ABSTRACT
Choline phospholipids can be conveniently synthesized by reaction of a lipophilic alcohol, such as diacylglycerol, with 2-bromoethyl dichlorophosphate followed by nucleophilic displacement of the bromine with trimethylamine. We found that the low yields often encountered in the initial phosphorylation step are particularly due to exchange of both chlorines for alkoxy functions (triester formation) and to chlorination of the alcohol by 2-bromoethyl dichlorophosphate. However, these drawbacks can be overcome by proper choice of the reaction medium and by optimizing other reaction conditions. The procedure described is efficient and most versatile, and it lends itself to the preparation of a wide range of choline phospholipids containing a glycerol, diol, or long-chain alkyl backbone and bearing various aliphatic functions. Proton and carbon-13 nuclear magnetic resonance spectroscopy proved useful in establishing the homogeneity and structures of the synthetic intermediates and byproducts and of the choline phospholipids synthesized.
ABSTRACT
Long chain 1,2-alkanediol diesters comprise about 15-20% of the acetone soluble skin surface wax of golden Syrian hamsters. The constituent 1,2-alkanediols, obtained through acidic methanolysis, were fractionated by preparative gas liquid chromatography of their isopropylidene derivatives. The major component (57%) was identified by nuclear magnetic resonance and mass spectrometry as 15-methyl-1,2-hexadecanediol.
Subject(s)
Fatty Alcohols/analysis , Waxes/analysis , Animals , Chromatography, Gas , Chromatography, Thin Layer , Cricetinae , Magnetic Resonance Spectroscopy , MesocricetusABSTRACT
The preparation of 24-nor-5beta-chol-22-enes from formyloxy-5beta-cholanic acids by oxidative decarboxylation with lead tetraacetate is described. NMR data is presented with other physical constants for the norcholenes derived from cholic, chenodeoxycholic, ursodeoxycholic, hyodeoxycholic, and deoxycholic acids. The facile synthesis of these norcholenes demonstrates the applicability of the formyloxy protecting group to oxidative decarboxylations in the bile acid series.
Subject(s)
Bile Acids and Salts , Cholenes/chemical synthesis , Decarboxylation , Norsteroids/metabolism , Oxidation-ReductionABSTRACT
The positional distribution of isovaleric acid in natural cetacean triglycerides has been studied using proton magnetic resonance with lanthanide shift reagents. Twenty-nine samples of melon, jaw, and blubber triglycerides from 13 genera in the Delphinidae, Phocoenidae, and Monodontidae families were examined. Isovaleric acid was found esterified only at the 1,3-positions in the monoisovaleroyl and diisovaleroyl triglycerides of these animals.
Subject(s)
Triglycerides , Adipose Tissue/analysis , Animals , Europium , Magnetic Resonance Spectroscopy , Molecular Conformation , Praseodymium , Species Specificity , Triglycerides/analysis , Valerates/analysis , WhalesABSTRACT
The proton magnetic resonance spectra of isomeric triglycerides of isovaleric and palmitic acids in the presence of the downfield and upfield chemical shift reagents Eu(fod)(3) and Pr(fod)(3) were studied. The resonance profiles of the gamma-protons on the isovaleroyl chains are distinctive for each of the four possible triglyceride isomers at low shift reagent/triglyceride ratios. With either reagent, the well defined gamma-methyl isovalerate doublets can be used to identify 2-isovaleroyl and 1,3-isovaleroyl structures and to analyze isomeric mixtures. This technique will be useful for positional analysis of natural cetacean triglycerides containing isovaleric acid.
