2355-56-8Relevant articles and documents
Designing multifunctional expanded pyridiniums: Properties of branched and fused head-to-tail bipyridiniums
Fortage, Jerome,Peltier, Cyril,Nastasi, Francesco,Puntoriero, Fausto,Tuyeras, Fabien,Griveau, Sophie,Bedioui, Fethi,Adamo, Carlo,Ciofini, Ilaria,Campagna, Sebastiano,Laine, Philippe P.
supporting information; experimental part, p. 16700 - 16713 (2011/02/23)
The multifaceted potentialities of expanded pyridiniums (EPs), based on one pyridinium core bearing a 4-pyridyl or 4-pyridylium as the N-pyridinio group, are established at both experimental and theoretical levels. Two classes of head-to-tail (htt) EPs were designed, and their first representative elements were synthesized and fully characterized. The branched (B) family is made up of 2,6-diphenyl-4-aryl-1,4′-bipyridin-1-ium (or 1,1′-diium) species, denoted 1B and 2B for monocationic EPs (with aryl = phenyl and biphenyl, respectively) and 1BMe and 2BMe for related quaternarized dicationic species. The series of fused (F) analogues comprises 9-aryl-benzo[c]benzo[1,2]quinolizino[3,4,5,6-ija][1,6]naphthyridin-15-ium species, denoted 1F and 2F, and their 2,15-diium derivatives referred to as 1FMe and 2FMe. Electrochemistry (in MeCN vs SCE) reveals that branched EPs undergo a single reversible bielectronic reduction at ca. -0.92 V for 1B/2B and -0.59 V for 1BMe/2BMe, whereas pericondensed species show two reversible monoelectronic reductions at ca. -0.83 and -1.59 V for 1F/2F and ca. -0.42 and -1.07 V for 1FMe/2F Me. Regarding electronic absorption features, all htt-EP chromophores show absorptivity in the range of ca. 1-4 × 104 M-1 cm-1, with red-edge absorptions extending toward 450 and 500 nm (in MeCN) for 2BMe and 2FMe, respectively. These lowest-energy pi-pi* transitions are ascribed to intramolecular charge transfer between the electron-releasing biphenyl group and the htt-bipyridinium electron-withdrawing subsystems. EPs display room-temperature photoemission quantum yields ranging from 10% to 50%, with the exception of 1B, and branched luminophores are characterized by larger Stokes shifts (8000-10 000 cm -1) than fused ones. Lastly, a method to predict the efficiency of photobiscyclization of branched EPs into fused ones, based on the analysis of computed difference maps in total electron density for singlet excited states, is proposed.
HYDROAMINATION OF PYRYLIUM SALTS
Reshetov, P. V.,Fedotova, O. V.,Kriven'ko, A. P.,Kharchenko, V. G.
, p. 513 - 516 (2007/10/02)
The catalytic reductive amination of pyrylium salts proceeded stereoselectively to give piperidine bases with a cis-structure.The reaction involved the formation of a pyridine intermediate; the course of the reaction depended on the structure of both the
Heterocycles in Organic Synthesis. Part 42. Preparation of Azides, Phthalimides, and Sulphonamides from Primary Amines
Katritzky, Alan R.,Liso, Gaietano,Lunt, Edward,Patel, Ranjan C.,Thind, Sukhpal S.,Zia, Abid
, p. 849 - 851 (2007/10/02)
N-Alkyl and N-benzyl substituents are displaced from 2,4,6-triphenylpyridinium cations by nucleophilic azide, phthalimide, succinimide, and sulphonamide anions.This enables the conversion of primary alkyl- and benzylamines into azides, and primary (with potential for inversion or labelling) and secondary amines.
