Citric Acid → 3-[4-(azetidin-1-ylcarbonyl)-2-fluorophenoxy]-5-((1S)-2-{[tert-butyl(dimethyl)silyl]oxy}-1-methylethoxy)benzoic acid

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Reaktionsschritte

A mixture of 3-[4-(azetidin-1-ylcarbonyl)-2-fluorophenoxy]-5-[(1S)-2-hydroxy-1-methylethoxy]benzoic acid (9.8 g, 0.025 mol), t-butyldimethylsilylchloride (11.3 g, 0.075 mol) and imidazole (17.08 g, 0.25 mol) in DMF (100 mL) was stirred at RT for 24 hours. Water (100 mL) was added and the mixture extracted into diethyl ether (3×100 mL). The extracts were combined and washed with water (3×100 mL), brine (100 mL), dried (MgSO4), filtered, and evaporated in vacuo to give a golden oil. Saturated aqueous sodium bicarbonate (100 mL) and diethyl ether (100 mL) were added and stirred for 30 mins. The aqueous layer was acidified with 1M citric acid solution and extracted into diethyl ether (3×100 mL). The extracts were combined, dried (MgSO4), filtered, and evaporated in vacuo and the crude product chromatographed on silica, eluting with ethyl acetate, to give the desired compound. (6.32 g).

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