Nucleosides and Nucleotides. 139. Stereoselective Synthesis of (2′S)-2′-C-Alkyl-2′-deoxyuridines

Abstract

A synthetic method for (2′S)-2′-C-alkyl-2′-deoxyuridines (9) has been described. Catalytic hydrogenation of 1-[2-C-alkynyl-2-O-methoxalyl-3,5-O-TIPDS-β-D-arabino-pentofuranosyl]uracils (5) gave 1-[2-C-(2-alkyl)-2-O-methoxalyl-3,5-O-TIPDS-β-D-arabino-pentofuranosyl]uracils (4) as a major product, which were then subjected to the radical deoxygenation, affording (2′S)-2′-alkyl-2′-deoxy-3′,5′-O-TIPDS-uridines (7) along with a small amount of their 2′R epimers.

     

Synthesis of 9-β-d-Glucopyranosyl-Adenine-6′-Phosphate

Synthesis of 9-β-d-glucopyranosyl-adenine-6′-phosphate is described. The method developed here involves the process of condensation of base (chloromercuri-6-benzamidopurine) (I) with phosphorylated sugar (2,3,4-tri-O-acetyl-6-diphenylphosphoryl-α-d-glucopyranosyl bromide) (II). This reaction gives crystalline 6-benzamido-9-(2′,3′,4′-tri-O-acetyl-6′-diphenylphosphoryl-β-d-glucopyranosyl)-purine (III) in high yield, which is converted to the desired nucleotide by alkaline hydrolysis.     

Nucleosides. 131. The Synthesis of 5-(2-Chloro-2-Deoxy-β-D-arabino-Furanosyl)Uracil. Reinterpretation of Reaction of ψ-Uridine With α-Acetoxyisobutyryl Chloride. Studies Directed Toward the Synthesis of 2′-Deoxy-2′-Substituted Arabino-Nucleosides. 2

Abstract

Treatment of ψ-uridine (3) with α-acetoxyisobutyryl chloride in acetonitrile gave, after deprotection, a mixture of four products: 5-(2-chloro-2-deoxy-β-D-arabinofuranosyl)uracil (10a), its 3′-chloro xylo isomer (11a), 2′-chloro-2′-deoxy-ψ-uridine (9a) and 4,2′-anhydro-ψ-uridine (8a). Each component was isolated by column chromatography. Compound 9 was converted to the known 1,3-dimethyl derivative 2 by treatment with DMF-dimethylacetal. Treatment of 10 and 11 with NaOMe/MeOH afforded the same 4,2′-anhydro-C-nucleoside 8. The 1,3-dimethyl analogues of 10 and 11, however, were converted to 2′,3′-anhydro-1,3-dimethyl-ψ-uridine (13) upon base treatment. The epoxide 13 was also prepared in good yield by treatment of 10 and 11 with DMF-dimethylacetal.     

Synthesis and Anti-HIV Activity of Novel 2′-Deoxy-2′-β-Fluoro-Threosyl Nucleoside Phosphonic Acid Analogues

Novel 2′-deoxy-2′-β-fluoro-threose purine phosphonic acid analogues were designed and racemically synthesized from 2-propanone-1,3-diacetate. Condensation successfully proceeded from a glycosyl donor 9 under Vorbrüggen conditions. Cross-metathesis of vinyl analogues 13 and 23 with diethyl vinylphosphonate yielded the desired nucleoside phosphonate analogues 14 and 24, respectively. Ammonolysis and hydrolysis of phosphonates yielded the nucleoside phosphonic acid analogues 16, 19, 26, and 29. The synthesized nucleoside analogues were subjected to antiviral screening against human immunodeficiency virus (HIV)-1. Adenine analogue 18 exhibited weak in vitro activities against human immunodeficiency virus (HIV)-1.     

