Methods for the synthesis of cinnolines (review)

Abstract

This review analyses the principal approaches to the synthesis of the cinnoline nucleus, used as synthetic precursors of arenediazonium salts, arylhydrazones, and arylhydrazines, and also reductive methods for the synthesis of polycondensed derivatives of cinnoline. The mechanisms of the transformations and the possibilities and limitations of the various methods are discussed. Special attention is paid to methods based on the cyclization of derivatives of arenediazonium salts, which have been developed substantially in recent years.

Synthesis and Properties of 6-Aryl-4-azidocinnolines and 6-Aryl-4-(1,2,3-1H-triazol-1-yl)cinnolines

“…The synthetic routes towards cinnolines include different cyclization techniques and named reactions [33,50,51]. One of them, which allows 4-halocinnolines to be obtained in high yields, is the Richter-type cyclization [52] of ortho -ethynylarenediazonium salts [53] and ortho -ethynylaryltriazenes [54,55,56].…”

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

“…An efficient modification of the Richter type cyclization [ 37 – 38 ] based on mono- [ 39 – 40 ] and diacetylene [ 41 – 43 ] aryltriazene derivatives as starting materials was chosen over the approach that uses unstable o -ethynyl- or o -(buta-1,3-diynyl)arenediazinium salts. This reaction was a key step for the synthesis of cinnoline-containing structural units – 4,6-dibromocinnolines 4a,b ( Table 1 ).…”

Treatment of o-alkynylphenylsydnones with acids: a new route to 3-arylcinnolines

“…15,17 In general, 3-arylcinnolines have been prepared using one or other of the aforementioned approaches 16,17 and methods for the synthesis of cinnolines, in general, have been reviewed. 25 …”