title: Transition-metal-free formal Sonogashira coupling and alpha-carbonyl arylation reactions.
abstract: Transition-metal-free formal Sonogashira coupling and alpha-carbonyl arylation reactions have been developed. These transformations are based on the nucleophilic aromatic substitution (S(N)Ar) of beta-carbonyl sulfones to electron-deficient aryl fluorides, producing a key intermediate that, depending on the reaction conditions, gives the aromatic alkynes or alpha-aryl carbonyl compounds. The development of these reactions is presented and, based on investigations under basic and acidic conditions, mechanisms have been proposed. To develop the formal Sonogashira coupling further, a milder, two-step protocol is also disclosed that expands the reaction concept. The scope of these reactions is demonstrated for the synthesis of Sonogashira and alpha-carbonyl arylated products from a range of electron-deficient aryl fluorides with a variety of functional groups and aryl-, heteroaryl-, alkyl-, and alkoxy-substituted sulfone nucleophiles. These transition-metal-free reactions complement the metal-catalyzed versions in terms of substitution patterns, simplicity, and reaction conditions.
authors.affiliation: Center for Catalysis, Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: Birgit
authors.initials: B
authors.lastname: Prüger
authors.forename: Gretchen E
authors.initials: GE
authors.lastname: Hofmeister
authors.forename: Christian Borch
authors.initials: CB
authors.lastname: Jacobsen
authors.forename: David G
authors.initials: DG
authors.lastname: Alberg
authors.forename: Martin
authors.initials: M
authors.lastname: Nielsen
authors.forename: Karl Anker
authors.initials: KA
authors.lastname: Jørgensen