Herein, a straightforward synthetic approach for the construction of phenanthridin-6(5H)-one skeletons is disclosed. The developed protocol relies on palladium catalysis, providing controlled access to a range of functionalized phenanthridin-6(5H)-ones in 59-88% yields. Furthermore, plausible reaction pathways are proposed based on mechanistic experiments.

The Wittig reaction is a valuable and powerful tool in organic synthesis, providing a convenient route from aldehydes and ketones to alkenes. Herein, a novel copper-assisted Wittig-type olefination of aldehydes with p-toluenesulfonylmethyl isocyanide (TosMIC) is disclosed, providing a direct and operationally simple approach to (E)-vinyl sulfones under mild conditions, compatible with a multitude of common functional groups. Experimental and computational investigations imply that the reaction proceeds through an intriguing electronically-controlled (3 + 2)/retro-(3 + 2) cycloaddition pathway.

A protocol for silver-catalyzed controlled intermolecular cross-coupling of silyl enolates is disclosed. The protocol displays good functional group tolerance and allows efficient preparation of a series of synthetically useful 1,4-diketones. Preliminary mechanistic investigations suggest that the reaction proceeds through a one-electron process involving free radical species in which PhBr acts as the oxidant. 

A protocol for a tandem Pd/Cu-catalyzed intermolecular cross-coupling cascade between o-bromobenzoic acids and 2-(2-bromoaryl)-1H-benzo[d]imidazoles or the corresponding imidazoles is presented. The protocol provides conceptually novel and controlled access to synthetically useful N-fused (benzo)imidazophenanthridine scaffolds with high efficiency, a broad substrate scope, and excellent functional group compatibility.

Harnessing free radical intermediates for selective functionalization of organic compounds has been widely demonstrated under photocatalytic conditions requiring a distinct photocatalyst. In this issue of Chem, Seo, Chang, and co-workers demonstrate an alternative photocatalyst- free light-mediated approach that allows efficient amidation of aldehydes via N-centered radical intermediate.

A method involving silver-catalyzed aerobic oxidation/6-endoheterocyclization ofortho-alkynylbenzaldehydes to yield 3-substituted isocoumarins is described. The developed protocol allows convenient access to a range of synthetically useful 3-substituted isocoumarins and related fused heterocyclolactones in good to high yields, using silver tetrafluoroborate as the catalyst, and atmospheric oxygen as the terminal oxidant and the source of endocyclic oxygen. Mechanistic studies suggest the involvement of a free-radical pathway. 

A silver-catalyzed protocol for [3+1+1] annulation of nitrones and isocyanoacetates is reported. The reaction is proposed to proceed through sequential [3+2] cycloaddition, ring-opening, cyclization-oxidation, and dealkylation, allowing access to a broad scope of valuable polysubstituted imidazoles in high yields.

An unprecedented silver-promoted regioselective (4 + 1) annulation of isocyanoacetates with pyridinium salts is reported. The established protocol provides controlled, facile, and modular access to a range of synthetically useful N-fused heterocyclic scaffolds containing indolizines, pyrrolo[1,2-a]quinolines, pyrrolo[2,1-a]isoquinolines, and 1H-imidazo[4,5-a]indolizin-2(3H)-ones. A mechanistic pathway involving nucleophilic addition/protonation/elimination/cydoisomerization is proposed.