Despite the significance of carbazole in pharmacy and material science, examples of the direct C-H functionalization of this privileged unit are quite rare. The N-(2-pyridyl)sulfonyl group enables the Pd(II)-catalyzed ortho-olefination of carbazoles and related systems, acting as both a directing and readily removable protecting group. This method features ample structural versatility, affording typically the double ortho-olefination products (at C1 and C8) in satisfactory yields and complete regiocontrol. The application of this procedure to related heterocyclic systems, such as indoline, is also described.

The easily installed and removed N-(2-pyridyl)sulfonyl group exerts complete C2 regiocontrol over the Pd(II)-catalysed C-H alkenylation of indoles and pyrroles, affording the corresponding products in good isolated yields (typically > or = 70 %). A remarkable feature of this catalyst system is that it tolerates a wide variety of substituted alkenes, including conjugated electron-deficient alkenes, styrenes and 1,3-dienes, as well as conjugated 1,1- and 1,2-disubstituted olefins. The final reductive desulfonylation affords the C2-substituted, free-NH indoles and pyrroles in good yield. This N-(2-pyridyl)sulfonyl-directing strategy has also been extended to the development of a protocol for the intermolecular, dehydrogenative homocoupling of indoles, providing 2,2'-biindoles. Mechanistic work based upon reactions with isotopically labelled starting materials and competitive kinetic studies of electronically varied substrates suggests a chelation-assisted electrophilic aromatic substitution palladation mechanism.

A practical Cu-catalyzed direct ortho-halogenation of anilines under aerobic conditions has been developed. The reaction shows typically excellent mono-substitution selectivity, high ortho-regiocontrol and large functional group tolerance.

Flexible friend: The N‐(2‐pyridyl)sulfonyl group acts as a removable directing group in the PdII‐catalyzed aryl CH ortho alkenylation of N‐alkyl aniline, benzylamine, and phenethylamine derivatives with electron‐poor alkenes. The products were obtained in high yields (70–90 %) and with complete regiocontrol. The mild reductive N‐sulfonyl removal enables the construction of a variety of nitrogen heterocycles. EWG=electron‐withdrawing group.

A series of peripherally dicyano-, tricyano-, and tetracyano-substituted subphthalocyanines (SubPcs) have been prepared through microwave-assisted, palladium-mediated cyanation of iodinated precursors. The introduction of π-accepting cyano groups in the macrocycle clearly influences its electronic and redox properties, which are dependent on the number and relative position of these substituents. Additional functionalization of the periphery of SubPcs with electron-donating or -withdrawing groups allows for a further fine-tuning of their features, leading to intensely absorbing, strongly electron-accepting panchromatic dyes with low-lying LUMO energy levels. Flash-photolysis time-resolved microwave conductivity measurements on vapor-deposited films demonstrate that some of these novel SubPc derivatives display remarkable intrinsic charge-carrier mobilities that are comparable to or larger than those of other known well-performing acceptor SubPcs; thus confirming their potential as n-type organic semiconductors for application in the fabrication of photovoltaic devices.