Ribofuranose 1.2.3.5- tetra-0-acetyl-4-deoxy

Hydroxypyrazine 1-oxide with trimethylsilyl chloride and bistrimethylsilyl-atnine heated at 90-95° for 1 hour and the 3-(trimethylsilyl)oxypyrazine 1-oxide in 1,2-dichloro ethane treated with l,23,5-tetra-0-acetyl-(3-D-ribofuranose and titanium tetrachloride at reflux for 4 hours followed by deacetylation produced 3-oxo4-(/J-D-ribofuranosyl)-3,4-dihydropyrazine 1-oxide (1035). Treatment of 3-(trimethylsilyl)oxypyrazine 1-oxide with 2-deoxy-3,5-di-0-(p-chlorobenzoyl)-a-D-eo rtro-pentofuranosyl chloride in benzene in the presence of 4A molecular sieves gave an anomeric mixture (a/0 = 1.2 1.0) of 4-[2 -deoxy-3, 5 -di-0-(p-chlorobenzoyl)-a(and 0)-D-e/y rhro-pentofuranosyl]-3-oxo-3,4-dihydropyrazine 1 -... 

N -(2 -deoxy-ribonucleoside) and the 7-deazaguanine C8-(-2 -deoxyribonucleo-side), compounds (47) and (48), respectively. Compound (47) was obtained from the glycosylation of 8-aza-7-deaza-6-methoxypurine with an appropriately protected a-halogenose while (48) was prepared from the reaction of 7-deazaguanine with l-0-acetyl-2,3,5-tribenzoyl-P-D-ribofuranose in the presence of tin tetra-chloride. ... 

Glycosylation of 7-nitro-IbP 277 with 1,2,3,5-tetra-O-acetyl-jS-D-ribofuranose (TAR) and SnCU gave a mixture of N-3 and N-4 jS-isomers 278 and 279 in 87% overall yield. The sodium salt of the same 7-nitro-IbP 277 at 25 °C with l-chloro-2-deoxy-3,5-di(p-toluyl)-D-erythro-pentafuranose in MeCN was converted into a single N-3 jS-isomer 280 in a good yield (95TL1601). 

Acetylated and Benzoylated Derivatives of Sugars.—1,2,3,5-Tetra-O-acetyl-jS-D-ribofuranose, 3-0-acetyl-jS-L-arabinofuranose 1,2,5-orthobenzoate, (Z)-l-O-acetyl-2,3 4,5-di-0-isopropylidene-D-e/ y/Aw- and -D-/Areo-pent-l-enitol, 2,3,4-tri-O-benzoyl-jS-D-xylopyranosyl chloride, 2,3,4-tri-0-acetyl-j9-D-xyIopyranosyI azide, 1,3,4-tri-0-acetyl-2-deoxy-2-fluoro-a-D-xylopyranose, 1,2,3,4-tetra-O-acetyl-a-D-Iyxopyranose, 2,3,4,6-tetra-0-acetyl-a -D-glucopyranosyl bromide, 3,4,6-tri-0-acetyl-l,2-0-(l-cyanoethyIidene)-a-D-glucopyranose, 3,4,6-tri-O-acetyl-)S-D-mannopyranose l,2-(methyi orthoacetate), 2,3-di-0-acetyI-l,6-anhydro-jS-D-galactopyranose, 2,3,4,6-tetra-0-acetyl-j8-D-galactopyranosyl cyanide, 1,2,3,4,6-penta-O-acetyl-a-D-idopyranose, 1,4,5-tri-0-acetyl-2,3-0-isopropyIidene-)S-D-fructopyranose, and 2,3,4-tri-O-acetyl-a-L-rhamnopyrano-syl and 2,3,4,6-tetra-O-acetyl-a-D-mannopyranosyl chlorides. ... 

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