ORGN 502 |
| Tilak Chandra, Shawn Zou, and Kenneth L Brown. Department of Chemistry and Biochemistry, Ohio university, 172-Clippinger lab, Athens, OH 45701 |
| Semi synthesis/partial synthesis of cobalamins modified in the axial base requires the synthesis of the lower axial ligand for the nucleotide loop. For this purpose, the most critical step is the synthesis of nucleoside which has the unusual alpha-N-glycosidic bond configuration. For the semi-synthesis of the indole derivative of cyanocobalamin, we have prepared the alpha-indoline nucleoside by reacting trimethylsilyl indoline with 2, 3-O-isopropylidene-5- O-triphenylmethyl-D-ribofuranose in presence of 2-fluoro-1-methyl pyridinium tosylate under appropriate conditions. Subsequently dehydrogenation at room temperature gives the indole nucleoside. 1-(5-O-triphenylmethyl-2, 3-O-isopropylidene-alpha-ribofuranosyl)indoline was dehydrogenated by activated manganese dioxide in dry benzene in the presence of molecular sieves at room temperature in good yield. The corresponding beta nucleoside undergoes dehydrogenation at slightly higher temperature. |
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Total Synthesis, Asymmetric Reactions and Syntheses, Bioorganic
9:00 AM-11:00 AM, Wednesday, March 31, 2004 Anaheim Convention Center -- Hall C, Poster
Division of Organic Chemistry |