Polyfluorinated phenyl(dihydroxy)boranes C6H5-nFnB(OH)(2) (n = 3 - 5) underwent hydrodeboration (formal replacement of the (dihydroxy)boryl group by hydrogen) in the presence of bases (MeOH, 33% H2O-MeOH, KOH (1 equiv.)/33% H2O-MeOH, pyridine and 9% D2O-pyridine) and formed the fluoroaromatic compounds ArH or ArD, respectively. The rate of reaction depends on the number of fluorine atoms in the phenyl group and on the position of the fluorine atoms, relative to the B(OH)(2) substituent.
Nucleophilicity vs. basicity of the hydroxide ion under extractive phase transfer catalysis conditions
作者:David Feldman、Mordecai Rabinovitz
DOI:10.1016/s0040-4039(01)93863-8
日期:1989.1
Extraction of hydroxideionunder phase transfer catalysisconditions (PTC) affords an extremely strong base and nucleophile. The competition between H/D exchange and nucleophilicaromaticsubstitution on 1,2,3,4-Tetrafluorobenzene (1) shows that under extractive phase transfer catalysisconditions the hydroxideion is more effective as a base than as a nucleophile.
Polyfluorinated phenyl(dihydroxy)boranes C6H5-nFnB(OH)(2) (n = 3 - 5) underwent hydrodeboration (formal replacement of the (dihydroxy)boryl group by hydrogen) in the presence of bases (MeOH, 33% H2O-MeOH, KOH (1 equiv.)/33% H2O-MeOH, pyridine and 9% D2O-pyridine) and formed the fluoroaromatic compounds ArH or ArD, respectively. The rate of reaction depends on the number of fluorine atoms in the phenyl group and on the position of the fluorine atoms, relative to the B(OH)(2) substituent.