Theoretical Insight into Ni(0)-Catalyzed Hydroarylation of Alkenes and Arylboronic Acids

The density functional theory (ωB97XD functional) is employed to clarify nickel(0)/P^tBu₃-catalyzed hydroarylation of alkenes and arylboronic acids with methanol. The computational results reveal that this reaction goes primarily through the ligand-to-ligand H transfer from the O-H bond to the alkene coordinated with nickel, complexation of arylboronic acid to the nickel-alkyl-methoxyl intermediate, attack of methoxyl on boron, transmetalation, and reductive elimination. The formation of the branched 1,1-diarylalkane, linear 1,1-diarylalkane, and alkene-dimer is also discussed in this work.

anti-Hydroarylation of Activated Internal Alkynes: Merging Pd and Energy Transfer Catalysis

A general catalytic anti-hydroarylation of electron-deficient internal alkynes compatible with both electron-poor and electron-rich aryl reagents is reported. This selectivity is achieved through a sequential syn-carbopalladation of the alkyne by an Ar-Pd species, followed by a tandem, Ir-photocatalyzed, counter-thermodynamic E → Z isomerization. The use of ortho-substituted boronic acids enables direct access to pharmaceutically relevant heterocyclic cores via a cascade process. Mechanistic insight into the involvement of Ar-Pd versus Pd-H as an active species is provided.

Palladium-Catalyzed [3+2] and [2+2+2] Annulations of 4-Iodo-2-quinolones with Activated Alkynes through Selective C-H Activation

The palladium-catalyzed reaction of 4-iodo-2-quinolones with activated alkynes was investigated. Cyclopenta[de]quinoline-2(1 H)-ones and/or phenanthridine-6(5 H)-ones were obtained through [3+2] annulation involving aromatic C-H activation or [2+2+2] annulation involving vinylic C-H activation, respectively. Reasonable mechanisms for the formation of these annulation products have been proposed based on density functional theory calculations.

Theoretical Study of the Copper-Catalyzed Hydroarylation of (Trifluoromethyl)alkyne with Phenylboronic Acid

The copper-catalyzed hydroarylation of 1,1,1-trifluoro-2-butyne with phenylboronic acid was investigated by performing density functional theory calculations, and a plausible mechanism was proposed. The initial transmetalation step was first examined to compare the feasibility of the catalytically active copper species. Subsequently, the carbocupration of 1,1,1-trifluoro-2-butyne by the phenylcopper species was examined in terms of regioselectivity. The impacts of the alkyne terminal group and the para-substituents of phenylboronic acids on the carbocupration were also examined. Moreover, to shed light on the role of the electron-withdrawing groups on the alkyne substrates, the activation barrier for the carbocupration of 1,1,1-trifluoro-2-butyne was compared to those for several alkyne substrates bearing ester, ketone, cyano, and pentafluorophenyl groups, as well as 2-butyne, which has no electron-withdrawing group. The final protodecupration step involving methanol, acetic acid, or phenylboronic acid was examined to determine possible proton donors.

The vinylogous Catellani reaction: a combined computational and experimental study

In the presence of 5 mol% Pd(OAc)₂, 1 equiv. of norbornene, and K₂CO₃, the reaction of 4-iodo-2-quinolones with tertiary o-bromobenzylic alcohols produced the desired benzopyran-fused 2-quinolones in moderate to high yields.

In the presence of 5 mol% Pd(OAc)₂, 1 equiv. of norbornene, and K₂CO₃, the reaction of 4-iodo-2-quinolones with tertiary o-bromobenzylic alcohols produced the desired benzopyran-fused 2-quinolones in moderate to high yields. A Catellani-type mechanism involving vinylic C–H cleavage is proposed based on the results of control experiments and density functional theory calculations.

Divergent Synthesis of Polymethoxylated 4-Aryl-2-quinolones

Polymethoxylated 4-aryl-2-quinolones were synthesized from the corresponding (o-aminophenyl)propiolates via Cu-catalyzed hydroarylation and subsequent deprotection/lactam formation. Selective iodination of the C3 position of the product followed by coupling reactions of the resulting 3-iodinated 4-aryl-2-quinolone afforded 3-substituted-4-aryl-2-quinolones. Moreover, the N-benzyl protecting group was successfully replaced with other polyoxygenated benzyl groups.