An improved synthesis of 24 13C labeled bile acids using formyl esters and a modified lead tetraacetate procedure
An improved synthesis of 24 14C labeled bile acids has been achieved using formyl derivatives of bile acids and a modified lead tetraacetate procedure. The formylated bile acids were degraded by lead tetraacetate and lithium chloride to formylated 23 chloronorcholanes in 72 to 83% yield. Formylated 23-chloronorcholanes were converted to nitriles in dimethylformamide, which were then hydrolyzed to obtain C-24 labeled bile acids in yield of 80 to 90% of labeled sodium cyanide used. This method results in a higher yield and a purer product with less manipulation than previously reported procedures for synthesis of labeled bile acids.
Tserng,Klein
p. 400 - 403
(2007/10/13)
Syntheses with stable isotopes: synthesis of deuterium and 13C labeled bile acids
A series of 5β cholanic acids labeled with deuterium in the A ring were prepared by exchange labeling of the corresponding ketone by column chromatography on deuterated alumina. Factors affecting yield and labeling efficiency are discussed. 5β Cholanic acids labeled with 13C in the carboxyl position were prepared by treatment of the corresponding 23 chloro 24 norcholane with sodium cyanide 13C followed by alkaline hydrolysis of the nitrile. The intermediates in the synthesis were characterized by high resolution NMR spectroscopy. Mass spectra are also reported for the 13C labeled products.