Photoredox‐Catalyzed Carbon Radical Generation from α‐Keto‐ N, O ‐acetals: Synthesis of Functionalized Azepino (1,2‐ a) indoles and Azepino (1,2‐ a) furo (3,2‐ b) indoles

Abstract: C10a‐Acetoxylated perhydroazepino[1,2‐a]‐indoles, accessible via visible light‐mediated sensitized photooxygenation of cyclo‐hepta[b]indoles, are precursors to structurally elaborate carbon‐centered radicals. Their photoredox‐catalyzed SET reduction by phenothiazine or phenoxazine photocatalysts, followed by fragmentation and C−O bond cleavage, liberates tricyclic α‐amino‐α‐carbonyl radicals that readily engage in radical addition reactions with silyl enol ethers and silyl ketene acetals. The C−C functionalized azepinoindole[1,2‐a]indoles are useful building blocks for the synthesis of polycyclic indole derivatives as shown by the controlled borohydride reduction of a C10a‐methylenecarboxylate derivative, which leads stereoselectively to tetracyclic azepino[1,2‐a]furo[3,2‐b]indoles. The photocatalytic method developed herein is also suitable for the radical functionalization of simple α‐acetoxy acetophenones.

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch

References and Relationships

• Bibliographic citation: Photoredox‐Catalyzed Carbon Radical Generation from α‐Keto‐ N, O ‐acetals: Synthesis of Functionalized Azepino (1,2‐ a) indoles and Azepino (1,2‐ a) furo (3,2‐ b) indoles ; day:28 ; month:11 ; year:2023 ; extent:8 ; Advanced synthesis & catalysis ; (28.11.2023) (gesamt 8)

Contributors, Places and Time

• Creator: Seefeldt, Paul ; Villinger, Alexander ; Brasholz, Malte

Further information

• DOI: 10.1002/adsc.202300967
• URN: urn:nbn:de:101:1-2023112914064480635218
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 15.08.2025, 7:34 AM CEST