Lewis acid-promoted synthesis of highly substituted pyrrole-fused benzoxazinones and quinoxalinones

Abstract

A synthesis of a series of novel fused tricyclic heterocyclic compounds has been achieved in one-pot reaction set up starting from (E)-3-(2-oxo-2-phenylethylidene)indolin-2-one and 1,4-benzoxazinone/quinoxalinone derivatives promoted by tin(IV) chloride. The reaction is supposed to occur via a sequential intermolecular Michael addition of the 1,4-benzoxazinone derivatives to the oxindoles, intramolecular cyclization, and aromatization with the elimination of water. Apart from spectroscopic characterization, the structure of one of the pyrrolo[1,4]benzoxazinone derivative is confirmed by single-crystal X-ray diffraction. Thus, the developed domino protocol provides easy access to multifunctional pyrrolo[1,4]benzoxazines in one-pot with high efficiency.

Graphical Abstract

Keywords:

• Benzoxazinone
• oxindole
• pyrrole
• quinoxalinones
• tin(IV) chloride

Acknowledgments

S.S and R.S.K gratefully acknowledge Chemistry Division and VIT Chennai, for financial support to S.S, infrastructure facilities, and instrumentation facilities (FT-IR and GC-MS) to complete this work. Thanks extended to SAIF, VIT Vellore for recording ¹H, NMR, and ¹³C NMR for our samples.