Structure and Synthesis of 6-(Substituted-imidazol-1-yl)purines: Versatile Substrates for Regiospecific Alkylation and Glycosylation at N91
摘要:
X-ray crystal structures of several 6-(azolyl) purine base and nucleoside derivatives show essentially coplanar conformations of the purine and appended 6-(azolyl) rings. However, the planes of the purine and imidazole rings are twisted similar to 57 degrees in a 2-chloro-6-(4,5-diphenylimidazol-1-yl) purine nucleoside, and a twist angle of similar to 61 degrees was measured between the planes of the purine and pyrrole rings in the structure of a 6-(2,5-dimethylpyrrol-1-yl) purine nucleoside derivative. Shielding "above" N7 of the purine ring by a proximal C-H on the 6-azolyl moiety is apparent with the coplanar compounds, but this effect is diminished in those without coplanarity. Syntheses of 6-(azolyl)purines from both base and nucleoside starting materials are described. Treatment of 2,6- dichloropurine with imidazole gave 2-chloro-6-(imidazol)-yl)purine. Modified Appel reactions at C6 of trityl-protected hypoxanthine and guanine derivatives followed by detritylation gave 6-(imidazol-1-yl)- and 2-amino-6-(imidazol-1-yl) purines. Imidazole was introduced at C6 of 2',3',5'-tri-O-acetylinosine by a modified Appel reaction, and solvolysis of the glycosyl linkage gave 6-(imidazol-1-yl) purine. Guanosine triacetate was transformed into the protected 2,6-dichloropurine nucleoside, which was subjected to SNAr displacement with imidazoles at C6 followed by glycosyl solvolysis to provide 2-chloro-6-(substituted-imidazol-1-yl) purines. Potential applications of these purine derivatives are outlined.
Methods For Selective N-9 Glycosylation of Purines
申请人:Robins Morris J.
公开号:US20080207891A1
公开(公告)日:2008-08-28
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.
Methods for selective N-9 glycosylation of purines
申请人:Brigham Young University
公开号:US07855285B2
公开(公告)日:2010-12-21
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.