4-Nitrobenzenesulfonyl chloride → (S)-3-{(R)-2-[4-(3,4-Dichloro-benzyloxy)-phenyl]-2,3-dihydro-benzo[1,4]dioxin-6-yl}-2-(4-nitro-benzenesulfonylamino)-propionic acid methyl ester

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Reaction Steps

(S)-2-Amino-3-{(R)-2-[4-(3,4-dichloro-benzyloxy)-phenyl]-2,3-dihydro-benzo[1,4]dioxin-6-yl}-propionic acid methyl ester hydrochloride (1.2 g) was dissolved in 100 mL EtOAc and 100 mL saturated aqueous NaHCO3 and 1.0 g p-nitrobenzenesulfonyl chloride was added. After stirring at room temperature for 2 hours, the layers were separated and the organic layer was dried over Na2SO4 and evaporated. The residue was purified by silica gel flash chromatography (hexanes to 7:3 hexanes/EtOAc) to give 1.7 g desired product after drying. 1H NMR (400 MHz, CDCl3): 8.27 (m, 2H), 7.89 (m, 2H), 7.54 (d, 1H), 7.45 (d, 1H), 7.35 (m, 2H), 7.28-7.24 (m, 1H), 7.20 (m, 2H), 6.81 (m, 1H), 6.56 (m, 2H) 5.26 (m, 1H), 5.02 (s, 2H), 4.99 (m, 1H), 4.26 (m, 2H), 3.95 (m, 1H), 3.66 (s, 3H), 3.05-2.85 (m, 2H).

Provenance & Evidence