In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.



Volume 50 No. 3 September 2001


Special issue on chemical organic synthesis of molecules of pharmaceutical and biological interest

Foreword; 123

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Margus LOPP

Asymmetric oxidation of ketones; 124–137

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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

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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

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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

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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

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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

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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

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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

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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.



Viktor Palm 75; 193

Ülo Lille 70; 195