Distorted amides as models for activated peptide N-C=O units. 2. The synthesis, hydrolytic profile, and molecular structure of 3,4-dihydro-2-oxo-1,4-propanoquinoline

A distorted anilide (3,4-dihydro-2-oxo-1,4-propanoquinoline (3)) has been synthesized, its structure determined by X-ray diffraction, and its hydrolysis profile from pH 0–13 investigated. The amide unit in 3 is distorted in that the N lone pair is twisted 35° and tilted 15° out of optimum conjugation with the C=O II system. Due to this distortion, 3 hydrolyses rapidly in H2O at 25 °C. The pH/rate constant profile exhibits domains consistent with OH− attack on 3[Formula: see text] and H2O attack on a protonated form of 3[Formula: see text]; pKa (3-H+) = 0.56). The kinetic pKa is most consistent with an N-protonated form. It is also shown that this mechanism of hydrolysis is common to the series of bridged anilides consisting of 3, 3,4-dihydro-2-oxo-1,4-ethanoquinoline (1), and 2,3,4,5-tetrahydro-2-oxo-1,5-ethanobenzazepine (2). Keywords: distorted amide, hydrolysis, X-ray structure.

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Reaktive E=C (p-p)π-Systeme, XL. / Reactive E=C(p-p)π Systems, XL.

Zeitschrift für Naturforschung B ◽

10.1515/znb-1995-0119 ◽

1995 ◽

Vol 50 (1) ◽

pp. 94-100 ◽

Cited By ~ 18

Author(s):

Thomas Albers ◽

Joseph Grobe ◽

Duc Le Van ◽

Bernt Krebs ◽

Mechtild Läge

Keyword(s):

Molecular Structure ◽

Main Product ◽

Chloroform Solution ◽

Lone Pair ◽

Secondary Amines ◽

Molar Ratio ◽

Electronic Interaction ◽

X Ray Diffraction ◽

X Ray ◽

New Compounds

The reaction of bis(trifluoromethyl)arsane 2 with secondary amines R2NH in a molar ratio of 1:3 at -60 °C allows the preparation of trifluoromethyl arsaalkenes of the type F3CAs=C(F)NR2 in moderate yields (15-35%) [NR2 = NMe2 (3a), NMeEt (3b), NEt2 (3c)]. The main product of the reaction of 2 with Me2NH is the 1,1-diamino compound F3CAs=C(NMe2)2 (4a). With ethyl(isopropyl)- or di(isopropyl)amine the corresponding derivatives F3CAs=C(F)NEt(iPr) (3d) and F3CAs=C(F)N(iPr)2 (3e), respectively, are formed only in traces (3d), or not at all (3 e). However, 3d and 3e can be prepared by reacting perfluoro-2-arsapropene with the corresponding secondary amines. The new compounds 3 a to 3 e can be stored at 20 °C in chloroform solution for hours without decomposition and show Z configuration without exception. The molecular structure of 1-(diethylamino)-1,3,3,3-tetrafluoro-2-arsapropene 3c, determined by an X-ray diffraction study on single crystals, indicates a strong electronic interaction of the lone pair on nitrogen with the AsC double bond. This results in a trigonal planar arrangement at the nitrogen atom, a strongly shortened sp2-CN-bond (1.312 Å), an elongated AsC distance (1.867 Å), and an almost planar skeleton of the molecule.

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Molecular structure, covalent and non-covalent interactions of an oxaborol derivative (L-PRO2F3PBA): FTIR, X-ray diffraction and QTAIM approach

Journal of Molecular Structure ◽

10.1016/j.molstruc.2021.130911 ◽

2021 ◽

pp. 130911

Author(s):

Ofelia Hernández-Negrete ◽

Rogerio R. Sotelo-Mundo ◽

Hilda E. Esparza-Ponce ◽

Javier Hernández-Paredes

Keyword(s):

Molecular Structure ◽

X Ray Diffraction ◽

X Ray ◽

Non Covalent Interactions ◽

Covalent Interactions

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Synthesis of Bis(Carboranyl)amides 1,1′-μ-(CH2NH(O)C(CH2)n-1,2-C2B10H11)2 (n = 0, 1) and Attempt of Synthesis of Gadolinium Bis(Dicarbollide)

Molecules ◽

10.3390/molecules26051321 ◽

2021 ◽

Vol 26 (5) ◽

pp. 1321

Author(s):

Yasunobu Asawa ◽

Aleksandra V. Arsent’eva ◽

Sergey A. Anufriev ◽

Alexei A. Anisimov ◽

Kyrill Yu. Suponitsky ◽

...

