Triethylamine → methyl (2R)-2-{[tert-butyl(diphenyl)silyl]oxy}propanoate

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To the mixture of (R)-2-Hydroxy-propionic acid methyl ester (1.0 g, 9.6 mmol), triethyl amine (4.0 mL, 28.81 mmol) in tetrahydrofuran (12 mL), was added tert-butyldiphenylsilylchloride (3.68 mL, 14.4 mmol) at room temperature and allowed the reaction mixture to stir for 12 h. After completion of the reaction, the reaction mixture was diluted with EtOAc (80 mL) and washed with water (70 mL) and brine (70 mL). The EtOAc layer was dried over Na2SO4 and solvent was evaporated in vacuo to afford methyl (2R)-2-{[tert-butyl(diphenyl)silyl]oxy}propanoate (3.28 g). The above crude material was sufficiently pure for the next step and used without further purification. The crude material was diluted with THF-MeOH—H2O (1:1:1, 20 mL) and added LiOH. H2O (1.17 g, 28.0 mmol). The reaction mixture was stirred for over night at room temperature. The reaction mixture neutralized with conc. HCl and concentrated in vacuo. The residue was diluted with 75 mL water and extracted with EtOAc (3×50 mL), the combined EtOAc layers were dried over Na2SO4 and evaporated in vacuo. The crude carboxylic acid was purified by Isco silica gel flash column using EtOAc to obtain the carboxylic acid (0.6 g). 1H NMR (CDCl3) δ 7.70-7.60 (m, 4H), 7.50-7.38 (m, 6H), 4.32 (q, J=6.6 Hz, 1H), 1.30 (d, J=7.0 Hz, 9H); LC-MS [M−H]+ 327.2

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