Direct Arylation via Cleavage of Activated and Unactivated C-H Bonds

Phosphine-Free Palladium-Catalyzed Direct C-3 Arylation of 2-Phenylimidazo[1,2-a]pyridine Using Silver(I) Carboxylate

Phosphine-free palladium-catalyzed direct arylation of 2-phenyl-imidazo[1,2-a]pyridine has been developed with the concept of using silver(I) carboxylate. This protocol efficiently catalyzes the C-H arylation of 2-phenyl-imidazo[1,2-a]pyridine with aryl iodides to afford the corresponding 2-phenyl-3-aryl-imidazo[1,2-a]pyridines in moderate to-good yields.

Direct α-arylation of α-amino carbonyl compounds with indoles using visible light photoredox catalysis

A general and mild method for the construction of functionalized 2-(1H-indol-3-yl)-2-amino-carbonyl compounds was achieved, which represents the first example of direct α-arylation of α-amino carbonyl compounds with indoles using the visible light photoredox catalysis strategy.

Synthesis of tetracyclic indoles via intramolecular α-arylation of ketones

An intramolecular palladium(0)-mediated α-arylation of ketones applied to the synthesis of various substituted tetracyclic indoles is reported. Most significantly, the efficiency of the transformation was enhanced by the use of monoligated Pd(0) complexes. This methodology was extended to double α-arylation of ketones using one-pot reactions with either simultaneous addition or sequential addition of two aryl halides for producing aryl substituted tetracyclic indoles.

Direct functionalization of (un)protected tetrahydroisoquinoline and isochroman under iron and copper catalysis: two metals, two mechanisms

A highly facile, straightforward synthesis of 1-(3-indolyl)-tetrahydroisoquinolines was developed using either simple copper or iron catalysts. N-protected and unprotected tetrahydroisoquinolines (THIQ) could be used as starting materials. Extension of the substrate scope of the pronucleophile from indoles to pyrroles and electron-rich arenes was realized. Additionally, methoxyphenylation is not limited to THIQ but can be carried out on isochroman as well, again employing iron and copper catalysis.

Synthesis of 2H-indazoles by the [3 + 2] dipolar cycloaddition of sydnones with arynes

A rapid and efficient synthesis of 2H-indazoles has been developed using a [3 + 2] dipolar cycloaddition of sydnones and arynes. A series of 2H-indazoles have been prepared in good to excellent yields using this protocol, and subsequent Pd-catalyzed coupling reactions can be applied to the halogenated products to generate a structurally diverse library of indazoles.

Control of product selectivity by a styrene additive in ruthenium-catalyzed C-H arylation

A unique effect of styrene additive on product selectivity was observed for RuH(2)(CO)(PPh(3))(3)-catalyzed C-H arylation of acetophenone derivatives bearing two ortho C-H bonds. Without styrene, the C-H arylation with arylboronates gives diarylation products as the major products throughout the reaction, but the use of styrene as an additive switches the product selectivity and leads to selective formation of monoarylation products.