Thermal intramolecular Diels-Alder reaction of furan; synthesis of nitrogen tetracycles, isobenzofuran and isobenzothiophene

Karaarslan M., GÖKTÜRK E., Demircan A.

Journal of Chemical Research, no.2, pp.117-120, 2007 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Publication Date: 2007
  • Doi Number: 10.3184/030823407x191967
  • Journal Name: Journal of Chemical Research
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.117-120
  • Keywords: Aromatisation, Cycloaddition, Intramolecular Diels-Alder
  • Hatay Mustafa Kemal University Affiliated: No

Abstract

Thermal intramolecular Diels-Alder (IMDA) reaction of furan cored compounds has been further investigated; a series of key precursors to the IMDA reaction of furan diene (9a-c) have been prepared via facile alkylation and protection. While the cycloaddition process for (10a-c) was afforded in hot toluene, a commercial microwave (2450 MHz) was used for the synthesis of (12a-b). Treatment of fused oxy- and thio-heterotricycles (12a-b) with borontrifluoride-etherate in dichloromethane at -78°C cleaved epoxy bridge and concomitant aromatisation gave the isobenzo-furan and thiophene (13a-b) in 72-76% yields respectively.