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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.
- Source :
-
Advanced Synthesis & Catalysis . 1/9/2024, Vol. 366 Issue 1, p24-30. 7p. - Publication Year :
- 2024
-
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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 16154150
- Volume :
- 366
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Advanced Synthesis & Catalysis
- Publication Type :
- Academic Journal
- Accession number :
- 174763595
- Full Text :
- https://doi.org/10.1002/adsc.202300967