Room-Temperature Synthesis of Isoindolone Spirosuccinimides: Merger of Visible-Light Photocatalysis and Cobalt-Catalyzed C–H Activation

Abstract

A room-temperature C–H bond functionalization of benzamides has been developed by merging a photocatalyst with a cobalt catalyst for the synthesis of isoindolone spirosuccinimides. The reaction proceeds in aerobic conditions and does not require any sacrificial external oxidants such as Ag­(I) or Mn­(III) salts. Visible light activates the photocatalyst, and it acts as an electron-transfer reagent and helps in the fundamental organometallic steps by modulating the oxidation state of the cobalt complex. This C–H bond functionalization and spirocyclization showed wide substrate scope and good functional group tolerance. A possible reaction mechanism was proposed from the experimental outcome, showing that C–H bond activation is irreversible and not the rate-determining step.

Dual Photoredox and Cobalt Catalysis Enabled Transformations

“…In 2020, Ghosh and coworkers developed CÀ H bond functionalization of benzamides using dual photoredox and cobalt catalysis for the synthesis of isoindolone spirosuccinimides at room temperature. [37] Combination of organic dye Eosin Y and Co(acac) 2 were used as dual catalytic system for this transformation (Scheme 17). This reaction shows a broad substrate scope and good functional group compatibility.…”

Visible Light‐induced Functionalization of C−H Bonds: Opening of New Avenues in Organic Synthesis

“…In the same year, the Sundararaju group employed cobalt catalysis merged with photoredox catalysis to synthesize dihydroisoquinolinones (Scheme 32). [72] The [4 + 2] annulation reaction of aryl amides (75) with unactivated olefins (83) to afford corresponding dihydroisoquinolinones (84) in good to excellent yields. Variously substituted carboxamides and terminal alkenes were examined under the reaction conditions to react smoothly.…”

Synthesis of Chiral Spirolactams via Sequential C−H Olefination/Asymmetric [4+1] Spirocyclization under a Simple CoII/Chiral Spiro Phosphoric Acid Binary System

“…Innovative methodologies, such as organocatalytic asymmetric annulation reaction [3] and catalytic asymmetric dearomatization (CADA) reaction, [4] have provided powerful strategies to access these chiral spirocycle scaffolds. Recently, transition metal‐catalyzed C−H activation/annulation with maleimides, [5] especially the use of group 9 M III catalysis (M=Co, [5a–e] Rh [5f–i] ), offers a promising alternative to construct spiro‐γ‐lactams. However, all the precedents were limited to the synthesis of racemic spiro‐γ‐lactams.…”