Cinnolines and pyrazolopyridazines. — Novel synthetic and mechanistic aspects of the Richter reaction

Sergei F. Vasilevsky, Eugene V. Tretyakov

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47 Citations (Scopus)


The thermal cyclization of 2‐alkynylbenzenediazonium salts 2 known as the Richter reaction and leading, as described in the literature, only to 4‐hydroxycinnolines 6 has been studied. A new probable route to these compounds involving intermediate formation of the 4‐chlorocinnolines 4 followed by hydrolysis of the latter to 6 is discussed. A new understanding of the reaction mechanism has induced us to change the reaction conditions in order to synthesize some 4‐bromo‐ (5), 4‐chloro‐ (4), and 4‐hydroxycinnolines 6 as well as 4‐bromo‐(8b) and 4‐chloropyrazolopyridazine 8a.

Original languageEnglish
Pages (from-to)775-779
Number of pages5
JournalLiebigs Annalen
Issue number5
Publication statusPublished - 24 Apr 1995
Externally publishedYes



  • 2‐Diazotolanes
  • Cinnolines
  • Diazotization
  • Pyrazolopyridazines
  • Richter reaction
  • Tolanes

ASJC Scopus subject areas

  • Chemistry(all)

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