Synthesis of 7-halogenated 8-aza-7-deaza-2 `-deoxyguanosines and related pyrazolo[3,4-d]pyrimidine 2 `-deoxyribonucleosides

Autor(en): Seela, F
Becher, G
Stichwörter: 2'-DEOXYRIBOFURANOSIDES; 7-DEAZA-2'-DEOXYGUANOSINE; 7-DEAZAPURINE DNA; BASE; BIOLOGICAL-ACTIVITY; Chemistry; Chemistry, Organic; glycosylation; halogenation; NUCLEOSIDES; OLIGONUCLEOTIDES; PHASE-TRANSFER GLYCOSYLATION; pyrazolo[3,4-d]pyrimidines; STABILITY; sugar conformation
Erscheinungsdatum: 1998
Ausgabe: 2
Startseite: 207
Seitenende: 214
The synthesis of 7-bromo and 7-iodo derivatives of 8-aza-7-deaza-2'-deoxyguanosine (2, 3) as well as the halogenated 4-alkoxy derivatives 4a-c and 5a-c is described. Glycosylation of the halogenated pyrazolo[3,4-d]pyrimidine anions of 7a-c or 8a-c with 2-deoxy-3,5-di-O-(p-toluoyl)-alpha-D-erythro-pentofuranosyl chloride (9) yields regioisomeric glycosylation products, the N(1)-isomers 10a-c and 11a-c as well as the N(2)-compounds 12a-c. The latter isomers lose their halogen during the glycosylation in the presence of non-anhydrous KOH. Anhydrous conditions (NaH) furnished 10c, 11c together with the halogenated N(2)-isomers 13a,b. Compounds 10a-c, and 11a-c were deprotected and converted to the 4-alkoxy nucleosides 4a-c and 5a-c. The N(1)-nucleosides 4c and 5c were hydrolyzed to give the 7-bromo or 7-iodo derivatives of 8-aza-7-deaza-2'-deoxyguanosines 2 and 3. Different from regular 2'-deoxyribonucleosides the sugar moiety of pyrazolo[3,4-d]pyrimidine 2'-deoxyribonucleosides shows a preferred N-type pucker (T-3(2)) in solution a conformation which is also detected in the solid state.
ISSN: 00397881

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