2-Acetyl-3-phenylquinoxaline 4-oxide

Benzoxadiazole 1-oxide (490) gave either 2-phenylquinoxaline 4-oxide (491) [PhCH=CHC(=0)Me, HN(CH2)4, MeCN, reflux, 24 h 35% note deacylation] or 2-acetyl-3-phenylquinoxaline 4-oxide (492) [PhCH +... 

Acetyl-3-phenylquinoxaline 2-Acetyl-3-phenylquinoxaline 4-oxide 6-Acetyl-2-phenylquinoxaline 4-oxide... 

Quinoxaline 1,4-dioxide undergoes reaction with acetyl chloride and substitution occurs in the benzene ring to give 6-chloroquinoxaline 1 -oxide and, on increasing the reaction time, 3-chloroquinoxaline 1-oxide and 6,7-dichloroquinoxaline appear as additional products.A similar reaction is observed with 3-phenylquinoxalin-2(l//)-one 4-oxide and its 7-substituted derivatives, where ring substitution at position 6 again is accompanied by deoxygenation. 2-Chloroquinoxalinc 1-oxide (19) is obtained in 60% yield by treatment of quinoxaline 1,4-dioxide with benzenesulfony chloride and consequent neutralization of the benzenesulfonate initially formed,and in addition about 3% of 3-chloroquinoxaline 1-oxide is formed. 

Attempted acylation of l,2-dihydro-2-oxo-3-phenylquinoxaline 4-oxide (69) with acetyl chloride results in nuclear chlorination and loss of... 

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