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.

Copper-catalyzed sequential Ullmann N-arylation and aerobic oxidative C-H amination: a convenient route to indolo[1,2-c]quinazoline derivatives.

An efficient synthesis of indolo[1,2-c]quinazoline derivatives has been developed by copper-catalyzed sequential Ullmann N-arylation and aerobic oxidative C-H amination. The protocol uses readily available 2-(2-halophenyl)-1H-indoles and (aryl)methanamines as the starting materials to afford indolo[1,2-c]quinazolines, which are the core units of hinckdentine A.

Palladium-catalyzed C-H alkenylation of arenes using thioethers as directing groups.

Thioethers have been proven to be reliable directing groups for palladium catalyzed alkenylation of arenes via C-H activation. Mechanistic investigation reveals that the C-H cleavage of arenes is the turnover-limiting step, and an acetate-bridged dinuclear cyclopalladation intermediate is involved. The alkenylated thioethers can be easily removed and transformed into a variety of useful groups.

Pd-catalyzed arylation/oxidation of benzylic C-H bond.

A palladium-catalyzed benzylic C-H arylation/oxidation reaction leading to diaryl ketones has been accomplished. The indispensable role of the bidentate system is disclosed for this sequential process. This chemistry offers a direct new access to a range of diarylketones.

Synthesis of functionalized indolizines via copper-catalyzed annulation of 2-alkylazaarenes with α,ß-unsaturated carboxylic acids.

A novel copper-catalyzed annulation of 2-alkylazaarenes with α,ß-unsaturated carboxylic acids has been accomplished. This reaction featuring C-H olefination and decarboxylative amination processes provides a concise access to C-2 arylated indolizines from simple and readily available starting materials.

Iron-promoted C-C bond cleavage of 1,3-diketones: a route to 1,2-diketones under mild reaction conditions.

A conceptual method for the preparation of 1,2-diketones is reported. The selective C-C bond cleavage of 1,3-diketones affords the 1,2-diketones in high yields under mild reaction conditions in air by the use of FeCl(3) as the catalyst and tert-butyl nitrite (TBN) as the oxidant without the use of solvent. The possible reaction mechanism is discussed. This protocol provides an expeditious route to the useful 1,2-diketones.