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Nitration in the imidazo[1,2-a]pyrazine series. Experimental and computational results

✍ Scribed by Olivier Vitse; Pierre-Antoine Bonnet; Jacques Bompart; Henri Viols; Guy Subra; Jean-Pierre Chapat; Gérard Grassy

Publisher
Journal of Heterocyclic Chemistry
Year
1997
Tongue
English
Weight
525 KB
Volume
34
Category
Article
ISSN
0022-152X

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✦ Synopsis

Abstract

Nitration was carried out on a series of imidazo[1,2‐a]pyrazine derivatives. The reactivities of diversely substituted derivatives and of all positions of substitution were analysed and experimental results compared with ^13^‐nmr data and semi empirical calculations (AMI). Although the unsubstituted heterocycle is highly resistant to nitration, electron‐donating groups such as alkoxy or alkylamino on position 8 enhance the reactivity of the imidazo[1,2‐a]pyrazine derivatives towards electrophilic substitution and, more specifically, nitration. The ^13^‐nmr experiments, electronic distributions and Molecular Electrostatic Potential isodensity surfaces calculated on the neutral forms are in good agreement with experimental results indicating position 3 is the most reactive position towards nitration.

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