Keyword(s):

Molecular Structure ◽

Single Crystal ◽

Quantum Chemical Calculations ◽

Quantum Chemical ◽

X Ray Diffraction ◽

Stable Conformation ◽

Acyl Chlorides ◽

X Ray ◽

Cesium Fluoride ◽

The Stability

Bis(carboranyl)amides 1,1′-μ-(CH2NH(O)C(CH2)n-1,2-C2B10H11)2 (n = 0, 1) were prepared by the reactions of the corresponding carboranyl acyl chlorides with ethylenediamine. Crystal molecular structure of 1,1′-μ-(CH2NH(O)C-1,2-C2B10H11)2 was determined by single crystal X-ray diffraction. Treatment of bis(carboranyl)amides 1,1′-μ-(CH2NH(O)C(CH2)n-1,2-C2B10H11)2 with ammonium or cesium fluoride results in partial deboronation of the ortho-carborane cages to the nido-carborane ones with formation of [7,7′(8′)-μ-(CH2NH(O)C(CH2)n-7,8-C2B9H11)2]2−. The attempted reaction of [7,7′(8′)-μ-(CH2NH(O)CCH2-7,8-C2B9H11)2]2− with GdCl3 in 1,2-dimethoxy- ethane did not give the expected metallacarborane. The stability of different conformations of Gd-containing metallacarboranes has been estimated by quantum-chemical calculations using [3,3-μ-DME-3,3′-Gd(1,2-C2B9H11)2]− as a model. It was found that in the most stable conformation the CH groups of the dicarbollide ligands are in anti,anti-orientation with respect to the DME ligand, while any rotation of the dicarbollide ligand reduces the stability of the system. This makes it possible to rationalize the design of carborane ligands for the synthesis of gadolinium metallacarboranes on their base.

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Crystal and molecular structure of diorganoammonium oxalatotrimethylstannate, [R2NH2][Me3Sn(C2O4)] (R=i-Bu, cyclohexyl)

Main Group Metal Chemistry ◽

10.1515/mgmc-2011-0018 ◽

2011 ◽

Vol 34 (5-6) ◽

pp. 127-130 ◽

Cited By ~ 3

Author(s):

Yaya Sow ◽

Libasse Diop ◽

Kieran C. Molloy ◽

Gabrielle Kociok-Köhn

Keyword(s):

Molecular Structure ◽

Hydrogen Bonds ◽

Diffraction Study ◽

Crystal And Molecular Structure ◽

X Ray Diffraction ◽

X Ray ◽

Trigonal Bipyramidal ◽

Trans Complex ◽

A Chain ◽

Distorted Trigonal Bipyramidal

Abstract The title compounds [R2NH2][C2O4SnMe3](R=i-Bu, Cy), in which tin atoms adopt a distorted trigonal bipyramidal configuration, have been prepared and submitted to an X-ray diffraction study. These compounds have been obtained from the reaction of (Cy2NH2)2C2O4·H2O or (i-Bu2NH2)2C2O4 with SnMe3Cl. In both [R2NH2][C2O4SnMe3] compounds, the trans complex has an almost regular trigonal bipyramidal geometry around the tin atom. The SnMe3 residues are connected as a chain with bridging oxalate anions in a trans-SnC3O2 framework, the oxygen atoms being in axial positions. The cations connect linear adjacent chains through NH…O hydrogen bonds giving layered structures.

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Reactions of (η5-C9H7)Rh(η2-C2H4)2 with quinones: molecular structure of [(η5-C9H7)Rh(2,3,5,6-C6O2(CH3)4)]

Canadian Journal of Chemistry ◽

10.1139/v98-228 ◽

1999 ◽

Vol 77 (2) ◽

pp. 199-204

Author(s):

Stephen A Westcott ◽

Nicholas J Taylor ◽

Todd B Marder

Keyword(s):

Molecular Structure ◽

Least Squares ◽

Ground State ◽

Slip Parameter ◽

X Ray Diffraction ◽

X Ray ◽

A Value ◽

Hinge Angle

Reactions of (η5-C9H7)Rh(η2-C2H4)2 (1) with quinones were investigated. Substitution of the labile ethylene ligands was observed upon addition of either duroquinone (2,3,5,6-tetramethyl-1,4-benzoquinone) or 1,4-benzoquinone to complex 1. The molecular structure of neutral (η5-C9H7)Rh(2,3,5,6-C6O2(CH3)4) (3), determined by X-ray diffraction, shows that the duroquinone ligand lies in a plane nearly parallel to the indenyl group. The carbonyl moieties of duroquinone lie in a plane incorporating Rh, C2, and the midpoint between C3a and C7a of the indenyl ring. The slip parameter (Δ= d(average Rh-C3a,7a) -d(average Rh-C1,3)) was calculated to be 0.112(2) Å; whereas a value of ca. 0.05 Å had been obtained previously from film data. Values for the hinge angle (HA = angle between normals to the least-squares planes defined by C1, C2, C3 and C1, C7a, C3a, C3) and fold angle (FA = angle between normals to the least-squares planes defined by C1, C2, C3 and C3a, C4, C5, C7, C7a) are 7.2° and 4.0°, respectively.Key words: indenyl, rhodium, quinones, ring-slippage, ground-state distortion.

