The large-scale synthesis of ethyl 4-bromocyclohex-3-enecarboxyalate, using a mild brominating reagent derived from triphenyl phosphite and bromine, is reported. The development and comparison of both continuous and batch processes are described.

A modified addition sequence was developed based on the knowledge garnered from flow-processing, resulting in a safe and efficient process for the in situ generation of the unstable active reagent and its immediate reaction with the ketone in a batch mode process.