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Hypervalent Iodine(III)‐Mediated Counteranion Controlled Intramolecular Annulation of Exocyclic β‐Enaminone to Carbazolone and Imidazo[1,2‐ a ]pyridine Synthesis
Author(s) -
Bhattacherjee Dhananjay,
Ram Shankar,
Chauhan Arvind Singh,
Das Pralay
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201806299
Subject(s) - annulation , hypervalent molecule , intramolecular force , chemistry , pyridine , iodine , stereochemistry , combinatorial chemistry , medicinal chemistry , organic chemistry , catalysis
A highly efficient and flexible protocol for intramolecular annulation of exocyclic β‐enaminones has been disclosed for the synthesis of carbazolones and imidazo[1,2‐ a ]pyridines through a counter‐anion‐controlled free‐radical mechanism promoted by hypervalent iodine(III). The cooperative behavior of HTIB and AgSbF 6 plays a crucial role in the intramolecular annulation process through C−C and C−N bond formation to give the desired products. The mechanistic insights suggest that the two competitive reactions involved in the system are guided by the nature of the counteranion, which determines the formation of the final products. A wide variety of carbazolones and imidazo[1,2‐ a ]pyridine molecules have been prepared and isolated in good to excellent yields.