v‐Triazolo[1,5‐b]pyridazinium salts 5a‐c synthesized from α‐pyridazinyl ketone arylhydrazones and 2,4,4,6‐tetrabromocyclohexa‐2,5‐dien‐1‐one (TBB) reacted selectively with nucleophiles to yield ‐ besides substituted derivatives 6 ‐ ring‐opened cyano compound 9 and/or v‐triazoles containing olefinic side chain 10–12. Mechanistic considerations reveal that cation 5 reacts with nucleophiles predominantly at C‐7 unless other positions are especially activated. This selectivity proved to be in good agreement with results of semiempirical quantum chemical calculations.
ASJC Scopus subject areas
- Organic Chemistry