Yunus Kara

A new and stereospecific synthesis of an inositol analogue: bis-homoinositol

Abstract The photooxygenation of trans -8-(acetyloxy)bicyclo[4.2.0]octa-2,4-dien-7-yl acetate afforded the bicyclic endoperoxide. Reduction of the endoperoxide with thiourea followed by acetylation gave the corresponding tetraacetate. The KMnO 4 oxidation of the tetraacetate followed by acetylation gave dihydroxytetraacetate Ammonolysis of tetraacetate afforded the bis-homoinositol, bicyclo[4.2.0]octane-2,3,4,5,7,8-hexol.

Synthesis of new conduritol analogues derived from bicyclooctatriene: Bis-homo-conduritol-D and bis-homoconduritol-F

Abstract The first synthesis of conduritol analogues 2 and 3 is reported. The key compound 7 reacted with KMnO 4 and m-chloroperbenzoic acid in a stereospecific manner to give syn -addition products 9 and 10 , respectively. Zinc-dust elimination of 10 followed by epoxide opening resulted in the formation of 3b . The free tetrol 3 was obtained by ammonolysis. The other tetrol isomer 2 was obtained by similar synthetic steps.

Low and high temperature bromination of exocyclic dienes: high temperature bromination. Part 16☆

Abstract The electrophilic addition of bromine to an exocyclic diene, 5,6-dimethylenebicyclo[2.2.1]hept-2-ene, in CCl4 at 0°C led to the formation of non-rearranged (73%) and rearranged products (27%). However, high temperature bromination of the exocyclic diene at 77°C suppressed the formation of the rearranged products. Similarly, bromination of 9,10-dimethylenetricyclo[6.2.1.02,7]undeca-2,4,6-triene at −10°C gave only the exo-1,2-addition product. Bromination at +5°C resulted in the formation of a mixture consisting of exo-1,2- and 1,4-addition products in a ratio of (1:4). High temperature bromination at 77°C resulted in the formation of the endo-1,2-addition product. Furthermore, it has been shown that the 1,4-addition product converts smoothly to the 1,2-addition product. The formation mechanism of the products is discussed and supported by calculations.

Synthesis of a new class of aminocyclitol analogues with the conduramine D-2 configuration.

Summary A new class of aminocyclitol derivatives with the bicyclo[4.2.0]octane skeleton was synthesized starting from cyclooctatetraene. Photooxygenation of trans-7,8-diacetoxy- and cis-7,8-dichlorobicyclo[4.2.0]octa-2,4-diene afforded the bicyclic endoperoxides. Reduction of the latter with thiourea followed by a Pd(0) catalyzed ionization/cyclization reaction gave the corresponding oxazolidinone derivatives. Oxidation of the double bond with KMnO4 or OsO4 followed by acetylation gave the acetate derivatives, the exact configuration of which was determined by spectroscopic methods. Hydrolysis of the oxazolidinone rings and removal of the acetate groups furnished the desired aminocyclitols.

Investigation of Solvent Effects on Photophysical Properties of New Aminophthalimide Derivatives-Based on Methanesulfonate

Novel aminophthalimide derivatives were synthesized starting from (3aR,7aS)-2-(2-hydroxypropyl)-3a,4,7,7a–tetrahydro-1H-isoindole-1,3(2H)-dione (9) , and solvent effects on the photo-physical properties of these newly synthesized aminophthalimide derivatives (compounds 14 and 15) were investigated using UV-Vis absorption spectroscopy, steady-state and time-resolved fluorescence measurements. Both absorption and fluorescence spectra exhibited bathochromic shift with the increased polarity of the solvents for both molecules. Solute-solvent interactions were analyzed using the Lippert-Mataga and Bakhshiev polarity functions, and Kamlet-Taft and Catalan multiple linear regression approaches. The results revealed that these two molecules experienced specific interactions. Furthermore, photo-physical parameters were calculated for both molecules in all of the solvents, such as the fluorescence quantum yield, fluorescence lifetime, radiative (kr) and non-radiative (knr) rate constant values. It was observed that the fluorescence quantum yield values decreased linearly with increasing solvent polarity. This study proved the new dyes including isopropyl methanesulfonate group displayed different behavior from previous studies of aminophthalimide derivatives in water. It was recommended that these new dyes having interesting properties by changing solvent can be used various applications such as environmentally sensitive fluorescent probes, labels in biology, laser industry.

