Synthesis of racemic cis and trans 2,4,5-tripyridylimidazolines

Article abstract of DOI:10.1016/S0040-4039(98)00957-5

Reaction of 2-pyridinecarboxaldehyde with ammonium hydroxide gives 1,3,5-triazine 6 which was converted to cis-2,4,5-tripyridylimidazoline, 9. The intermediate 2,4-diazapentadiene is not observed, but believed to undergo deprotonation and cyclization to afford cis-2,4,5-tripyridylimidazoline. Base catalyzed isomerization (5 mol% KO-t-Bu, 23°C) of cis-2,4,5- tripyridylimidazoline gives trans-imidazoline (10). Compounds 6, 9, and 10 have been characterized by X-ray crystallography.