Low and high temperature bromination of exocyclic dienes: high temperature bromination. Part 16


Horasan N., Kara Y., Azizoglu A., Balci M.

TETRAHEDRON, vol.59, no.21, pp.3691-3699, 2003 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 59 Issue: 21
  • Publication Date: 2003
  • Doi Number: 10.1016/s0040-4020(03)00549-0
  • Title of Journal : TETRAHEDRON
  • Page Numbers: pp.3691-3699

Abstract

The electrophilic addition of bromine to an exocyclic diene, 5,6-dimethylenebicyclo[2.2.1]hept-2-ene, in CCl4 at 0degreesC led to the formation of non-rearranged (73%) and rearranged products (27%). However, high temperature bromination of the exocyclic diene at 77degreesC suppressed the formation of the rearranged products. Similarly, bromination of 9,10-dimethylenetricyclo[6.2.1.0(2.7)]undeca-2,4,6-triene at -10degreesC gave only the exo-1,2-addition product. Bromination at +5degreesC resulted in the formation of a mixture consisting of exo-1,2- and 1,4-addition products in a ratio of (1:4). High temperature bromination at 77degreesC resulted in the formation of the endo-1,2-addition product. Furthermore, it has been shown that the 1,4-addition product converts smoothly to the 1,2-addition product. The formation mechanism of the products is discussed and supported by calculations. (C) 2003 Elsevier Science Ltd. All rights reserved.