N2 - In the presence of a catalytic amount of Pd2+ or Pd0, oxidative homo-coupling of arylzinc compounds was achieved by the use of N-chlorosuccinimide (NCS) or O2 as an oxidant. Different reaction pathways were involved in the catalytic reactions depending on the oxidants; NCS or O2 probably oxidized I- or Pd0 to I+ or Pd2+, respectively. This reaction disclosed a new and facile synthetic method of biaryls from aryl halides or arenes via arylzinc intermediates.
The direct and selective synthesis of phenols from aryl/heteroaryl halides and KOH has been achieved through the use of highly active monophosphine-based catalysts derived from Pd2dba3 and ligands L1 or L2 and the biphasic solvent system 1,4-dioxane/H2O. We have also demonstrated a one-pot method of phenol formation/alkylation for the preparation of alkyl aryl ethers from aryl halides. In many instances, this protocol overcomes limitations in existing Pd-catalyzed coupling reactions of aliphatic alcohols with aryl halides. Finally, we demonstrate that substituted benzofurans can be prepared efficiently via a Pd-catalyzed phenol formation/cyclization protocol starting from 2-chloroaryl alkynes.
Synthesis of Biaryls via Catalytic Decarboxylative Coupling
()We present a safe and convenient cross-coupling strategy for thelarge-scale synthesis of biaryls, commercially important structuresoften found in biologically active molecules.
Volume 94 (2017) Preface Scott E
The synthetic value of these alcoholysis reactions for asymmetric biaryl synthesis is illustrated by the transformation of 5 into a broad series of enantiopure biaryls of type 6 with various functional groups ortho to the axis.">