Dipole-stabilized carbanions in series of cyclic aldonitrones: Part 4. C-13, N-14 and Li-7 NMR spectra of dipole-stabilized organolithiums derived from a cyclic aldonitrone

C-13, N-14 and Li-7 NMR spectra of a lithiation product of the cyclic aldon itrone 1,2,2,5,5-pentamethyl-3-imidazoline 3-oxide were obtained. The C-13 NMR spectrum of the lithiated particle exhibits the resonances of the C-4 a nd C-5 atoms (delta 213 ppm and 73 ppm, respectively) shifted to high frequ ency relative to the signals of the corresponding nuclei of the starting ni trone (deltaC-4 132 ppm. and deltaC-5 60 ppm). The N-14 NMR spectrum of the particle shows the resonance of the N-3 atom (-115 ppm) at lower frequency in comparison with -74 ppm for the starting nitrone. The calculated chemic al shift changes are in good agreement with those observed experimentally. The electronic structure of the lithiated particle is discussed. Copyright (C) 2001 John Wiley & Sons, Ltd.