Asymmetric synthesis of 2,3-dihydrofurans with bifunctional quinine / squaramide organocatalysts

Bozdemir, Merve
Organocatalytic asymmetric reactions are efficient and environmentally friendly methods to synthesize products with higher enantioselectivities. Asymmetric domino Michael-SN2 reactions are one of the type of organocatalytic reaction frequently used to form carbon-carbon bonds in the synthesis of the derivatives of dihydrofurans, which are intermediates mainly utilized as precessor materials in the pharmaceutical fields. In this thesis, the reaction occuring between acetylacetone and (Z)-(2-bromo-2-nitrovinyl)benzene was chosen as a model reaction. As a first step, bifunctional 2-aminoDMAP and quinine-anchored squaramide organocatalysts were tested. Then, quinine / t-butyl squaramide organocatalyst was identified as the most suitable organocatalyst for our reaction. Subsequently, optimization studies were done and using different α-bromonitroalkenes and 1,3-dicarbonyl compounds, 14 different derivatives were synthesized. In optimized conditions with 10 mol% organocatalyst loading, the best result gave 97 % enantiomeric excess.


Enantioselective sulfa-Michael addition reaction of methyl thioglycolate to chalcones derivatives with sterically encumbered quinine squaramide organocatalyst
HASILCIOĞULLARI, DENİZ; Tanyeli, Cihangir (2018-04-04)
Asymmetric organocatalytic sulfa-Michael reactions give access to enantiomerically enriched sulfur containing adducts that can be used as valuable chiral building blocks. A variety of chalcone derivatives were allowed to react with methyl thioglycolate under optimized conditions, in the presence of a bifunctional quinine derived sterically encumbered squaramide organocatalyst, giving rise to excellent stereoselectivities, up to 99% ee. The designed catalyst system proved to be efficient even at gram scale a...
Asymmetric solution-phase mixture aldol reaction using oligomeric ethylene glycol tagged chiral oxazolidinones
Türkyılmaz, Serhan (2017-05-24)
Sorting tags are oligomeric structures that can be used as protecting groups or chiral auxiliaries enabling solution-phase mixture syntheses of multiple tagged compounds in one pot and allowing for facile and predictable chromatographic separation of products at the end of synthetic sequences. Perfluorinated hydrocarbon and oligomeric ethylene glycol (OEG) derivatives are known classes of sorting tags. Herein we describe the preparation of OEGylated chiral oxazolidinones and their use in asymmetric solution...
Enantioselective michael addition of 1-nitropropane to nitroolefins with 2-aminodmap and quinine based bifunctional organocatalysts
Kanberoğlu, Esra; Tanyeli, Cihangir; Department of Chemistry (2015)
1,3-dinitro compounds are key materials in the synthesis of a variety of important fine chemicals. Moreover, they are reduced to 1,3-diamines which are starting materials of biologically active compounds, agrochemicals and pharmaceuticals. In this study, ((2S,3S)-1,3-dinitropentan-2-yl)benzene was synthesized via the Michael addition of 1-nitropropane to trans-β-nitrostyrene in the presence of chiral bifunctional 2-aminoDMAP and quinine based organocatalysts. In the first part of study, reaction conditions ...
Real-time benchtop NMR spectroscopy for the online monitoring of sucrose hydrolysis
Soyler, Alper; Bouillaud, Dylan; Farjon, Jonathan; Giraudeau, Patrick; Öztop, Halil Mecit (Elsevier BV, 2020-01-01)
The online monitoring of chemical reactions by using benchtop Nuclear Magnetic Resonance (NMR) spectroscopy has become increasingly attractive for the past few years. The use of quantitative online NMR spectroscopy is a promising alternative to traditional analytical methods with its rapid, quantitative and non-invasive nature that makes it applicable to complex and diverse biochemical mixtures like food systems. In this study, sucrose hydrolysis by invertase was chosen as a model reaction for online monito...
Enantioselective Michael Addition of Nitroalkanes to Nitroalkenes Catalyzed by Chiral Bifunctional Quinine-Based Squaramides
KANBEROĞLU, Esra; Tanyeli, Cihangir (2016-01-01)
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--nitroalkenes. The cooperation of the quinine and the sterically encumbered squaramide moieties catalyzed the Michael addition reactions at 0 degrees C by using a catalyst loading of only 2mol% to afford the 1,3-dinitro Michael adducts with excellent enantioselectivity and diastereoselectivity (up to 95%ee and syn/anti isomers ...
Citation Formats
M. Bozdemir, “Asymmetric synthesis of 2,3-dihydrofurans with bifunctional quinine / squaramide organocatalysts,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Chemistry., Middle East Technical University, 2019.