modified Ullmann couplingreactions creating C–O bonds, including diaryl ethers or phenols, are vital to organic synthesis. Synthesized N-phenyl-2-pyridinecarboxamide and its derivatives were used as ligands in conjunction with catalytic copper sources in the formation of various diaryl ethers and phenols. Various aryl and heteroaryl halides with electron donating and withdrawinggroups were reacted with
concerning the involvement of traces of metals is presented, supported by an unexpected ''ligand'' effect in the absence of added metal catalysts. We believe that the frontier between nucleophilic aromatic substitution and catalysis will likely prove to be much harder to delimit than is generally thought.
An unprecedented ligand-free copper-catalyzed O-arylation of arenesulfonamides with phenols has been developed. Thus, a range of unsysmmetric biaryl ethers were synthesized in excellent yields. The reaction occurs efficiently with excellent regioselectivity through the cleavage of C-ary-S bond and with a good tolerance of functional groups on the phenyl ring of phenols. The reaction is appreciated for its readily accessible substrates, mild conditions, and simple operation under air.[GRAPHICS].
WARDROP A. W. H.; SAINSBURY G. L.; HARRISON J. M.; INCH T. D., J. CHEM. SOC. PERKIN TRANS., PART 1, <JCPK-BH>, 1976, NO 12, 1279-1285
作者:WARDROP A. W. H.、 SAINSBURY G. L.、 HARRISON J. M.、 INCH T. D.