A short route to 3-alkynyl-4-bromo(chloro)cinnolines by Richter-type cyclization of ortho-(dodeca-1,3-diynyl)aryltriaz-1-enes

作者：Vinogradova Olga V; Sorokoumov Viktor N; Balova Irina A^*

来源：Tetrahedron Letters, 2009, 50(46): 6358-6360.

DOI：10.1016/j.tetlet.2009.08.103

• ortho-(Alka-1,3-diynyl)aryltriazenes
• ortho-(Alka-1,3-diynyl)arenediazonium salts
• Richter cyclization
• 3-Alkynyl-4-halocinnolines
• Synthesis: pyrrolo[3,2-c]cinnolines, thieno[3,2-c]cinnoline, 3,4-diethynylcinnoline

Cleavage of ortho-(dodeca-1,3-diynyl)triazenes in HCl or HBr medium and subsequent cyclization of the resulting diazonium salts is investigated. In the absence of a strong electron-withdrawing substituent, the reaction affords 3-alkynyl-4-bromo(chloro)cinnolines as the only product. A methoxycarbonyl group promotes hydrolysis of 4-halocinnolines which results in the formation of by-products: furo[3,2-c]cinnoline and cinnolinone. Substitution of bromine in 3-(alk-1-ynyl)-4-bromocinnolines is achieved with methylamine, Na(2)S and ethynylbenzene affording pyrrolo[3,2-c]cinnoline, thieno[3,2-c]cinnoline and 3,4-diethynylcinnoline, respectively.

• 出版日期2009-11-18