Synthesis and Some Properties of Modified Oligonucleotides. II. Oligonucleotides Containing 2′-Deoxy-2′-fluoro-β-D-arabinofuranosyl Pyrimidine Nucleosides

Abstract

In order to find the effects of unnatural nucleosides on the stability of duplex, several oligonucleotides containing 1-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)-uracil(FAU),-cytosine (FAC) and -thymine (FMAU) were synthesized by two alternative approaches: phosphoramidite method on an ABI 392 synthesizer and H-phosphonate procedure on our GeneSyn I universal module synthesizer. It was shown from the melting profiles that the presence of FMAU has a large stabilizing effect on the duplex. Replacement of thymidine with FAU, or deoxycytidine with FAC resulted in the formation of less stable duplexes. Temperature-dependent CD spectroscopy demonstrated that the structures of the fluorine containing oligomers are very similar to those of unmodified oligomers.     

Synthesis and Properties of Phosphorylated 3′-O-β-D-Ribofuranosyl-2′-deoxythymidine

Abstract

A strategy was developed for the synthesis of 3′-O-β-D-ribofuranosyl 2′-deoxythymidine derivatives using three different protecting groups, which allows the synthesis of a phosphoramidite building block for oligonucleotide synthesis. Likewise the 5′-O- and 5″-O-phosphorylated analogues were synthesized and their conformation was determined using NMR spectroscopy.     

Microbial Synthesis of Purine 2′-Amino-2′-deoxyribosides

The microbial synthesis of some purine 2′-amino-2′-deoxyribonucleosides from purine bases and 2′-amino-2′-deoxyuridine is described. Various bacteria, especially Erwinia herbicola, Salmonella schottmuelleri, Enterobacter aerogenes and Escherichia coli, were able to transfer the aminoribosyl moiety of 2′-amino-2′-deoxyuridine to purine bases (transaminoribosylation) in the presence of inorganic phosphate. The optimum conditions for the reaction were pH 7.0 and 63°C. No reaction was observed in the absence of inorganic phosphate and the optimum concentration of it was around 30 mm. Adenine, guanine, 2-chlorohypoxanthine and hypoxanthine were transformed to the corresponding 2′-amino-2′-deoxyribonucleosides by the catalytic activity of the wet cell paste of Enterobacter aerogenes AJ 11125. The enzymatically synthesized purine 2′-amino-2′-deoxyribonucleosides were isolated and identified by physicochemical means. 2′-Amino-2′-deoxyadenosine strongly inhibited the growth of Hela cells in tissue culture, and the ED⁵⁰ was 2.5μ/ml.     

A Convenient and Stereoselective Synthesis of 2′-Deoxy-β-L-Ribonucleosides

Abstract

2′-Deoxy-β-L-ribonucleosides containing usual bases which are useful as synthons for modified oligodeoxyribonucleotides, were conveniently synthesized by a stereoselective glycosylation procedure. The method is suitable for large-scale preparations.     

Efficient Synthesis of 2′-Amino-2′-deoxypyrimidine 5′-Triphosphates

Abstract

The synthesis of 2′-amino-2′-deoxypyrimidine 5′-triphosphates is described. The 2′-amino-2′-deoxyuridine 5′-triphosphate is obtained from uridine in four steps with 25% overall yield. The 2′-amino-2′-deoxycytidine 5′-triphosphate is obtained from uridine in seven steps with 13% overall yield.     

Nucleosides and Nucleotides. 232. Synthesis of 2′-C-Methyl-4′-thiocytidine: Unexpected Anomerization of the 2′-Keto-4′-thionucleoside Precursor

The synthesis of 2′-C-methyl-4′-thiocytidine (16) is described. Since the 2′-keto-4′-thiocytidine derivative 2β unexpectedly isomerized to 2α and the methylation of 2β proceeded predominantly from the less hindered α-face to give 7, the desired product 16 was synthesized via the Pummerer reaction of the sulfoxide 14 and N ⁴ -benzoylcytosine.     

