title: Continuous-Flow N-Heterocyclic Carbene Generation and Organocatalysis.
abstract: Two methods were assessed for the generation of common N-heterocyclic carbenes (NHCs) from stable imidazol(in)ium precursors using convenient and straightforward continuous-flow setups with either a heterogeneous inorganic base (Cs2CO3 or K3PO4) or a homogeneous organic base (KN(SiMe3)2). In-line quenching with carbon disulfide revealed that the homogeneous strategy was most efficient for the preparation of a small library of NHCs. The generation of free nucleophilic carbenes was next telescoped with two benchmark NHC-catalyzed reactions; namely, the transesterification of vinyl acetate with benzyl alcohol and the amidation of N-Boc-glycine methyl ester with ethanolamine. Both organocatalytic transformations proceeded with total conversion and excellent yields were achieved after extraction, showcasing the first examples of continuous-flow organocatalysis with NHCs.
authors.affiliation: Center for Integrated Technology and Organic Synthesis, Department of Chemistry, University of Liège, 4000, Liège, Belgium.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Di Marco
authors.affiliation: Center for Integrated Technology and Organic Synthesis, Department of Chemistry, University of Liège, 4000, Liège, Belgium.
authors.forename: Morgan
authors.initials: M
authors.lastname: Hans
authors.affiliation: Laboratory of Organometallic Chemistry and Homogeneous Catalysis, Department of Chemistry, University of Liège, 4000, Liège, Belgium.
authors.forename: Lionel
authors.initials: L
authors.lastname: Delaude
authors.affiliation: Center for Integrated Technology and Organic Synthesis, Department of Chemistry, University of Liège, 4000, Liège, Belgium. jc.monbaliu@ulg.ac.be.
authors.forename: Jean-Christophe M
authors.identifier: http://orcid.org/0000-0001-6916-8846
authors.initials: JC
authors.lastname: Monbaliu
keywords: carbenes; continuous-flow; microreactors; organocatalysis; transesterification