title: Palladium-catalyzed cross-coupling reactions of pyridylboronic acids with heteroaryl halides bearing a primary amine group: synthesis of highly substituted bipyridines and pyrazinopyridines.
abstract: A range of halogenated aromatics and heteroaromatics bearing a primary amine group are shown to be suitable substrates for Suzuki cross-coupling reactions with arylboronic acids and pyridylboronic acids under standard conditions, without the need for protection/deprotection steps. New amino-substituted arylpyridines, bipyridines, and pyrazinopyridines have thereby been obtained. Conditions for the efficient syntheses of 2-methoxy-5-pyridylboronic acid 1 and 2-methoxy-3-pyridylboronic acid 2 in ca. 75 g batches have been defined. A 2-fold reaction of 2-amino-5-bromopyrazine with 2,5-dimethoxy-1,4-benzenediboronic acid affords 1,4-dimethoxy-2,5-bis[2-(5-aminopyrazyl)]benzene 31. The X-ray crystal structures of 1 and 31.DMF are reported.
authors.affiliation: Department of Chemistry, University of Durham, Durham DH1 3LE, England.
authors.forename: Amy E
authors.initials: AE
authors.lastname: Thompson
authors.forename: Gregory
authors.initials: G
authors.lastname: Hughes
authors.forename: Andrei S
authors.initials: AS
authors.lastname: Batsanov
authors.forename: Martin R
authors.initials: MR
authors.lastname: Bryce
authors.forename: Paul R
authors.initials: PR
authors.lastname: Parry
authors.forename: Brian
authors.initials: B
authors.lastname: Tarbit