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Remote C-H functionalization at C5 is the most sparingly observed selectivity in the functionalization of indole templates. Herein, we reported that the combination of a AgSbF6 catalyst and phenyliodine diacetate oxidation enabled the C-H selenylation at the C5 position of indole scaffolds in a selective version, thus leading to the formation of a wide scope of 5-selenylated indole derivatives, which are otherwise difficult to prepare. Mechanistic studies indicated that current transformation follows a radical process, and the tethered C3 pivaloyl group on indole scaffolds plays roles in both blocking the active C3 position and manipulating the electronic affinity of the arenes.

Palladium(II) can catalyze the oxidative coupling of tert-butyl 2-alkynylbenzoates with olefins such as acrylates and styrenes, leading to isocoumarines. The reaction was carried out under simple aerobic conditions, and in most cases, high selectivity has been attained.

Selective synthesis of quinolines has been achieved via oxidative annulation of functionalized pyridines with two alkyne molecules under Rh(III)-catalyzed cascade C-H activation of pyridines using Cu(OAc)(2) as an oxidant. The selectivity of this reaction is oxidant-dependent, particularly on the anion of the oxidant.

A methodology for the high yield and facile synthesis of isoquinolones from benzamides and alkynes via the oxidative ortho C-H activation of benzamides has been developed. Ag(2)CO(3) proved to be an optimal oxidant when MeCN was used as a solvent, and [RhCp*Cl(2)](2) was utilized as an efficient catalyst. Both N-alkyl and N-aryl secondary benzamides can be applied as effective substrates. Furthermore, primary benzamides react with two alkyne units, leading to tricyclic products via double C-H activation and oxidative coupling. The reactivity of the structurally related 1-hydroxyisoquinoline was also demonstrated, where both N- and O-containing rhodacyclic intermediates can be generated, leading to the construction of different O- or N-containing heterocycles.

Intramolecular oxygen transfer of nitrone- and sulfoxide-alkynes was achieved using a catalytic amount of Au(I) and a stoichiometric amount of iodine. The Au(I)-catalyzed cyclization of a nitrone-terminal alkyne afforded a cyclic iminoester, while cyclization of analogous nitrone-internal alkynes yielded aldehyde-enones. The I(2)-mediated cyclization of nitrone-alkynes afforded iodinated γ-lactams and the I(2)-mediated internal redox of the closely related sulfoxide-alkynes gave diketones functionalized with a thoiether.

Rh(III)-catalyzed oxidative coupling reactions between isoquinolones with 3-aryl groups and activated olefins have been achieved using anhydrous Cu(OAc)(2) as an oxidant to give tetracyclic products. The nitrogen atom acts as a directing group to facilitate ortho C-H activation. This reaction can be one-pot starting from methyl benzohydroxamates, without the necessity of the isolation of isoquinolone products. A broad scope of substrates has been demonstrated, and both terminal and internal activated olefins can be applied. In the coupling of N-methylmaleimide, a Wacker-like mechanism was proposed, where backside attack of the NH group in isoquinolones is suggested as a key step. Selective C-H activation has also been achieved at the 8-position of 1-naphthol, leading to an olefination product.