Accessing Novel Process Windows in a High‐Temperature/Pressure Capillary Flow Reactor

High‐temperature/pressure organic synthesis can be performed under continuous flow conditions in a stainless steel microtubular flow reactor capable of achieving temperatures of 350 °C and 200 bar (X‐Cube Flash™). Using these extreme experimental environments, the Claisen rearrangement of allyl phenyl ether together with the ensuing rearrangement chemistry of the resulting 2‐allylphenol product was investigated. Reaction optimization was performed by changing the temperatures, pressures and flow rates “on‐the‐fly”. In addition, the high‐temperature/pressure flow system allowed the study of these transformations in low boiling point solvents in or near their supercritical state. In general, the chemistry optimized under high‐temperature microwave batch conditions could be successfully translated to a scalable flow regime.