Palladium-catalyzed ortho-selective C–H bond chlorination of aromatic ketones

A palladium-catalyzed ortho-selective C–H bond chlorination reaction for the preparation of 2-chloro aromatic ketones was described. Both electron-withdrawing and electron-donating groups on the aromatic rings are well tolerated under the optimized conditions. The 2-chloro aromatic ketones obtained by our method could be applied to synthesize the derivatives of 1H-indazole or benzo[d]isoxazole.     

Palladium-catalyzed intramolecular C-H activation/C-C bond formation: a straightforward synthesis of phenanthridines

The palladium-catalyzed intramolecular C-H activation/C-C cross-coupling has been developed for a straightforward and efficient synthesis of phenanthridines. With Pd(OAc)(2) (4 mol %) as the catalyst, PCy(3) (8 mol %) as the ligand, and Cs(2)CO(3) as the base, this protocol was applied to synthesize a small library of phenanthridine derivatives in good yields in THF.     

Palladium-catalyzed direct C-H bond alkynylations of heteroarenes using gem-dichloroalkenes

Palladium-catalyzed direct alkynylations of heteroarenes were accomplished with inexpensive gem-dichloroalkenes as user-friendly electrophiles, which set the stage for a modular, step-economical synthesis of diversely decorated heteroaryl alkynes with ample scope.     

Palladium-catalyzed oxidation of Boc-protected N-methylamines with IOAc as the oxidant: a Boc-directed sp3 C-H bond activation

[Structure: see text] Pd-catalyzed selective oxidation of Boc-protected N-methylamines with IOAc as the oxidant is described. Evidence for the involvement of a Boc-directed C-H activation process is provided.     

Pd-catalyzed double C-H bond activation of diaryl ketones for the synthesis of fluorenones

An efficient synthesis of fluorenones from diaryl ketones by Pd-catalyzed oxidative cyclization is described. A possible mechanism involving a carbonyl group assisted ortho-C-H activation and cyclometalation followed by a second C-H activation to form a six-membered palladacycle and reductive elimination is proposed.     

Palladium-catalyzed asymmetric synthesis of silicon-stereogenic dibenzosiloles via enantioselective C-H bond functionalization

A Pd-catalyzed asymmetric synthesis of Si-stereogenic dibenzosiloles is developed through enantioselective C-H bond functionalization of prochiral 2-(arylsilyl)aryl triflates. High chemo- and enantioselectivities are achieved by employing a Josiphos-type ligand under mild conditions.     

Annulation of aromatic imines via directed C-H bond activation

A directed C-H bond activation approach to the synthesis of indans, tetralins, dihydrofurans, dihydroindoles, and other polycyclic aromatic compounds is presented. Cyclization of aromatic ketimines and aldimines containing alkenyl groups tethered at the meta position relative to the imine directing group has been achieved using (PPh3)3RhCl (Wilkinson's catalyst). The cyclization of a range of aromatic ketimines and aldimines provides bi- and tricyclic ring systems with good regioselectivity. Different ring sizes and substitution patterns can be accessed through the coupling of monosubstituted, 1,1- or 1,2-disubstituted, and trisubstituted alkenes bearing both electron-rich and electron-deficient functionality.     

Palladium-catalyzed ortho-arylation of benzamides via direct sp(2) C-H bond activation

The palladium-catalyzed ortho-arylation of benzamides by aryl iodides has been demonstrated with the simplest amide CONH(2) as a directing group for the first time. This protocol can be applied to various benzamides and aryl iodides with both electron-donating and electron-withdrawing groups. In addition, the synthesized biphenyl-2-carboxamides can be further transformed to other biphenyl derivatives such as nitriles, carboxylic acids, carbamates, and amines.     

Palladium-catalyzed C-N bond formation via direct C-H bond functionalization. Recent developments in heterocyclic synthesis

The formation of carbon-nitrogen bonds by reaction between a nitrogen atom and an unactivated carbon-hydrogen bond is a highly atom-economical process that attracted the attention of the chemists in the last two decades. The widely useful amination and hydroamination reactions, which furnish acyclic or cyclic products, give access to various nitrogen-containing basic and fine chemicals. This review highlights recent progress in the development of palladium-catalyzed reactions that occur by direct functionalization of simple carbon-hydrogen bonds to give heterocyclic products. Pd(0)- and Pd(II)-catalyzed reactions are described separately, emphasizing the different behavior of the metal in these two oxidation states.     

Synthesis of aza-fused polycyclic quinolines via double C-H bond activation

Simple but efficient: Aza-fused polycyclic quinolines were efficiently assembled through rhodium(III)-based direct double C-H activation of N-aryl azoles followed by cyclization with alkynes without heteroatom-assisted chelation. Copper(II) acetate, aside from acting as an oxidant, could also play an important role in the C-H activation process.     

Palladium-catalyzed C-H bond functionalization of C6-arylpurines

A highly regioselective Pd-catalyzed C(Ar)-H bond activation method was developed for the modification of purines (nucleosides) with different functional groups by using purine as a directing group. This approach provides a new access to a variety of functionalized purines (nucleosides) which are potentially of great importance in medicinal chemistry.     

Enantioselective synthesis of a PKC inhibitor via catalytic C-H bond activation

[reaction: see text] The syntheses of two biologically active molecules possessing dihydropyrroloindole cores (1 and 2) were completed using rhodium-catalyzed imine-directed C-H bond functionalization, with the second of these molecules containing a stereocenter that can be set with 90% ee during cyclization using chiral nonracemic phosphoramidite ligands. Catalytic decarbonylation and direct indole/maleimide coupling provide efficient access to 2.