N-Acylated 2-substituted anilines undergo slow Ar-N bond rotation, allowing in some cases isolation of enantiomeric or diastereoisomeric atropisomers and in others the determination of the rate of Ar-N bond rotation by NMR. 2-Iodoanilides bearing a branched N-substituent demonstrate sufficient enantiomeric stability to be resolvable, either by HPLC or by formation of diastereoisomeric lactanilide derivatives. For the first time, the rates of Ar-N rotation in 2-substituted N,N-diarylureas have been established: they mainly fall in the region of 50-70 kJ mol-1 with a relatively weak dependence on substituent size.
|Number of pages||11|
|Journal||Organic and Biomolecular Chemistry|
|Early online date||26 Jul 2005|
|Publication status||Published - 7 Sep 2005|