Adenine Adenosine, 2-deoxy

A nucleoside consists of a purine or pyrimidine base linked to a pentose, either D-ribose to form a ribonucleo-side or 2-deoxy-D-ribose to form a deoxyribonucleoside. Three major purine bases and their corresponding ribo-nucleosides are adenine/adenosine, guanine/guanosine and hypoxanthine/inosine. The three major pyrimidines and their corresponding ribonucleosides are cytosine/ cytodine, uracil/uradine and thymine/thymidine. A nucleotide such as ATP (Fig. 17-1) is a phosphate or polyphosphate ester of a nucleoside. 

The analogons deamination reaction is not observed in l-methyl-2 -deoxy-adenosine nncleosides. ° Rather, in the adenine series, the Dimroth rearrangement occnrs (Scheme 8.4). On the contrary, in styrene adducts of 2 -deoxyadenosine, the hydroxyl residue of the adduct undergoes intramolecular reaction with the base to initiate deamination (Scheme 8.6). ° ° Similarly, cytosine residues bearing styrene adducts at the N3-position undergo rapid deamination (nearly complete deamination is seen within 75h). °°... 

The reaction of adenosine with 2-acetoxy-2-methylpropanoyl chloride or the corresponding bromide is less regioselective than that of uridine,400 and gives 9-(2-0-acetyl-3-deoxy-3-halo-/3-D-xylofuranosyl)-and9-(3-0 - acetyl - 2 - deoxy - 2 - halo - /3 - D - arabinofuranosyl) - adenine,... 

Other sulfide photoreactions result when appropriate nucleoside derivatives are photolyzed. Upon irradiation in acetonitrile, 9-[5-deoxy-2,3-0-isopropylidene-5-(phenylthio)-/3-D-ribofuranosyl]-adenine (53) is converted into the anhydronucleoside 8,5 -anhydro-(5 -deoxy-2, 3 -0-isopropylidene-adenosine) (55) in 66% yield.111 Similar reactions were observed when other sulfur-containing nucleosides were irradiated (see Table XIII). The reaction of the sulfide 53... 

Adenine, 9-(a-D-ribofuranosyl)-, 115 Adenosine, 115 5-phosphate, 204 5-pyrophosphate, 204 5-triphosphoric acid, 204, 231 —, 2-deoxy-, 228, 229 5-triphosphste, 231 —, iV -hydroxy-, 5-phosphate, 232 Adenylyl peptides, 204 Aerobacter aerogenes, 314, 315 Agrobacterium tumefaciens, 327 Alanine, (3,4-dihydroxyphenyl)-, 269 —, phenyl-, 236, 237, 264, 265, 268 Alditols, acid dissociation constants of, 32,... 

The first synthesis of FddA (1) from 3 -deoxy adenosine derivative by Herdewijn et al. gave the fluorination product in only 10% overall yield after deprotection and purification [59]. Several years later, we also examined a similar reaction with the 5 -O-acetyl compound, but the yield was confirmed to be very poor [71]. We hypothesized that one possible reason for the low fluorination yield in the above reaction might be the nucleophilic participation of N-3 of the adenine ring, and that this might be overcome by using 6-chloropurine 3 -deoxyriboside as a starting material (see also Section 7.3.1.2.1). 

Many anti-viral compounds are analogues of the natural nucleic acid nucleosides such as adenosine 225. This example 226, known as (5, 5 )-iso-ddA (dda stands for di-deoxy-adenosine), has a severely modified sugar 227 but the purine, adenine 228, is unaltered. The purine is attached to C-2 instead of C-1 making the molecule more stable and two of the OH groups have been removed. Coupling adenine to the modified sugar 227 needs a Mitsunobu process.42... 

AdoHcy hydrolase is inactivated by a variety of other nucleosides, including the cyclopentenyl analog of adenosine, neplanocin A (Borchardt et al., 1984). Complete inactivation is observed with 0.5 equivalents of neplanocin A per active site, yielding 0.5 equivalents each of NADH and adenine (Wolfson et al., 1986). The mechanism of the reaction was proposed to parallel that suggested for 2 -dAdo, although the elimination of adenine would require a cis-elimination, in contrast to the trans-elimination possible with a 2 -deoxy-3 -ketonucleoside. Subsequent studies concurred that NADH was formed in the reaction but demonstrated that the inactivation is reversible by addition of NAD, suggesting that inactivation is simply due to reduction of the coenzyme (Matuszewska and Borchardt, 1987). 

Structures of the ribonucleoside that contains adenine, called adenosine (9-p-D-ribofuranosyl adenine left), and the deoxyribo-nucleoside that contains cytosine, called cytidine (l,2 -deoxy-p-o-ribofuranosyl cytosine right). 

Anhydro-adenosine has been isomerized to 2, 3-anhydro-jS-D-lyxo-furanosyl-adenine in 42% overall yield by the sequence outlined in Scheme 8. Deamination of l-(3-amino-3-deoxy-j3-D-xylofuranosyl)-uracil with nitrous acid did not yield any 2, 3 -anhydro-uridine or products derived from this anhydro-sugar derivative, uracil being the major product. ... 

Treatment of 5-deoxy-5-halogeno nucleosides of adenine and uracil with trimethylamine yielded the corresponding 5-deoxy-5-trimethylammonium salts, whose interaction with anionic polynucleotides was then examined. Various A -alkyl, A -cycloalkyl, and iV-alkaryl derivatives of 3-amino-3-deoxy-and 3, 5 -diamino-3, 5 -dideoxy-adenosine have been prepared from the amino-sugar nucleosides the 3 -benzylamino derivative gave the unusual oxazolidine derivative (52). ° ... 

---