Development and Execution of a Production-Scale Continuous [2 + 2] Photocycloaddition

This article details the approach to large-scale production of cyclobutane 2 by the continuous-flow [2 + 2] photocycloaddition of maleic anhydride and ethylene, including (1) focused reaction optimization and development of a robust isolation protocol, (2) the approach to equipment design and process safety, and (3) the results of commissioning tests and production runs delivering the target compound at throughputs exceeding 5 kg/day.