Unusual photorearrangement of 1,7-disubstituted 7-azabenzonorbornadiene

Abstract1-(11-Benzoyl-11-azatricyclo[6.2.1.02,7]undeca-2,4,6,9-tetraen-1-yl)ethanone was synthesized by cycloaddition of 2-acetyl-N-benzoylpyrrole to benzyne. Direct photolysis of 1-(11-benzoyl-11-azatricyclo-[6.2.1.02,7]undeca-2,4,6,9-tetraen-1-yl)ethanone in benzene gave N-(4-acetylnaphthalen-1-yl)benzamide. The formation of this product is discussed in terms of radical-stabilizing and destabilizing effect of electron-withdrawing group in the formation of cyclopropane ring.

Syntheses of and photochemical studies of 2,3-disubstituted 1,4-epoxy-1,4-dihydronaphthalenes

A method for synthesis of 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carboxylic acid and 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carbonitrile was developed starting from 1,4-epoxy-1,4-dihydronaphthalene; direct photolysis of 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carbonitrile and methyl 3-methyl-1,4-epoxy-1,4-dihydronaphthalene-2-carboxylate in benzene gave indene derivatives.

Synthesis and anticancer activity evaluation of new isoindole analogues

We have developed a versatile synthetic approach for the synthesis of new isoindole derivatives via the cleavage of ethers from tricyclic imide skeleton compounds. An exo-cycloadduct prepared from the Diels–Alder reaction of furan and maleic anhydride furnished imide derivatives. The epoxide ring was opened with Ac2O in the presence of a catalytic amount of H2SO4 in order to yield new isoindole derivatives (8a and 8b). The anticancer activity of these compounds was evaluated against MCF-7 (breast adenocarcinoma) and A549 (adenocarcinomic human alveolar basal epithelial) cell lines. The synthesized compounds showed concentration- and time-dependent inhibitory effects on the viability of both cell lines. Compound 8a was more toxic compared to 8b in both cancer cell lines, having higher cytotoxicity against A549 cells. Testing the toxicity properties of these compounds on the BEAS 2B (human bronchial epithelial) cell line indicated that while both compounds decreased the cell viability of cancer cells, they were less toxic on healthy lung cells. Microscopy images of A549 cells after treatment with the new isoindole derivatives displayed characteristic apoptotic morphology compared to BEAS 2B cells. The results demonstrated here suggest that these new compounds might be considered as possible potential anticancer agents for the treatment of lung and breast cancer.

Synthesis of new hexahydro-1H-isoindole-1,3(2H)-dione derivatives from 2-ethyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3-(2H)-dione

A new and appropriate synthesis for hexahydro-1H-isoindole-1,3(2H)-dione derivatives has been developed starting from 3-sulfolene. The epoxidation of 2-ethyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3-(2H)-dione and then the opening of the epoxide with nucleophiles gave hexahydro-1H-isoindole-1,3(2H)-dione derivatives. Amino and triazole derivatives of hexahydro-1H-isoindole-1,3(2H)-dione were synthesized from the formed product by the opening reaction of the epoxide with sodium azide. Hydroxyl analogues were obtained from cis-hydroxylation of 2-ethyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3-(2H)-dione. The hydroxyl groups were converted to acetate.

rac-3,4-trans-Dichloro-1,2,3,4-tetra­hydro-2-naphthyl acetate

The title compound, C12H12Cl2O2, has a bicyclic skeleton containing cyclohexene and benzene fragments. The cyclohexene ring adopts a half-chair conformation with displacements of two atoms out of the least-squares plane of 0.311 (2) and −0.336 (2) Å. The Cl atoms are trans-positioned.