Abstract
One-, two- and three-bond carbon-13; proton scalar spin-spin coupling constants ( 1 J C,H, 2 J C,H, 3 J C,H) have been determined for a series of hydantoin- and 2-thiohydantoin derivatives in DMSO- d 6 solution using one- and two-dimensional NMR techniques. Simultaneous consideration of several coupling data allowed reliable estimates to be deduced for the ring dihedrals equivalent to the ϕ, ψ and ω angles in peptides. These data are in support of a quasi-planar geometry for the hydantoin ring in solution in close agreement with previous results obtained for the solid state. Rotamer population distributions around the C5C1′ bond have been determined for some 5-substituted derivatives. The existence of four-bond couplings between amide NH protons in 1,3-positions of the imidazolidine ring has been demonstrated for the first time.
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