Cihangir Tanyeli

Synthesis of polymer-supported TEMPO catalysts and their application in the oxidation of various alcohols

We describe the synthesis of a recyclable polymer-supported TEMPO as a catalyst in the Anelli oxidation of various primary alcohols to afford the corresponding aldehydes in good yields.

Manganese triacetate mediated regeneration of carbonyl compounds from oximes

Abstract A new method for the direct conversion of oximes into aldehydes and ketones by treatment with manganese triacetate is described. Manganese triacetate can be used for an effective and mild oxidizing agent for the regeneration of carbonyl compounds from oximes in good yield. Many functional groups are tolerated under the reaction conditions.

Oxidation of Aryl Alkyl Ketones To α-Acyloxy, α-(Camphorsulfonyloxy), or α-Hydroxy Derivatives Using Manganese(III) Acetate in Combination with Carboxylic Acids or (1S)-(+)-10-Camphorsulfonic Acid

Abstract The α-oxidation of aryl alkyl ketones using manganese(III) acetate in the presence of various carboxylic acids and (1S)-(+)-10-camphorsulfonic acid provided a convenient synthesis of α-acyloxy, α-(10-camphorsulfonyloxy), and α-hydroxy derivatives in good yield.

Bioactive thiazole and benzothiazole derivatives

The heterocycles are the versatile compounds existing in almost all natural products and synthetic organic compounds, usually associated with one or the other biological activity. Among the heterocycles the thiazoles and benzothiazoles occupy a prominent position. They possess a broad range of biological activities and are found in many potent biologically active molecules and drugs such as vitamin thiamine, sulfathiazol (antimicrobial drug), ritonavir (antiretroviral drug), abafungin (antifungal drug) and tiazofurin (antineoplastic drug). The thiazole moiety is abundantly found in natural products while benzothiazole moiety is rare. In this review we disclose the literature reports of thiazoles and benzothiazoles possessing different biological activities.

Synthesis and Rhizopus oryzae mediated enantioselective hydrolysis of α-acetoxy aryl alkyl ketones

Abstract Mn(OAc)3 oxidation of aromatic ketones afforded the α-acetoxy ketones in good yield. Selective hydrolysis of the acetoxy ketones by the fungus Rhizopus oryzae yields (R)-hydroxy ketones in high enantiomeric excess.

A simple synthesis of 1-aminophosphonic acids from 1-hydroxyiminophosphonates with NaBH4 in the presence of transition metal compounds

Abstract A new procedure has been developed for the synthesis of 1-aminophosphonic acids. Diethyl phosphonates are converted to hydroxyiminophosphonates when treated with hydroxylamine hydrochloride. Reduction of hydroxyiminophosphonates with NaBH 4 in MeOH in the presence of MoO 3 or NiCl 2 and hydrolysis of 1- aminophosphonates gave 1-aminophosphonic acids in good yield.

Functionalization of poly-SNS-anchored carboxylic acid with Lys and PAMAM: surface modifications for biomolecule immobilization/stabilization and bio-sensing applications.

Poly(2-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl) (SNS) acetic acid) was electrochemically deposited on graphite electrodes and functionalized with lysine (Lys) amino acid and poly(amidoamine) derivatives (PAMAM G2 and PAMAM G4) to investigate their matrix properties for biosensor applications. Glucose oxidase (GOx) was immobilized onto the modified surface as the model enzyme. X-Ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to report the surface properties of the matrices in each step of the biosensor construction. The biosensors were characterized in terms of their operational and storage stabilities and the kinetic parameters (K(app)(m) and I(max)). Three new glucose biosensors revealed good stability, featuring low detection limits (19.0 μM, 3.47 μM and 2.93 μM for lysine-, PAMAM G2- and PAMAM G4-functionalized electrodes, respectively) and prolonged the shelf lives (4, 5, and 6 weeks for Lys-, PAMAM G2- and PAMAM G4-modified electrodes, respectively). The proposed biosensors were tested for glucose detection on real human blood serum samples.

Synthesis and application of poly-SNS-anchored carboxylic acid: a novel functional matrix for biomolecule conjugation

Here we report the synthesis of a novel conducting polymer and its properties as an immobilization platform for biosensor application. The conducting polymer has functional groups used for the formation of amide bonding with the enzyme immobilized on the polymer surface. After covalent immobilization of glucose oxidase (GOx) on the polymeric matrix, its application for glucose biosensing was investigated in detail. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to monitor the surface properties of the polymer before and after biomolecule conjugation. The optimized biosensor showed a very good linearity between 0.01 mM and 1.2 mM, a 13 s response time and a detection limit (LOD) of 0.004 mM to glucose. Also, kinetic parameters, operational and storage stabilities were determined. Apparent Michaelis constant (Kmapp) and Imax values of 1.17 mM and 11.28 μA, respectively, were obtained.

New chiral synthon from the PLE catalyzed enantiomeric separation of 6-acetoxy-3-methylcyclohex-2-en-1-one

Abstract (±)-6-Acetoxy-3-methylcyclohex-2-en-1-one was resolved by PLE catalyzed hydrolysis to afford (+)-6-hydroxy-3-methylcyclohex-2-en-1-one in >95% e.e. (+)-6-Hydroxy-3-methylcyclohex-2-en-1-one was transformed to its ( S )-O-acetyllactyl ester derivative to determine the e.e. %.

ROMP-Polymers in Asymmetric Catalysis: The Role of the Polymer Backbone

Ring-opening metathesis polymerization (ROMP) is utilized for the synthesis of highly functionalized polymers with covalently bound chiral prolinol units. The linear macromolecules act as multifunctional ligands in homogeneous asymmetric catalysis. The solubility of the polymers and their catalytic performance can be tuned by random co-polymerization with achiral units in a simple and flexible manner. Use of norbornenes with additional well-defined stereogenic centers in the polymerizable core of the monomers leads to polymers which show cooperative effects between the various elements of chirality during the course of the catalysis.