ORGN 589 |
| Carbohydrate diphosphates are required for the biosynthesis of complex carbohydrates, glycoproteins, and glycolipids. Nucleosides diphosphates are intracellularly converted to nucleosides triphosphates in the presence of kinases. Organic chemists investigating these fields are required to prepare many kinds of pure nucleosides and carbohydrates monodiphosphates and monodiphosphodithioates in sufficient quantities. Two classes of aminomethyl polystyrene resin-bound linkers of p-acetoxybenzyl alcohol were subjected to reactions with bis(2-cyanoethyl diisoproylphosphoramidite) to produce the corresponding polymer-bound phosphitylating reagents. Several unprotected nucleosides (e.g., thymidine, adenosine, AZT) and carbohydrates (e.g., galactose, mannose, melibiose) were reacted with the polymer-bound reagents. Oxidation with tert-butyl hydroperoxide or sulfurization with Beaucage's reagent, followed by removal of cyanoethoxy group with DBU, afforded the corresponding polymer-bound diphosphodiesters or diphosphodithioesters. The cleavage of polymer-bound compounds under acidic conditions afforded nucleosides and carbohydrates diphosphates and diphosphodithioates with high regioselectivity in 47-78% overall yield, while the linkers remained trapped on the resins.
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Asymmetric Reactions, Heterocycles, Aromatics, Combinatorial, and Physical Organic Chemistry
8:00 PM-10:00 PM, Wednesday, 31 August 2005 Washington DC Convention Center -- Hall A, Poster
Division of Organic Chemistry |
