Wyniki wyszukiwania - Biblioteka Nauki

1

Conformational properties of N',N'-dimethylamides of N-acetyldehydroalanine and N-acetyl-(Z)-dehydropheny-alanine.

100%

Siodłak D. , Broda M. A. , Rzeszotarska B. , Kozioł A. E. , Dybała I.

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tom 48

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nr 4

1179-1183

EN

Conformational preferences of Ac-ΔAla-NMe2 and Ac-(Z)-ΔPhe-NMe2 were studied and compared with those of their monomethyl counterparts as well as with those of their saturated analogues. X-Ray data and energy calculations revealed a highly conservative conformation of the dehydro dimethylamides, which is located in a high-energy region of the Ramachandran map.

2

Transformation of O-Amidinylhydroxylamine into Benzothiazoles via Iminocarbonyl Sulfenamides

100%

Sączewski F. , Kornicka A. , Gdaniec M.

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2005

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tom Vol. 79 / nr 1

115-120

EN

The reaction of O-amidinylhydroxylamine 3 with aryl isothiocyanates leads to the formation of benzothiazole derivatives 5a-c. The proposed mechanism of the reaction involves initial formation of iminocarbonyl sulfenamides A which, in turn, undergo spontaneous sulfurization of aromatic ring with loss of amine 7. The later compound reacts with excess aryl isothiocyanate to give ,3-diazaspiro[4,5]decane-2-thione 6.

3

Conformational investigation of α,β-dehydropeptides. XIII. Conformational properties of N-acetyl-α,β-dehydrovaline N',N'-dimethylamide.

86%

Siodłak D. , Rzeszotarska B. , Broda M. A. , Kozioł A. E. , Kołodziejczyk E.

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2004

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tom 51

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nr 1

145-152

EN

The crystal structure of Ac-ΔVal-NMe2 (ΔVal = α,β-dehydrovaline) was determined by X-ray crystallography. The found angles φ = -60° and ψ = 125° correspond exactly to the respective values of the (i + 1)th residue in idealised β-turn II/VIa. Ab initio/DFT studies revealed that the molecule adopts the angle ψ restricted only to about |130°| and very readily attains the angle φ = about -50°. This is in line with its solid-state conformation. Taken together, these data suggest that the ΔVal residue combined with a C-terminal tertiary amide is a good candidate at the (i + 1)th position in a type II/VIa β-turn.

4

Conformational properties of N',N'-dimethylamides of N-acetyldehydroalanine and N-acetyl-[Z]-dehydrophenylalanine

72%

Siodlak D. , Broda M. A. , Rzeszotarska B. , Koziol A. E. , Dybala I.

Acta Biochimica Polonica

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2001

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tom 48

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nr 4

EN

Conformational preferences of Ac-ΔAla-NMe2 and Ac-(Z)-ΔPhe-NMe2 were studied and compared with those of their monomethyl counterparts as well as with those of their saturated analogues. X-Ray data and energy calculations revealed a highly conservative conformation of the dehydro dimethylamides, which is located in a high-energy region of the Ramachandran map.

5

Structural basis for the antibacterial activity of the 12-membered-ring mono-sugar macrolide methymycin

58%

Auerbach T. , Mermershtain I. , Bashan A. , Davidovich C. , Rozenberg H. , Sherman D. H. , Yonath A.

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nr 1

24-35

6

Survival in extremes

58%

Malecki P. H. , Rypniewski W.

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nr 1

7

Structural and vibrational studies of the molecular crystal formed by benzenamine with trifluoroacetic acid

58%

Baran J. , Barnes A. J. , Barycki J. , Pietraszko A. , Ratajczak H.

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2001

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tom Vol. 49, No. 2

115-124

EN

The crystal structure of benzenamine-trifluoroacetic acid has been found to belong to the P2i space group of the monoclinic system, with Z = 8, o = 10.294(2) A, b = 9.126(2) A, c = 20.603(4) A, and Beta = 98.77(3)°. In the crystal the amine is protonated and the resulting benzenammonium and trifluoroacetate ions are interlinked by a network of N—H- • -O hydrogen bonds. The observed infrared spectrum is in accordance with such a structure.