2.3- Diphenyl-5 -quinoxalinone

Diphenyl-5(l//)-quinoxalinone (83) gave 5-(dimethoxyphosphinyloxy)-2,3-diphenylquinoxaline (85) via intermediate (84) (neat POCl3, reflux, 18 h then cooled mixture into excess MeOH, 0°C 60%).638... 

Cycloaddition of diphenyl ketene with benzoquinone diimides (44) gives quinoxalinones of type 45.45 Analogous additions of olefins lead to tetrahydroquinoxalines these reactions are classified as Diels-Alder additions with inverse electronic demand. 

Quinoxaline 1-oxide (209) reacts with phenyl isocyanate to give 2-anilinoquinoxaline (210) together with 1,3-diphenyl-l-(2-quinoxalinyl)-urea (211) and cyclized oxidation product of the urea 212.215 2-Quinoxalinone 4-oxide (205) and its 1-methyl derivative undergo addition reactions, e.g., with phenyl isocyanate and benzyne to give compounds 214 and 216, respectively.216 These reactions are formulated as proceeding via the intermediate cycloadducts 213 and 215. Compound 216 has also been obtained by photolysis of 3-(o-hydroxy-phenyl)quinoxaline 1-oxide.51 1,3-Dipolar cycloaddition of quinoxaline... 

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