Copper-catalyzed reaction of ketenimine and in situ generated immonium ion: access to α,ß-unsaturated amidines.

A Cu-catalyzed three-component reaction of alkyne, azides (sulfonyl or phosphoryl azides), and N,N-dialkyloxyformamide dialkyl acetal via electrophilic addition of immonium ion to copper ketenimine is reported. This new protocol for the preparation of α,ß-unsaturated amidine derivatives appears to offer high yield, mild conditions, and wide substrate scope. The reaction might involve the processes of copper ketenimine intermediate formation, electrophilic addition, and isomerization.

Silver ion promoted, Pd(II)-catalyzed arylation of arenes with a free amine as directing group in aqueous medium.

Palladium(II)-catalyzed arylation of arenes with aryl boronic acids and a free amine as directing group in aqueous medium has been developed. High reactivity and chemoselectivity for the formation of carbon-carbon bonds were achieved by the use of soluble silver salts. The addition of water is crucial to improve the arylation yield.

Cu(II)-promoted palladium-catalyzed C-H ortho-arylation of N,N-dimethylbenzylamines.

A novel protocol for palladium-catalyzed arylation of the C(sp(2))-H bond directed by a N,N-dimethylaminomethyl group in the presence of AgOAc and Cu(OAc)2·H2O is described. Various aryl iodides proved to be efficient coupling partners, furnishing the corresponding ortho monoarylated or diarylated arenes in moderate to good yields. Cu(OAc)2·H2O is found to be the important additive to improve the yields in this transformation.

Free-amine-directed alkenylation of C(sp2)-H and cycloamination by palladium catalysis.

A new protocol for the palladium-catalyzed free-amine-directed alkenylation of C(sp(2))-H bonds and cycloamination is described. Substituted biaryl-2-amines react with various alkenes, including electron-deficient alkenes, aryl alkenes and alkyl alkenes, to give the corresponding phenanthridines with exclusive regioselectivity. The use of α-branched styrenes leads to the formation of tricyclic compounds with a seven-membered amine ring. The method operates through a free-amine-directed alkenylation and a subsequent hydroamination cyclization reaction.

Palladium(II)-catalyzed direct alkenylation and arylation of arenes: removable 2-pyridylsulfinyl group assisted C-H bond activation.

Palladium-catalyzed C-H activation reactions directed by a removable 2-pyridylsulfinyl group were developed. Aromatic olefination products were formed in good yields on treatment of 2-(phenylsulfinyl)pyridines with alkenes in the presence of a Pd catalyst. The reaction tolerates a wide range of substituted alkenes, including various acrylates and styrenes. The controlled experiments indicated that the 2-pyridyl moiety, rather than the sulfinyl, played the role of ligand. The final reductive desulfonylation affords the stilbenes, sulfides, and disulfides with different reductive conditions, respectively. More importantly, this transformation could also be applied in arylation through dual C-H activation.

Palladium-catalyzed regioselective oxidative coupling of indoles and one-pot synthesis of acetoxylated biindolyls.

Mild conditions have been developed to achieve Pd-catalyzed homocoupling of indoles with excellent regioselectivity in the presence of Cu(OAc)(2) x H(2)O in DMSO at room temperature in high efficiency. This method provides a simple route to 2,3'-biindolyls from the electron-rich to moderately electron-poor indoles. The reaction tolerates the bromide substituent on indoles. In addition, a one-pot approach to C3-position acetoxylated biindolyls is realized via palladium catalysis by the use of AgOAc under oxygen atmosphere as oxidants.

Iron-catalyzed amidation of alkynyl bromides: a facile route for the preparation of ynamides.

A facile route to obtain ynamides in high yields was described. The products were achieved through the iron-catalyzed C-N coupling reaction of amides with alkynyl bromides in the presence of 20 mol % of N,N'-dimethylethane-1,2-diamine (DMEDA).

Free-amine directed arylation of biaryl-2-amines with aryl iodides by palladium catalysis.

A new palladium-catalyzed free-amine directed arylation of C(sp(2))-H bonds in the presence of AgOAc and TFA is described. Biaryl-2-amines react with various aryl iodides to give the corresponding mono- or diarylated products with exclusive regioselectivity.

Ni-catalyzed intramolecular cycloaddition of methylenecyclopropanes to alkynes.

Ni-catalyzed intramolecular cycloaddition of methylenecyclopropanes (MCPs) to arkylalkynes via proximal bond cleavage is reported. The reaction provides a facile route for the preparation of cyclopenta[a]indene derivatives.

Pd(OAc)2-catalyzed regioselective arylation of indoles with arylsiloxane in acidic medium.

Mild conditions have been developed to achieve a Pd(OAc)(2)-catalyzed cross-coupling between indoles and arylsiloxanes in the presence of TBAF and Ag(2)O in acidic medium. Electron-deficient arylsiloxanes presented high efficiency in this system to give the arylated indoles in excellent yields.