Copper(II)-Catalyzed Domino Synthesis of Indolo[3,2‑<i>c</i>]quinolinones via Selective Carbonyl Migration

A Cu­(II)-catalyzed domino process involving the carbene N–H insertion, intramolecular aldol-type trapping and unprecedented ring-expansion of oxindole core through C3-selective 1,2-carbonyl migration is described for the synthesis of indolo­[3,2-c]­quinolinones. This tetracyclic core, having an all-carbon quaternary center, was efficiently synthesized in high yields from amines and 3-diazo-oxindoles. Mechanistic studies revealed that this reaction proceeds via a stepwise pathway and the involvement of the synergistic catalysis between Lewis acidic copper and hidden Brønsted acidity of in-situ-formed TfOH traces

An efficient synthesis of pyrido[1,2-a]indoles through aza-Nazarov type cyclization

Transition metal free Brønsted acid mediated synthesis of pyrido[1,2-a]indole scaffolds has been developed through aza-Nazarov type cyclization of readily available diaryl(2-pyridyl)methanol using formic acid for the synthesis of biologically and medicinally important pyrido[1,2-a]indole, indolo[1,2-a]quinoline and pyrimido[1,2-a]indole derivatives.</p

Phosphine-Free and Reusable Palladium Nanoparticles-Catalyzed Domino Strategy: Synthesis of Indanone Derivatives

The carbene migratory insertion involving a domino reaction by highly stable, reusable, and binaphthyl-stabilized Pd-nanoparticles (Pd-BNP) is disclosed. The reaction was catalyzed by 2 mol % of a heterogeneous Pd-BNP catalyst under external ligand-free conditions, and it afforded 3-aryl-substituted indanone derivatives in up to a 90% yield with exclusive <i>E</i>-selectivity. Furthermore, a one-pot reaction and derivatization of indanone derivatives were also successfully demonstrated

Palladium-Catalyzed Intermolecular Carbene Insertion Prior to Intramolecular Heck Cyclization: Synthesis of 2‑Arylidene-3-aryl-1-indanones

A domino process that converges the migratory insertion of carbene with a Heck reaction has been established as a versatile tool for the synthesis of 2-arylidene-3-aryl-1-indanones from very stable and easily accessible <i>N</i>-tosylhydrazones and 2′-iodochalcones. The reaction selectively proceeds through 5-<i>exo</i>-<i>trig</i> cyclization and delivers the products selectively with the <i>E</i> configuration of the double bond in excellent yields. The one-pot synthesis of 2-arylidene-3-aryl-1-indanones involving in situ synthesis of both 2′-iodochalcones and <i>N</i>-tosylhydrazones has also been demonstrated

A metal-free aromatic cascade for the synthesis of diverse heterocycles

A unique retrosynthetic disconnection to access diverse heterocyclic scaffolds using a 6π-electrocyclization strategy.</p

Dictating the Reactivity of η³‑Oxoallyl Pd-Intermediate toward 5‑<i>exo‑trig</i> Cyclization: Access to Indano-spirooxindoles

A facile synthesis of indanone-fused spirooxindoles is disclosed by directing the reactivity of η3-oxoallyl Pd-intermediate toward 5-exo-trig mode of cyclization. The Pd-catalyzed reaction of the rationally designed starting material 3-arylidene oxindoles with isatin-derived tosylhydrazone afforded the spirooxindoles having all-carbon quaternary center through carbene migratory insertion followed by Heck-type cyclization sequence. The photophysical studies and DFT calculations were conducted to understand their electronic properties. Moreover, the synthesis of XEN 907 analogue is also featured by employing the present methodology