3′-3′,3′-5′ and 5′-5′ TpT-Amides: Synthesis,Characterization and Alkaline Hydrolysis

Abstract

A simple procedure is described for the preparation of the title compounds 1, 8 and 9. 3′-3′ or 3′-5′ or 5′-5′ TpT was reacted with a twofold molar excess of TPS in anhydrous DMF, at room temperature, for 5 min, followed by a 1 min in situ treatment of the reaction mixture with excess 7.0 N NH₄OH, at 0°C. The alkaline hydrolysis of 1, 8 and 9 proceeds without the assistance of 3′- and 5′-hydroxyl groups resulting in equimolar mixtures of thymidine (4) and thymidine 3′-phosphoramidate (6) (for the 3′-3′ isomer) or thymidine 5′-phosphoramidate (7) (for the 5′-5′ isomer) or 6 and 7 in equal quantities (for the 3′-5′ isomer).     

Synthesis of Certain 5′-Substituted Derivatives of Ribavirin and Tiazofurin

Abstract

The synthesis of several 5′-substituted derivatives of ribavirin (1) and tiazofurin (3) are described. Direct acylation of 1 with the appropriate acyl chloride in pyridine-DMF gave the corresponding 5′-O-acyl derivatives (4a-h). Tosylation of the 2′, 3′-O-isopropylidene-ribavirin (6) and tiazofurin (11) with p-toluenesulfonyl chloride gave the respective 5′-O-p-tolylsulfonyl derivatives (7a and 12a), which were converted to 5′-azido-5′-deoxy derivatives (7b and 12b) by reacting with sodium/lithium azide. Deisopropylidenation of 7b and 12b, followed by catalytic hydrogenation afforded 1-(5-amino-5-deoxy-β-D)-ribofuranosyl)-1, 2, 4-triazole-3-carboxamide (10b) and 2 - (5 -amino- 5-deoxy- β-D-ribofuranosyl) thiazole-4-carboxamide (16), respectively. Treatment of 6 with phthalimide in the presence of triphenylphosphine and diethyl azodicarboxylate furnished the corresponding 5′-deoxy-5′-phthaloylamino derivative (9). Reaction of 9 with n-butylamine and subsequent deisopropylidenation provided yet another route to 10b. Selective 5′-thioacetylation of 6 and 11 with thiolacetic acid, followed by saponification and deisopropylidenation afforded 5′-deoxy-5′-thio derivatives of 1-β-D-ribofuranosyl-1, 2, 4-triazole-3-carboxamide (8a) and 2-β-D-ribofuranosylthiazole-4-carboxamide (15), respectively.     

Synthesis of Pyrazolo[3, 4-d]Pyrimidine Ribonucleoside 3′, 5′-Cyclic Phosphates Related to cAMP,cIMP and cGMP1

Abstract

The synthesis of pyrazolo[3,4-d]pyrimidine ribonucleoside 3′, 5′-cyclic phosphates related to cAMP, cIMP and cGMP has been achieved for the first time. Phosphorylation of 4-amino-6-methylthio-1-β-D-ribo-furanosylpyrazolo[3,4-d]pyrimidine (1) with POCl₃ in trimethyl phosphate gave the corresponding 5′-phosphate (2a). DCC mediated intramolecular cyclization of 2a gave the corresponding 3′, 5′-cyclic phosphate (3a), which on subsequent dethiation provided the cAMP analog 4-amino-1-β-D-ribofuranosylpyrazolo[3, 4-d]pyrimidine 3′, 5′-cyclic phosphate (3b). A similar phosphorylation of 6-methylthio-1-β-D-ribofuranosylpyrazolo[3, 4-d]pyrimidin-4(5H)-one (5), followed by cyclization with DCC gave the 3′, 5′-cyclic phosphate of 5 (9a). Dethiation of 9a with Raney nickel gave the cIMP analog 1-β-D-ribofuranosylpyrazolo[3, 4-d]pyrimidin-4(5H)-one 3′, 5′-cyclic phosphate (9b). Oxidation of 9a with m-chloroperoxy benzoic acid, followed by ammonolysis provided the cGMP analog 6-amino-1-β-D-ribofuranosylpyrazolo [3, 4-d] pyrimidin-4(5H)-one 3′, 5′-cyclic phosphate (7). The structural assignment of these cyclic nucleotides was made by UV and H NMR spectroscopic studies.     

Some Aspects of Ribonucleoside Chemistry

Abstract

New routes to the preparations of 2′-deoxy-3′-C-methyl uridine (2c) and 1-(5′-0-trityl-3′-deoxy-β-D-glycero-pentofuran-2-ulosyl)uracil (4) from 5′-0-trityl-2′-0-tosyl uridine (1) and 5′-0-trityl-3′-0-tosyl uridine (3) respectively are described.     

