Studies of Nucleosides and Nucleotides. XXX. Syntheses of 8-Substitute Guanosine Derivatives

Synthesis and reactions of 6-methylsulfonyl-9-.beta.-D-ribofuranosylpurine

“…Vinyl triflates were prepared from the appropriate ketones and triflic anhydride on a 10-50 mmol scale using pyridine as base and anhydrous CC14 as solvent by standard procedures.5 Triflates 3, 5, and 7 have been previously prepared7 as have 11 and 13.® Triflate 9 was prepared from commercial 3-methyl-2-pentanone: bp 54-55°( 13 mm); ir (thin film) 2967 (CH), 1692 (C=C), 1412 (S=0), and 1211 cm-1 (CF); nmr (CC14) 2.06 (q, 2 H, J = 7.0 Hz, -CH2-), 1.98 (br s, 3 H, a-CHs), 1.70 (br s, 3 H, d-CH3), 1.02 (t, 3 H, J = 7.0 Hz,CH3CH2).…”

Synthesis of 2-substituted derivatives of 5-amino-1-.beta.-D-ribofuranosylimidazole-4-carboxamide. Ring opening reactions of 2-azapurine nucleosides

“…7d-D-Ribofuranosylimidazo[4,5-d ]-u -triazine-4,6-dione (11). Compound 5a (174 mg, 0.5 mmol) was treated with 6 ml of 3% NaOH for 16 hr at 4°, then passed through a column (1 X 15 cm) of Amberlite IRC 50 ([H+], 100-200 mesh).…”

“…The latter compound was ring closed with nitrous acid to afford 6-bromo-7-(2,3,5-tri-0-acetyl-S-D-ribofuranosyl)imidazo[4,5-(j]-u-triazin-(3/i)4-one (5). The bromine of 5 was displaced by various nucleophiles to give 6-substituted imidazo [4,5-d]-u-triazine nucleosides such as 6-azido-7-(2,3,5-tri-0-acetyl-/3-D-ribofuranosyl)imidazo [4,5-(i]-v-triazine-(3//)4-one (6), 6-methoxy-7-/3-n-ribofuranosylimidazo [4,5-d]-u-triazin-(3/i)4-one (9), 7-d-D-ribofuranosylimidazo [4,5-d]-u-triazine-4,6-dione (11), and 6-thio-7-/3-D-ribofuranosylímidazo [4,5-d]-u-triazin-(3fí")4-one (12). Compound 6 in the presence of hydrogen and Pd/C was reduced to corresponding 6-amino-7-(2,3,5-tri-0-acetyl-j3-D-ribofuranosyl)imidazo [4,5-d]-utriazin-(3J7)4-one (7).…”

“…The replacement of the bromine atom at C-6 of 5a by two other nucleophiles further illustrates the versatility of this intermediate. When 6-bromo-7-(d-D-ribofuranosyl)imidazo [4,5-d ]-v-triazin-(3hi)4-one was treated with aqueous sodium hydroxide it gave the desired 7-(/?-D-ribofuranosyl)imidazo[4,5-d]-o-triazine-4,6-dione (11). In a similar experiment when sodium hydroxide was replaced by sodium hydrosulfide the corresponding 6-thio-7-(/3-D-ribofuranosyl)imidazo[4,5-d ]-v-triazin-4-one (12) was obtained.…”

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

“…Other reported examples of imidazole formation by ring opening include the interception of 1 -methyl4ureidoimidazole-5-carbonitrile during the a1 kaline hydrolysis of 2-chloro-7-methyladenine (208); isolation of 2-(methylsulfonyl)AIC ribonucleoside (or a derivative) after treatment of 8-(methylsulfonyl)guanosine with tert-butoxide ion in dimethyl sulfoxide (209); and the nonenzymatic formation of A1 ribonucleoside from adenosine, a ketopentose, cupric ions, and pyrophosphate (210).…”