Selective Hydrogenation of Halogenated Nitroaromatics to Haloanilines in Batch and Flow

The selective hydrogenation of functionalized nitroaromatics poses a major challenge from both academic as well as industrial viewpoints. As part of the CHEM21 initiative (www.chem21.eu), we are interested in highly selective, catalytic hydrogenations of halogenated nitroaromatics. Initially, the catalytic reduction of 1-iodo-4-nitrobenzene to 4-iodoaniline served as a model system to investigate commercial heterogeneous catalysts. After determining optimal hydrogenation conditions and profiling performances of the best catalysts, hydrogenations were transferred from batch to continuous flow. Finally, the optimized flow conditions were applied to transformations which represent important steps in the syntheses of the active pharmaceutical ingredients clofazimine and vismodegib.