Stereoselective synthesis of optically active cyclitol precursors via chemoenzymatic method and synthesis of a nucleoside precursor

Oğuzkaya, Funda
α'-acetoxylation of α,ß-unsaturated cyclic ketones was adjusted via Mn(OAc)3 in regioselective manner. Then, PLE hydrolysis was carried out so as to afford enantiomerically enriched α'-acetoxylated and α'-hydroxylated cyclic compounds. From our knowledge about the literature and previous works dealing with α'-hydroxylated products which are easily racemized, protection was directly adjusted via acetylation so as to prevent this possibility. Resulting enantiomerically enriched products were subjected to Upjohn Dihydroxylation to obtain cyclitol precursors and following Luche Reduction of ketone was adjusted so as to obtain corresponding cyclitols. In addition with such synthetic design, firstly dimethyl cyclopent-3-ene-1,1-dicarboxylate was obtained so as to reach in former manner 3-cyclopentene-1,1-dicarboxylic acid, and in latter manner cyclopent-3-enecarboxylic acid. Resulting compound was converted to 6-iodo-2-oxa-bicyclo[2.2.1]heptan-3-one and followingly to the target nucleoside precursor which is 2-oxa-bicyclo[2.2.1]hept-5-en-3-one.


Photocatalytic hydrosilylation of conjugated dienes with triethylsilane in the presence of Cr(CO)(5)L(L=CO, P(CH3)(3), P(OCH3)(3))
Özkar, Saim; Kayran, C (Elsevier BV, 1997-04-15)
The effect of donor ligands on the chromium carbonyl photocatalysed hydrosilylation of 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, trans-1,3-pentadiene with triethylsilane was studied. Photocatalytic hydrosilylation of dienes conducted in the presence of Cr(CO)(5)L (L = P(CH3)(3) or P(OCH3)(3)) yields the cis-1,4-adducts, 1-triethylsilyl-2-butene derivatives, as the main products; these have been isolated by distillation or preparative GC and fully characterised by NMR spectroscopy. A...
Stereoselective synthesis of optically active cyclitol precursors via a chemoenzymatic method
Oguzkaya, Funda; Sahin, Ertan; Tanyeli, Cihangir (Elsevier BV, 2006-11-17)
Racemic alpha'-acetoxy alpha,beta-unsaturated cyclohexanone has been converted to the corresponding enantiomerically enriched alpha'-hydroxylated and acetoxylated compounds with 97% ee via enzymatic resolution with PLE. OSO4-Catalyzed dihydroxylation of enantiomerically enriched alpha'-acetoxylated compound afforded a single diastereomer in 85% chemical yield. The absolute configuration of 2,3,6-triacetoxycylohexanone was determined by X-ray diffraction analysis. Subsequent Luche reduction allowed us to obt...
HACIOGLU, B; Akbulut, Ural; Toppare, Levent Kamil (Wiley, 1989-10-01)
Electroinitiated polymerization of acrylamide was carried out in acetonitrile–tetrabutylammonium fluoroborate by electrolytic reduction of monomer. It was shown by cyclic voltammetry that direct electron transfer from the cathode to the monomer can be achieved in this solvent–electrolyte system. Reduction peak potentials measured by cyclic voltammetry indicated that sodium salts will interfere with such a mechanism. Since the reduction peak potential of sodium salt and dimethylformamide are found to be lowe...
Chemoenzymatic synthesis of alpha(1)- and alpha-acetoxylated cyclic ketones
Tanyeli, Cihangir; Akhmedov, M (Elsevier BV, 2004-06-07)
alpha,beta-Unsaturated and saturated cyclic ketones were selectively oxidized at the alpha'- and alpha-positions using Mn(OAc)(3) and Pb(OAc)(4), respectively, resulting in high chemical yields. The resultant racemic alpha'- and alpha-acetoxylated substrates were resolved into corresponding enantiomerically enriched alpha'- and alpha-hydroxylated and acetoxylated compounds with 96-98% ee via PLE hydrolysis. The absolute configurations of alpha'-acetoxy-alpha,beta-unsaturated cyclic ketones were determined b...
Chemoenzymatic synthesis of enantiomerically enriched 2-oxobicyclo[m.1.0]alkan-3-yl acetate derivatives
Atlı, Selin; Tanyeli, Cihangir; Department of Chemistry (2005)
a,β-Unsaturated cyclic ketones were selectively oxidized on a'- positions using Mn(OAc)3 and Pb(OAc)4, respectively. The resultant racemic a'-acetoxylated substrates were resolved into corresponding enantiomerically enriched a'-hydroxylated and a'-acetoxylated compounds via PLE hydrolysis. a'-Hydroxylated compounds are racemized quickly, so they were acetylated with acetyl chloride and pyridine in situ to give the corresponding a'-acetoxylated compounds. Resultant a'-acetoxy a,β-unsaturated cyclic ketones r...
Citation Formats
F. Oğuzkaya, “Stereoselective synthesis of optically active cyclitol precursors via chemoenzymatic method and synthesis of a nucleoside precursor,” M.S. - Master of Science, Middle East Technical University, 2006.