Potassium tert-butoxide → 3-(5-Bromo-4-fluoro-2-methyl-phenyl)-4-hydroxy-8-methoxy-1,8-diazaspiro[4.5]dec-3-en-2-one

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Reaction Steps

To a solution of 4-[2-(5-bromo-4-fluoro-2-methyl-phenyl)-acetylamino]-1-methoxy-piperidine-4-carboxylic acid methyl ester (6.0 g) in dimethylformamide (20 ml) at 100° C. is added potassium tert-butoxide (3.23 g) and stirring continued at 100° C. for 10 minutes. The reaction mixture is quenched at room temperature by addition of acetic acid (1.64 ml), diluted with water (20 ml) and extracted with tert-butyl methyl ether (3×). The combined organic layers are washed with brine, dried over sodium sulfate and concentrated. The residue is triturated with acetonitrile, filtered and dried. Yield: 3.69 g of 3-(5-bromo-4-fluoro-2-methyl-phenyl)-4-hydroxy-8-methoxy-1,8-diaza-spiro[4.5]dec-3-en-2-one as a solid, mp: 229-230° C.

Provenance & Evidence