scholarly journals Synthesis and Application of Thiosquaramides and Their Derivatives: A Review

2018 ◽  
Vol 62 (4) ◽  
Author(s):  
Sándor Nagy ◽  
Péter Kisszékelyi ◽  
József Kupai
Keyword(s):  
Hydrogen Bonding ◽  
Asymmetric Catalysis ◽  
Chemical Biology ◽  
Pharmaceutical Research ◽  
Ring System ◽  
Membered Ring ◽  
Squaric Acid ◽  
Concomitant Increase ◽  
Structural Rigidity ◽  
Interesting Family

Thiosquaramides are the thio analogues of squaramides that are widely applicable in the fields of asymmetric catalysis, pharmaceutical research, and chemical biology. Having four-membered ring system derived from squaric acid, thiosquaramides are feasible hydrogen bond donors and acceptors. A high affinity for hydrogen bonding is driven through a concomitant increase in aromaticity of the ring. In this review the structural properties, acidity, and lipophilicity of thiosquaramides and squaramides are compared. Different synthetic procedures starting from squarates, half-squaramides or squaramides are shown, and the main derivatization methods are outlined. Finally, the yet only few applications of this interesting family are reviewed. Considering their hydrogen bonding and aromatic switching, in combination with structural rigidity, they bear the possibility of becoming robust and tunable bifunctional organocatalysts for a range of synthetically useful transformations in the future.

scholarly journals Crystal structure ofN1-phenyl-N4-[(quinolin-2-yl)methylidene]benzene-1,4-diamine

2014 ◽  
Vol 70 (9) ◽  
pp. o905-o906 ◽  
Author(s):  
Md. Serajul Haque Faizi ◽  
Ashraf Mashrai ◽  
Saleem Garandal ◽  
M. Shahid
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Benzene Ring ◽  
Title Compound ◽  
Phenyl Ring ◽  
Bond Angle ◽  
Ring System ◽  
Dihedral Angles ◽  
Quinoline Ring ◽  
Compound C

In the title compound, C22H17N3, the dihedral angles between the central benzene ring and the terminal phenyl ring and quinoline ring system (r.m.s. deviation = 0.027 Å) are 44.72 (7) and 9.02 (4)°, respectively, and the bond-angle sum at the amine N atom is 359.9°. In the crystal, the N—H group is not involved in hydrogen bonding and the molecules are linked by weak C—H...π interactions, generating [010] chains.

scholarly journals Homocoupling Reactions of Azoles and Their Applications in Coordination Chemistry

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5950
Author(s):  
Steffen B. Mogensen ◽  
Mercedes K. Taylor ◽  
Ji-Woong Lee
Keyword(s):  
Coordination Chemistry ◽  
Reaction Mechanisms ◽  
Metal Organic Frameworks ◽  
Ring System ◽  
Membered Ring ◽  
Materials Chemistry ◽  
Structural Class ◽  
Basic Nitrogen ◽  
Metal Organic ◽  
Metal Catalyzed

Pyrazole, a member of the structural class of azoles, exhibits molecular properties of interest in pharmaceuticals and materials chemistry, owing to the two adjacent nitrogen atoms in the five-membered ring system. The weakly basic nitrogen atoms of deprotonated pyrazoles have been applied in coordination chemistry, particularly to access coordination polymers and metal-organic frameworks, and homocoupling reactions can in principle provide facile access to bipyrazole ligands. In this context, we summarize recent advances in homocoupling reactions of pyrazoles and other types of azoles (imidazoles, triazoles and tetrazoles) to highlight the utility of homocoupling reactions in synthesizing symmetric bi-heteroaryl systems compared with traditional synthesis. Metal-free reactions and transition-metal catalyzed homocoupling reactions are discussed with reaction mechanisms in detail.

scholarly journals Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

2019 ◽  
Vol 15 ◽  
pp. 2419-2427
Author(s):  
Sachin S Burade ◽  
Sushil V Pawar ◽  
Tanmoy Saha ◽  
Navanath Kumbhar ◽  
Amol S Kotmale ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Amino Acid ◽  
Molecular Modeling ◽  
Intramolecular Cyclization ◽  
Membered Ring ◽  
Conformational Study ◽  
Oxazole Ring ◽  
Solution State ◽  
Modeling Studies ◽  
Molecular Modeling Studies

The intramolecular cyclization of a C-3-tetrasubstituted furanoid sugar amino acid-derived linear tetrapeptide afforded an oxazolone pseudo-peptide with the formation of an oxazole ring at the C-terminus. A conformational study of the oxazolone pseudo-peptide showed intramolecular C=O···HN(II) hydrogen bonding in a seven-membered ring leading to a γ-turn conformation. This fact was supported by a solution-state NMR and molecular modeling studies. The oxazolone pseudotetrapeptide was found to be a better Cl−-selective transporter for which an anion–anion antiport mechanism was established.

