For the first time, the highly efficient and regioselective hydrogenation of quinoline derivatives to 1,2,3,4-tetrahydroquinolines using unsupported nanoporous gold (AuNPore) as a catalyst and organosilane with water as a hydrogen source is reported. The AuNPore catalyst can be readily recovered and reused without any loss of catalytic activity.

We have demonstrated for the first time that carboxylic acids are able to catalyze the direct hydroboration of various terminal and internal alkynes with pinacolborane without using any metal catalysts. This unprecedented catalytic hydroboration exhibits a broad functional groups compatibility, giving the corresponding alkenyl diboronates and monoboronates in good to high yields with exclusive regio- and stereoselectivities.

Indole-tethered ynones form an intramolecular electron donor–acceptor complex that can undergo visible-light-induced charge transfer to promote thiyl radical generation from thiols.

We report for the first time that zero-valent nanoporous gold (AuNPore) is a robust and green heterogeneous catalyst for α-C-H functionalization of various tertiary amines. AuNPore combines with molecular oxygen at 80 °C or tert-butyl hydrogen peroxide at room temperature and catalyses the heterogeneous cross-dehydrogenative coupling (CDC) reaction efficiently to afford the corresponding C-C and C-heteroatom coupling products in good to excellent yields with excellent reusability.

A novel intramolecular oxidative diamination of bis(2-aminophenyl)acetylene for the synthesis of the structurally intriguing π-conjugated polyheterocyclic scaffold, 5,10-dihydroindolo[3,2-b]indole (DHII), has been developed under Cu(hfacac)2/O2 oxidation systems. The structure design of bis(2-aminophenyl)acetylene bearing both N,N-dimethylamine and primary amine groups is crucial for constructing the corresponding DHII scaffold. Notably, an intermolecular N-methyl transfer from the nitrogen atom of N,N-dimethylamine to the primary amine takes place, which is a critical step for the successful implementation of the present annulation process.

A one-pot protocol for the dearomatizing spirocyclization/cross-coupling of alkyne-tethered indoles/ pyrroles is described. Mechanistic studies support a process by which palladium complexes generated in situ act as both πacid and cross-coupling catalysts. Overall, this facilitates an efficient cascade process that enables the simultaneous preparation of synthetically challenging quaternary spirocyclic carbons and tetrasubstituted alkenes in a single operation.

Indoles are amongst the most important classes of heteroaromatics in organic chemistry,c ommonly found in biologicallya ctive naturalp roductsa nd therapeutically useful compounds. The synthesis of indoles is therefore important and severalm ethods for their synthesis that make use of silver(I)c atalysts and reagents have been developed in recent years. This Minireview contains, to the best of our knowledge,acomprehensive coverageo fs ilver-mediated indole forming reactions since the first reactiono ft his type was reported in 2004.Scheme1.Generalsilver(I)-catalyzed hydroaminations equence.[a] Dr.Scheme4.Ag I -catalyzed hydroamination to prepare indole 14.Scheme5.Ag I -catalyzed hydroamination to prepare indoles 18.Scheme6.Ag I -catalyzed hydroamination to prepare 3-vinyli ndoles 21. Scheme 7. Proposed mechanism for the synthesis of indole 21.

Indole-ynones have been established as general substrates for radical dearomatizing spirocyclization cascade reactions. Five distinct and varied synthetic protocols have been developedcyanomethylation, sulfonylation, trifluoromethylation, stannylation and borylationusing a variety of radical generation modes, ranging from photoredox catalysis to traditional AIBN methods. The simple and easily prepared indole-ynones can be used to rapidly generate diverse, densely functionalized spirocycles and have the potential to become routinely used to explore radical reactivity. Experimental and computational investigations support the proposed radical cascade mechanism and suggest that other new methods are now primed for development.