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


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

TETRAHEDRON, cilt.59, ss.3691-3699, 2003 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 59 Konu: 21
  • Basım Tarihi: 2003
  • Doi Numarası: 10.1016/s0040-4020(03)00549-0
  • Dergi Adı: TETRAHEDRON
  • Sayfa Sayıları: ss.3691-3699

Özet

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.