The deoxy-cyanation of 2-substituted quinoxaline 4-oxides (Ia-k) with trimethylsilyl cyanide in the presence of 1, 8-diazabicyclo[5.4.0]undec-7-ene gave the corresponding 3-substituted 2-quinoxalinecarbonitriles (IIa-k). However, in the case of 2-(p-tolylsulfonyl)quinoxaline 4-oxide (II), the substitution with cyanide ion proceeded together with deoxy-cyanation to give 2, 3-quinoxalinedicarbonitrile (III).