Scalable Palladium-Catalyzed C(sp3)-H Carbonylation of Alkylamines in Batch and Continuous Flow

Abstract

Development of scalable processes for C(sp3)-H oxidative carbonylation of alkylamines is reported to provide convenient access to the β-lactam scaffol d. A study of the kinetics of the process revealed that the reaction is CO-limited even at elevated pressures and that there is an optimal CO concentration for the most effective outcome─this understanding led to an increase in the turnover number from 7 to 420 in the optimized process. Two scalable processes were then developed: a batch process, characterized by a very low catalyst loading, and a continuous process for an oxidative C-H carbonylation reaction that uses a copper-tube-flow reactor as a heterogeneous source of Cu2+ oxidant. The continuous process was tested on oxidative carbonylation of several alkylamines, yielding very good results with virtually no optimization required. This study thereby builds upon the utility of flow chemistry applications to oxidative carbonylations and scalable metal-catalyzed processes more generally.