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


Thesis Type: Postgraduate

Institution Of The Thesis: Middle East Technical University, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2006

Thesis Language: English

Student: Funda Oğuzkaya

Supervisor: CİHANGİR TANYELİ

Abstract:

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.