The structures of the novel pyrazines and dithienopyrazines were fully characterized by NMRspectroscopy and high-resolution mass spectra (HRMS). The 1 H-NMR spectra of the targeted isomeric dithienopyrazines 5 and 6 are nearly identical and show two doublets at 7.88(9) ppm und 7.54(3) ppm with a 3 J coupling constant of 6.2 Hz and correspond to the -(H2) and -protons (H3) of the fused thiophene units, respectively. This -H-coupling constant is larger than for other thiophene-fused acenes, such as thieno[2,3-b]pyrazine (6 Hz), thieno[2,3-b]pyridine (5.9 Hz), or benzodithiophene (5.5 Hz). The assignment of the protons and resulting 1 JCH coupling constants were taken on the basis of non-decoupled heteronuclear single quantum coherence (HSQC) NMR spectra (vide ultra). The 13 C-NMR spectra of the targeted isomeric dithienopyrazines 5 and 6 are as well nearly identical and show four signals. Two of them at 146-154 ppm are assigned to the quaternary carbons (C4 and C5), those at higher field at 132 ppm to the tertiary -(C2) and at 122 ppm to the -carbons (C3) of the fused thiophene units. The assignment of the tertiary carbons was taken on the basis of non-decoupled HSQC spectra.