914084-44-9Relevant academic research and scientific papers
METHODS FOR SELECTIVE N-9 GLYCOSYLATION OF PURINES
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Page/Page column 29, (2010/11/25)
A process for providing regiospecific and highly stereoselective synthesis of 9-β anomeric purine nucleoside analogs is described. The introduction of the sugar moiety on to 6-(azolyl)-substituted purine bases is performed so that highly stereoselective formation of the β anomers of only the 9 position regioisomers of the purine nucleoside analogs (either D or L enantiomers) is obtained. This regiospecific and stereoselective introduction of the sugar moiety allows the synthesis of nucleoside analogs, and in particular 2'-deoxy, 3'-deoxy, 2'-deoxy-2'-halo-arabino and 2',3'-dideoxy-2'-halo-threo purine nucleoside analogs, in high yields without formation of the 7-positional regioisomers. Processes for providing novel 6-(azolyl)purines for the regiospecific and highly stereoselective synthesis of 9-β anomeric purine nucleoside analogs are described. The compounds are drugs or intermediates to drugs.
Regiospecific and highly stereoselective coupling of 6-(substituted- imidazol-1-yl)purines with 2-deoxy-3,5-di-O-(p-toluoyl)-α-D-erythro- pentofuranosyl chloride. Sodium-salt glycosylation in binary solvent mixtures: Improved synthesis of cladribine
Zhong, Minghong,Nowak, Ireneusz,Robins, Morris J.
, p. 7773 - 7779 (2007/10/03)
(Chemical Equation Presented) Glycosylation of 6-(substituted-imidazol-1- yl)purine sodium salts with 2-deoxy-3,5-di-O-(p-toluoyl)-α-D-erythro- pentofuranosyl chloride proceeds with regiospecific formation of the N9 isomers. Base substrates with lipophilic substituents on the C6-linked imidazole moiety are more soluble in organic solvents, and the solubility is further increased with binary solvent mixtures. Selective solvation also diminishes the extent of anomerization of the chlorosugar. Stirred reaction mixtures of the modified-purine sodium salts generated in a polar solvent and cooled solutions of the protected 2-deoxysugar chloride in a nonpolar solvent give 2′-deoxynucleoside derivatives with N9 regiochemistry and enhanced β/α configuration ratios. Application of the binary-solvent methodology with 2-chloro-6-(substituted-imidazol-1-yl)purine salts in cold acetonitrile and the chlorosugar in cold dichloromethane gives essentially quantitative yields of the N9 isomers of β-anomeric 2′- deoxynucleoside intermediates. Direct ammonolysis (NH3MeOH) of such intermediates or benzylation of the imidazole ring followed by milder ammonolysis of the imidazolium salt gives high yields of the clinical anticancer drug cladribine (2-chloro-2′-deoxyadenosine).
