SYNTHESIS OF RACEMIC CIS AND TRANS 2,4,5-TRIPYRIDYLIMIDAZOLINES

Reaction of 2-pyridinecarboxaldehyde with ammonium hydroxide gives 1,3 ,5-triazine 6 which ,vas converted to cis-2, 4,5-tripyridylimidazoline , 9. The intermediate 2,4-diazapentadiene is not observed, but believe d to undergo deprotonation and cyclization to afford cis-2,4,5-tripyri dylimidazoline. Base catalyzed isomerization (5 mol% KO-t-Bu, 23 degre es C) of cis-2,4,5-tripyridylimidazoline gives trans-imidazoline (10). Compounds 6, 9, and 10 have been characterized by X-ray crystallograp hy. (C) 1998 Elsevier Science Ltd. All rights reserved.