Combination of Sonogashira coupling and 5-endo-dig cyclization for the synthesis of 2,6-disubstituted-5-azaindoles

Abstract

The synthesis of a library of 2,6-disubstituted-azaindoles relying on Sonogashira cross-coupling and intramolecular cyclization is described. Eleven examples of 6-alkynyl derivatives and three examples of 3-bromo-5-azaindoles are reported. One of the 3-bromo-5-azaindoles was also further functionalized with two different aryl trifluoroborate salts via Suzuki-Miyaura coupling reaction.

Graphical Abstract

Keywords:

• Alkynes
• cyclization
• heterocycle
• Sonogashira
• tandem reaction

Acknowledgments

We thank Professor Regina H. A. Santos from IQSC-USP for the X-ray data collection.

Additional information

Funding

The authors are grateful for the financial support provided by the São Paulo Research Foundation (Fundação de Amparo a Pesquisa do Estado de São Paulo - FAPESP, Grant 2017/24821-4, fellowships 2014/19221-0 to M. N. B., 2017/26673-2 to C.H.A.E. and 2016/02392-1 to J.S.R.), the National Council for Scientific and Technological Development (CNPq-306119/2014-5 to H. A. S. and 303207/2017-5 to J. Z. S.) and Coordination for the Improvement of Higher Education Personnel (CAPES for a scholarship to M. J. D. R.).