Nonlinear effects in proline-thiourea host-guest complex catalyzed aldol reactions in nonpolar solvents

Demir, Ayhan Sıtkı
Eymur, Serkan
An aldol reaction catalyzed by a proline-thiourea host-guest complex in a nonpolar solvent shows excellent nonlinear effects. This proline-thiourea system has the ability to form a hydrogen-bonding network. The enantiomeric excess of proline in a solution can be significantly enhanced by its incorporation with a urea molecule into its solid racemate. This suggests a general and facile route to homochirality, which may be involved in the origin of chirality on earth.


Study of asymmetric aldol and Mannich reactions catalyzed by proline-thiourea host-guest complexes in nonpolar solvents
Demir, Ayhan Sıtkı; BAŞÇEKEN, SİNAN (Elsevier BV, 2013-04-30)
A proline-thiourea host-guest complex has been described as a good catalyst for asymmetric reactions such as aldol and Mannich reactions. High stereoselectivities were obtained under optimal conditions. Thiourea was observed to have an important effect on the reactivity and selectivity, even in an unconventional nonpolar reaction medium and without the need to utilize low temperatures. This proline-thiourea host-guest system has the ability to participate in a hydrogen bonding network.
Functionalization of oxabenzonorbornadiene: Manganese(III)-mediated oxidative addition of dimedone
ÇALIŞKAN, Raşit; Sari, Ozlem; Balcı, Metin (Wiley, 2017-09-01)
3-Chloro-1,2,3,4-tetrahydro-1,4-epoxynaphthalen-2-yl)-3-hydroxy-5,5-dimethylcy-clohex- 2-en-1-one, synthesized by the reaction of oxabenzonorbornadiene with Mn(OAc)(3) and dimedone in the presence of HCl in acetic acid, was submitted to ring-opening reactions with BBr3 and H2SO4. Reaction with BBr3 yielded 2 products, a 5-membered ring and an 8-membered ring, with the former being the major product. However, the H2SO4-supported reaction exclusively formed an 8-membered ring. The mechanism of formation of th...
Axial water substitution kinetics of sulphato- and hydrogenphosphato-bridged binuclear platinum(III) complexes
Camadanli, S; Deveci, N; Gokagac, G; Isci, H (Elsevier BV, 2003-07-22)
The kinetics of the axial water substitution reactions for [Pt-2(B-B)(4)(H2O)(2)](2-) (B-B = SO42-, HpO(4)(2-)) with Cl-, Br- and SCN- are reported in acidic aqueous solution. With a large excess of entering ligand and hydrogen ion, only the disubstituted product complex was formed. The reaction rates are first order with respect to the substrate complex and entering ligand and decrease with increasing H+ concentration. In the presence of 0.10 M H+, the rate constants for the replacement of the first water ...
Enantioselective synthesis of both enantiomers of 2-amino-2-(2-furyl)ethan-1-ol as a flexible building block for the preparation of serine and azasugars
Demir, Ayhan Sıtkı; Sesenoglu, O; Aksoy-Cam, H; Kaya, H; Aydogan, K (Elsevier BV, 2003-05-16)
The selective conversion of 1-(2-furyl)-2-hydroxyethan-1-one and ethyl 2-(2-furyl)-2-oxo acetate into (E)- and (Z)-oximes and oxime ethers followed by oxazaborolidine-catalyzed enantioselective reduction using different amino alcohols furnished both enantiomers of the important chiral building block 2-amino-2-(2-furyl)ethan-1-ol with an ee of up to 96%.
Conformational control on remote stereochemistry in the intramolecular Pauson-Khand reactions of enynes tethered to homoallyl and homopropargyl alcohols
Sezer, Serdar; Ozdemirhan, Devrim; Sahin, Ertan; Tanyeli, Cihangir (Elsevier BV, 2006-11-17)
An intramolecular Pauson-Khand reaction of enynes derived from homoallyl and homopropargyl alcohols is described. 2-Furyl substituted homoallyl and homopropargyl alcohols are easily and efficiently resolved through enzymatic resolution in a high ee (93-99%) with a known stereochemistry. Each enantiomerically enriched enyne affords the conformationally most stable diastereomeric cyclopenta[c]pyran ring system.
Citation Formats
A. S. Demir and S. Eymur, “Nonlinear effects in proline-thiourea host-guest complex catalyzed aldol reactions in nonpolar solvents,” TETRAHEDRON-ASYMMETRY, pp. 405–409, 2010, Accessed: 00, 2020. [Online]. Available: