Quinoxaline, 2-chloro-, reaction with nucleophiles

Chloroquinoxaline undergoes facile nucleophilic displacement reactions with amines and aryloxides to give the corresponding 2-substituted quinoxalines. With diamines, besides the 2-amino derivatives, bis(quinoxalinyl)alkylenediamines are produced. When 2-chloro-quinoxaline is treated with a sodium aryloxide in an excess of the corresponding phenol, a mixture of the expected 2-aryloxyquinoxaline and the corresponding benzofuro[2,3-6]quinoxaline (144) is obtained. 2-Aryloxyquinoxalines are readily cyclized with polyphosphoric acid to benzofuro[2,3-6]quinoxalines. 2-Arylfuro[2,3-h]quinoxalines (146) result from cyclization of 2-phenacyl-3-quinoxalinones (145). ... 

Substituted quinoxalines undergo some interesting reactions when treated with nucleophilic reagents. When 6-bromoquinoxaline is treated with potassium amide in liquid ammonia the main product is benzimidazole. Minor amounts of 2-amino- and 2,3-diaminoquinoxalines are also formed, but none of the expected 5- and 6-aminoquinoxalines are obtained (Scheme ) Similar treatment of 6-chloroquinoxaline gives a mixture of 2-amino-7-chloroquinoxaline and 6-chloro-2,3-diamino-quinoxaline. It has been suggested that the difference in behavior between the 6-bromo and 6-chloro compounds may be explained by the... 

Nucleophilic displacement of 2-chloro-3-phenylquinoxaline with methylamine at 100°-150° and with sodium phenoxide in excess of phenol of 100° gives the expected 2-methylamino- and 2-phenoxy-3-phenylquinoxalines.155 2-Chloroquinoxaline and its 3-phenyl derivative undergo ring closure with aminoacetaldehyde dimethylacetal to an imidazo[l,2-a]quinoxaline.136 Nucleophilic substitution of 2-chloro-quinoxaline with hydroxide ion in water is accelerated by cationic micelles and retarded by anionic micelles. These results were correlated with reactions of l-chloro-2,4-dinitrobenzene, and the characteristics of their transition states were discussed.137... 

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