“…However, these differences in chemical shifts are less pronounced in compounds 5, 6, 12 and 13 with a chloro atom linked to pyrazine C-3. Here, a safe identification of H-5 and thus the starting point for unambiguous assignments of all carbon atoms can be accomplished by 2D (δ,J) long-range www.interscience.wiley.com/journal/mrc [21] 3, [22,23,24] 4, [23,25] 5, [26,27] 6, [28] 7, [29] 9, [30] 10, [31] 11, [32] 12, [33] 14, [27] INEPT experiments with selective excitation considering the above mentioned characteristic 5 J(CO,H5) coupling. From Table 2 it is apparent that, for 5-9 and 11-13 the absolute value of 2 J(C5,H6) is slightly larger than 2 J(C6,H5); however, the relationship 3 J(C3,H5) > 3 J(C2,H6) is not true stringent in every case.…”