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Five-Membered Heterocycles. Part V. Impact of Heteroatoms on Aromaticity of Five-Membered Heterocycles

Mrozek A., Karolak-Wojciechowska J.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

721-730

EN

The aromaticity (in the form ofHOMAindex) of various five-membered heterorings systems and their bicyclic derivatives containing N, S, O, and P were studied on the basis of statistical data from Cambridge Structural Database (CSD). The calculations of HOMA were done for pyrroles, furans, thiophenes, phospholes, imidazoles, oxazoles, thiazoles, phosphazoles as well as for 6 + 5 fused systems: benzimidazoles, benzoxazoles, benzothiazoles, and benzophosphazoles. Detailed analysis showed that relationship between classical aromaticity and electronegativity of heteroatom is described by squared equation. An optimal value of electronegativity is about 2.9 (Pauling’s scale) for which aromaticity of heterorings reaches the highest level. For fused systems, the presence of benzene ring causes the evident increasing of average value of HOMA indices.

2

Bicyclic [b]-Heteroannulated Pyridazine Derivatives. 10. Acid Cleavage of Some Beta-Keto Esters in the Reaction with 4,4-Dimethyl- and 4-Penyltetrahydropyridazine-3,6-dione 3-Hydrazones

Wejroch K., Karolak-Wojciechowska J., Lange J., Sośnicki J. G.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 11

1577-1586

EN

4,4-Dimethyltetrahydropyridazine-3,6-dione 3-hydrazone (1) reacted with _-keto esters in refluxing ethanol to give the acid cleavage products: 7,8-dihydro-3,8,8-trimethyltriazolo[ 4,3-b]pyridazin-6(5H)-one (7) and esters 9. The yield of the reaction in most cases was nearly quantitative. At room temperature mostly the simple condensation products 4 were isolated. In analogous reactions, 4-phenyltetrahydropyridazine-3,6- dione 3-hydrazone (2) was found to be much less reactive. The hydrazone-ester condensation products 4 and some 5 were converted into the corresponding pyrazolylpyridazine derivatives 10 and 11, respectively, by heating above their melting points; the formation of 7 was noted in the reactions with 4. The results support the concept of different tautomeric preferences in 1 and 2.

3

Synthesis of 1-aminoalkanephosphonous acids bearing furan moiety and its stereochemical aspect [1]

Grabowski A., Lewkowski J., Nazarski R., Skowroński R., Karolak-Wojciechowska J.

Polish Journal of Chemistry

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1999

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vol. 73 nr 2

307-311

EN

A series of variously N-substitued (2-furyl)aminomethylanephosphonous acids was synthesized in fair yields. The synthesis of optically pure (S0-(2-furyl)-(R )-N-a-methylbenzylaminomethanephosphonous acid is also presented.

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Structure and activity studies of glycine receptor ligands : Part 4. N-[(7-arylalkyl, 7-aryloxyalkyl)-8-theophyllyl]-glycines

Drabczyńska A., Karolak-Wojciechowska J., Kieć-Kononowicz K.

Polish Journal of Chemistry

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1999

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vol. 73 nr 5

783-792

EN

Preparation of N-[(7-arylalkyl, 7-aryloxyalkyl)-8-theophyllyl]-glycines by condensation of 8-bromo-theophylline with arylalkyl- and aryloxyalkylbromides and aminolysis with glycine is described. The structure of one of the obtained glycine derivatives was confirmed by X-ray analysis. A comparison of the glycine receptor binding model (molecule L-689,560) and the 3-D structure of that molecule indicates serious differences in molecule shape, explaining their inactivity.

5

Molecular structure of 5-chloro-2-[p-t-butylphenyl]benzoxazole : Relation between structure and antimicrobial activity of 2,5-disubstituted benzoxazoles

Mrozek A., Trzeźwińska H., Karolak-Wojciechowska J.

Polish Journal of Chemistry

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1999

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vol. 73 nr 4

625-633

EN

As part of our investigation on antimicrobial agents, the structure of 5-chloro-2[p-t-butylophenyl]benzoxazole is reported: C17h16ClNO, mol.mass 285.77, monoclinic, space group: C2/c; a=32.164(6) A, b=6.756(1) A, c=13.710(3) A; b=92.73(3)0, V=2975.8(10) A3; d=1.276 g cm-3; Z=8; F(000)=1200; m(CuKa)=2.219 mm-1. Final R=0.0658 for 2621 reflections with F>4s(F). Final atomic coordinates for this 2,5-disubstitued benzoxazole were used as a starting point in molecular modeling of remaining 32 derivatives eearched as antimicrobial agents. Electronic parameters calculated with quantum chemistry methods and classical Hansch's constants were applied in searching for structure-activity correlation. It was established that geometrical parameters (area and volume) and LUMO energy values seem to be most important for the activity.

6

Crystal and Molecular Structure of (-)-(S)- and (+)-(R)-Bromofosfamide

Karolak-Wojciechowska J., Wieczorek M., Grynkiewicz G., Kutner A.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 11

1877-1885

EN

The crystal and molecular structures of (-)-(S)- and (+)-(R)-bromofosfamide were determined as a part of our research on therapeutically useful oxazaphosphorines. Both compounds crystallized in strictly enantiotropic crystals. Both sompound undergo partial decomposition during diffractometric exposition with emission of free bromine.