Manganese(III)-mediated oxidative free-radical additions of 1,3-dicarbonyl compounds to homobenzonorbornadiene and benzobarrelene: mechanistic studies


Ali M. F. , Caliskan R. A. , ŞAHİN E., BALCI M.

TETRAHEDRON, vol.65, no.7, pp.1430-1437, 2009 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 65 Issue: 7
  • Publication Date: 2009
  • Doi Number: 10.1016/j.tet.2008.12.012
  • Journal Name: TETRAHEDRON
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.1430-1437
  • Keywords: Manganese triacetate, Free radicals, Cycloaddition, Rearrangement, Homobenzonorbornadiene, Benzobarrelene, HIGH-TEMPERATURE BROMINATION, GAMMA-LACTONES, METAL-SALTS, BETA-DIESTERS, ACETIC-ACID, CYCLIZATIONS, ACETATE, BENZONORBORNADIENE, DERIVATIVES, ANNULATION

Abstract

Homobenzonorbornadiene and benzobarrelene were reacted with dimedone/acetylacetone and Mn(OAc)(3) in the presence of Cu(OAc)(2) in acetic acid. Mainly rearranged products having a [2.2.2]skeleton and the nonrearranged dihydrofuran derivatives were obtained. These observations clearly indicated that the second oxidation takes place before the cyclization reaction. Furthermore, intramolecular tandem oxidations were observed where unusually oxyl radicals attack the double bond to form the products. The mechanism of the formation of the products is discussed. (C) 2008 Elsevier Ltd. All rights reserved.