A Robust and Efficient Catalyst Possessing an Electron-Deficient Ligand for the Palladium-Catalyzed Direct Arylation of Heteroarenes

Alkyne Aminopalladation/Heck and Suzuki Cascades: An Approach to Tetrasubstituted Enamines

Alkyne aminopalladation reactions starting from tosylamides are reported. The emerging vinylic Pd species are converted either in an intramolecular Heck reaction with olefinic units or in an intermolecular Suzuki reaction by using boronic acids exhibiting broad functional group tolerance. Tetra(hetero)substituted tosylated enamines are obtained in a simple one-pot process.

Pd-N-heterocyclic carbene complex catalysed C–H bond activation of 2-isobutylthiazole at the C5 position with aryl bromides

An effective and efficient catalytic system has been reported for the synthesis of C5-arylated 2-isobutylthiazoles.

Ag(I)-C-H Activation Enables Near-Room-Temperature Direct α-Arylation of Benzo[ b]thiophenes

The first example of near-room-temperature α-arylation of benzo[b]thiophenes is reported. The discovery rests on the observation of a switch in α-/β-regioselectivity at different loadings of Pd₂(dba)₃·CHCl₃ in the coupling between benzo[b]thiophene and 4-iodotoluene. We show that this unprecedented regioselectivity switch is driven by a Ag(I)-mediated C–H activation at the α-C–H position, which becomes the dominant mode of reactivity at low concentrations of Pd. Competition experiments, kinetic studies, KIE, and D/H scrambling experiments have been carried out supporting this mechanism.

The Goldilocks Principle in Phase Labeling. Minimalist and Orthogonal Phase Tagging for Chromatography-Free Mitsunobu Reaction

An inexpensive and chromatography-free Mitsunobu methodology has been developed using low molecular weight and orthogonally phase-tagged reagents, a tert-butyl-tagged highly apolar phosphine, and a water-soluble DIAD analogue. The byproduct of the Mitsunobu reactions can be removed by sequential liquid-liquid extractions using traditional solvents such as hexanes, MeOH, water, and EtOAc. Owing to the orthogonal phase labeling, the spent reagents can be regenerated. This new variant of the Mitsunobu reaction promises to provide an alternative and complementary solution for the well-known separation problem of the Mitsunobu reaction without having to resort to expensive, large molecular weight reagents and chromatography.

Camphyl-based α-diimine palladium complexes: highly efficient precatalysts for direct arylation of thiazoles in open-air

Bulky camphyl-based α-diimine palladium complexes have been developed and exhibited high reactivity for the direct arylation of thiazoles in air.

Selective Pd-catalyzed α- and β-arylations of the furan rings of (ortho-bromophenyl)furan-2-yl-methanones: C(CO)–C bond cleavage with a furan ring as a leaving group and synthesis of furan-derived fluorenones

Selective palladium diacetate-catalyzed α- and β-arylations of the furan rings of (ortho-bromophenyl)furan-2-yl-methanones 1 under two different conditions are reported.

Bulky α-diimine palladium complexes: highly efficient for direct C–H bond arylation of heteroarenes under aerobic conditions

Through the strategy to enhance the bulkiness on both the backbone and the N-aryl moieties, we designed and synthesized a type of bulky α-diimine palladium complex (i.e., {[Ar–NC(R)–C(R)N–Ar]PdCl₂, (Ar = 2-benzhydryl-4,6-dimethylphenyl)}, C1, R = H; C2, R = An; C3, R = Ph).

Regioselectivity in palladium-catalysed direct arylation of 5-membered ring heteroaromatics

In the past few years, several results using modified catalysts and new reaction conditions have been reported permitting better control of the regioselectivity of Pd-catalysed arylations.