Enantioselective decarboxylative michael and aldol reactions with bifunctional squaramide organocatalysts

Bayer, Ezgi
The decarboxylative Michael and aldol reactions are quite new in the asymmetric studies and are used for forming new C-C bonds by nucleophilic attack. In the first part of this thesis, decarboxylative Michael reaction of isatylidene malononitriles with ethyl benzoyl acetate was accomplished in the presence of chiral 2- aminoDMAP and quinine derived bifunctional acid/base organocatalysts, which are developed in our research group. In this part, 12 derivatives were synthesized with quinine based 1-adamantyl squaramide bifunctional organocatalyst up to 46% ee under the optimized condition with 10 mol% catalysts loading at -20 °C. In the second part, the enantioselective decarboxylative aldol reactions of α- amidohemimalonates with various aldehydes were accomplished in the presence of the organocatalysts developed in our research group. In this part, the best result was achieved with 10 mol% t-butyl squaramide quinine organocatalyst as 63% ee.


Enantioselective synthesis of (S)-2-hydroxypropanone derivatives by benzoylformate decarboxylase catalyzed C-C bond formation
Dunnwald, T; Demir, Ayhan Sıtkı; Siegert, P; Pohl, M; Muller, M (2000-06-01)
Chiral 2-hydroxypropanone derivatives 5a-v, 8a-d, and 10a, b were formed by benzoylformate decarboxylase (BFD) catalyzed C-C bond formation. A donor aldehyde and acetaldehyde as an acceptor were carboligated in aqueous buffer solution with remarkable ease in high chemical yield and good to high optical purity. The substrate range of this thiamin diphosphate dependent enzyme was examined to employ this benzoin condensation type reaction in stereoselective synthesis. The observed dependence of the enantiomeri...
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...
Enantioselective reduction of ketones with borane catalyzed by cyclic β- amino alcohols prepared from proline
Demir, Ayhan S; Mecitoglu, Idris; Tanyeli, Cihangir; Gülbeyaz, Volkan (Elsevier BV, 1996-12)
New catalysts have been prepared from (S)- and (R)- proline and the asymmetric borane reduction of prochiral ketones using these catalysts has been studied. The secondary alcohols were obtained in 76-95% yield with 57-96% enantiomeric excesses. Copyright (C) 1996 Elsevier Science Ltd
Enantioselective Michael addition of diethyl malonate to nitroolefins with bifunctional 2-aminodmap/urea organocatalyst
Bakırcı Çetinkaya, İrem; Tanyeli, Cihangir; Department of Chemistry (2016)
The enantioselective organocatalytic Michael addition reaction has gained increased attention as an asymmetric synthesis strategy for C-C bond formation. In this regard, (1R,2R)-trans-1,2-cyclohexanediamine derived C1 symmetrical 2-aminoDMAP has been synthesized in our group. The remaining primary amine was modified with 1-isothiocyanato-(3,5)-bis(trifluoromethyl) benzene 3,5-Bis (trifluoromethyl) phenyl isothiocyanate and 3,5-bis(trifluoromethyl) phenyl isocyanate to afford bifunctional 2-aminoDMAP/thioure...
Enantioselective synthesis of hydroxy ketones through cleavage and formation of acyloin linkage. Enzymatic kinetic resolution via C-C bond cleavage
Demir, Ayhan Sıtkı; Pohl, M; Janzen, E; Muller, M (2001-01-01)
Both enantiomers of benzoins and (R)-2-hydroxy-1-phenylpropanone analogues were obtained in high yield on a preparative scale starting from aromatic aldehydes, rac-benzoins and aliphatic aldehydes via enzyme-catalysed C-C bond cleavage and C-C bond formation reactions.
Citation Formats
E. Bayer, “Enantioselective decarboxylative michael and aldol reactions with bifunctional squaramide organocatalysts,” M.S. - Master of Science, Middle East Technical University, 2018.