title: An alternative role for acetylenes: activation of fluorobenzenes toward nucleophilic aromatic substitution.
abstract: Acetylenes are increasingly versatile functional groups for a range of complexity-building organic transformations and for the construction of desirable molecular architectures. Herein we disclose a previously underappreciated aspect of arylacetylene reactivity by utilizing alkynes as electron-withdrawing groups (EWG) for promoting nucleophilic aromatic substitution (S(N)Ar) reactions. Reaction rates for the substitution of 4-(fluoroethynyl)benzenes by p-cresol were determined by (1)H NMR spectroscopy, and these rate data were used to determine substituent (Hammett) constants for terminal and substituted ethynyl groups. The synthetic scope of acetylene-activated S(N)Ar reactions is broad; fluoroarenes bearing one or two ethynyl groups undergo high-yielding substitution with a variety of oxygen and arylamine nucleophiles.
authors.affiliation: Department of Chemistry, Colby College, 5754 Mayflower Hill Drive, Waterville, Maine 04901, United States.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Bizier
authors.forename: Jay Wm
authors.initials: JW
authors.lastname: Wackerly
authors.forename: Eric D
authors.initials: ED
authors.lastname: Braunstein
authors.forename: Mengfei
authors.initials: M
authors.lastname: Zhang
authors.forename: Stephen T
authors.initials: ST
authors.lastname: Nodder
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Carlin
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Katz