Enantiodifferentiation of γ-and δ-Lactones by Gas Chromatographic Separation of Diastereomeric Carbamoyloxy Carboxamide Derivatives

Enantiodifferentiation of chiral γ- and δ-lactones has been achieved by capillary gas chromatographic separation of diastereomeric 4- and 5-[(R)-[(l-phenylethyl)carbamoyl]oxy] N-butylcarboxamides. The derivatization procedure involves (1) ring-opening of lactones to hydroxycarboxamides by heating with butylamine and (2) subsequent conversion to diastereomeric carbamates by reaction with (R)- (+)-1-phenylethyl isocyanate. High separation factors were determined for the complete series of C₅-C₁₂ γ-lactones and C₆-C₁₂ δ-lactones, naturally occurring (trace) constituents of many fruits and vegetables.