Continuous Platinum‐Mediated Hydrogenation of RefametinibRefametinib Iodo‐nitroaniline Key Intermediate DIM‐NA: The Combined Challenges of Selectivity and Catalyst Deactivation

摘要

>The chemoselective, continuous, multistep reduction of iodo‐nitroaromatics in a fixed‐bed hydrogenation reactor has been investigated. This transformation poses challenges upon both the catalyst and process conditions if high yields are to be achieved. First, the stability and selectivity of four flow‐compatible Pt catalysts, Pt(X)/C (X = Fe, V), were investigated by using 1‐iodo‐4‐nitrobenzene as the model substrate. Granular Pt(Fe) on carbon was identified as the most promising candidate. With this catalyst, iodo‐nitroaromatic API (active pharmaceutical ingredient) intermediate DIM‐NA [(2,3‐difluoro‐5‐methoxy‐6‐nitrophenyl)(2‐fluoro‐4‐iodophenyl)amine] could be converted into the corresponding aniline with high selectivity on a preparative scale. UV/Vis spectroscopy was successfully applied for online conversion control, proving to be highly useful for detecting the effects of catalyst deactivation.