title: Continuous Flow Synthesis and Purification of Aryldiazomethanes through Hydrazone Fragmentation.
abstract: Electron-rich diazo compounds, such as aryldiazomethanes, are powerful reagents for the synthesis of complex structures, but the risks associated with their toxicity and instability often limit their use. Flow chemistry techniques make these issues avoidable, as the hazardous intermediate can be used as it is produced, avoiding accumulation and handling. Unfortunately, the produced stream is often contaminated with other reagents and by-products, making it incompatible with many applications, especially in catalysis. Herein is reported a metal-free continuous flow method for the production of aryldiazomethane solutions in a non-coordinating solvent from easily prepared, bench-stable sulfonylhydrazones. All by-products are removed by an in-line aqueous wash, leaving a clean, base-free diazo stream. Three successful sensitive metal-catalyzed transformations demonstrated the value of the method.
authors.affiliation: Department of Chemistry, Université de Montréal, P.O. Box 6128 Stn Downtown, Montreal, Quebec, H3C 3J7, Canada.
authors.forename: Éric
authors.initials: É
authors.lastname: Lévesque
authors.affiliation: Department of Chemistry, Université de Montréal, P.O. Box 6128 Stn Downtown, Montreal, Quebec, H3C 3J7, Canada.
authors.forename: Simon T
authors.initials: ST
authors.lastname: Laporte
authors.affiliation: Department of Chemistry, Université de Montréal, P.O. Box 6128 Stn Downtown, Montreal, Quebec, H3C 3J7, Canada.
authors.forename: André B
authors.initials: AB
authors.lastname: Charette
mesh_terms: D001391:Azo Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000302:isolation & purification*; D006835:Hydrazones / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000302:isolation & purification*; D015394:Molecular Structure
chemical_list: D001391:Azo Compounds; D006835:Hydrazones; D008697:Methane
keywords: continuous flow; cyclopropanation; diazo compounds; hydrazones; ring expansion