Nucleosides. Part 3.1 Synthesis of 2-N-Substituted 1-β-D-Arabinofuranosylisocytosine Derivatives by The Reaction of 2′,5′-Dichloro-2′,5′-Dideoxyuridine with Amines

Abstract

Reaction of 2′,5′-dichloro-2′,5′-dideoxyuridine (1) with ammonia and benzylamine afforded the corresponding 2-N-substituted 1-(5-chloro-5-deoxy-β-D-arabinofuranosyl)-isocytosine derivatives (2 and 10). Reaction of 1 with ammonia, methylamine, cyclohexylamine, and benzylamine followed by treatment with methanolic sodium methoxide gave the corresponding 2-N-substituted 1-(2,5-anhydro-β-D-arabino-furanosyl)isocytosine derivatives (6, 11, and 12).     

Synthesis of 1-β-L-Arabinofuranosylcytosine (β-L-Ara-C) and 2′-Deoxy-2′-methylene-β-L-cytidine (β-L-DMDC) as Potential Antineoplastic Agents

Abstract

1-β-L-Arabinofuranosylcytosine (β-L-Ara-C, 7) and 2′-deoxy-2′-methylene-β-L-cytidine (β-L-DMDC, 14) have been synthesized via a multi-step synthesis from L-arabinose. These compounds were tested in vitro against L1210, P388, Sarcoma 180, and CEM cells, and found not to be active at a concentration up to 100 μM. β-L-Ara-C and β-L-DMDC were also tested against HSV-1 and HSV-2 and yielded ID₅₀ values of 100 μM.     

Synthesis of 2-chloro-2′-deoxyadenosine by washed cells ofE. coli

Summary Washed cells ofE. coli ATCC 5275, a thymine auxotroph, catalysed formation of 2-chloro-2-deoxyadenosine when incubated with 2-chloroadenosine and a variety of deoxynucleosides. This transdeoxyribosylation reaction was complete after 4 h of shaking at 37°C. The equilibrium reaction mixture favoured product formation when purine rather than pyrimidine deoxyribonucleosides were used as cosubstrates, and when the ratio of deoxysugar donor to 2-chloroadenosine was high. Using deoxyadenosine as cosubstrate, chlorodeoxyadenosine was purified from larger scale reaction mixtures by treatment with Dowex-1 (OH-form) or by high performance liquid chromatography.     

Synthesis of 2′-Deoxyformycin B and 2′-Deoxyoxoformycin B

Abstract

3-β-D-Ribofuranosylpyazolo[4,3-d]pyrimidines (formycins)¹ modified in the heteroaromatic moiety are of biological interest as analogues of adenosine and guanosine, and have been the objects of intensive synthetic chemical effort by several groups.^2-9 2′-Deoxynucleosides^2c,2d,7b,13 and other analogties of the formycins modified in the sugar moiety^10-12 are also of potential interest, but have been less extensively studied. Examples of the 2′-deoxyribonucleoside type known to date include the 2′-deoxy-6-thioguanosine analogue 1, the 2′-deoxyadenosine (dAdo) analogue 2 (2′-deoxyformycin A),^10,13 and the 2-chloro-2′-deoxyadenosine analogue 3.^7b Compound 2 was found to be 10-15 times more potent than 2′-deoxyadenosine as an inhibitor of the growth of S49 cells, a murine lymphoma line of T-cell origin.¹³ Activity depended on 5′- phosphorylation, since mutants lacking the enzymes adenosine kinase (AK) and deoxycytidine kinase (dCK) were insensitive to the drug. Furthermore, activity was comparable in the presence and absence of an AK inhibitor, suggesting that 2, unlike dAdo, may be a poor substrate for adenosine deaminase. That 5′-phosphorylation of 2 was mediated by AK rather than dCK was indicated by the fact that miitants lacking only dCK retained sensitivity. This contrasted with the behavior of dAdo, which is known to be n substrate for both AK and dCK.¹⁴     

Facile Synthesis of Base-Labile 2′-Deoxyribonucleosides: An Improved Synthesis of 2′-Deoxy-5-aza-Cytidine

Abstract

The use of the Fmoc group for the protection of the hydroxy functions of the sugar moiety gave an improved overall yield of 2′-deoxy-5-azacytidine (6β), due to the mildly-basic conditions required for its removal from the protected nucleoside.     

