2-Methoxybenzaldehyde → 2-tert-Butoxycarbonylamino-5-[hydroxy-(2-methoxy-phenyl)-methyl]-thiazole-4-carboxylic acid ethyl ester

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Reaction Steps

Butyl lithium (2.5 M, 53 mL, 132 mmol) was slowly added to a solution of 2-tert-butoxycarbonylamino-thiazole-4-carboxylic acid ethyl ester (16.4 g, 60 mmol) in anhydrous tetrahydrofuran (250 mL) at −78° C. under a nitrogen atmosphere. A solution of 2-methoxybenzaldehyde (10.89 g, 79.99 mmol) in tetrahydrofuran (50 mL) was then added dropwise at −78° C. The mixture was warmed slowly to room temperature and stirred for 15 hours. The reaction mixture was quenched with a saturated aqueous solution of ammonium chloride (500 mL). The separated aqueous layer was extracted with ethyl acetate and the combined organic layers were washed with a saturated aqueous solution of sodium chloride, dried over sodium sulfate, filtered, and evaporated to dryness. The crude product was then purified by column chromatography to yield the pure product (12 g, 29 mmol, 48%).

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