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    Regioselective bromination: Synthesis of brominated methoxyquinolines
    (Pergamon-Elsevier Science Ltd, 2017) Cakmak, Osman; Okten, Salih
    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.
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    Reinvestigation of bromination of 8-substituted quinolines and synthesis of novel phthalonitriles
    (Acg Publications, 2016) Okten, Salih; Cakmak, Osman; Saddiqa, Aisha; Keskin, Bahadir; Ozdemir, Seda; Inal, Merve
    Bromination of a series of 8-substituted quinolines was reinvestigated and specified for optimum yields and isolation conditions. Mono bromination of 8-hydroxyquinoline (2a) and 8-aminoquinoline (2c) gave mixture of mono and dibromo derivatives 5,7-dibromo-8-hydroxyquinoline (3a), 5,7-dibromo-8aminoquinoline (3c), 7-bromo-8-hydroxyquinoline (3d), 5-bromo-8-aminoquinoline (3e) while 8methoxyquinoline (2b) furnished 5-bromo-8-methoxyquinoline (3f) as sole product. Novel phthalonitriles, 4(quinolin-8-yloxy) phthalonitrile (6) and 4-chloro-5-(quinolin-8-yloxy) phthalonitrile (8) of 8-hydroxyquinoline (2a) were synthesized and converted into their respective bromo derivatives 4-(5-bromoquinolin-8yloxy) phthalonitrile (7) and 4-((5-bromoquinolin-8-yl) oxy)-5-chlorophthalonitrile (9).
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    Öğe
    A SAR Study: Evaluation of Bromo Derivatives of 8-Substituted Quinolines as Novel Anticancer Agents
    (Bentham Science Publ Ltd, 2017) Okten, Salih; Cakmak, Osman; Tekin, Saban; Koprulu, Tugba Kul
    Background: Brominated 8-hydroxy, 8-methoxy, 8-amino quinolines 5, 6, 8, 9 and novel cyano 8-hydroxyquinolines 11, 12 were evaluated in vitro for their anticancer effects on various cell lines. 5,7-Dibromo-5, 7-bromo-6, 7-cyano-11 and 5,7-dicyano-12 8-hydroxyquinolines were shown to have strong antiproliferative activity against various tumor cell lines, including C6 (rat brain tumor), HeLa (human cervix carcinoma), and HT29 (human colon carcinoma) with IC50 values ranged from 6.7 to 25.6 mu g/mL. Methods: A structure activity relationship (SAR) was conducted that quinoline core containing hydroxly group at C-8 positon led to more anti cancer potentials. Results: The results of Lactate Dehydrogenase (LDH) cytotoxic, DNA laddering and inhibition assays indicated that 5, 6, 11 and 12 have high cytotoxic effects and appototic potentials. Conclusion: Furthermore, 5 and 12 have inhibitory effects on relaxation of supercoiled plazmid DNA by supressed the Topoisomerase I enzyme. As a result, 5, 6, 11 and 12 may have promising anticancer drug potential and 5 and 12 may be novel topoisomerase inhibitors.