ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synthesis of 2,9-dihydropyrano[2,3-b]-indoles via intramolecular oxa-6π-electrocyclization reaction from synthesized 3-allylideneindolin-2-one intermediates

Parisa Abbasi Varnakesh and Javad Azizian

Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran

E-mail: azizian@srbiau.ac.ir

Received: 28 July 2023  Accepted: 17 March 2024

Abstract:

Intramolecular oxa-6π-electrocyclization reaction are described for 3-allylideneindolin-2-one derivatives in the presence of easily prepared B(HSO4)₃ catalyst and their conversion to 2,9-dihydropyrano[2,3-b]-indoles in up to 72% yield under mild condition. 3-allylideneindolin-2-one has been obtained from the reaction of isatin and 1,3-dichloropropene. Comfortable synthetic conversions of the products readily lead to pharmacologically interesting numerous functional groups.

Keywords: 2,9-Dihydropyrano[2,3-b]-indoles; Oxa-6π-electro-cyclization; Intramolecular reaction; 3-Allylideneindolin-2-ones; Isatin

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-024-03427-0

Chemical Papers 78 (8) 4787–4799 (2024)