Pyrazolo[3,4-d]pyrimidine ribonucleosides related to 2-aminoadenosine and isoguanosine: synthesis, deamination and tautomerism
作者:Frank Seela、Kuiying Xu
DOI:10.1039/b708736e
日期:——
than that of the related purines. The pK(a) values indicate that the 7-non-functionalized nucleosides 1a (pK(a) 5.8) and 15 (pK(a) 6.4) are possibly protonated in neutral conditions when incorporated into RNA. The nucleosides 3a-d exist predominantly in the keto (lactam) form with K(TAUT) (keto/enol) values of 400-1200 compared to 10(3)-10(4) for pyrrolo[2,3-d]pyrimidine isoguanosine derivatives 4a-c
Isoguanine (2-Hydroxyadenine) and 2-Aminoadenine Nucleosides with an 8-Aza-7-deazapurine Skeleton: Synthesis, Functionalization with Fluorescent and Clickable Side Chains, and Impact of 7-Substituents on Physical Properties
作者:Dasharath Kondhare、Peter Leonard、Frank Seela
DOI:10.1021/acs.joc.1c01283
日期:2021.11.5
was performed either on 8-aza-7-deaza-7-iodo-2-amino-2′-deoxyadenosine followed by selective deamination of the 2-amino group or on 7-iodinated 8-aza-7-deaza-2′-deoxyisoguanosine. Sonogashira and Suzuki–Miyauracross-couplingreactions were employed for this purpose. Octadiynyl side chains were selected as linkers for click reactions with azido pyrenes. KTaut values calculated from H2O/dioxane mixtures
Seela, Frank; Ramzaeva, Natalya; Becher, Georg, Collection of Czechoslovak Chemical Communications, 1996, vol. 61, p. S258 - S261
作者:Seela, Frank、Ramzaeva, Natalya、Becher, Georg
DOI:——
日期:——
Unexpected Dehalogenation of 3-Bromopyrazolo[3,4-d]pyrimidine Nucleosides During Nucleobase-Anion Glycosylation
作者:Frank Seela、Matthias Zulauf、Georg Becher
DOI:10.1080/07328319708001351
日期:1997.3
The anion-glycosylation (KOH, MeCN, TDA-1) of 3-bromopyrazolo[3,4-d]pyrimidines 4a and 4b with 2-deoxy-3,5-di-O-(p-toluoyl)-alpha-D-erythro-pentofuranoysl chloride (5) furnishes the regioisomeric N-1-beta-D-2'-deoxyribonucleosides 6a and 6b together with the dehalogenated N-2-regioisomers 8a and 8b, stereoselectively. The dehalogenation takes place after the glycosylation and results from the sensitivity of the N-2 nucleosides toward aqueous base. An addition/elimination mechanism is suggested for the dehalogenation reaction.