Showing papers by "Zygmunt Kazimierczuk published in 1991"
TL;DR: In this article, the synthesis of 2-deoxyisoguanosine (2), and the pyrrolo[2,3-d]pyrimidine and pyrazolo[3,4-d]-pyridine 2-Deoxyribonucleosides 3 and 4 is described.
Abstract: The synthesis of 2′-deoxyisoguanosine (2), and the pyrrolo[2,3-d]pyrimidine and pyrazolo[3,4-d]pyrimidine 2′-deoxyribonucleosides 3 and 4 is described. Condensation of the imidazole precursor 5 with benzoyl isocyanate followed by reaction with ammonia gave 2. Its N(7) regioisomer was obtained from 6. Compound 2 was also prepared by the photochemically induced conversion of 2-Chloro- and 2-bromopurine 2′-deoxyribofuranosides 9a and 10, respectively, in aqueous solution, The photo reaction was further used for the synthesis of the compounds 3 and 4 starting with the amino-chloro-2′-deoxynucleosides 9b and 9c, respectively.
61 citations
TL;DR: First-order rate constants for the acid-catalysed hydrolysis of ribo- and 2′-deoxyribonucleosides derived from 1H, 2H, and 3H-benzotriazoles and 7H, 8H- and 9H-8-azaadenines have been determined over a wide pH range.
Abstract: First-order rate constants for the acid-catalysed hydrolysis of ribo- and 2′-deoxyribonucleosides derived from 1H-, 2H- and 3H-benzotriazoles and 7H-, 8H- and 9H-8-azaadenines have been determined over a wide pH range. Partial rate constants for reactions via mono- and di-protonated substrates have been calculated with the aid of spectrophotometrically determined pKa values. The mechanisms of hydrolysis reactions have been elucidated by the effects that polar substituents on the base moiety exert on the protonation and heterolysis steps. Reactivities of various regioisomers have been compared, and reasons for the exceptional hydrolytic instability of N3-alkylated purine nucleosides briefly discussed.
10 citations
TL;DR: In this article, the photolysis of 2-aza-2′-deoxyadenosine (1) results in the formation of a single reaction product, which is assigned as 5-amino-4-cyano-1-imidazolyl 2deoxyribofuranoside (2).
7 citations
TL;DR: In this paper, the acid-catalyzed hydrolysis of regioisomeric 2′-deoxyribonucleosides of 8-azaadenine and various substituted benzotriazoles has been studied.
Abstract: Kinetics for the acid-catalyzed hydrolysis of regioisomeric 2′-deoxyribonucleosides of 8-azaadenine and various substituted benzotriazoles have been studied.
2 citations
TL;DR: In this article, the photolysis of 2-aza-2′-deoxyadenosine (1) results in the formation of a single reaction product, which is assigned as 5-amino-4-cyano-1-imidazolyl 2deoxyribofuranoside (2).
Abstract: The photolysis of 2-aza-2′-deoxyadenosine (1) results in the formation of a single reaction product. Its structure was assigned as 5-amino-4-cyano-1-imidazolyl 2-deoxyribofuranoside (2). The latter is also obtained independently from the glycosylation of the 5-amino-4-imidazolecarbonitrile (4) anion with the halogenose 5. The reaction is stereoselective but regioisomers are formed: the N-1 compound 6 in 21% and the N-3 regiosomer 7 in 45% yield. The structures of the regioisomeric imidazole nucleosides 2 and 3 have been assigned by 13C-NMR and 1H-NMR NOE difference spectroscopy.