Cytidine 2,3-0-isopropylidene

The structures of these cytidine nucleotides were confirmed by synthesis. Condensation of 1,2-0-isopropylidene-L-glyceritol 3-phosphate with cytidine 5-phosphate in the presence of dicyclohexylcarbodiimide, followed by careful acid hydrolysis of the isopropylidene group, yielded cytidine glyceritol pyrophosphate identical with the natural product. 

Reist and coworkers [9,10] described the first sulfur-containing furanose rings. They prepared 4-thio-D-ribofuranose 14 (Figure 9.4) and 4-thio-L-ribofuranose via nucleophihc displacement of the tosylate in 2,3-(9-isopropylidene-4-(9-toluenesulfonyl-a-D- and -a-L-lyxopyranosides, respectively, with potassium thiobenzoate in DMF. Several nucleosides of 4-thiofuranoses were subsequently synthesized. For example, the 4 -thio analog 15 of natural thymidine and the corresponding derivative of cytidine were prepared by Whistler and coworkers [11]. 

As pyrimidine nucleosides are rather stable under acidic conditions, they may be phosphorylated with a mixture of 85% phosphoric acid and phosphorus pentaoxide ( polyphosphoric acid )- The 2, 3 -0-isopropylidene acetals of uridine and of cytidine were treated with polyphosphoric acid for two hours at 60°. After acid hydrolysis, the 5 -phosphates of these nucleosides were obtained in good yield. 2, 3 -0-Benzylidenecytidine was phosphorylated similarly to cytidine 5 -phosphate. The polyphosphoric acid method was also used to convert the 2, 3 -0-isopropylidene acetals of 5-bromouridine, 3-methyluridine, and A -methyl- and A -dimethyl-cytidine into their respective nucleoside 5 -phosphates. 

Nudeosides, Nudeotides, and their Derivatives.—Uridine, uridine 5 -(niethyl oxyacetate), 6-chloro-9-j8-D-ribofuranosylpurine, 6-methyl-9-j8-D-ribofurano-sylpurine, 5-acetyl-l-(3,5-0-isopropylidene-j8-D-xylofuranosyl)uracil, 2 -de-oxycytidine, the 1 1-complex of cytidine and iV-benzyloxycarbonylglutamic acid, l-(3-0-methyl-j8-D-arabinofuranosyl)cytosine, 2 -deoxyadenosine 5 -(sodium phosphate), 9-j8-D-arabinofuranosyladenine hydrochloride, 8-j8-D-ribofuranosyladenine, 8 - (2 - deoxy - oc - d - erythro - pentofuranosyl) - 6 -hydroxy-purine, l-methyl-4-jS-D-erythrofuranosyl-4-imida2oline-2-thione, and 4,6-di-0-acetyl-l,3 -anhydro-2,3-dideoxy-3-[3-hydroxy-5-methyl-(2if)-l,2,6-thiadiazin-2-yl l,l-dioxide]-a-D-n 6o-hexopyranose (455). ... 

Nucleoades and their Analogues and Derivatives Thereof. - 5-Acetyi-l-(3,5-0-isopropylidene-a-D-xylofuranosyl)uracil monohydrate has the furanose ring in a C2 -endo, C3 -endo conformation and a glycosidic torsion angle of —31°. X-ray structures of adenosine, cytidine, uridine and thymidine were interpreted in terms of C-H-- 0 interactions, while guanosine lacks these interactions. Another structural analysis of cytidine was reported and studies of crystal... 

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