0000000001300134
AUTHOR
Anna Kusakiewicz-dawid
Ethyl 1-acetyl-3-amino-1H-pyrazole-4-carboxylate, a tetragonal structure with Z′ = 4
The title compound, C8H11N3O3, crystallizes with Z' = 4. One pyrazole N atom is substituted and excluded from intermolecular contacts. The amine N, acetyl O and an ester O atom are involved in the formation of nearly planar molecular layers. The layers are perpendicular to the c axis, with an interlayer distance of 3.333 Å. The hydrogen-bonding patterns are similar for each molecule, i.e. intramolecular N-H...O, as well as intermolecular N-H...O and C-H...N(pyrazole), bonds are present.
Pyrazole amino acids: hydrogen bonding directed conformations of 3-amino-1H-pyrazole-5-carboxylic acid residue
A series of model compounds containing 3-amino-1H-pyrazole-5-carboxylic acid residue with N-terminal amide/urethane and C-terminal amide/hydrazide/ester groups were investigated by using NMR, Fourier transform infrared, and single-crystal X-ray diffraction methods, additionally supported by theoretical calculations. The studies demonstrate that the most preferred is the extended conformation with torsion angles ϕ and ψ close to ±180°. The studied 1H-pyrazole with N-terminal amide/urethane and C-terminal amide/hydrazide groups solely adopts this energetically favored conformation confirming rigidity of that structural motif. However, when the C-terminal ester group is present, the second con…
The synthesis, structure and properties of N-acetylated derivatives of ethyl 3-amino-1H-pyrazole-4-carboxylate.
Ethyl 3-amino-1H-pyrazole-4-carboxylate (1) was yielded through total synthesis and reacted with acetic anhydride to give the acetylated products 2-6. Compounds 1-6 were studied with HPLC, X-ray, FT-IR, (1)H-NMR, (13)C-NMR and MS. Acetylation was carried out in solvents of various polarity, namely; chloroform; dioxane; DMF; acetic anhydride, at room temperature and at boiling points; and in the presence and absence of DMAP. The acetylated products are mainly nitrogen atoms in the ring. The position of the ring proton in the solution was based on NOESY; multinuclear HMBC, HSQC spectra and calculations. For equivalent amounts (1-1.5 mol) of acetic anhydride at room temperature two products of…
Susceptibility of Methyl 3-Amino-1H-pyrazole-5-carboxylate to Acylation
Abstract In the search for a new method of synthesis of hybrid peptides with aminopyrazole carboxylic acid, we tried to force selective acylation at the aromatic amino group instead of at the ring nitrogen atom with fairly gentle acylating agents. The acylating agents used were acid anhydrides: acetic anhydride, tert-butyl pyrocarbonate, and 2-(2-methoxyethoxy)ethoxyacetic acid/dicyclohexylcarbodiimide. We succceded in acylation at this amino group with almost none at the ring nitrogen atom. Sometimes, however, acylation in small quantities at the ring nitrogen atom was observed as a by-product. To remove this by-product, imidazole was used. Thus, we were able to obtain the hybrid peptides …
Annular Tautomerism of 3(5)-Disubstituted-1H-pyrazoles with Ester and Amide Groups
A series of disubstituted 1H-pyrazoles with methyl (1), amino (2), and nitro (3) groups, as well as ester (a) or amide (b) groups in positions 3 and 5 was synthesized, and annular tautomerism was investigated using X-ray, theoretical calculations, NMR, and FT-IR methods. The X-ray experiment in the crystal state showed for the compounds with methyl (1a, 1b) and amino (2b) groups the tautomer with ester or amide groups at position 3 (tautomer 3), but for those with a nitro group (3b, 4), tautomer 5. Similar results were obtained in solution by NMR NOE experiments in CDCl3, DMSO-d6, and CD3OD solvents. However, tautomer equilibrium was observed for 2b in DMSO. The FT-IR spectra in chloroform …
CCDC 1534810: Experimental Crystal Structure Determination
Related Article: Anna Kusakiewicz-Dawid, Monika Porada, Wioletta Ochędzan-Siodłak, Małgorzata A. Broda, Maciej Bujak, Dawid Siodłak|2017|J.Pept.Sci.|23|716|doi:10.1002/psc.3018
CCDC 1825064: Experimental Crystal Structure Determination
Related Article: Anna Kusakiewicz-Dawid, Monika Porada, Błażej Dziuk, Dawid Siodłak|2019|Molecules|24|2632|doi:10.3390/molecules24142632
CCDC 1825063: Experimental Crystal Structure Determination
Related Article: Anna Kusakiewicz-Dawid, Monika Porada, Błażej Dziuk, Dawid Siodłak|2019|Molecules|24|2632|doi:10.3390/molecules24142632
CCDC 1825061: Experimental Crystal Structure Determination
Related Article: Anna Kusakiewicz-Dawid, Monika Porada, Błażej Dziuk, Dawid Siodłak|2019|Molecules|24|2632|doi:10.3390/molecules24142632
CCDC 1844066: Experimental Crystal Structure Determination
Related Article: Anna Kusakiewicz-Dawid, Monika Porada, Błażej Dziuk, Dawid Siodłak|2019|Molecules|24|2632|doi:10.3390/molecules24142632
CCDC 1825062: Experimental Crystal Structure Determination
Related Article: Anna Kusakiewicz-Dawid, Monika Porada, Błażej Dziuk, Dawid Siodłak|2019|Molecules|24|2632|doi:10.3390/molecules24142632