Synthesis of 2′-Substituted Sulfide-Linked Dinucleotides

Abstract

3′-Deoxy-3′-(2-mesyloxyethyl)ribofuranosylthymine derivative 3, and its 2′-methoxy (16) and 2′-deoxy (38) analogs were condensed with 5′-deoxy-5′-thiothymidine 4 and 17 or 2′-O-methyl-5′-deoxy-5′-thiouridine 34 and 37 to provide, after standard functional group transformations, thymidine-thymidine and uridine-thymidine dimers 9, 21, 43 and 47. Oxidation of model sulfide dimer 48 with oxone gave sulfone 49. It was not stable to 27% ammonia.     

Synthesis of 2′,3′-Dideoxyribavirin

Abstract

A synthesis of 1-(2,3-dideoxy-β-D-ribofuranosyl)-1,2,4-triazole-3-carboxamide (2′,3′-dideoxyribavirin, ddR) is described. Glycosylation of the sodium salt of 1,2,4-triazole-3-carbonitrile (5) with 1-chloro-2-deoxy-3,5-di-0-p-toluoyl-α-D-erythro-pentofuranose (1) gave exclusively the corresponding N-1 glycosyl derivative with β-anomeric configuration (6), which on ammonolysis provided a convenient synthesis of 2′-deoxyribavirin (7). Similar glycosylation of the sodium salt of methyl 1,2,4-triazole-3-carboxylate (2) with 1 gave a mixture of corresponding N-1 and N-2 glycosyl derivatives (3) and (4), respectively. Ammonolysis of 3 furnished yet another route to 7. A four-step deoxygenation procedure using imidazolylthiocarbonylation of the 3′-hydroxy group of 5′-0-toluoyl derivative (9a) gave ddR (11). The structure of 11 was proven by single crystal X-ray studies. In a preliminary in vitro study ddR was found to be inactive against HIV retrovirus.     

Synthesis of 2′-O-Photocaged Ribonucleoside Phosphoramidites

The chemical synthesis and incorporation of the phosphoramidite derivatives of 2?′-O-photocaged ribonucleosides (A, C, G and U) with o-nitrobenzyl, α-methyl-o-nitrobenzyl or 4,5-dimethoxy-2-nitrobenzyl group into oligoribonucleotides are described. The efficiency of UV irradiated uncaging of these 2′-O-photocaged oligoribonucleotides was found in the order of α-methyl-o-nitrobenzyl < 4,5-dimethoxy-2-nitrobenzyl < 2′-O-o-nitrobenzyl.     

Conformationally Locked Nucleoside Analogs. Synthesis of 2′-Deoxy-2′-C, 4′-C-Bridged Bicyclic Nucleosides

Abstract

1-α-Methylarabinose was converted, in three steps, to 2-deoxy-2-methyleneribose derivative 3, which was subjected to hydroboration to give 2-α-hydroxymethyl derivative 4 exclusively. 4 was converted to 2,4-bis(hydroxymethyl)ribose derivative 6 in four steps. Mesylation, detritylation, and ring closure, followed by hydrolysis of the mesyl group at O5, gave 3,6-dioxabicyclo[3,2,1]octane derivative 8. After acetylation, 8 was coupled with silylated 6-chloropurine to give desired α- and β-bicyclic-sugar nucleosides.     

Modified Nucleosides. II.1 Economical Synthesis of 2′,3′-Dideoxycytidine

Abstract

An economical two pot synthesis of 2′,3′-dideoxycytidine (2) from N⁴-acetyl-cytidine (4) has been developed. The key feature of this sequence is the in situ reductive elimination of a mixture of 1-(3-bromo-3-deoxy-2,5-di-O-acetyl-β-D-xylofuranosyl)-N⁴-acetylcytosine (5) and 1-(2-bromo-3-deoxy-3,5-di-O-acetyl-β-D-arabinofuranosyl)-N⁴-acetylcytosine (6) and subsequent hydrogenation of the resultant olefin over palladised charcoal.