Intramolecular Heck Reaction on Bromobenzyloxy-Substituted Chromenes: Formation of Chelated Ketones

Abstract

Heck reaction on 2-bromobenzyloxy-substituted 4H-chromene derivatives using Pd(OAc)₂ in Aliquat 336 and N,N-dimethylformamide mixture leads to intramolecular heteroannulation along with hydrolysis, affording chelated 6H-benzo[c]chromen-2-yl ketones. The method offers Pd(0)-catalysis and regioselectivity in product formation.

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GRAPHICAL ABSTRACT

Keywords:

• Aliquat 336
• chelated ketones
• intramolecular Heck cyclization
• Pd(0) catalysis

ACKNOWLEDGMENTS

We thank the CAS Instrumentation Centre, Department of Chemistry, University of Calcutta, India, for spectral data and the University Grants Commission, New Delhi, and University of Calcutta, Calcutta, for financial assistance.

Notes

^a Yields of pure isolated product.

^a Yields of pure isolated product.