title: Functionalized heteroarylpyridazines and pyridazin-3(2H)-one derivatives via palladium-catalyzed cross-coupling methodology.
abstract: A general method for the synthesis of functionalized pyridazinylboronic acids/esters is described involving a directed ortho metalation (DoM)--boronation protocol (Schemes 1 and 2). A comprehensive study of the reactivity of the C-B bond in palladium-catalyzed cross-couplings with aryl/heteroaryl halides is presented. Aryl-/heteroarylpyridazines are thereby obtained in synthetically viable yields (typically 40-75%) although in some cases competing protodeboronation has been observed. A series of pyridazin-3(2H)-one derivatives, including 4,6-diaryl/heteroaryl derivatives, have been obtained from the corresponding 3-methoxypyridazines in straightforward procedures (Schemes 3 and 4). Several X-ray crystal structures of aryl-/heteroarylpyridazines and derived pyridazin-3(2H)-one derivatives are reported. These multi-ring systems are of considerable interest in contemporary N-heterocyclic chemistry.
authors.affiliation: Department of Chemistry, Durham University, Durham, DH1 3LE, England.
authors.forename: Kate M
authors.initials: KM
authors.lastname: Clapham
authors.forename: Andrei S
authors.initials: AS
authors.lastname: Batsanov
authors.forename: Ryan D R
authors.initials: RD
authors.lastname: Greenwood
authors.forename: Martin R
authors.initials: MR
authors.lastname: Bryce
authors.forename: Amy E
authors.initials: AE
authors.lastname: Smith
authors.forename: Brian
authors.initials: B
authors.lastname: Tarbit
mesh_terms: D001897:Boronic Acids / Q000737:chemistry; D002384:Catalysis; D018360:Crystallography, X-Ray; D018020:Lithium Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D011724:Pyridazines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D001897:Boronic Acids; D018020:Lithium Compounds; D011724:Pyridazines; D010165:Palladium