Process-Optimised Access to Triarylamines through Catalytic Dehydrogenative Aromatisation

Abstract

Despite the growing interest in triarylamines as rapidly advancing materials for optoelectronic and organic photovoltaic applications, their synthesis generally relies on multistep routes and requires functionalization of the starting materials. The development of atom- and step-economical strategies for their preparation remains highly desirable. In parallel, engineering new reaction pathways beyond C–N bond formation via cross-coupling is crucial to enhance process sustainability, reduce waste generation and resource consumption, and improve overall system performance. Here, we report the development of a multigram-per-day production Pd-catalysed dehydrogenative aromatisation route to triarylamines, using anilines and potentially lignin-derived cyclohexanones as readily available arylating partners in place of arylalides. Mild oxidant conditions have been provided by molecular oxygen as the sole oxidant. To enable scale-up while ensuring effective gas-liquid contact, the methodology is implemented in a continuous-flow system comprising multiple packed-bed reactors, where slug flow maintains the aerobic conditions required. Green metrics are assessed against benchmark protocols to contextualise the process within current sustainability frameworks.