C-3 Functionalization of 2-Aryl-2H-indazoles under Photo/Electrocatalysis

Abstract

2H-Indazole is a privileged scaffold widely existing in drugs and bioactive molecules. The C-H functionalization of 2H-indazole is the cutting edge in medicinal chemistry and organic chemistry. Compared with traditional synthetic methods, the visible light/electrochemical-promoted synthetic method has mild conditions and is an environmentally friendly synthetic strategy. The C-H functionalization of 2-aryl-2H-indazoles at the C-3 position catalyzed by photochemical/electrochemical strategies in recent years is summarized in terms of catalytic systems, with special emphasis on the corresponding reaction mechanism, which might inspire the further development of new catalytic methods.

Visible-Light Photocatalyzed C3–H Alkylation of 2H-Indazoles/Indoles with Sulfoxonium Ylides via Diversified Mechanistic Pathways

“…On the other hand, sulfoxonium ylides might be attacked by other radicals. For 2 H -indazoles and indoles under photocatalytic conditions, the formation of corresponding radical cations/anions and excited triplet state species via SET and energy transfer mechanistic pathway, respectively, cannot be ruled out . Potentially various reactivity of sulfoxonium ylides deserves more research attention .…”

Proflavine (PFH+): as a photosensitizer (PS) biocatalyst for the visible-light-induced synthesis of pyrano [2,3-d] pyrimidine scaffolds

“…Additionally, the process of extracting homogeneous catalysts from reaction mixtures can pose a significant difficulty. Recently, the use of visible-light-induced photochemical reactions has attracted the attention of researchers and many advances have been made so far ( Ma C. H. et al, 2022 ; Ma C. et al, 2022 ; Danfeng et al, 2022 ; Mohamadpour, 2022e ; Mohamadpour, 2023c ). The current investigation delineates the use of photocatalysts in the synthesis of heterocyclic compounds, with a particular emphasis on the incorporation of eco-friendly methodologies.…”

Rhodium-Catalyzed Asymmetric N2-C5 Allylation of Indazoles with Dienyl Allylic Alcohols

“…2 H -Indazoles are an important privileged scaffold of heteroarenes that widely exist in numerous drugs and biologically active molecules (Figure ). Their biological activities allow for use as PARP inhibitor (MK-4827, Figure ), WEGF inhibitor (pazopanib), anti-inflammation (dazidamine), toll-like receptor 7/8 antagonists (5-indazol-5-yl-pyridones), Na channel modulator (CFM-6058), S1P2 inhibitor, and so on. Many efforts have been devoted toward the development of concise and efficient catalytic systems for the direct alkylation of azoles in recent years .…”