Imidazole → (S)-3-{2-[1-(tert-Butyl-dimethyl-silanyloxy)-ethyl]-2-methyl-but-3-enoyl}-4-isopropyl-oxazolidin-2-one

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Reaction Steps

A solution of (S)-3-[2-(1-hydroxy-ethyl)-2-methyl-but-3-enoyl]-4-isopropyl-oxazolidin-2-one (1.742 g, 6.809 mmol) and tert-butyldimethylsilyl chloride (1.231 g, 8.17 mmol) in anhydrous N,N-dimethylformamide (10 mL) was treated with imidazole (927 mg, 13.618 mmol). After stirring at room temperature for 6 h, tert-butyldimethylsilyl chloride (1.1 g, 7.3 mmol) and imidazole (950 mg, 13.954 mmol) were added. After stirring at room temperature for 12 days, the reaction was quenched with a saturated solution of ammonium chloride. The aqueous layer was extracted with diethyl ether (2×). The organics were combined, dried over anhydrous sodium sulfate, filtered and the volatiles were removed in vacuo. The residue was purified by silica gel chromatography using a 100 g Isolute cartridge eluted with a continuous gradient of iso-hexanes/diethyl ether 1:0 to 1:1 to afford the title compound (1.729 g, 69%) as an undetermined mixture of diastereoisomers and as a yellow oil. LCMS (m/z) 370.1 [M+H], Tr=3.96 min and 370.1 [M+H], Tr=4.22 min.

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