Adenosine 2,3-anhydro

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... 

Adenosine 3 -phosphate dihydrate180 Aristeromycin hydrobromide181 5, 8-Anhydro-2, 3 -0-isopropylidene-8-endo-mercaptoadenosine hydrate182... 

Ethyl l-oxo-6-piperidino-l//-pyrimido[l,2-a]quinoline-2-carboxylate showed potent in vitro anticoccidial activity (92AAC2338). anhydro-1,3-Diethyl-2-hydroxy-4-oxo-4//-pyrimido[2,l-a]isoquinolinium hydroxyde (318) exhibits nonselective Ar and A2-adenosine receptor activities (84JMC1364) and proved to be an inhibitor of cyclic-AMP phosphodiesterase (81JMC1284). 8,9,10,ll-Tetrahydro-3-(l//-5-tetrazolyl)-4//-pyrimido[2,l-a]iso-quinolin-4-one exhibits antiulcer activity (84USP4457932). 

Regarding the 1,3-oxazocines, it was reported that the isolation of 5, 8-anhydro-adenosine in an attempt of obtaining 8-fluoroadenosine <2007T3782>, a decaline-fused 1,3-oxazocine, which was unexpectedly obtained in the contest of an attempted synthesis of axinyssamine <2007T1544>, an efficient synthesis and X-ray crystal structure analysis of [ 1 ]bcnzopyrano[4,3-r/]l,3-benzoxazocin-13-onc and its derivatives and 5,6-dihydro-2,4-... 

It should be noted, however, that a stereospecific glycosylation of the sodium salt of adenine by 1,2-anhydro-5-0-trityl-L-ribofuranose to give 5 -0-L-adenosine in 90% yield had been previously published in 1969, ° but in this case a substituent at C2 of the sugar directs the stereochemistry of the incoming nucleophile. 

While OH radicals readily add to double bonds, they undergo electron transfer reactions with reluctance. This implies that, since there is evidence that heteroatom-centered radicals are formed from guanine and adenine derivatives (see also below), the precursor of the intermediates must under these conditions be an OH-adduct radical rather than the radical cation. Rapid transformation has been observed with adenosine and guanosine. Part of this is attributed to solvent-catalyzed water elimination such as in reaction (73) [5]. In the case of acid catalysis, the intermediate is a radical cation (see below). It can be seen that OH-adducts with OH attached in several different positions lead to a single anhydro radical. 

Anhydro-2, 3 -O-isopropylideneadenosine iodide Adenosine 3, 5 -phosphate, P,0-ethyl ester, monohydrate N -[(Carboxymethyl)aminocarbonyl]adenosine (Glycylglycinato)copper(II)cytidine, dihydrate... 

O-Isopropylideneadenosine 2-(Ethylthio)-8-methylinosine, monohydrate 8-( 1 -Hydroxyisopropyl)adenosine, dihydrate 8,5 -Anhydro-(7-bromo-8-hydroxy-2, 3 -O-isopropylidenetu-bercidin)... 

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. ... 

Methylcytidine (correction to previous paper), platinum complex of cytidine 3 -phosphate, l- 3-D-arabinofuranosylcytosine 5 -phosphate (2 independent analyses), 2,2 -anhydro-l-/3-D-arabinofuranosyl-5-dimethylsulphonio-6-oxocytosine chloride, 2,2 -anhydro-l-(3, 5 -di-0-acetyl-j3-D-arabinofuranosyl)-5-chloro - 6 - oxocy tosine, 2,l -anhy dro -1 - - D -arabinofuranosylcy tosine 2 5 -diphosphate, and 6,2 -anhydro-1 - 3-D-arabinofuranosyl-6-hydroxycytosine. Adenosine 5 -triphosphate disodium salt, adenosine 5 -methylphosphate, adenosine 5-methylphosphonate, 8-methyladenosine 3-phosphate, 2-aza-adenosine, 9-ce-D-arabinofuranosyladenine, 8,2 -anhydro-9- 3-D-arabino-... 

Improved syntheses have been described for cordycepin (3 -deoxy-adenosine), using 2, 3 -anhydro-adenosine in a high-yield, one-step procedure, the 3 -deoxy compound was obtained directly using lithium triethylborohydride alternatively, an N, 0 -bis-monomethoxy-trityl derivative was used with LAH, with subsequent deprotection. Both groups also prepared the 3-deuterio analogue (17). 

Tubercidin (7-deaza-adenosine) (535) has been converted, via treatment of its 2, 3 -0-methoxyethylidene derivative with pivaloyl chloride in refluxing pyridine, into A -epi-, 3 -deoxy-, and 2, 3 -dideoxy-tubercidin. 2, 3 -Anhydrotubercidin was also prepared and converted into its 2, 3 -anhydro-jS-D-lyxofuranosyl analogue. These epoxides were then used to prepare D-xylo and D-arabino analogues [(536) and (537), respectively] of tubercidin. 7-Methyltubercidin (538) and its a-anomer have been prepared from the products obtained on condensation of 2,3,5-tri-O-benzyl-D-ribofuranosyl bromide and an appropriately protected 7-methylpyrrolo[2,3-d] pyrimidine. ... 

C1iH1SCIN3O5S, 2,2 -Anhydro-1-/3-D-arabinofuranosyl-5-dimethylsul-phonio-6-oxocytosine chloride, 45B, 497 CiiHisN20bS, 2-Thio-5-carboxymethyluridine monohydrate, 44B, 424 Cl iHi sNijObS, 6-Methylmercaptopurine-riboside monohydrate, 42B, 346 CiiHigNsOgP 0.5 HjO, Adenosine 5 -methylphosphonate hemihydrate, 45B, 498... 

Further syntheses of oxetanocin have been described. A branched-chain tetroside whose synthesis is covered in Chapter 14 was converted in standard steps to oxetanocin (17) together with its o(-anomer. Another sequence started from adenosine, and proceeded via a 3 -deoxy analogue to the diazoketone (18), which underwent the necessary ring contraction to give (19) on photolysis.An oxetanocin analogue derived from 3,5-anhydro-D-xylofuranose is mentioned in Chapters 20 and 22. 

A number of 2 -deoxv-B-D-threo-pentofuranosvl nucleosides (15, R=H) have been prepared from alcohols (15, R=OH) by Barton deoxygenation the alcohols were prepared by selective hydrazlnolysis of 2 -Q-acetyl systems.42 3 -Deoxv-B-D-threo-pentofuranosvl nucleosides can be prepared efficiently from 2, 3 -anhydro-P-D-lyxofuranosyl analogues by reductive opening of the epoxide with lithium triethylaluminium hydride.An improved preparation of 5 -deo7 adenosine uses a standard coupling procedure, as opposed to manipulation of adenosine itself. ... 

A number of 2,5 -anhydro- derivatives of AZT and similar compounds with other substituents at C-5 have been prepared by base-catafysed tycllzation of 5 -0-tosylates. 2 When the 5 -0-tosyl derivative of 2, 3 -0-isopropylidene adenosine was treated with Me2CuU. the product was unexpectedly the... 

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