1,2-Difunctionalizations of alkynes entailing concomitant C–C and C–N bond-forming carboamination reactions

Nickel-Catalyzed Three-Component Carboamination/Cyclization of Alkynes To Access 2,3-Disubstituted Quinolines

Presented herein is a nickel-catalyzed chemo- and regioselective three-component tandem carboamination and cyclization of terminal alkynes with organoboronic acids and anthranils for facile and modular access to 2,3-substituted quinolines. In this process, anthranil has dual roles: serving as an electrophilic aminating reagent and a redox buffer to suppress the generation of an off-cycle Ni(0) complex. Moreover, the anionic acetylacetonate (acac) ligand was found to be vital to ensure a productive Ni(I)-Ni(III)-Ni(I) catalytic cycle.

Palladium-immobilized triazine dendrimer on magnetic nanoparticles: as reusable microreactor for solvent-dependent synthesis strategy of 2,3-diphenylindoles and pentaphenylpyrrole derivatives

In this work, we demonstrate that palladium-immobilized triazine dendrimer on magnetic nanoparticles in proper solvents, provides an impressive, atom-economical and compelling approach for the selective synthesis of 2,3-diphenylindole or pentaphenylpyrrole derivatives via annulation of diphenylacetylene with diverse anilines. Both the annulation methods were taken place under copper- and phosphine-free conditions with high yields at air atmosphere. Likewise, bis-indoles were obtained with excellent yields under optimized reaction conditions. Besides, the catalyst was isolated and reused for seven cycles without decrease potential of catalytic activity. Two mechanistic pathways were proposed and geometry optimizations, electronic properties as well as vibrational characterizations of all structures were performed with density functional theory (DFT). Also, the investigation of atomic basin properties of these molecular systems was carried out utilizing the quantum atoms-in-molecules theory (QTAIM). The results showed that 2,3-diphenylindole and pentaphenyl pyrrole molecular systems can be used as intramolecular acceptor/donor (n-like/p-like) sections.

Enamine Synthesis via Regiocontrolled 6-endo-dig and 5-exo-dig Tethered Carboamination of Propargylic Alcohols

Enamines are versatile building blocks for the synthesis of biologically active compounds. Nevertheless, only a limited number of strategies have been reported for preparing trisubstituted enamines in a regio- and stereoselective manner. Herein, we report a regiocontrolled 6-endo and 5-exo tethered carboamination of propargylic alcohols for the synthesis of trisubstituted enamines. High regioselectivity was achieved through fine-tuning of the amine protecting group during the Pd-catalyzed carboamination. The introduced trifluoromethylated tether enables further stereoselective functionalizations, such as hydrogenation and fluorination.

Transition metal catalysed cascade C-C and C-O bond forming events of alkynes

The past few decades have witnessed the emergence of domino reactions as a powerful tool for the multi-functionalization of alkynes for the rapid and smooth construction of complex molecular architectures. In this context, employing transition metal catalysis, vicinal/geminal cascade functionalization of alkynes involving C-C and C-O bond-formation reactions, has become a preferred strategy for the synthesis of oxygenated motifs. Despite this significant progress, reviews documenting such strategies are either metal/functional group-centric or target-oriented, thus hampering further developments. Therefore, in this review, different conceptual approaches based on C-C and C-O bond-forming events of alkynes such as carboxygenation (C-C and CO bond formation), carboalkoxylation (C-C and C-OR bond formation), and carboacetoxylation (C-C and C-OAc bond formations) are discussed, and examples from the literature from the last two decades are presented. Further, we have presented detailed insights into the mechanism of different transformations.