(1-Naphthyl)(trifluoromethyl) <i>O</i>-Carboxy Anhydride as a Chiral Derivatizing Agent: Eclipsed Conformation Enforced by Hydrogen Bonding

The preparation of the (1-naphthyl)(trifluoromethyl) O-carboxy-anhydride 1 and its use as a chiral derivatizing agent with several α-chiral primary amines are reported. The very large ΔδRS values observed in 1H NMR have been correlated with a marked preference of the corresponding α-hydroxy-amides for the eclipsed conformation. In comparison, the related O-methylated amides are shown to adopt staggered conformations, which substantiates the critical role of intramolecular hydrogen bonding in maximizing the anisotropic effect.