Collect. Czech. Chem. Commun. 1994, 59, 2677-2690
https://doi.org/10.1135/cccc19942677

Sterically Crowded Heterocycles. I. Molecular Structure of 3-Chain Substituted 2-Phenylimidazo[1,2-a]pyridinium Salts

Stanislav Böhma, Richard Kubíka, Martin Hradilekb, Jan Němečekc, Michal Hušákd, Svetlana Pakhomovad, Jan Ondráčekd, Bohumil Kratochvíld and Josef Kuthana

a Department of Organic Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic
b Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague 6, Czech Republic
c Institute of Microbiology, Academy of Sciences of the Czech Republic, 142 20 Prague 4, Czech Republic
d Department of Solid State Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6, Czech Republic

This article is part of serial Sterically crowded heterocycles.

Abstract

2-Phenyl-3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridine (I) was converted to corresponding 1-alkyl-2-phenyl-3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridinium salts III - VI and 2-phenyl- 3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridinium perchlorate (VII). The protonation site is discussed in terms of calculated molecular energies of alternative cations. The X-ray structure analyses of enone I and its quaternary periodide III are reported and compared with the PM3 molecular optimizations. 1H NMR and 13C NMR spectra reveal well changes of molecular structures caused by the transformation of the base I into salts III - VII.