title: Synthesis of 3-Aminoimidazo[1,2-a]pyridines from α-Aminopyridinyl Amides.
abstract: 3-Aminoimidazo[1,2-a]pyridines are rapidly synthesized via a facile and mild cyclodehydration-aromatization reaction starting from readily available amides. The cyclodehydration step is mediated by the activation of N-Boc-protected 2-aminopyridine-containing amides by triflic anhydride (Tf2O) in the presence of 2-methoxypyridine (2-MeO-Py). Subsequently, the addition of K2CO3in THF ensured a clean deprotection-aromatization sequence to afford the desired heterocycle. A wide variety of functional groups and substitution patterns were tolerated under the optimized procedure, and good to excellent yields were obtained for the fused bicyclic 3-aza-heterocycles. In addition, the reaction was found to be scalable to gram-scale and could be performed with unprotected acyclic amide precursors. We also found that the resulting products were valuable intermediates for both Pd- and Ru-catalyzed C-H arylation reactions, allowing for the elaboration to diversely functionalized building blocks.
authors.affiliation: Centre in Green Chemistry and Catalysis, Department of Chemistry, University of Montreal , P.O. Box 6128, Station Downtown, Montreal, Quebec H3C 3J7, Canada.
authors.forename: Sophie
authors.initials: S
authors.lastname: Régnier
authors.affiliation: Centre in Green Chemistry and Catalysis, Department of Chemistry, University of Montreal , P.O. Box 6128, Station Downtown, Montreal, Quebec H3C 3J7, Canada.
authors.forename: William S
authors.initials: WS
authors.lastname: Bechara
authors.affiliation: Centre in Green Chemistry and Catalysis, Department of Chemistry, University of Montreal , P.O. Box 6128, Station Downtown, Montreal, Quebec H3C 3J7, Canada.
authors.forename: André B
authors.initials: AB
authors.lastname: Charette