An Alternative Role for Acetylenes: Activation of Fluorobenzenes toward Nucleophilic Aromatic Substitution
作者:Nicholas P. Bizier、Jay Wm. Wackerly、Eric D. Braunstein、Mengfei Zhang、Stephen T. Nodder、Stephen M. Carlin、Jeffrey L. Katz
DOI:10.1021/jo400668v
日期:2013.6.21
aspect of arylacetylene reactivity by utilizing alkynes as electron-withdrawing groups (EWG) for promoting nucleophilicaromaticsubstitution (SNAr) reactions. Reaction rates for the substitution of 4-(fluoroethynyl)benzenes by p-cresol were determined by 1H NMR spectroscopy, and these rate data were used to determine substituent (Hammett) constants for terminal and substituted ethynyl groups. The synthetic
afford a series of biologically potent fused seven-membered (6–7–6) ring compounds under mild reaction conditions. This reaction was believed to proceed through Friedel–Crafts type sequential carbometallation followed by protonation to produce phenyldibenz[b,f]oxepines. This method was also extended to synthesize seven-membered rings that are fused with coumarins.