Atropisomeric benzamides and naphthamides as chiral auxiliaries

Atropisomeric compounds whose chirality resides in a rotationally restricted aryl-CONR₂ bond may be employed as chiral auxiliaries. The electron-withdrawing amide group causes problems in the diastereoselective functionalisation of enolates derived from atropisomeric phenyl esters, but a strategy based on atroposelective nucleophilic addition to a chiral aldehyde followed by stereospecific [3,3] sigmatropic rearrangement allows atropisomeric naphthamides to be used as auxiliaries. The auxiliaries are resolved by dynamic resolution during aminal formation using a proline-derived diamine.