scholarly journals Synthesis, Structural Characterization and Ligand-Enhanced Photo-Induced Color-Changing Behavior of Two Hydrogen-Bonded Ho(III)-Squarate Supramolecular Compounds

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1369 ◽  
Author(s):  
Wang ◽  
Ke ◽  
Feng ◽  
Ho ◽  
Chang ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Uv Light ◽  
Squaric Acid ◽  
Water Molecules ◽  
Light Illumination ◽  
Supramolecular Architecture ◽  
Bridging Ligands ◽  
Coordination Modes ◽  
Oxygen Atoms ◽  
Hydrogen Bonded

Two coordination polymers (CPs) with chemical formulas, [Ho2(C4O4)2(C2O4)(H2O)8]·4H2O (1) and [Ho(C4O4)1.5(H2O)3] (2), (C4O42− = dianion of squaric acid, C2O42− = oxalate), have been synthesized and their structures were determined by single-crystal X-ray diffractometer (XRD). In compound 1, the coordination environment of Ho(III) ion is eight-coordinate bonded to eight oxygen atoms from two squarate, one oxalate ligands and four water molecules. The squarates and oxalates both act as bridging ligands with 1,2-bis-monodentate and bis-chelating coordination modes, respectively, connecting the Ho(III) ions to form a one-dimensional (1D) ladder-like framework. Adjacent ladders are interlinked via O–HO hydrogen bonding interaction to form a hydrogen-bonded two-dimensional (2D) layered framework and then arranged orderly in an AAA manner to construct its three-dimensional (3D) supramolecular architecture. In compound 2, the coordination geometry of Ho(III) is square-antiprismatic eight coordinate bonded to eight oxygen atoms from five squarate ligands and three water molecules. The squarates act as bridging ligands with two coordination modes, 1,2,3-trismonodentate and 1,2-bis-monodentate, connecting the Ho(III) ions to form a 2D bi-layered framework. Adjacent 2D frameworks are then parallel stacked in an AAA manner to construct its 3D supramolecular architecture. Hydrogen bonding interactions between the squarate ligands and coordinated water molecules in 1 and 2 both play important roles on the construction of their 3D supramolecular assembly. Compounds 1 and 2 both show remarkable ligand-enhanced photo-induced color-changing behavior, with their pink crystals immediately turning to yellow crystals under UV light illumination.

Untersuchungen zur Ringkontraktion am 1,4-Dithia-2,6-diaza-3,5-diborinan-System/ Studies on Ring Contraction of the l,4-Dithia-2,6-diaza-3,5-diborinane System

1988 ◽  
Vol 43 (8) ◽  
pp. 959-962 ◽  
Author(s):  
Carl Habben ◽  
Anton Meiler ◽  
Stefan Pusch
Keyword(s):  
Mass Spectra ◽  
Ring System ◽  
Membered Ring ◽  
Ring Contraction ◽  
C Nmr

AbstractThe 1,4-dithia-2,6-diaza-3,5-diborinanes 1a-d react with elemental sodium with formation of the 1,3-diaza-2,4-diboretidines 2a-d. By use of more sodium in case of 1 d or 3,5-bis(diethylamino)- 2-cyclohexyl-6-trimethylsilyldiborinane, the 1,3-thiaza-2,4-diboretidines 3 were formed. 3.5-Dimethyl-2,6-bis(trimethylsilyl)-1,4-dithia-2,6-diaza-3,5-diborinane gives the borazine 4, The reaction of di-t-butyl-sulfurdiimide with 2,6-di-t-butyl-3,5-dimethyl-1,4-dithia-2,6-diaza-3,5-diborinane leads by ring contraction to the four-membered ring system 5. 1H, 11B, 13C NMR and mass spectra are reported and discussed.

Reaktion von N-Trimethylsilyl-N′(N″ -trimethylsilylammodiphenylphosphoranylidenimino) sulfamid mit Wolframoxitetrachlorid und die Struktur von (Cl3WNPPh2N)2 Reaction of N-Trimethylsilyl-N′(N″ -trimethylsilylaminodiphenylphosphoranylidene)sulfamide with Tungstenoxitetrachloride and the Structure of (Cl3WNPPh2N)2

1992 ◽  
Vol 47 (2) ◽  
pp. 171-174 ◽  
Author(s):  
H. W. Roesky ◽  
T. Raubold ◽  
M. Noltemeyer ◽  
M. Witt ◽  
R. Bohra
Keyword(s):  
Molecular Structure ◽  
Structure Analysis ◽  
Ring System ◽  
Membered Ring ◽  
X Ray

1The reaction of ClSO2N = PPh2Cl () with NH3 yields H2NSO2N = PPh2NH2 (2).This compound is converted to Me3Si(H)NSO2N = PPh2N(H)SiMe3 (3) by Me3SiNMe2. 3 reacts with WOCl4 under elimination of (Me3Si)2O and ClSO2NH2 to yield the eight-membered ring system (Cl3WNPPh2N)2 (4).The molecular structure of 4 was investigated by an X-ray structure analysis.

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