Oxidative coupling of arylboronic acids with arenes via Rh-catalyzed direct C-H arylation

Oxidative coupling of three different arenes and a thiophene derivative with various arylboronic acids was achieved with a [RhCl(C2H4)2]2/P[p-(CF3)C6H4]3 catalyst system. Commercially available 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO) was used as a stoichiometric oxidant. A 2-pyridyl group and an imine functional group served as ortho-directing groups to mediate the direct C-H arylation by a Rh complex. Moderate to excellent yields were obtained for the coupling reactions.     

Direct C-H bond arylation of 2-hydroxybenzaldehydes with arylboronic acids via ligand-free palladium catalysis

A mild and efficient ligand-free palladium-catalyzed direct C-H bond arylation reaction was developed to afford 2-hydroxybenzophenones in good to excellent yields from easily available 2-hydroxybenzaldehydes and arylboronic acids. The given reaction provided one of the easiest pathways for accessing 2-hydroxybenzophenones, and a variety of functional groups could be tolerated in this process.     

Direct C-H bond arylation of arenes with aryltin reagents catalysed by palladium complexes

Direct C-H bond arylation of simple arenes with aryltin reagents has been successfully catalysed by PdCl2 in the presence of CuCl2. CuCl2 proved to be an activator for a palladium intermediate as well as an oxidant.     

Copper-catalyzed oxidative sp3 C-H bond arylation with aryl boronic acids

An efficient method was developed for arylation of sp(3) C-H bonds using copper bromide as catalyst in absence of directing group with arylboronic acids. The oxidative arylation provides easy access to biologically active tetrahydroisoquinoline derivatives and can either use peroxide or molecular oxygen as oxidant.     

Palladium-catalyzed direct arylation of 4-hydroxycoumarins with arylboronic acids via C-OH bond activation

Operationally simple PdCl₂-catalyzed direct arylation of 4-hydroxycoumarins with arylboronic acids via C-OH bond activation under mild conditions is described, which gave rise to the corresponding 4-arylcouamrins in good to excellent yields.     

Copper-mediated coupling of aminopurines and aminopyrimidines with arylboronic acids

Selective N-arylation of aminopurines and aminopyrimidines 1-3 with arylboronic acids 4-6 was explored using copper(II) acetate and the corresponding N-arylated purine and pyrimidine derivatives 7-15 were obtained in moderate to good yields.     

Enantioselective rh-catalyzed arylation of N-tosylarylimines with arylboronic acids

The asymmetric arylation of N-tosylarylimines with arylboronic acids was realized by using rhodium/(S)-ShiP as catalyst. The reaction proceeded in aqueous toluene to give diarylmethylamines in good yields with up to 96% ee. [reaction: see text]     

Palladium-catalyzed direct C-H arylation of unactivated arenes with aryl Halides

An efficient palladium-catalyzed direct C-H arylation of unactivated arenes has been discovered. This method employs aryl halides as the direct coupling partners with arenes without using any external ligands. This catalysis opens a new methodology for the preparation of symmetrical as well as unsymmetrical biaryls in a user-friendly approach.     

Pd-catalyzed arylation of chlorotrifluoroethylene using arylboronic acids

The palladium-catalyzed cross-coupling of chlorotrifluoroethylene and arylboronic acids proceeds in the presence of a base and H(2)O to provide α,β,β-trifluorostyrene derivatives in satisfactory yields.     

Copper-catalyzed arylation of indolin-2,3-ones with arylboronic acids

A convenient and efficient Cu(OTf)₂-catalyzed arylation of indolin-2,3-ones with arylboronic acids using cheap 1,10-phenanthroline hydrate as ligand was developed under air atmosphere, achieving 3-aryl-3-hydroxy-2-oxindoles in good to excellent yields. This catalytic system shows broad functional group tolerance. Moreover, the rigorous exclusion of air/moisture is not required in these transformations.     

Ni-catalyzed mild arylation of alpha-halocarbonyl compounds with arylboronic acids

A simple yet powerful Ni catalyst can be used to promote direct arylations of alpha-halocarbonyl compounds, including a range of esters, amides, and ketones, with various arylboronic acids under mild conditions. The method tolerates beta-hydrogens and functional groups in the substrates and offers reactivity and selectivity profiles that are complementary to those found in the well-established Buchwald-Hartwig approach.     

Copper-mediated trifluoromethylation of arylboronic acids by trifluoromethyl sulfonium salts

The ligand-free trifluoromethylation of arylboronic acids with a [Ph(2)SCF(3)](+)[OTf](-)/Cu(0) system has been carefully investigated. Aryl-, alkenyl- and heteroarylboronic acids with a variety of functional groups were suitable substrates for this reaction. It is suggested that a CuCF(3) species is formed under the reaction conditions.     

Ru-catalyzed aerobic oxidative coupling of arylboronic acids with arenes

A Ru-catalyzed oxidative coupling of arenes with boronic acids using molecular oxygen via direct C-H activation is reported. Both the scope and the mechanism of the process are discussed.     

C-H arylation of unactivated arenes with aryl halides catalyzed by cobalt porphyrin

A general procedure for cobalt-catalyzed direct C-H arylation of unactivated arenes has been discovered. This method employs aryl halides as the direct coupling partners with arenes without using any Grignard-type reagents. This catalysis opens a new methodology for the preparation of symmetrical as well as unsymmetrical biaryls in a user-friendly approach.     

Autocatalysis for C-H bond activation by ruthenium(II) complexes in catalytic arylation of functional arenes

Kinetic data for the C-H bond activation of 2-phenylpyridine by Ru(II)(carboxylate)(2)(p-cymene) I (acetate) and I' (pivalate) are available for the first time. They reveal an irreversible autocatalytic process catalyzed by the coproduct HOAc or HOPiv (acetonitrile, 27 °C). The overall reaction is indeed accelerated by the carboxylic acid coproduct and water. It is retarded by a base, in agreement with an autocatalytic process induced by HOAc or HOPiv that favors the dissociation of one carboxylate ligand from I and I' and consequently the ensuing complexation of 2-phenylpyridine (2-PhPy). The C-H bond activation initially delivers Ru(O(2)CR)(o-C(6)H(4)-Py)(p-cymene) A or A', containing one carboxylate ligand (OAc or OPiv, respectively). The overall reaction is accelerated by added acetates. Consequently, C-H bond activation (faster for acetate I than for pivalate I') proceeds via an intermolecular deprotonation of the C-H bond of the ligated 2-PhPy by the acetate or pivalate anion released from I or I', respectively. The 18e complexes A and A' easily dissociate, by displacement of the carboxylate by the solvent (also favored by the carboxylic acid), to give the same cationic complex B(+) {[Ru(o-C(6)H(4)-Py)(p-cymene)(MeCN)](+)}. Complex B(+) is reactive toward oxidative addition of phenyl iodide, leading to the diphenylated 2-pyridylbenzene.     

Palladium‐catalyzed arylation of arylglyoxals with arylboronic acids

A palladium‐catalyzed coupling‐type reaction of arylglyoxals with arylboronic acids was achieved by use of trimesitylphosphine as the ligand and K₂CO₃ as base in toluene, providing symmetrical and unsymmetrical benzil derivatives with yields ranging from moderate to excellent. Of particular mention, the rigorous exclusion of air and moisture is not required in these transformations. Copyright © 2009 John Wiley & Sons, Ltd.