The conversion of 4- acetoxy -6- chloro -1, 2- dihydro -2- oxo -3-
phenylquinoxalinium perchlorate into the ring -contracted product 1-
benzoyl-6- chlorobenzimidazol -2 -one and 6, 8-dichloro-7- hydroxyquinoxalin -2(1H) -one, by treatment with water, is described and mechanisms
accounting for these rearrangements are discussed. The attempted base - catalysed ring contraction of 4- acetoxy -6- chloro -1, 2- dihydro -2- oxo -3-
phenylquinoxalinium perchlorate using triethylamine and hydroxide ion
as catalysts proved unsuccessful.The reactions of a series of 4- acetoxy -1, 2- dihydro -2- oxo -3-
phenylquinoxalinium perchlorates with morpholine have been investigated.
Mechanisms accounting for the formation of the products of morpholinesubstitution and /or ring contraction are discussed.The scope of the nucleophilic substitution reactions of 4 -Nac etoxy- 6 -chlor o- l - methyl -3- morpholino -3 -phenylquinoxalin- 2( 1H)- one
has been investigated. Reaction to afford 7- substituted quinoxalin-2(1H)-
ones has been demonstrated with chloride, bromide, azide, cyanate,
thiocyanate and hydride ions. Reaction with benzenesulphinate and
cyanide ion gave unresolved mixtures of 5- and 7- substituted quinoxalin2(1H) -ones. Reaction with iodide and fluoride ions and with hydrobromic
acid gave 6- chloro-1- methyl -3- phenylquinoxalin -2(1H) -one. Mechanisms
accounting for the formation of these products are discussed. Attempted
reaction with phenoxide and acetylacetonate ions, diethylamine and ethyl
magnesium bromide proved unsuccessful.Treatment of 4-N-acetoxy-6-chloro-l- methyl -3- morpholino -3-
phenylquinoxalin -2(1H) -one with boron trifluoride -etherate in dioxan gave
di(6- chloro -1, 2- dihydro -1- methyl -2- oxo -3- phenylquinoxalin -7 -yl) ether.
A mechanism to account for this rearrangement is proposed.A series of 3- cyanoquinoxalin -2(1H) -one 4- oxides has been prepared
by the base -catalysed cyclisation of the appropriate 2- nitro- a- cyanoacetanilides. The reactions of these compounds and those of 3- cyano -lmethylquinoxalin -2(1H) -one 4- oxide, 3- benzoylquinoxalin -2(1H) -one
4 -oxide and 3- aminoquinoxalin -2(1H) -one 4- oxide with acetyl chloride
in acetic acid have been investigated. Mechanisms accounting for the
formation of the products of these reactions are proposed and discussed.
The reactions of selected 3- cyanoquinoxalin -2(1H) -ones with acetic
anhydride have also been investigated and mechanisms are proposed to
account for the mode of reaction observed.A series of 1- hydroxyquinoxaline -2, 3(1H, 4H)- diones has been
prepared by base -catalysed conversion of the appropriate 2- nitro -acyanoacetanilides. The attempted base -catalysed syntheses of 1- hydroxy6- methylquinoxaline -2, 3(1H, 4H) -dione and 6, 7- dimethyl- 1 -hydr oxyquinoxaline-2, 3(1H, 4H) -dione from both the corresponding 2- nitro -acyanoacetanilides and 3- cyanoquinoxalin -2(1H) -one 4- oxides proved unsuccessful. The reactions of the 1- hydroxyquinoxaline -2, 3( 1H, 4H)- diones
and a series of 4- alkyl-l-hydr oxyquinoxaline-2, 3(1H, 4H)- diones with
acetyl chloride in acetic acid and with acetic anhydride have been investigated
and mechanisms are discussed to account for the formation of the products
of substitution and ring- contraction obtained.A series of 3- cyano -l- hydroxyquinoxaline -2(1H) -one 4- oxides has
been prepared by the base -catalysed reaction of ethyl cyanoacetate with
the appropriate benzofuroxan. The base -catalysed conversion of the
3- cyano- 1- hydroxyquinoxaline -2(1H) -one 4- oxides into 1, 4-di-N-hydr oxyquinoxaline-2, 3(1H, 4H)- diones is described and mechanisms accounting
for the formation of these products are discussed.The reactions of 1, 4- di- N- hydroxyquinoxaline -2, 3(1H, 4H)- diones
with acetyl chloride and acetyl bromide in acetic acid have been investigated.
Mechanisms are proposed for the formation of the products of substitution
and ring- contraction obtained. The attempted reaction of 1, 4- dihydroxyquinoxaline-2, 3(1H, 4H) -dione with acetic anhydride and with sodium acetate
in acetic anhydride proved unsuccessful as did attempts to demonstrate
nucleophilic substitution of the quinoxalinedione nucleus by toluene -psulphonyl chloride in the presence of dimethylformamide, aqueous sodium
hydroxide, and triethylamine. Evidence for the formation of chloroquinoxalinediones was obtained in the reaction of 1,4- dihydroxyquinoxaline -
2, 3(1H, 4H) -dione with tosyl chloride in dimethylformamide in the presence
of triethylamine.The thermal rearrangement of 1- acetoxy -4- methylquinoxaline - 2, 3(1H, 4H) -dione to the 7- acetoxy isomer and the thermally induced ring - contraction of 1- acetoxyquinoxaline -2, 3(1H, 4H)- diones to benzimidazolone
derivatives has been demonstrated and mechanisms accounting for these
transformations are discussed. The attempted thermal rearrangement of
1, 4- diacetoxyquinoxaline -2, 3(1H, 4H) -di one proved unsuccessful. The
thermolytic deoxygenation of 1-hydroxyquinoxaline-2, 3(1H, 4H)-diones to
the parent heterocycle in high boiling solvents has been demonstrated. The
attempted thermolytic de oxygenation of 1, 4- dihydroxyquinoxaline -2, 3(1H,
4H) -dione proved unsuccessful as did the attempted photolytic de oxygenation
of 1- hydroxyquinoxaline -2, 3(1H, 4H)- dione
