Hamdullah Kilic

Effect of additives on chemoselectivity and diastereoselectivity in the catalytic epoxidation of chiral allylic alcohols with hydrogen peroxide and binuclear manganese complexes.

The catalytic oxidations of chiral allylic alcohols 2 by manganese complexes of the cyclic triamine 1,4,7-trimethyl-1,4,7-triazacyclononane (tmtacn) 1 and hydrogen peroxide as oxygen donor in the presence of co-catalyst are investigated to understand the factors that affect the catalyst selectivity. Chemoselectivity and diastereoselectivity of catalyst 1 are significantly affected by the structure of the allylic alcohol and the nature and amount of co-catalyst. More pronounced is the influence of the amount of added molar equivalents of H(2)O(2) (20-110 mol % with respect to the substrate). Our present results reflect the complex redox chemistry of the Mn catalyst 1/H(2)O(2)/co-catalyst system in the early phase of the alkene oxidation.

Singlet Oxygen Generation from [Bis(trifluoroacetoxy)iodo]benzene and Hydrogen Peroxide

Decomposition of hydrogen peroxide with a hypervalent iodine compound was examined. The results indicate that treatment of a hypervalent iodine compound with hydrogen peroxide produces singlet molecular oxygen ((1)O(2)). Convergent evidence for the production of singlet molecular oxygen ((1)O(2)) by decomposition of hydrogen peroxide with a hypervalent iodine compound comes from chemical trapping experiments and the specific chemiluminescence detection of (1)O(2) at 1270 nm. Substantial evidence demonstrates that hydroperoxyl radical produced from hydrogen peroxide with hypervalent iodine reacts via a tetraoxidane intermediate, decomposing to give singlet molecular oxygen.

Diastereoselective control through hydrogen bonding in the aziridination of the chiral allylic alcohols by acetoxyaminoquinazolinone.

A high diastereoselectivity (up to >99:1) is found for the aziridinations of chiral allylic alcohols with acetoxyaminoquinazolinone (Q-NHOAc). The selectivity is explained in terms of hydrogen bonding between the hydroxy functionality of the allylic alcohol and the remote carbonyl group of the quinazolinone.

Production of (R)-1-phenylethanols through bioreduction of acetophenones by a new fungus isolate Trichothecium roseum.

A total of 120 fungal strains were isolated from soil samples and evaluated in the bioreduction of substituted acetophenones to the corresponding (R)-alcohols. Among these strains, isolate Trichothecium roseum EBK-18 was highly effective in the production of (R)-alcohols with excellent enantioselectivity (ee > 99%). Gram scale preparation of (R)-1-phenylethanol is reported.

ESSENTIAL OIL COMPOSITION OF Tanacetum alyssifolium, AN ENDEMIC SPECIES FROM TURKEY

Faculty of Agriculture, Department of Field Crops, Erzurum 25240, Turkey; fax: + 9

Composition of the essential oil of Salvia longipedicellata from Turkey

2312493, e-mail: haozer@atauni.edu.tr; 2) Ataturk University, Faculty of Art and Science, Department of Chemistry, Erzurum 25240, Turkey; 3) Ataturk University, Faculty of Art and Science, Department of Biology, Erzurum 25240, Turkey; 4) Ataturk University, Biotechnology Application and Research Center, 25240, Turkey . Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 190-191, March-April, 2007. Original article submitted January 18, 2006.

A new antiaromatic compound: 1,4-biphenylenequinone synthesis and trapping reactions: can a quinone unit stabilize the cyclobutadiene?

Abstract The photooxygenation of 4a,8b-dihydrobiphenylene affords an endoperoxide. NE t 3 -catalyzed rearrangement of this endoperoxide gave the corresponding hydroxy enone, while the CoTPP-catalyzed rearrangement afforded a bisepoxide. MnO 2 oxidation of hydroxy enol leads to 4a,8b-dihydrobiphenylene-1,4-dione. The NBS bromination of this dione produces mono- and dibromides. NE t 3 -supported elimination of monobromide and zinc elimination of dibromide afforded the target compound, 1,4-biphenylenequinone, which was trapped as the dimer and cycloadducts with cyclopentadiene and anthracene, respectively. Furthermore, 1,4-biphenylenequinone was generated upon oxidation of biphenylene-1,4-diol with bis(trifluoroacetoxy)iodobenzene (PIFA). The stability and reactivity of the title compound is discussed.

Generation of singlet oxygen (1O2) from hydrogen peroxide decomposition by in situ generated hypervalent iodoarene reagents

Abstract A novel method for the production of singlet oxygen from H2O2 was developed. A combination of iodoarene (ArI), methyltrioxorhenium (MTO), and H2O2 in the presence of pyridine as the co-catalyst efficiently produced singlet molecular oxygen (1O2) under biphasic conditions. The existence of 1O2 was demonstrated by trapping experiments with aromatic dienes, 1,3-cyclodienes, and alkenes. The mechanism of 1O2 production from the iodoarene/MTO/35 % H2O2 system and the reaction scope was also discussed.