Exploring the Photochemical Reactivity of Multifunctional Photocaged Dienes in Continuous Flow

Abstract

Flow reactors become more and more automated by enabling on‐line reaction monitoring and adjusting the process parameters. On‐line monitoring of chemical processes is a valuable tool to steer processes, leading to precise engineering of macromolecular materials. Detailed information about specific product patterns, end‐group functionality or material composition can be obtained by coupling a flow reactor to a mass spectrometer (e. g. ESI‐MS). In this work, we study the deprotection of maleimides and its subsequent photoenol functionalization to synthesize complex macromolecules using a photo flow reactor coupled to an ESI‐MS. Using a trapping agent (TA), furan is efficiently removed from the maleimide Diels−Alder adduct within just minutes at 175 °C and quantitatively converted into an unreactive species that does not interfere with further reactions of the maleimide. The photoenol reaction was likewise shown to be highly effective to proceed in microreactors, reaching quantitative conversion of trifunctional molecules in as little as 2 min.