Preparation of 4,4-Dimethyloxazoline and Pyrrolidine Derivatives from Fatty Acid Methyl Esters Using Sodium Borohydride: Mild and Simple One-Pot Derivatization Procedures for a Gas Chromatographic-Mass Spectrometric Analysis of Fatty Acids

Procedures for preparing 4,4-dimethyloxazoline (DMOX) and pyrrolidine derivatives from fatty acid methyl esters (FAMEs) were modified to provide milder and simpler conditions for the derivatization reactions widely used in the mass spectrometric analysis of fatty acids. DMOX and pyrrolidine derivatives were obtained overnight at room temperature in the presence of sodium borohydride. The proposed method, involving a low-temperature condensation-cyclization of FAME to DMOX, allows for the direct preparation of DMOX derivatives from non-hydroxy, 2- and 3-hydroxy acid methyl esters. The described simple one-pot procedures are "mild" alternatives to existing methods, which require the use of elevated temperatures.