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Transition‐Metal‐Free Synthesis of N‐Substituted Phenanthridinones and Spiro‐isoindolinones: C( sp 2 )−N and C( sp 2 )−O Coupling through Radical Pathway
Author(s) -
Verma Ajay,
Singh Banjara Lal,
Meena Rahul,
Kumar Sangit
Publication year - 2020
Publication title -
asian journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.846
H-Index - 44
eISSN - 2193-5815
pISSN - 2193-5807
DOI - 10.1002/ajoc.201900704
Subject(s) - chemistry , intramolecular force , medicinal chemistry , ring (chemistry) , transition metal , intermolecular force , nitrogen atom , stereochemistry , catalysis , molecule , organic chemistry
Iodine‐mediated intramolecular coupling of C−H and N−H bonds through radical pathways has been achieved for the synthesis of substituted phenanthridinones from 2‐phenylbenzamides using iodine, succininmide and di‐ tert ‐butylperoxide (DTBP) oxidant in dichloroethane at 130 °C. The developed protocol provides substituted phenanthridinones, particularly N‐alkyl substituted, which are difficult to access either by base‐mediated or transition‐metal‐catalyzed methodologies due to acidic nature of the C−H bond adjacent to nitrogen atom in the amides. Serendipitously, switching the oxidant from DTBP to phenyliodine(III) diacetate (PIDA) afforded spiro‐isoindolinones, involving intramolecular C−N, intermolecular C−O coupling and dearomatization of the phenyl ring in one pot.