Rhodium-Catalyzed Alkylation of C-H Bonds in Aromatic Amides with Non-activated 1-Alkenes: The Possible Generation of Carbene Intermediates from Alkenes.

The alkylation of C-H bonds (hydroarylation) in aromatic amides with non-activated 1-alkenes using a rhodium catalyst and assisted by an 8-aminoquinoline directing group is reported. The addition of a carboxylic acid is crucial for the success of this reaction. The results of deuterium-labeling experiments indicate that one of deuterium atoms in the alkene is missing, suggesting that the reaction does not proceed through the commonly accepted mechanism for C-H alkylation reactions. Instead the reaction is proposed to proceed through a carbene mechanism. The carbene mechanism is also supported by preliminary DFT calculations.

Cobalt(II)-Catalyzed Acyloxylation of C-H Bonds in Aromatic Amides with Carboxylic Acids.

The cobalt(II)-catalyzed acyloxylation of C-H bonds in aromatic amides containing an 8-aminoquinoline moiety as the directing group with carboxylic acids is reported. Various carboxylic acids including aromatic and aliphatic carboxylic acids are applicable to the reaction. The reaction displays a broad substrate scope and high functional group tolerance. The reaction is carried out under air.

An unusual endo-selective C-H hydroarylationof norbornene by the Rh(I)-catalyzed reactionof benzamides.

Hydroarylation is an environmentally attractive strategy which incorporates all of the atoms contained in the substrates into the desired products. Almost all the hydroarylations of norbornene reported to date involve an exo-selective reaction. Here we show the endo-selective hydroarylation of norbornene in the Rh(I)-catalyzed reaction of aromatic amides. The addition of sterically bulky carboxylic acids enhances the endo-selectivity of the reaction. The results of deuterium-labeling experiments show that both the ortho-carbon and the ortho-hydrogen atoms of aromatic amides were attached to the same carbon atom of the norbornane skeleton in the hydroarylation product. These results clearly suggest that hydrometalation or carbometalation, which are commonly accepted mechanisms for the catalytic hydroarylation of C-H bonds, are not involved as the key step in the present reaction, and suggest that the reaction involves a rhodium carbene complex generated from norbornene as the key intermediate.

Rhodium-Catalyzed Alkenylation of C-H Bonds in Aromatic Amides with Alkynes.

The rhodium-catalyzed alkenylation of C-H bonds of aromatic amides with alkynes is reported. A variety of functional groups, including OMe, OAc, Br, Cl, and even NO2, are applicable to this reaction to give the corresponding hydroarylation products. The presence of an 8-aminoquinoline group as the directing group is crucial for the success of the reaction.