4-Methylmorpholine → 3-(2-{[(2,5-Dichloro-thiophene-3-carbonyl)-amino]-methyl}-4-hydroxy-phenyl)-propionic acid tert-butyl ester

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Reaction Steps

A solution of the 2,5-dichloro-thiophene-3-carboxylic acid (12.9 g, 65.5 mmol) and 4-methylmorpholine (7.17 mL, 65.2 mmol) in dry THF (400 mL) was cooled to −15° C. Isobutyl chloroformate (8.46 mL, 65.2 mmol) was added. The mixture was stirred 3 min and triethylamine (9.1 mL, 65 mmol) was added. A solution of 3-(2-aminomethyl-4-hydroxy-phenyl)-propionic acid tert-butyl ester (16.4 g, 65.3 mmol) in DMF (130 mL) pre-cooled to −15° C. was added via cannula over 15 min. After stirring 1 h, TLC indicated complete reaction. The reaction mixture was allowed to warm to ambient temperature. Solids were removed by filtration and washed with THF (100 mL). The filtrate was diluted with Et2O (500 mL) and washed with water (250 mL) then brine (150 mL). The organic layer was dried (Na2SO4) and concentrated. The crude brown oil was purified by silica gel chromatography (hexanes/EtOAc 2/1) and recrystallization (toluene) to afford the title compound as a white crystalline solid (22.3 g, 79.6%). MS (ES+) m/z 430.1 [M+H]+.

Provenance & Evidence