Amino 4-nitrobenzoate → 3-(N-tert-butoxycarbonyl-hydrazino)-5-(3,3-dimethyl-but-1-ynyl)-thiophene-2-carboxylic acid methyl ester

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Reaction Steps

To a solution of 3-tert-butoxycarbonylamino-5-(3,3-dimethyl-but-1-ynyl)-thiophene-2-carboxylic acid methyl ester (4.3 g, 12.8 mmol) in NMP (64 mL) was added K-OtBu (1.6 g, 14.1 mmol). After 10 min a solution of O-4-nitrobenzoylhydroxylamine (3.0 g, 16.6 mmol) in NMP (16 mL) was added dropwise and the reaction was allowed to stir for 16 h. The reaction was quenched with LiCl solution (5% in water, 50 mL) and diluted with EtOAc (50 mL). The crude product was washed 3×50 mL with 5% LiCl solution, dried over Na2SO4, and purified by silica gel chromatography 0-30% EtOAc/hexanes to give 3-(N-tert-butoxycarbonyl-hydrazino)-5-(3,3-dimethyl-but-1-ynyl)-thiophene-2-carboxylic acid methyl ester (2.6 g, 7.4 mmol).

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