2-(Azulen-1-yl)-4,6-diphenyl substituted six-membered heteroaromatics

✍ Scribed by Alexandru C. Razus; Liviu Birzan; Oana Zaharia; Cristian Enache

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2008
• Tongue: English
• Weight: 652 KB
• Volume: 45
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570450431

✦ Synopsis

Abstract

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2‐(Azulen‐1‐yl)‐4,6‐diphenyl substituted pyranylium salts, pyridinium salts and pyridines were efficiently synthesized and the new obtained compounds were completely characterized. Comparative structural analysis between these compounds and their corresponding isomers that contain the azulen‐1‐yl moiety in the 4‐position of the heterocycle, were carried out. These studies are based on calculated dihedral angles formed between central heterocycle and the aromatic substituents and on the obtained electronic and NMR spectra. Due to the restriction in the rotation around azulenyl‐pyridinium bond produced by the quaternary nitrogen substituent, in the herein reported pyridinium salts, the substitution groups of the quaternary nitrogen atom are prochiral. This property leads to the non‐equivalence of gem‐protons or gem‐methyl groups of N‐substituents in the ^1^H nmr spectra of the synthesized pyridinium salts.