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The 'H and uC NMR spectra of tetrahydroquinoxalines condensed with pyridazme, pyrazine, oxazine, oxadiazine, thiadiazine or triazine rings have been measured in DMSO-d, solution. The effects of six-membered heterocycles on 'H and uC chemical shifts and the values of one-bond 'J(CH) and vicinal 3J(HH) coupling constants for the ring junction fragment are considered. The differences between the 'H and =C spectral parameters of tetrahydroquinoxalines aunelated with five-or six-membered heterocycles with the same set of heteroatoms attached to the ring junction carbons are also discussed.

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