Among the known aromatic nitrogen heterocycles, pyrrole represents a privileged aromatic heterocycle ranging its occurrence in the key component of “pigments of life” to biologically active natural products to active pharmaceuticals. Pyrrole being an electron‐rich heteroaromatic compound, its predominant functionalization is legendary to aromatic electrophilic substitution reactions. Although a few excellent reviews on the functionalization of pyrroles including the reports by Baltazzi in 1963, Casiraghi and Rassu in 1995, and Banwell in 2006 are available, they are fragmentary and over fifteen years old, and do not cover the modern aspects of catalysis. A review covering a comprehensive package of direct functionalization on pyrroles via catalytic and non‐catalytic methods including their translational potential is described. Subsequent to statutory yet concise introduction, the classical functionalization on pyrroles using Lewis acids largely following an ionic mechanism is discussed. The subsequent discussion follows the various metal‐catalyzed C−H functionalization on pyrroles, which are otherwise difficult to implement by Lewis acids. A major emphasize is given on the radical based pyrrole functionalization under metal‐free oxidative conditions, which is otherwise poorly highlighted in the literature. Towards the end, the current development of pyrrole functionalization under photocatalyzed and electrochemical conditions is appended. Only a selected examples of substrates and important mechanisms are discussed for different methods highlighting their scopes and limitations. The aromatic nucleophillic substitution on pyrroles (being an electron‐rich heterocycle) happened to be the subject of recent investigations, which has also been covered accentuating their underlying conceptual development. Despite great achievements over the past several years in these areas, many challenges and problems are yet to be solved, which are all discussed in summary and outlook.

The development of Minisci acylation on electron-rich pyrroles under silver-free neutral conditions has been reported featuring the regioselective monoacylation of (NH)-free pyrroles. Unlike conventional Minisci conditions, the avoidance of any acid that could result in the polymerization of pyrroles was the key to success. The umpolung reactivity of the nucleophilic acyl radical, generated in situ from arylglyoxylic acid, could help explain the mechanism of product formation with electron-rich pyrroles. Alternatively, the nucleophilic substitution of the acyl radical on the electron-deficient pyrrole radical cation is proposed.

While persulfate activation at room temperature using glucose is primarily focused on kinetic studies of sulfate radical anion, utilization of this protocol in organic synthesis is rarely demonstrated. We reinvestigated...

We revealed intramolecular oxidative arylations in 7-azaindoles and pyrroles that, for the first time, provided direct access to 7-azaindole- or pyrrole-fused isoindolines and tetrahydroisoquinolines. In addition, N-benzylation of 7-azaindoles or pyrroles with sterically hindered sec-benzyl alcohols by Mitsunobu reaction followed by intramolecular oxidative arylation allowed access to chiral congeners of fused isoindolines that have little precedence. A new opportunity in the design and synthesis of fluorene-based organic emitters is demonstrated in the preparation of novel fused N-heterocycle tethered fluorenes, including a chiral fluorene architecture.

A palladium-catalyzed tandem oxidative annulation of primary benzamides with acrylates via intermolecular N-alkenylation followed by intramolecular C-alkenylation yielded a stereoselective synthesis of (E)-3-methyleneisoindolin-1-ones. The study unveils, for the first time, that only E-enamides could undergo intramolecular oxidative cyclization under the optimized conditions to give isoindolinones. The current strategy represents an umpolung strategy when compared to the literature approaches that use benzamides.