A DNMR study on the ring inversion of oxazolidines

Ring inversion of eight substituted 2-phenyl-4, 4-dimethyloxazolidines in o-dichlorobenzene-d₄ was studied by ¹H DNMR. Very high inversion barriers (ΔG_o^≠ = 86.7–93.4 kJ·mol^?1) were found for these oxazolidine rings. The magnitude of the inversion barrier is dependent on the polarity of the substituent on the phenyl group. A linear correlation is present between the ΔG_o^≠ of the inversion and the substituent constant, σ+, of the substituent.