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