title: An Umpolung Approach to Alkene Carboamination: Palladium Catalyzed 1,2-Amino-Acylation, -Carboxylation, -Arylation, -Vinylation, and -Alkynylation.
abstract: Conventional approaches to Pd-catalyzed alkene 1,2-carboamination rely upon the combination of a nucleophilic nitrogen-based component and an internal C-based or external oxidant. In this study, we outline an umpolung approach, which is triggered by oxidative initiation at an electrophilic N-based component and employs "standard" organometallic nucleophiles to introduce the new carbon-based fragment. Specifically, oxidative addition of a Pd(0)-catalyst into the N-O bond of O-pentafluorobenzoyl oxime esters generates imino-Pd(II) intermediates, which undergo 5-exo cyclization with sterically diverse alkenes. The resultant alkyl-Pd(II) intermediates are intercepted by organometallic nucleophiles or alcohols, under carbonylative or noncarbonylative conditions, to provide 1,2-carboamination products. This approach provides, for the first time, a unified strategy for achieving alkene 1,2-amino-acylation, -carboxylation, -arylation, -vinylation, and -alkynylation. For carbonylative processes, orchestrated protodecarboxylation of the pentafluorobenzoate leaving group underpins reaction efficiency. This process is likely a key feature in related Narasaka-Heck cyclizations and accounts for the efficacy of O-pentafluorobenzoyl oxime esters in aza-Heck reactions of this type.
authors.affiliation: †School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
authors.forename: Adele
authors.initials: A
authors.lastname: Faulkner
authors.affiliation: ‡AstraZeneca, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom.
authors.forename: James S
authors.initials: JS
authors.lastname: Scott
authors.affiliation: †School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
authors.forename: John F
authors.initials: JF
authors.lastname: Bower
mesh_terms: D000215:Acylation; D000475:Alkenes / Q000138:chemical synthesis*; D000480:Alkynes / Q000737:chemistry*; D000586:Amination; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D010165:Palladium / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: D000475:Alkenes; D000480:Alkynes; D002264:Carboxylic Acids; D014753:Vinyl Compounds; D010165:Palladium