Condensed pyridazine and pyrazine rings (cinnolines, phthalazines and quinoxalines): By J. C. E. Simpson, Late Member of Scientific Staff, Medical Research Council, England. Interscience Publishers, Inc., New York, N. Y., 1953. xvi + 394 pp. Price $12.50

Abstract

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, Na2S and ethynylbenzene affording pyrrolo[3,2-c]cinnoline, thieno[3,2-c]cinnoline and 3,4-diethynylcinnoline, respectively.