Cesium carbonate → 3-[4-(Tert-butyl-dimethyl-silanyloxy-methyl)-phenyl]-2-[2-(4-fluoro-phenyl)-ethylsulfanyl]-propionic acid methyl ester

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Reaction Steps

To a solution of 3-[4-(tert-butyl-dimethyl-silanyloxymethyl)-phenyl]-2-chloro-propionic acid methyl ester (6.56 g, 42 mmol) in anhydrous DMF (200 mL) was added Cs2CO3 (14.34 g, 44 mmol) at 0° C. After stirring for 30 min 2-(4-fluoro-phenyl)-ethanethiol (13.72 g, 40 mmol), dissolved in anhydrous DMF (100 mL), was added dropwise and the resulting organe mixture was stirred for 18 h without removing the cooling bath. The mixture was diluted with Et2O and extracted with three times with H2O. The organic phase was concentrated under reduced pressure and the residue was dissolved in Et2O again and repeatedly extracted with H2O. After drying the separated organic layer over MgSO4, the solvent was removed under reduced pressure to afford the crude product as an orange oil which was purified by chromatography using n-heptane/EtOAc 20:1 as the eluent. The desired product was obtained as an oil (4.93 g, 25.4%). 1H NMR (400 MHz, CDCl3): δ 7.16 (d, 2H), 7.06-6.99 (m, 4H), 6.88 (t, 2H), 4.62 (s, 2H), 3.58 (s, 3H), 3.41 (dd, 1H), 3.10 (dd, 1H), 2.82 (dd, 1H), 2.74-2.76 (m, 4H), 0.85 (s, 9H), 0.00 (s, 6H).

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