Reactivity of 2-substituted imidazo[1,2-b]pyridazines: preparation of 3-nitro, nitroso and chloro derivatives

The synthesis of 2-substitutedimidazo [1,2-b]pyridazines and their reactivity towards electrophilic substitutions are reported. The nitration was shown to be very dependent on the nature of the 2 substituent. Nitrosation using sodium nitrite in acetic acid media as a general method failed in all cas...

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Bibliographic Details
Published inJournal of heterocyclic chemistry Vol. 39; no. 4; pp. 737 - 742
Main Authors Hervet, M, Galtier, C, Enguehard, C, Gueiffier, A, Debouzy, JC
Format Journal Article
LanguageEnglish
Published HOBOKEN Wiley 01.07.2002
Subjects
Chemistry
Chemistry, Organic
Physical Sciences
Science & Technology
PYRIDAZINE
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Summary:The synthesis of 2-substitutedimidazo [1,2-b]pyridazines and their reactivity towards electrophilic substitutions are reported. The nitration was shown to be very dependent on the nature of the 2 substituent. Nitrosation using sodium nitrite in acetic acid media as a general method failed in all cases whereas chlorination was observed in warm hydrochloric acid. In order to ascertain the structure of some chloro derivatives, chlorination using N-chlorosuccinimide was also reported. Depending of the nature of the substituent, the reaction occurred at the C-3 imidazolic position and/or at the substituent on position 2. The 3-nitroso-2-phenyl derivative was finally obtained using an alternative synthetic pathway by direct condensation of 3-amino-6-chloropyridazine to omega-chloro-omega-nitrosoacetophenone. The structural determinations were ascertained using high field H-1 and C-13-NMR.
ISSN:0022-152X
1943-5193
DOI:10.1002/jhet.5570390419