Yılmaz Turgut

Synthesis of C 2-Symmetric Chiral Amino Alcohols: Their Usage as Organocatalysts for Enantioselective Opening of Epoxide Ring

A series of β-amino alcohols derivatives were synthesized from (R)-2-amino-1-butanol and (S)-1,2-propanediol, and they have been used as organocatalaysts in the racemic ring opening of epoxide in good yields with high enantiomeric excess (up to 97%).

The Solvent Extraction of Boron with Synthesized Aliphatic 1,3‐Diols: Stripping and Extraction Behavior of Boron by 2,2,5‐Trimethyl‐1,3‐hexanediol

Abstract A variety of aliphatic 1,3‐diols (4a–c, 5a–c, 6a–c) was synthesized from β‐hydroxy carbonyl compounds (1–3) for potential use in the solvent extraction of boron. Primary‐secondary and primary‐tertiary alcohol structures of 1,3‐diols substituted with isopropyl, isobutyl, and isopentyl groups have been demonstrated to be very efficient for the solvent extraction of boric acid from aqueous solutions. The extraction ability of 2,2,5‐trimethyl‐1,3‐hexanediol (5b) was investigated as a function of 5b concentration, solution pH, solvent properties, and stripping conditions. Extraction efficiency increased with increasing concentration of 5b, and the best extraction of boron (96.8%) was found to be at an equilibrium pH of 2 with 0.5 M of 5b. Chloroform, toluene, chlorobenzene, 2‐octanol, and n‐amyl alcohol were found to be suitable solvents for the solvent extraction of boron. The boron complex can be recovered from the organic phase by treatment with an aqueous solution of sodium hydroxide. The highest ratio (96.7%) of boron was recovered by 0.1 M of sodium hydroxide solution.

A practical synthesis of chiral 3-aryloxy-1,2-propanediols

Chiral 3-aryloxy-1,2-propanediols (1–5) of >96 % ee were obtained in high yield by the nucleophilic addition of substituted phenols to chiral glycidol in the presence of piperidine hydrochloride as catalyst.

β‐Hydroxyamide‐Based Ligands and Their Use in the Enantioselective Borane Reduction of Prochiral Ketones

Hydroxyamide-based ligands have occupied a considerable place in asymmetric synthesis. Here we report the synthesis of seven β-hydroxyamide-based ligands from the reaction of 2-hydroxynicotinic acid with chiral amino alcohols and test their effect on the enantioselective reduction of aromatic prochiral ketones with borane in tetrahydofuran (THF). They produce the corresponding secondary alcohols with up to 76% enantiomeric excess (ee) and good to excellent yields (86-99%).

Synthesis of new chiral diaza 18-crown-6 ethers from chiral amines

Practical syntheses of versatile building blocks of crown ethers 1 and 2, chiral amine precursors 3–6 and chiral diaza 18-crown-6 ethers 7–12 are reported starting from chiral amines.

Synthesis of novel chiral monoaza-15-crown-5 ethers and their molecular recognition of amino acid esters

The chiral monoaza-15-crown-5 ethers 4 and 5 were prepared from L-phenylalaninol and L-leucinol, respectively. The molecular recognition of these chiral crown ethers for L-amino acid ethyl esters was characterised by UV-visible spectroscopy. Binding constants (Ka), free-energy changes (–ΔGo), enthalpy changes (ΔH) and entropy change (ΔS) values were determined for hosts 4 and 5 with L-amino acid ethyl ester hydrochlorides in CHCl3.