Yuanbo Zheng, Stephen T. Hilton
The combination of microwave heating and visible-light irradiation provides a potentially powerful approach to reaction intensification by combining rapid thermal activation with selective photochemical excitation. Herein, we report MAPS, a modular Microwave-Assisted Photochemical Synthesis platform that integrates a removable 3D-printed light-delivery module with a commercial Biotage microwave reactor. The system enables irradiation of sealed reaction vials while retaining conventional temperature, pressure and stirring control, and allows rapid exchange of external Kessil LED light sources. Application to nickel-catalysed Negishi cross-coupling demonstrated that simultaneous microwave heating and 450 nm irradiation accelerated conversion relative to microwave heating alone, with the greatest benefit observed for less reactive aryl and heteroaryl coupling partners. Reaction performance was also influenced by the source of the organozinc reagent, with freshly prepared and titrated benzylzinc bromide giving higher conversion and cleaner chromatographic profiles than the commercially stored reagent. MAPS therefore provides a practical and adaptable platform for investigating combined thermal and photochemical activation within an established sealed-vial workflow.