2876-13-3Relevant articles and documents
Novel hydrogen- and halogen-bonding anion receptors based on 3-iodopyridinium units
Amendola, Valeria,Bergamaschi, Greta,Boiocchi, Massimo,Fusco, Nadia,La Rocca, Mario Vincenzo,Linati, Laura,Lo Presti, Eliana,Mella, Massimo,Metrangolo, Pierangelo,Miljkovic, Ana
, p. 67540 - 67549 (2016)
Novel tripodal 3-iodopyridinium-based receptors were investigated through (i) UV-vis and NMR titrations with anions in solution, (ii) theoretical calculations, and (iii) X-ray diffraction studies. Their anion binding properties were compared to those of the monobranched model and/or non-halogenated model systems. Investigations in acetonitrile pointed out that the iodine atom in the meta position to pyridinium enhances anion affinity. According to computational studies, this effect seemed to depend on the electron-withdrawing nature of the iodine-substituents. Notably, 1:1 adducts were observed to form in solution with all the investigated anions. The strong de-shielding effect observed on the receptors' protons upon anion binding indicated their participation in hydrogen-bonds with the coordinated anion. This result was supported by theoretical calculations and, in the solid state, by X-ray diffraction studies on the complexes with nitrate and bromide. In the crystalline state, the pyridinium arms of the tripodal receptor assume a 2-up, 1-down conformation. Both nitrate and bromide anions are included in the receptor's cavity, forming two hydrogen-bonding interactions with the protons of the 2-up arms, and one halogen-bonding interaction with the C-I group of a second molecular cation. The combination of hydrogen and halogen bonds leads to supramolecular chains in the crystals.
Glutaconaldehyde as an Alternative Reagent to the Zincke Salt for the Transformation of Primary Amines into Pyridinium Salts
Asskar, Ghada,Rivard, Michael,Martens, Thierry
, p. 1232 - 1239 (2019/12/24)
In the presence of amines, the degradation of glutaconaldehyde in acidic medium can be prevented. By exploitation of this behavior, primary amines are transformed into their corresponding pyridinium salts, including those substrates that remain unreactive toward the Zincke salt, which is the reagent typically used to perform this transformation. The use of glutaconaldehyde also allows control of the nature of the counterion of the pyridinium with no need for additional salt metathesis reaction.
S8-Mediated Cyclization of 2-Aminophenols/thiophenols with Arylmethyl Chloride: Approach to Benzoxazoles and Benzothiazoles
Gan, Haifeng,Miao, Dazhuang,Pan, Qiang,Hu, Renhe,Li, Xiaotong,Han, Shiqing
, p. 1770 - 1774 (2016/07/07)
A metal-free approach to benzazoles from arylmethyl chlorides and 2-mercaptan/2-hydroxyanilines using elemental sulfur as a traceless oxidizing agent has been developed. The reactions proceeded in good to excellent yields, exhibiting good functional groups tolerance and gram-scale ability. A key mechanistic investigation indicated that the key intermediate trisulfide 6, which was characterized by NMR, HRMS and crystal X-ray crystallography, was separated in the reaction prior to the formation of the product.