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Influence of 3-{5-[4-(diethylamino)benzylidene]rhodanine}propionic acid on the conformation of 5-(4-chlorobenzylidene)-2-(4-methylpiperazin-1-yl)-3H-imidazol-4(5H)-one

Acta Crystallographica Section C Structural Chemistry ◽

10.1107/s2053229618013980 ◽

2018 ◽

Vol 74 (11) ◽

pp. 1427-1433 ◽

Cited By ~ 3

Author(s):

Ewa Żesławska ◽

Wojciech Nitek ◽

Waldemar Tejchman ◽

Jadwiga Handzlik

Keyword(s):

Crystal Structures ◽

Crystal Packing ◽

Protonated Form ◽

Acid Form ◽

Asymmetric Unit ◽

X Ray Diffraction ◽

Basic Form ◽

Piperazine Ring ◽

X Ray ◽

Intermolecular Contacts

The arylidene–imidazolone derivatives are a group of compounds of great interest in medicinal chemistry due to their various pharmacological actions. In order to study the possible conformations of an arylidene–imidazolone derivative, two new crystal structures were determined by X-ray diffraction, namely (Z)-5-(4-chlorobenzylidene)-2-(4-methylpiperazin-1-yl)-3H-imidazol-5(4H)-one, C15H17ClN4O, (6), and its salt 4-[5-(4-chlorobenzylidene)-5-oxo-4,5-dihydro-3H-imidazol-2-yl]-1-methylpiperazin-1-ium 3-{5-[4-(diethylamino)benzylidene]-4-oxo-2-thioxothiazolidin-3-yl}propionate, C15H18ClN4O+·C17H19N2O3S2 −, (7). Both compounds crystallize in the space group P\overline{1}. The basic form (6) crystallizes with two molecules in the asymmetric unit. In the acid form of (6), the N atom of the piperazine ring is protonated by proton transfer from the carboxyl group of the rhodanine acid derivative. The greatest difference in the conformations of (6) and its protonated form, (6c), is observed in the location of the arylidene–imidazolone substituent at the N atom. In the case of (6c), the position of this substituent is close to axial, while for (6), the corresponding position is intermediate between equatorial and axial. The crystal packing is dominated by a network of N—H...O hydrogen bonds. Furthermore, the crystal structures are stabilized by numerous intermolecular contacts of types C—H...N and C—H...Cl in (6), and C—H...O and C—H...S in (7). The geometry with respect to the location of the substituents at the N atoms of the piperazine ring was compared with other crystal structures possessing an N-methylpiperazine moiety.

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1,2-Hydroboration of Alkyn-1-yldichlorosilanes using Triethylborane

Zeitschrift für Naturforschung B ◽

10.1515/znb-2008-1105 ◽

2008 ◽

Vol 63 (11) ◽

pp. 1267-1275 ◽

Cited By ~ 7

Author(s):

Bernd Wrackmeyer ◽

Ezzat Khan ◽

Wolfgang Milius

Keyword(s):

Molecular Structure ◽

Single Crystal ◽

Hydrogen Transfer ◽

X Ray Diffraction ◽

X Ray ◽

Ethyl Group ◽

Nmr Data

Abstract Triethylborane, BEt3, can act as a 1,2-hydroborating reagent towards alkyn-1-ylsilanes, depending on the nature of the silane. A mechanism is proposed invoking hydrogen transfer from the β -carbon of one ethyl group, quite different from the 1,2-hydroboration mechanism using tri-n-propylborane, BnPr3. The structure of the products has been confirmed by comparison with that obtained using 9-borabicyclo[3.3.1]nonane, 9-BBN, as a well established 1,2-hydroborating reagent. All products have been characterized by a consistent set of NMR data (1H, 11B, 13C and 29Si NMR). The molecular structure of (Z)-1-dichlorosilyl-1-[9-(9-borabicyclo[3.3.1]nonyl)]-2-phenylethene has been determined by single crystal X-ray diffraction.

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