An efficient protocol has been developed for the preparation of π-extended N-heterocycles involving a Rh­(III)-catalyzed C–H activation reaction starting from 3-acetamidocoumarins and internal alkynes. The isolation of the intermediate pyrrolo-coumarin suggests that the −COCH3 group in acetamidocoumarins performs the role of a traceless directing group. Besides, the use of commercially available [Cp*RhCl2]2 adds more importance as no additional modification of the catalyst is required. A two-step protocol bearing intermediate pyrrolo-coumarin can be further functionalized to highly decorated heterocyclic moieties materializing sp2 C–H and sp2 N–H coupling. Moreover, one of the pyrrolo-coumarin compounds (3da) is capable of differentiating between Cr­(III) and Cr­(VI) ions as revealed via fluorescence spectroscopy. In addition, intermediate pyrrolo-coumarin is further functionalized to spirocyclic N-heterocycles.

An efficient palladium catalyzed diastereoselective addition of arylboronic acids to complex spirocyclopropyl dinitriles is developed in the presence of a catalytic amount of DBSA as a Brønsted acid surfactant in aqueous media.

A practical ligand free Nano Nickel ferrite (NNF) catalysis has been established for the one pot direct sulfenylation of 4‐hydroxycoumarin, 4‐hydroxyquinolinone and pyrazolone derivatives by reacting them with several easily available aromatic iodides and elemental sulfur. Additionally, the protocol is highly facile for direct selenoetherification of 4‐hydroxycoumarin, 4‐hdroxyquinolinone scaffolds employing elemental selenium. The important aspects of this direct chalcogenation protocol are the use of easily recyclable nano Nickel ferrite catalyst, inexpensive reactants, use of elemental sulfur and selenium under aerobic condition.

An efficient and fascinating protocol has been devised for the preparation of fused furan moieties involving a Rh(II) catalyzed one-pot C–H activation/concomitant tandem annulation process, employing an enolic compound and β-keto sulfoxonium ylide as the reacting conjugates. The developed technique demands only Rh2(TFA)4 as the catalyst to proceed forward and is devoid of additional metallic or nonmetallic additives. The skeletal transformation of naphthoquinone fused furan to highly decorated naphthoquinone fused indolizines is a promising synthetic application.

Quinazoline moieties and particularly C4-substituted quinazoline scaffolds are widely distributed in biologically active molecules, and thus, direct C4-functionalization of quinazolines is the most convenient way to materialize new, straightforward, and sustainable strategies for the synthesis of useful medicinal targets. Retrospecting that, effort has been directed toward electrocatalytic C4–H bond diversification of quinazoline and related electron-deficient N-heterocycles (quinoxaline) offering C4 and C3 benzoyl-, acetyl-, phenol-, ether-, phosphonate-, and nitroalkane-incorporated N-heterocycles via a radical addition pathway under sacrificial oxidant- and additive-free conditions. Various coupling partners and quinazolines, as well as other structurally similar heterocyclic motifs, respond well, providing moderate to high yields of coupled products along with the gram-scale upgradation. Additionally, the performed control experiments and cyclic voltammetry investigations also nicely justified the proposed mechanism of the coupling process. Further, late-stage functionalization leading to the synthesis of indolo quinolines and vinyl-sulfonated products using the ruthenium-catalyzed skeletal transformation of benzoylated quinazoline 3b nicely appropriated the developed methodology. Finally, this reaction can be summarized as (a) anodic activation of the functionalized Hantzsch ester to furnish key radical species; (b) radical addition to an activated N-heterocycle; and (c) oxidation leading to the target product without the assistance of any metal chelation.