Exploring the Photochemical Reactivity of Multifunctional Photocaged Dienes in Continuous Flow

Abstract

Flowreactorsbecomemoreand moreautomatedby enablingon-linereactionmonitoringand adjustingthe processparame-ters. On-linemonitoringof chemicalprocessesis a valuabletoolto steerprocesses,leadingto preciseengineeringof macro-molecularmaterials.Detailedinformationaboutspecificprod-uct patterns,end-groupfunctionalityor materialcompositioncan be obtainedby couplinga flowreactorto a massspectrometer(e.g. ESI-MS).In this work,we studythe depro-tectionof maleimidesand its subsequentphotoenolfunctional-izationto synthesizecomplexmacromoleculesusinga photoflow reactorcoupledto an ESI-MS.Usinga trappingagent(TA),furanis efficientlyremovedfromthe maleimideDielsAlderadductwithinjustminutesat 175°C andquantitativelyconvertedinto an unreactivespeciesthat doesnot interferewith furtherreactionsof the maleimide.The photoenolreactionwaslikewiseshownto be highlyeffectiveto proceedinmicroreactors,reachingquantitativeconversionof trifunctionalmoleculesin as little as 2 min