CONTENTS &
ABSTRACTS
In
English. Summaries in Estonian
Proceedings of the Estonian Academy of Sciences.
Chemistry
Volume 50 No. 3
September 2001
Special issue on chemical organic synthesis of molecules
of pharmaceutical and biological interest
Foreword; 123
Margus LOPP
Asymmetric oxidation of ketones; 124–137
Margus LOPP, Anne PAJU, Tõnis KANGER, Kadri KRIIS, Kaja
ILMARINEN, and Tõnis PEHK
Abstract. The Ti(OiPr)4/tartaric acid diethyl ester/t-BuOOH complex (Sharpless catalyst) was successfully used for the direct asymmetric oxidation of ketones resulting in lactones from cyclobutanones; a,b-dihydroxy ketones from b-hydroxy ketones; alkyl lactone carboxylic acids from 3-alkylcyclopentane-1,2-diones; and spiro-g-dilactone from 3-(2-hydroxyethyl)cyclopentane-1,2-dione in high enantioselectivity and satisfactory yield.
Key words: asymmetric oxidation, ketones, a-hydroxy ketones, spiro-g-dilactones, chiral catalysts.
Oxidation of substituted
bicyclo[4.4.0]decen-3-ones; 138–146
Riina AAV, Tõnis KANGER, Tõnis PEHK, and Margus LOPP
Abstract. The results of the oxidation of 6-methyl-7-tert-butyldimethylsilyloxybicyclo[4.4.0]dec-1-en-3-one and its derivative 6-methyl-7-tert-butyldimethylsilyloxybicyclo[4.4.0]dec-10-en-3-one by O2, H2O2, and t-BuOOH under basic conditions in the presence of K2CO3, Et3N, and t-BuOK are reported. The relevant g-hydroxyenones, 1,4-diketoenone, and 1,2-diketoenone were isolated. The oxidation was found to proceed through the dienolate formation. A possible mechanism for a- and g-oxidation is discussed.
Key words: oxidation, regioselectivity, dienolate, enone.
Synthesis of new N-tetrasubstituted derivatives of
R,R-tartaric
acid and their use as chiral ligands in oxidation catalysts; 147–155
Kaja ILMARINEN, Kadri KRIIS, Anne PAJU, Tõnis PEHK, and
Margus LOPP
Abstract. N,N,N¢,N¢-tetraphenyl-R,R-tartramide, N,N,N¢,N¢-tetrabenzyl-R,R-tartramide, and N,N,N¢,N¢-tetrabenzyl-1,4-diamino-S,S-2,3-butanediol and their acetals were prepared from commercially available (+)-dimethyl-R-R-tartrate in good yields. A preliminary screening of the compounds as chiral ligands in catalysts for Baeyer–Villiger oxidation was performed.
Key words: chiral R,R-tartramides, asymmetric oxidation, reduction.
Synthesis and CZE analysis of PAMAM dendrimers
with an ethylenediamine core; 156–166
Janek PETERSON, Arkadi EBBER, Veiko ALLIKMAA, and Margus
LOPP
Abstract. Generations 0 through 5 of ethylenediamine core poly(amidoamine) dendrimers were synthesized. The half-generations of the dendrimeric compounds were purified on silica gel and/or Sephadex LH-20. Capillary zone electrophoresis was applied to characterize the homogeneity of the individual generations.
Key words: PAMAM dendrimers, capillary electrophoresis, capillary zone electrophoresis.
Fragmentation of PAMAM dendrimers in methanol;
167–172
Janek PETERSON, Veiko ALLIKMAA, Tõnis PEHK, and Margus LOPP
Abstract. The decomposition of ethylenediamine core poly(amidoamine) (PAMAM) dendrimers (generation – 0.5) was investigated by gas chromatography. The decomposition of PAMAM dendrimer G–0.5 into triester 2 is caused by the retro-Michael reaction. Equilibrium between the Michael and retro-Michael reactions is shifted towards the retro-Michael reaction at an elevated temperature. Similar decomposition is possible in the case of higher PAMAM dendrimer generations.
Key words: PAMAM dendrimer, retro-Michael reaction.
Synthesis of (2S,2¢S)-bimorpholine; 173–179
Kadri KRIIS, Tõnis KANGER, Tõnis PEHK, and Margus LOPP
Abstract. (2S,2¢S)-bimorpholine was synthesized starting from 2,3-di-O-isopropylidene-L-threitol derived from (R,R)-tartaric acid. The key steps were O-alkylation of hydroxyl groups in (2S,3S)-1,4-diazidobutane-2,3-diol and one-pot reduction and intramolecular cyclization of (2S,3S)-2,3-di-(2¢,2²-bismethanesulphonyl)ethoxy-1,4-diazidobutane.
Key words: chiral diamine, O-alkylation, intramolecular cyclization, bimorpholine.
A convenient method for the construction of the
imidazolone ring in the synthesis of benzamidine derivatives; 180–185
Veiko ALLIKMAA, Margus EEK, Tõnis PEHK, and Margus LOPP
Abstract. The benzamidine derivatives containing an imidazolone ring and structural fragments of b-amino acid are known as platelet aggregation inhibitors. A new synthetic route was developed to one of them – ethyl 3-{[[(1-(4-(aminoiminomethyl)phenyl)-4,5-dihydro-2(3H)-oxo-1H-imidazol-3-yl)methyl]carbonyl]amino}propanoate. The structure of the target compound and intermediates was confirmed by 1H and 13C NMR analysis.
Key words: benzamidine derivatives, imidazolone ring, platelet aggregation inhibitor.
A computerized storage and retrieval system of pKa values of hydrogen acids;
186–192
Alla JALAS, Viktor PALM, and Tiina TENNO
Abstract. A computerized system was created and elaborated for information storage and retrieval of a database including information on approximately 20 000 organic and inorganic hydrogen acids. This paper describes the graphic menu system for a fast search of pKa values of compounds on the basis of their chemical structure.
Key words: database, pKa values.
CHRONICLE
Viktor Palm 75; 193
Ülo Lille 70; 195