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Chemistry. 2019 Apr 23;25(23):5934-5939. doi: 10.1002/chem.201806299. Epub 2019 Apr 1.

Hypervalent Iodine(III)-Mediated Counteranion Controlled Intramolecular Annulation of Exocyclic β-Enaminone to Carbazolone and Imidazo[1,2-a]pyridine Synthesis.

Author information

1
Natural Product Chemistry and Process Development Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur-, 176061, H.P, India.
2
Academy of Scientific and Innovative Research, New Delhi, India.

Abstract

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 AgSbF6 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.

KEYWORDS:

annulation; hypervalent compounds; iodine; metathesis; nitrogen heterocycles

PMID:
30688379
DOI:
10.1002/chem.201806299

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