Synthesis of a Crizotinib Intermediate via Highly Efficient Catalytic Hydrogenation in Continuous Flow

Abstract

Kilogram-scale highly selective catalytic hydrogenation of the aryl nitro group in the intermediate of crizotinib has been developed, which adopted continuous-flow technology with prepassivated Raney Ni as a catalyst at room temperature. According to the reaction condition optimization, side reactions such as dehalogenation, debenzylation, and reduction of other unsaturated functional groups were inhibited eminently. Moreover, catalytic hydrogenation of (R)-3-(1-(2,6-dichloro-3-fluorophenyl)ethoxy)-2-nitropyridine (compound I) afforded the desired product (R)-3-[1-(2,6-dichloro-3-fluorophenyl)ethoxy]pyridin-2-amine (compound II) with high selectivity (99.9%) and high conversion (99.5%). Finally, high-quality crizotinib was synthesized from intermediate II.