Proton Magnetic Resonance Study of the Conformational Equilibria in Some Substituted N-Acetylpyrrolidines

In the p.m.r. spectra of eight N-acetyl-2-(p-methoxybenzyl)-pyrrolidines, the acetamido methyl group gives rise to two peaks in the range 7.7–8.5 τ Compounds 9 and 10 also exhibit two peaks for the acetoxy methyl group in the same range. When the samples were heated, the pairs of peaks coalesced to give singlets. These results are interpreted as evidence for the existence of conformational equilibria.