Asymmetric synthesis of tetrahydrothiophenes in the presence of bifunctional organocatalysts

Download

12626076.pdf

Date

2021-1-22

Author

Tümer, Mustafa Faik

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

229
views

285
downloads

In general, nitroolefins are convenient structures as Michael acceptors. To make it clear for this work, attack of a sulfur-containing nucleophile to a nitroolefin forms a C-S bond and opening the double bond would create a nucleophilic center on the nitroolefin which leads to the formation of a new C-C bond. In this study, asymmetric organocatalytic sulfa-Michael addition of 1,4-dithiane-2,5-diol to trans-β-nitrostyrene derivatives was carried out which yielded polyfunctional tetrahydrothiophenes that have the potential of biological activities, building blocks for chiral ligands and benefit in the synthesis of gold nanoparticles. In the first part, several quinine-based and 2-aminoDMAP-based bifunctional organocatalysts and different conditions were tested to find the optimized conditions for the reaction generating relatively high yield and stereoselectivity in a shorter time. Then, derivatization studies were performed by using diverse trans-β-nitrostyrenes in the optimized conditions determined previously. Increase in stereoselectivity was reached up to 70 % ee and 96:4 dr for the tetrahydrothiophene derivatives.

Subject Keywords

Asymmetric synthesis, Enantioselectivity, Sulfa-Michael addition, Bifunctional organocatalysts

URI

https://hdl.handle.net/11511/89577

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

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 synthesis of 2,3-dihydrofurans with bifunctional quinine / squaramide organocatalysts Bozdemir, Merve; Tanyeli, Cihangir; Department of Chemistry (2019) 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-nitroviny...
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 ...
Nonlinear structural modification and nonlinear coupling Kalaycioglu, Taner; Özgüven, Hasan Nevzat (Elsevier BV, 2014-06-03) Structural modification methods were proved to be very useful for large structures, especially when modification is local. Although there may be inherent nonlinearities in a structural system in various forms such as clearances, friction and cubic stiffness, most of the structural modification methods are for linear systems. The method proposed in this work is a structural modification/coupling method developed previously, and extended to systems with nonlinear modification and coupling. The method is most ...
Enantioselective sulfa-michael addition to trans-chalcone derivatives with quinine derived bifunctional organocatalysts Tözendemir, Deniz; Tanyeli, Cihangir; Department of Chemistry (2020-12-28) The use of organocatalysts has brought profound advantages in the context of asymmetric synthesis, in terms of ease of use and better compatibility with the environment. More than 20 organocatalysts of four different classes (squaramide, urea, thiourea, and sulfonamide) have been developed and used to catalyze various asymmetric reactions in our research group. In this thesis, asymmetric sulfa-Michael type additions were carried out in the presence of cinchona alkaloid derived squaramide and sulfonamide-typ...

Citation Formats

M. F. Tümer, “Asymmetric synthesis of tetrahydrothiophenes in the presence of bifunctional organocatalysts,” M.S. - Master of Science, Middle East Technical University, 2021.