Arabinofuranosyl bromide

Numerous syntheses have also been reported for arabinofuranosyl nucleoside analogues, prepared either conventionally from arabinofuranosyl derivatives or via 2,2-anhydro-nucleosides obtained from appropriate ribonucleosides. 5-Aza-cytosine-D-arabinoside has been synthesized and found to show similar antiviral activity to Ara-C(arabinosyl-cytosine). 7-a-, 7-<3-, 9-0 -, and 9- 3-arabino-furanosyl derivatives of 3-deazaguanine have also been prepared, but none showed any anti-tumour activity. 9-(o -D-Arabinofuranosyl)-8-aza[2- C]-adenine, 7-(/3-D-arabinofuranosyl)-pyrrolo[2,3-d]pyrimidine-4(3//)-one (15)," l-(a-D-arabinofuranosyl)- and l-(/3-D-xylofuranosyl)-4-nitropyrazole, and Ot-arabino-nucleosides of 5-fluoro-cytosine and -uracil derivatives have also been prepared. An improved synthesis of 9-(/3-D-arabinofuranosyl)-2-fluoro-adenine has been reported. The ratio of o to 3 anomers obtained by phase-transfer reaction of 2,3,5-tri-O-benzyl-D-arabinofuranosyl bromide with 6-chloro-2-thiomethyl-7-deazapurine varied with the quaternary ammonium salt used as a catalyst, although the jU-anomer predominated in every case. 2,2-Anhydro-nucleosides have been used to prepare l-j3-D-arabinofiiranosyl derivatives of 5-alkylthio-uracils, 5-ethyl-cytosine, and 5-ethyl-uracil, 8-alkylamino-purines, and 2-aralkylamino-l,4-dihydro-4-imino-pyrimidine hydrochlorides (16). ... 

CB tribenzyl-D-arabinofuranoside 59 was efficiently prepared from methyl tribenzyl-D-arabinofuranoside 57 as shown in Scheme 3. Treatment of 57 with acetyl bromide in trifluoroacetic acid and subsequent coupling of the resulting crude arabinofuranosyl bromide with benzyl 2-(hydroxymeAyl)benzoate (1) followed by selective hydrogenoiysis of the resulting BCB arabinofuranoside 58 (a/p=4 l) afforded the desired CB arabinoside 59. CB 3,5-di-(9-benzoyl-2-0-benzylarabinofuranoside 60 was also prepared in like fashion. 

Dibenzoyl, 2-Ac 2-0-Acetyl-3,5-di-0-henzoyl-oi-L-arabinofuranosyl bromide C2iHi9Br07 463.281... 

Anhydrotalopyranosyl fluoride p-D-/orm, A-704 Arabinofuranosyl bromide a-D-form Tris-4-nitrobenzoyl, A-793 Arabinofuranosyl bromide, A-793... 

In addition to the approach outlined in Scheme 4, several other approaches to the synthesis of glycofuranosides have been reported during the past year. Hanessian and Banoub have used cyclic amide acetals derived from vicinal diols as the source of the aglycone in condensations with l-0-acetyl-2,3,5-tri-0-benzoyl-jS-D-ribofuranose in the presence of stannic chloride (Scheme 5). Disaccharide derivatives are obtained when the cyclic amide acetal is derived from carbohydrate vicinal diols (Scheme 6), and selective methanolysis of the formate ester exposed an hydroxy-group that can be subjected to further manipulation or glycosylation. 2,3,5-Tri-0-benzoyl-a)8-L-arabinofuranosyl bromide or chloride has been condensed with 4-nitrophenyl 2,3-di-O-acetyl-a-L-arabinofuranoside to yield, after deacylation, 4-nitrophenyl 5-O-a-L-arabinofuranosyl-a-L-arabino-furanoside, with jS-peltatin A [isolated from podophyllin Podophyllum peltatum)] in glycosidation of the phenolic 8-OH group in an attempt to reduce... 

The guanine and hypoxanthine analogues of F-ara-A, F-ara-G (lb) and F-ara-H (Ic), were synthesized by us as well as by others, by condensation of 3-0-acetyl-5-0-benzoyl-2-deoxy-2-fluoro-D-arabinofuranosyl bromide with N -benzoyladenine, 6-chloropurine, 2,6-dichloropurine, or 2-acetamido-6-chloropurine, followed by appropriate functional group replacement and deprotection. It was found that the guanine nucleoside lb is selectively toxic to T-cells while the hypoxanthine congener Ic is a potent inhibitor of the growth of Leishmania tropica promastigotes . 

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