 1.01 (m, 3H), 0.96 (m, 3H); LCMS (ESI) m/e 324.2 [(M+H), calcd for C18H30NO4 324.4].

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