N→N Alkyl and Glycosyl Migration of Purines and Pyrimidines. III. N→N Alkyl and Glycosyl Migration of Purine Derivatives

Synthesis of novel xylofuranosyloxymethyl nucleosides

“…Compounds 10, 13, 16 were characterized as natural nucleoside by comparison of 1 H NMR, melting point and specific rotation with that reported in the literature. [16][17][18] Compound 9, 12, 15 (17) 20 Coupling of 4 with guanine derivative 24 using SnCl 4 in MeCN at room temperature resulted in the isolation of oxymethylguanine nucleosides, (27) were assigned by 1 H NMR. In case of the compound 29 derived from compound 25, the appearance of H-8 at  7.78 as a singlet ( 1 H NMR) and C-5 at  116.4 ( 13 C NMR) was characteristic of N 9 -regioisomer.…”

Solution structure, enzymatic, and non-enzymatic reactivity of 3-isoadenosylcobalamin, a structural isomer of coenzyme B12 with surprising coenzymic activity

“…Since 3-isoadenosine has been reported to be unstable in acid [37,59] and AdoCbl is known to be acid labile [60][61][62], the stability of 3-IsoAdoCbl in acid solution was studied in order to be able to carry out the acidbase chemistry studies described above. The kinetics ( Table 1) and products of the decomposition of 3-IsoAdoCbl (0.25 mM) at pHÕs between 2.0 and 6.5 (0.1 M acetate or phosphate buffers) and at 25 or 50°C were monitored by HPLC.…”

The ThermalN9/N7 Isomerization ofN2-Acylated 2′-Deoxyguanosine Derivatives in the Melt and in Solution

“…The mechanism of the glycosylation reaction has been discussed by Garner and Ramakanth [3] and also recently by Robins and co-workers [4]. The isomerization of glycosylated intermediates is described for purine N 3 -nucleosides [5]. Little attention has been paid to the fact that preformed purine N 7 -or N 9 -nucleosides can isomerize at elevated temperature.…”

“…Little attention has been paid to the fact that preformed purine N 7 -or N 9 -nucleosides can isomerize at elevated temperature. Miyaki and Shimizu have noted a reversible conversion of the N 2 -acetyl-N 7 -(2',3',5'-tri-O-benzoylribosyl)guanine to the corresponding N 9 -nucleoside [5]. Later, it was observed that N 9 -ribosylated 6-oxopurines or corresponding acyclo derivatives, which are fully acylated undergo thermal isomerization to N 7 /N 9 -mixtures [6 ± 8].…”