Systèmes aromatiques à 10 électrons π dérivés de l'aza-3a-pentalène. XI. Etude par résonance magnétique nucléaire de l'imidazo [1,2-b] pyrazole et du pyrazolo [1,5-a] benzimidazole

Autor:	José Elguero, Leif Knutsson, Alain Fruchier, René Lazaro, Jan Sandström
Rok vydání:	1974
Předmět:	Nitrogen atom Chemistry Stereochemistry Organic Chemistry Aromaticity General Chemistry Nuclear magnetic resonance spectroscopy Tautomer Catalysis
Zdroj:	Canadian Journal of Chemistry. 52:2744-2750
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v74-400
Popis:	Nuclear magnetic resonance spectroscopy has allowed us to determine the annular tautomerism in two [5,5]-heteroaromatic systems and the position of the acetyl group in their acetyl derivatives. In each case, the more stable compound is the one in which the imidazolic nitrogen atom is bearing H or COCH3. We have also found unusual couplings with the N—H in the N-unsubstituted compounds and abnormally high barriers for the azolides. These observations agree well with the hypothesis of a decrease in the aromaticity of the imidazolic part.
Databáze:	OpenAIRE
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