1268. Purines, pyrimidines, and imidazoles. Part XXIII. The use of 5-phospho-β-D-ribosyl azide in a new direct synthesis of nucleotides

Novel carbohydrate modified berberine derivatives: synthesis andin vitroanti-diabetic investigation

“…This transformation generated an α, β mixture of 19 with only 29% total yield. As an alternative, we employed a new strategy based on Carrington's method, 34,35 which could directly afford the azido sugar 19α under mild conditions. Therefore, treatment of 17 with TMSN 3 under the promotion of SnCl 4 in CH 2 Cl 2 produced 19α with absolute α-selectivity and 88% isolated yield.…”

Syntheses and Biological Activity of 5-Aminoimidazoles and 5-Triazenoimidazoles

“…Methyl l -methyl-4nitroimidazole-karboxylate (XVIIIb) was the only reported product of methylation of the silver salt of VI (32,33); the nitro styryl derivative (IV), like VII, gave a mixture of N-methyl isomers (32), and alkylation of the sodium salts of IV and its 2-methyl derivative gave mixtures of isomers (15). Ikehara et al (47) isolated XVIIIa tribenzoate as the main product of glycosidation of the chloromercury derivative of VI with 2,3,5-tri-O-benzoylribofuranosyl chloride and, in contrast, 4-methyl-5-nitro-l-P-~-ribofuranosy~imidazole tribenzoate as the main product (44%) of glycosidation of 4-methyl-5-nitroimidazole (111). These results suggest either that the position of attack varies with the type of nitroimidazole substrate, the alkylating agent, and the conditions or that the methods of isolation or detection sometimes failed to reveal a second isomer.…”

“…(c) Using AI-COOH ribonucleotide and l-cyclohexyl AI-COOH (as a model compound), Franks et al(213) have further shown that the steps from GAR to C-AIR may be caused to proceed nonenzymatically in the reverse direction simply by varying the pH and by heating. (d) By these degradative methods and by synthetic procedures, the open-chain precursors (GAR, FGAR, and FGAM) and the analogous cyclohexyl derivatives have been formed by purely chemical means(110,111,213,258). (e) Nonenzymatic carboxylation o f AIR with bicar-bonate at 85" has been demonstrated (215).…”

Imidazole Nucleosides and Nucleotides

“…Since the manipulations required to convert a free riboside to a ribotide (5'-phosphate) are inherently difficult, it seemed of interest to prepare the ribotides directly. This required the precursor 2,3-O-isopropylidene-5-phospho-D-ribofuranosylamine (LXIX), which was prepared in situ (50,51) by hydrogenation of 2,3-0 -isopropylidene -5 -phosphodribofuranosyl azide (LXVIII). Reaction of LXIX, prepared in situ, with the appropriate imidate followed by removal of the isopropylidene group produced methyl 5-amino-l-(/3-D-ribof uranosyl) imidazoIe-4-carboxylate 5 '-phosphate (LXV).…”