Synthesis of Alkoxy-Substituted Pyridines from Mono- and Tricationic Pyridinium Salts

Abstract

Nucleophilic substitution reactions on 4-(4-dimethylamino)-pyridinium-substituted tetrachloropyridine with oxygen nucleophiles such as alkoxides and phenolates resulted in the formation of 4-or 2,4-alkoxy-or -phenoxy-substituted chloropyridines depending on the reaction conditions. Substitution on 2,4,6-tris(4-dimethylamino)pyridinium-substituted 3,5-dichloropyridine gave the corresponding 2,4,6-tris-alkoxy-or -phenoxy-substituted pyridines which are not available by other routes.

Hetarenium salts from pentafluoropyridine. Syntheses, spectroscopic properties, and applications

“…The 3 J NH -coupling between the nitrogen atom of the pyridine ring and the secondary NH proton proves that the isopropylamino group is attached to C2 of the pyridine ring. In accordance with the assigned structure, three 19 F nmr resonance frequencies appear at -177.1, -164.4, and 97.0 ppm, respectively.…”

“…In accordance to the assigned structure, only one 19 F nmr resonance frequency is detectable at = -160.0 ppm as a singlet. A priori, two mechanisms for the formation of 8a-c and 9 have to be considered.…”

“…The value of the FF coupling constants through five, three, and four bonds were measured as -34.3, -17.5 Hz, and -4.6 Hz, respectively. As expected, the bispropoxy derivative 5 gave three distinct 19 F nmr resonance frequencies …”

“…The -pentasubstituted pyridines in the presence of sodium amide as base, whereas morpholine gave the 4-amino-2,6-bismorpholino-substituted 3,5-difluoropyridine. 19 F,…”

Synthesis of a Pyrazol-3-ylidene Palladium Complex, Pyrazolium Salts and Mesomeric Betaines of Pyrazole as N-Heterocyclic Carbene Precursors

“…The ligand donor strength of pyrazol-3-ylidene and pyrazol-4-ylidene has been determined by 13 C NMR spectroscopy [32]. In continuation of our studies of heterocylic mesomeric betaines [33,34], zwitterions [35,36], N-heterocyclic carbenes [37 -39], and the chemistry of organic polycations [40], we describe here the synthesis of a new pyrazol-3-ylidene palladium complex, as well as new aspects of the syntheses and properties of pyrazolium salts and pyrazolium-3-and -4-carboxylates as potential N-heterocyclic carbene precursors.…”