Asymmetric syntheses of various novel chiral ligands with norbornene backbone : the use of chiral catalyst in asymmetric reactions

Elmalı, Olcay
The synthetic strategy of this study mainly depends upon the asymmetric desymmetrization of meso norbornene type an anhydride. Asymmetric desymmetrization was achieved by using chinchona alkaloids under kinetically controlled conditions. The resultant mono ester carboxylic acid was epimerized to trans configuration. Subsequent esterification followed by lithium aluminum hydride reduction afforded the first chiral diol ligand with 98 % ee. Transformation of diol to corresponding trans diamine was achieved via Mitsunobu-Gabriel combination. The resultant diamine was first transformed into salen type ligand with 3,5-di-tert-butyl-2-hydroxybenzaldehyde. Throughout this process, no racemization was observed and all the ligands tested in asymmetric reactions have 98 % ee value. The second part of the thesis involves the asymmetric test reactions of the chiral ligands to check the effectiveness of them. The first testing method was diethylzinc addition to benzaldehyde. The ligands showed moderate effectiveness. The salen type ligand was tested in asymmetric epoxidation and aziridination reactions and it showed good effectiveness. Another applied method was desymmetrization of meso 2-cyclohexene-3,4-diol in which 2-(diphenylphosphino)benzoic acid attached trans-diol and trans-diamine type ligands were tested. Since norbornene type strained bicyclic systems are available in ring opening methathesis polymerization (ROMP) reactions, trans-diamine was subjected to ROMP to get an enlarged macromolecular system


Recent progress in asymmetric synthesis of aziridine derivatives (microreview)
Doğan, Özdemir (Springer Science and Business Media LLC, 2018-04-01)
This microreview describes recent advances in asymmetric synthesis of aziridine derivatives, which have been published over the last two years.
Tanyeli, Cihangir (Informa UK Limited, 1989-01-01)
Some phenolic biphenyl compounds have been synthesised via the annulation reactions of 4-methoxy-2- pyrone with various active methyl compounds.
Enantioselective Michael Addition of Nitroalkanes to Nitroalkenes Catalyzed by Chiral Bifunctional Quinine-Based Squaramides
Kanberoğlu, Esra; Tanyeli, Cihangir (Wiley, 2015-10-26)
A family of chiral bifunctional acid-/base-type quinine/squaramide organocatalysts is shown to be highly active promoters of the conjugate addition of 1-nitropropane to various trans-β-nitroalkenes. The cooperation of the quinine and the sterically encumbered squaramide moieties catalyzed the Michael addition reactions at 0 °C by using a catalyst loading of only 2 mol % to afford the 1,3-dinitro Michael adducts with excellent enantioselectivity and diastereoselectivity (up to 95 % ee and syn/anti isomers
Silafluorene-based polymers for electrochromic and polymer solar cell applications
ERLIK, Ozan; UNLU, Naime A.; HIZALAN, Gonul; HACIOGLU, Serife O.; COMEZ, Seda; Yildiz, Esra D.; Toppare, Levent Kamil; Çırpan, Ali (Wiley, 2015-07-01)
In this study, four novel silafluorene (SiF) and benzotriazole (Btz) bearing conjugated polymers are synthesized. In the context of electrochemical and optical studies, these polymers are promising materials both for electrochromic device (ECD) and polymer solar cell (PSC) applications. All of the polymers are ambipolar (both p- and n-dopable) and multichromic. Electrochemistry experiments indicate that incorporation of selenophene instead of thiophene unit increases the HOMO energy level of the polymers. P...
A new approach for the synthesis of spiro and gem-dimethyl-substituted 1,4-oxazepines from N-propargylic beta-enaminones
Karadeniz, Eda; Kelgökmen, Yılmaz; Zora, Metin (Wiley, 2020-11-01)
An efficient and general method for the synthesis of spiro-1,4-oxazepines and 3,3-dimethyl-1,4-oxazepines is reported. When treated with ZnI2 and AgSbF6 in refluxing DCE, cyclohexane-embedded N-propargylic beta-enaminones underwent 7-exo-dig cyclization to afford spiro-1,4-oxazepines, specifically 12-methylene-11-oxa-7-azaspiro[5.6]dodeca-7,9-dienes, in good to high yields. Accordingly, N-(1,1-dimethyl)propargylic beta-enaminones produced 3,3-dimethyl-1,4-oxazepines. Cyclization was found to be general for ...
Citation Formats
O. Elmalı, “Asymmetric syntheses of various novel chiral ligands with norbornene backbone : the use of chiral catalyst in asymmetric reactions ,” Ph.D. - Doctoral Program, Middle East Technical University, 2005.