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DOI: 10.1055/s-1997-1215
Syntheses of Linear Dimeric and Cyclic Oligomeric Cholate Ester Derivatives
Publication History
Publication Date:
31 December 2000 (online)
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One-step syntheses of cyclic trimer 2 and tetramer 3 of lithocholate were achieved from the cycloesterification of lithocholic acid (1) by using 2-chlorobenzoyl chloride and 4-dimethylaminopyridine (DMAP). The tetramer 5 of 7,12-diacetyl-24-norcholid acid (4) was synthesized by a similar method. These results suggest that the cyclotrimer is the preferred cycle size for the cholic acid system and that the cyclotetramer is the preferred cycle size for the 24-norcholic acid system. Cyclotetramerization of lithocholic acid is preferred over cyclodimerization. The structure of tetramer 3 was verified by a multistep synthesis. The structures and stereochemistry of all dimers, oligomers, and intermediate products were determined by means of spectroscopic analyses.
oligomeric cholate ester derivatives - cycloesterification - cyclotetramerization - lithocholate - lithocholic acid