Synthesis, characterization and applications of densely functionalized pyridazines and fulvene-type compounds containing azulene moiety

摘要

Ethyl 4-ethoxyazulene-1-carboxylate (1) is highly efficient and novel substrate for electrophilic substitution reactions. These derivatives (2-4) were treated with NH_2NH_2/PhNHNH_2 in ethanol to produce pyridazine, and fulvene derivatives with azulene frameworks (5, 6, 17, 19) via intramolecular cyclization. The substrates 5-8, 11, and 19 were effectively converted into densely functionalized heterocyclic molecules via Vilsmeier-Haack, Friedel-Crafts, and Michael addition reactions.