Methyl 6-amino-5-chloronicotinate → Methyl 6-amino-5-chloronicotinate

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Reaction Steps

A mixture of 6-amino-5-chloronicotinic acid methyl ester (0.588 g, 3.15 mmol), {1-[4-(2-bromo-2-phenyl-acetyl)-phenyl]-cyclobutyl}-carbamic acid tert-butyl ester [Int-1-A] (2.00 g, 70% purity by UPLC-MS, 3.15 mmol) and powdered activated 3 Å molecular sieves in isopropanol (9.7 mL) was heated at reflux for 20 hours. On cooling, the mixture was diluted with DCM and water, filtered through Celite and the organic extract washed with brine, dried and concentrated in vacuo. Purification was achieved by chromatography on silica gel (gradient elution: hexane-hexane/ethyl acetate 1:1) to give the title compound contaminated with 6-amino-5-chloronicotinic acid methyl ester. Further purification was achieved by acid extraction of a solution of the crude product in ethyl acetate with dilute aqueous hydrochloric acid (1 M). The organic extract was washed with brine, dried and concentrated in vacuo to give the title compound;

Provenance & Evidence