AlCl₃/PCC-SiO₂-Promoted Oxidation of Azaindoles and Indoles

Abstract

A simple and efficient method is described for the oxidation of 7-azaindoles and indoles to 7-azaisatins and isatins using pyridinium chlorochromate–silica gel (PCC-SiO₂) with the aid of Lewis acid catalyst aluminium chloride (AlCl₃) in dichloroethane. Simplicity of the reaction conditions, easy workup procedure, and good yields are the key features of this protocol.

GRAPHICAL ABSTRACT

Keywords:

• Aluminium chloride (AlCl₃)
• azaindoles
• azaisatins
• indoles
• isatins
• oxidation
• pyridinium chlorochromate (PCC)

ACKNOWLEDGMENTS

The authors at the Indian Institute of Chemical Technology (IICT) thank the director, IICT, and the head of the Division Organic II for encouragement. The authors at Kakatiya University (KU) thank the dean and BOS of the University College of Pharmaceutical Sciences, Kakatiya University. C. H. N. S. S. P. and V. R. thank the council of Scientific and Industrial Research and the University Grants Commission, New Delhi, and R. S. thanks the Department of Science and Technology (Inspire), New Delhi, for fellowships. This is main laboratory project work of IICT.

Notes

^a Catalyst 1.3 mol%.