Scalable Quasi-Divided Cell Operation Using Spinning Cylinder Electrode Technology: Multigram Electrochemical Synthesis of an Axitinib Intermediate

Electrochemical synthesis of a key thiol intermediate in the preparation of axitinib has been achieved on a multi-10 g scale using a modified spinning cylinder electrode reactor adapted for "quasi-divided" cell operation. This concept enables the target cathodic reduction to occur without the need for sacrificial electrodes or divided cells equipped with ion exchange membranes. The new reactor design, based on a scalable platform, features an inner spinning cathode made of leaded bronze and a reactor vessel to which a variable number of counter-electrode rods can be attached. This setup permits high flexibility in the cathode/anode surface area ratio required for "quasi-divided" cell operation. The setup has been shown to provide excellent yields for the target thiol intermediate in batch and flow recirculation modes. Continuous operation using a cascade of three reactors was also demonstrated.