Thiolysis, Alkanethiolysis, Arenethiolysis, or Arenesulfinolysis of Nuclear Halogenoquinoxalines

Thiolysis, Alkanethiolysis, Arenethiolysis, or Arenesulfinolysis of Nuclear Halogenoquinoxalines 

The 2- and 3-halogenoquinoxalines may be converted into the corresponding quinoxalinethiones by treatment with sodium hydrogen sulfide, sodium thiosulfate, thioacetic acid (with concomitant decarboxylation), or (indirectly) by treatment with thiourea followed by alkaline hydrolysis of the thiouronio intermediate (usually as a one-pot procedure). The same substrates furnish corresponding alkylthio-, arylthio-, or arylsulfonylquinoxalines by treatment with a salt of the appropriate alkanethiol, thiophenol, or benzenesulfinic acid. The following classified examples illustrate such processes. 

3- Chloro-2-quinoxalinecarbonitrile (153) gave 3-thioxo-3,4-dihydro-2-quinoxa- 

2-Chloroquinoxahne gave 2-ethylthioquinoxaline (156, R = Et) (EtSH, NaOH, H20-Me2NCH0, 20°C, 1 h 78%) or 2-benzylthioquinoxaline (156, 

2-Chloro-3-methylquinoxaline gave 2-carboxymethylthio-3-methylqumoxaline (157) (HSCH2CO2H, K2CO3, PhH, reflux, 4h %).  

3-Dichloroquinoxaline (159) gave 2-butylthio-3-chloroquinoxaline (158) [BuSNa (1 equiv, made in situ), Bu OH, exothermic then reflux, 3h 78%],237 2,3-bisbutylthioquinoxaline (160, R = Bu) [BuSNa (2 equiv), Bu OH, exothermic then reflux, 4h 88%] 237 or 2,3-bis-ferf-butylthioqui-noxaline (160, R = Bu ) [excess Bu SNa, THF, 20°C, 1 h 95%].887 

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