N-Substituted pyridinium salts constitute one of the most valuable reagent classes in organic synthesis, due to their versatility and ease of use. Herein we report a preliminary synthesis and detailed structural analysis of several N-(1-ethoxyvinyl)pyridinium triflates, an unusual class of pyridinium salts with potentially broad use as a reagent in organic synthesis. Treatment of pyridines with...

Isatin, N-methyl isatin and N-benzylisatin were smoothly monobrominated in the 5-position by treatment with pyridinium bromochromate (PBC) in acetic acid medium. In the similar conditions indigo underwent bromination and oxidation to give 5-bromoisatin in high yield.

Two neurotoxic pyridinium metabolites of haloperidol, 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxybutyl]pyridinium ion (HPP(+)) and 4-(4-(chlorophenyl)-1-4-(fluorophenyl)-4-hydroxybutyl-pyridinium (RHPP(+)), are formed in the liver and found in the brain. To understand how these neurotoxic pyridinium metabolites are distributed in the brain, HPP(+) and RHPP(+) were evaluated as substrates for...

The title compound, (C(6)H(9)N(2))(2)[CuCl(4)], contains a distorted tetra-hedral [CuCl(4)](2-) anion and two protonated amino-pyridinium cations. The geometries of the protonated amino-pyridinium cations reveal amine-imine tautomerism. The crystal packing is influenced by N-H⋯Cl and C-H⋯Cl hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances = 3.635 (4) and 3.642 (4)°].

2-(Pyridinium-1-yl)-1,1-bis(triflyl)ethanides have been used as 1,2-dipole precursors in a metal-free direct [2+2] cycloaddition reaction of alkynes. Starting from stable zwitterionic pyridinium salts, the electron deficient olefin 1,1-bis(trifluoromethylsulfonyl)ethene is generated in situ and immediately reacted at room temperature with an alkyne to afford substituted cyclobutenes. Remarkably...

Reactivation of organophosphate (OP)-inhibited acetylcholinesterase (AChE) by oximes is the primary reason for their effectiveness in the treatment of OP poisoning. Reactivation is reported to accelerate by quaternary ligands such as decamethonium, which is devoid of nucleophilicity. The mechanism of this enhancement is not known. To better understand the acceleration phenomenon, we examined li...

BACKGROUND AND OBJECTIVE Volatile sulfur compounds may be the main source of oral malodor. The aim of this study was to clarify the relationship between periodontal parameters and volatile sulfur compounds and to evaluate the improvement of several halitosis-related outcomes by tongue scraping, nonsurgical periodontal treatment (including oral hygiene instruction) and oral hygiene instruction/c...

The complexation behavior of a series of paraquats (G1.2PF(6)-G5.2PF(6)) and bis(pyridinium) derivatives (G6.2PF(6)-G14.2PF(6)) with pillar[5]arene (P5A) host has been comprehensively investigated by (1)H NMR, ESI mass and UV-vis absorption spectroscopy. It is found that P5A forms 2 : 1 external complexes with N,N'-dialkyl-4,4'-bipyridiniums (G1-G4.2PF(6)); while it forms 1 : 1 pseudorotaxane-t...

Natural products and their signature fragments are an enduring resource for identifying biological modulators. A number of biologically active alkaloids, such as strychnofoline and isorhynchophylline (Fig. 1), feature spiroindolizidine oxindoles. This fragment is considered ‘privileged’ for potential therapeutic investigation and there is much interest in developing expedient synthesis of such ...