Synthesis of fatty aldehydes and their cyclic acetals (new derivatives for the analysis of plasmalogens)

Abstract

Saturated and unsaturated fatty aldehydes were prepared in good yield by the reduction of acid chlorides with lithium aluminum tri-t-butoxy hydride. Saturated odd and even numbered aldehydes were prepared by the ozonolysis-reduction of 1-alkenes. Ozonides were hydrogenated with a Lindlar catalyst or reduced with dimethyl sulfide. Several diols, including 1,3-propanediol and ethylene glycol, were used to synthesize cyclic acetals from aldehydes and plasmalogens in quantitative yield. Cyclic acetals were synthesized from 2,4-dinitrophenyl hydrazones when an exchanger such as acetone or acetylacetone was included in the reaction mixture. A number of physical and chemical properties indicate that cyclic acetals are stable compounds which do not decompose during storage or gas-liquid chromatographic (GLC) analysis. The cyclic acetals have unusually long retention volumes which are probably related to the large dipole moments found with cyclic compounds. These derivatives are, therefore, readily separated from their aldehyde and methyl ester analogues on polar and nonpolar stationary phases. GLC analysis of the aldehydogenic moieties in plasmologens may be conveniently carried out by direct conversion to cyclic acetals without preliminary isolation of aldehydes or removal of methyl esters by saponification.