To a stirred suspension of (S)-4-[2-(4-amino-phenyl)-ethyl]-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester (150 mg, example 14 (b)) in THF (4 ml) were added sequentially triethylamine (0.13 ml) and 6-chloronicotinoyl chloride (107 mg, CAS 58757-38-3) and the mixture was heated at 50° C. for 4 h. The mixture was then concentrated in vacuo and the residue was purified by column chromatography (SiO2; gradient: heptane/EtOAc) to give (S)-4-(2-{4-[(6-chloro-pyridine-3-carbonyl)-amino]-phenyl}-ethyl)-2,2-dimethyl-oxazolidine-3-carboxylic acid tert-butyl ester (177 mg, 82%) as a white solid. MS (ISP): 484.3 ([{37Cl}M+Na]+), 482.3 ([{35Cl}M+Na]+), 462.4 ([{37Cl}M+H]+), 460.5 ([{35Cl}M+H]+), 406.4 ([{37Cl}M+H—C4H8]+), 404.3 ([{35Cl}M+H—C4H8]+).
