Miscellaneous Transformations of Aminoquinoxalines

Aminoquinoxalines undergo several other important but seldom used transformations that are illustrated in the following classified examples. 

Methyl 3-amino-2-quinoxalinecarboxylate (157) gave methyl 3-(A -methyl-ureido)-2-quinoxalinecarboxylate (158) (excess neat MeNCO, 20°C, dark. 

3 days 34% after separation from a tricyclic byproduct). 

3-Amino-4-methyl-4,6,7,8-tetrahydro-2-quinoxalinecarbonitrile (159) gave 4-methyl-3-[(A(-phenylcarbamoyl)imino]-3,4,5,6,7,8-hexahydro-2-quinoxaline-carbonitrile (160) (authors formulations) (PhNCO, CHCI3, 20°C, 24 h 55% several analogs likewise). 

1-Methyl-1,2,3,4-tetrahydroquinoxaline (161) gave 1-methyl-4-[A -phenyl(thio-carbamoyl)]-l,2,3,4-tetrahydroquinoxaline (162) (PhNCS, CH2CI2, reflux, 1 h 30%).  

Note The only examples of the formation of dichlorosulfimido derivatives, including 3-chlorothioquinoxalin-2-yliminosulfur dichloride, have been given in Section 5.1.2. 

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