Synthesis 2013; 45(9): 1235-1246
DOI: 10.1055/s-0032-1316870
paper
© Georg Thieme Verlag Stuttgart · New York

Cyclization Routes for the Synthesis of Functionalized Pyrano[2,3-b]indolones, Pyrazolo[3,4-b]indoles, and Furo[2,3-b]indoles

Arepalli Sateesh Kumar
School of Chemistry, University of Hyderabad, Hyderabad 500 046, India   Fax: +91(40)23012460   Email: rnsc@uohyd.ernet.in
,
Rajagopal Nagarajan*
School of Chemistry, University of Hyderabad, Hyderabad 500 046, India   Fax: +91(40)23012460   Email: rnsc@uohyd.ernet.in
› Author Affiliations
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Publication History

Received: 08 December 2012

Accepted after revision: 03 March 2013

Publication Date:
27 March 2013 (online)


Abstract

The synthesis of biologically active core structures containing pyrano[2,3-b]indol-2(9H)-ones, pyrano[2,3-b]indol-4(9H)-ones, pyrazolo[3,4-b]indoles, and furo[2,3-b]indoles are described. Pyrano[2,3-b]indol-2(9H)-ones are synthesized by three different metal-free syntheses (DCC, DMSO; CDI, DBU, CH2Cl2; or Mukaiyama’s reagent, Et3N, MeCN) and pyrano[2,3-b]indol-4(9H)-ones are prepared by one-pot or two-step synthesis. Pyrazolo[3,4-b]indoles are synthesized by Fischer indole type cyclization and McMurry coupling is employed for the synthesis of furo[2,3-b]indoles. All these core structures are synthesized from simple, common 3-acetylindol-2-ols.

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