Preparation and reactions of pyrylium salts containing α-pyridyl groups

Donor‐Functionalized Polydentate Pyrylium Salts and Phosphinines: Synthesis, Structural Characterization, and Photophysical Properties

“…As a matter of fact this procedure has been investigated before to some extend for the synthesis of pyridines or pyridinium salts by reaction of substituted pyrylium salts with NH 3 or primary amines, respectively. [10] However, this modular approach has never been used for a rational design and synthesis of donor-functionalized phosphinines so far. In this respect, we further explored the incorporation of additional donor groups into the pyrylium framework and prepared the strongly fluorescent pyrylium tetrafluoroborates 4-7, containing thienyl and pyridyl functionalities according to Scheme 1.…”

Phosphinines as ligands in homogeneous catalysis: recent developments, concepts and perspectives

“…Both synthetic protocols usually have some limitations and the right reaction conditions have to be selected individually. [38][39][40][41][42][43] The last step of the phosphinine synthesis via pyrylium salts is the introduction of the phosphorus atom into the aromatic ring. This can readily be achieved with highly nucleophilic PH 3analogues, such as P(CH 2 OH) 3 or P(SiMe 3 ) 3 , which can be prepared on a large scale according to suitable literature procedures (Scheme 3).…”

Syntheses and UV/Vis-Spectroscopic Properties of Hydrophilic 2-, 3-, and 4-Pyridyl-Substituted Solvatochromic and Halochromic PyridiniumN-Phenolate Betaine Dyes as New Empirical Solvent Polarity Indicators

“…[7,30,43Ϫ48] In order to obtain the desired pyridyl-substituted betaine dyes 3Ϫ11, it was first necessary to synthesize pyridyl-substituted pyrylium salts and 2,6-dipyridyl-substituted 4-aminophenols. None of these compounds were known previously, with the exception of an inseparable mixture of 4-phenyl-2,6-bis(pyridin-2-yl)pyrylium tetrafluoroborate and 4,6-diphenyl-2-(pyridin-2-yl)pyrylium tetrafluoroborate, obtained by Katritzky et al [49] from 3-phenyl-1-(pyridin-2-yl)prop-2-en-1-one, [50] acetophenone, and tetrafluoroboric acid. Our attempts to obtain the former pyrylium salt in pure form by various classical methods for the synthesis of substituted pyrylium salts [51,52] were unsuccessful.…”