Regioselective bromination: Synthesis of brominated methoxyquinolines

Cakmak O., Okten S.

TETRAHEDRON, cilt.73, sa.36, ss.5389-5396, 2017 (SCI-Expanded) identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 73 Sayı: 36
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1016/j.tet.2017.07.044
  • Dergi Adı: TETRAHEDRON
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.5389-5396
  • Anahtar Kelimeler: Quinoline, 1,2,3,4-Tetrahydroquinoline, Bromo quinoline, Methoxy quinoline, Bromination of methoxy quinoline, Multifunctionalization of quinoline, Regioselective bromination, Molecular bromine, QUINOLINE DERIVATIVES, CATALYZED SYNTHESIS, SUBSTITUTION, CYCLIZATION, EFFICIENT, WATER
  • Yıldız Teknik Üniversitesi Adresli: Hayır

Özet

Simple synthetic methods are described for the synthesis of valuable polyfunctional brominated methoxyquinolines 10-13, 20-21, and 24-25. Three regioselective routes are described for convenient preparation of brominated methoxyquinolines at the C-2, C-3, and C-5 positions with consecutive reaction steps under mild reaction conditions using molecular bromine. While bromination of 6-bromo-8methoxy-1,2,3,4-tetrahydroquinoline (8) selectively gave 3,6-dibromo-8-methoxyquinoline (10) and 3,5,6-tribromo-8-methoxyquinoline (11), the reaction of 6,8-dimethoxy-1,2,3,4-tetrahydroquinoline (9) resulted in the formation of 3-bromo-6,8-dimethoxyqinoline (12) and tribromide 13. On the other hand, direct bromination of 6-methoxy- 17 and 6,8-dimethoxyquinoline (19) gave 5-bromo derivatives 20 and 21. However, the reaction 3,6-dimethoxyquinoline (8) resulted in dibromination to form 2,5dibromoquinoline (24). This process selectively led to functionalization of the quinoline ring at both the C-2 and C-5 positions. (C)2017 Elsevier Ltd. All rights reserved.