Hindered rotation and exchange in trimethylsilylanilides

A series of trimethylsilylanilides were prepared and characterized as amide—imidate mixtures. Low temperature NMR spectra reveal both hindered rotation and exchange processes for the formanilides and benzanilides and exchange for the acetanilides. Isomer ratios and free energies of activation are reported and used to postulate a mechanism for the exchange process.