Conformation and Antiherpes Activity of 3′- and 5′-Azido and Amino Analogs of 5-Methoxymethyl-2′-Deoxyuridine

Abstract

The molecular conformations of 3′- and 5′-azido and amino derivatives of 5-methoxymethyl-2′-deoxyuridine, 1, were investigated by nmr. The glycosidic conformation of 5-methoxymethyl-5′-amino-2′,5′-dideoxy-uridine, 5 had a considerable population of the syn form. The 5′-derivatives show a preference for the S conformation of the furanose ring as in 1. In contrast, the 3′-derivatives show preference for the N conformation. For 5-methoxymethyl-3′-amino-2′,3′-dideoxyuridine, 3, the shift towards the N state is pH dependent. The preferred conformation for the exocyclic (C4′,C5′) side chain is g⁺ for all compounds except 5 which has a strong preference for the t rotamer (79%). Compounds 1, 3 and 5 inhibited growth of HSV-1 by 50% at 2, 18 and 70 μg/ml respectively, whereas 2 and 4 were not active up to 256 μg/ml (highest concentration tested). The compounds were not cytotoxic up to 3,000 μM.     

P1-(Thymidine 5′-)P1-amino-triphosphate: Synthesis,Hydrolysis and Reaction with Cytidine in Alkali1

Abstract

The title compound 1 is prepared from thymidine 5′-phos-phorodiamidate (2) and inorganic pyrophosphate (3) in anhydrous DMF, at 30–32°C. The products of alkaline hydrolysis of 1, at room temperature, are: thymidine 5′-phosphoramidate (4), thymidine 3′-phosphoramidate (8) and thymidine (9) as well as 3 and inorganic trimetaphosphate (10). In 1 N NH₄OH, 1 reacts with cytidine (15) to form cytidylyl-/2^T(3′)-5′/-thymidine (16) and a mixture of cytidine 2′,3′-cyclic phosphate (17) and 9.     

5′-O-[N-(Amnoacyl)Sulfamoyl]Nucleosides. Synthesis and Antiviral and Cytostatic Activities

Abstract

5′-O-[N-(Aminoacyl)sulfamoyl]-uridines and -thymidines 4a-12a and 4b-12b have been synthesized and tested against Herpes Simplex virus type 2 (HSV-2) and as cytostatics. Condensation of 2′,3′-O-isopropylidene-5′-O-sulfamoyluridine and 3′-O-acetyl-5′-O-sulfamoylthymidine with the N-hydroxysuccinimide esters of Boc-L-Ser(Bzl), (2R, 3S)-3-benzyloxycarbonylamino-2-hydroxy-4-phenylbuta-noic acid [(2R, 3S-N-Z-AHPBA], (2R, 3S) and (2S, 3R)-N-Boc-AHPBA gave 4a,b-7a,b, which after removal of the protecting groups provided 1Oa,b-12a,b. A study of the selective removal of the O-Bzl protecting group from the L-Ser derivatives 4a,b, without hydrogenation of the pyrimidine ring, has been carried out. Only the fully protected uridine derivatives 4a-7a did exhibit high anti-HSV-2 activity, and none of the synthesized compounds showed significant cytostatic activity against HeLa cells cultures.     

Photochemical Synthesis of Phosphonopyrimidine and Phosphonopurine Ribonucleosides

Abstract

Photochemical reaction of 2′,3′-di-O- or 2′,3′, 5′-tri-O-protected 5-bromouridine (1), 8-bromoadenosine (4) and 8-bromoguanosine (10) with triethyl phosphite in a mixture of dimethyl formamide (DMF) and acetonitrile, followed by deprotection, provided the corresponding diethyl phosphonate derivatives (3, 7 and 12).     

Nucleotide recognition seouence at the cleavage site of Haemophilus aegyptius II (Hae II) restriction endonuclease

We have determined the nucleotide sequence recognized by the restriction endonuclease Hae II from Haemophilus aegyptius which cleaves the simian virus 40 (SV40) DNA at a single specific site. By using terminal radioactive labeling of the cleavage site at both the 5′ and 3′-ends we have deduced the recognition sequence,

with elements of a two-fold rotational symmetry. The endonuclease produces staggered ends with protruding 3′-terminated single-strands, four nucleotides in length. In plasmid RSF 2124 DNA, which contains multiple Hae II cleavage sites, it was observed that the 5th nucleotide from the 3′ terminus is either a pdA or a pdG, indicating alternating recognition sequences.     

Partial Protection of Carbohydrate Derivatives. Part 24.1 Synthesis of Adenylyl-(2′–5′)-Adenylyl-(2′–5′)-Adenosine Using a 3′-O-(Tetrahydropyran-2-YL) Adenosine Derivative

Abstract

The synthesis of the title compound was performed using a 3′-O-(tetrahydropyran-2-yl) adenosine derivative as the starting material, i.e., a coupling reaction of triethylammonium N ⁶-benzoyl-5′-O-dimethoxytrityl-3′-O-(tetrahydropyran-2-yl) adenosine 2′-(4-chlorophenyl)phosphate with N ⁶-benzoyl-2′,3′-di-O-benzoyladenosine, followed by a sequence of reactions, O-dedimethoxytritylation, a coupling reaction with the former triethylammonium salt, and complete deblocking of the resultant 2′, 5′-triadenylic acid derivative.     

The Bis-Trityl Route to (S)-HPMPA

Abstract

(S)-HPMPA, (S)-9-(3-hydroxy-2-phosphonyl)methoxypropyl)-adenine 1, a broad spectrum adenine nucleotide antiviral, was prepared from (S)-DHPA 2. Protection of (S)-DHPA 2 as its′ N,O-di-trityl derivative 3 followed by regioselective 2′-O-alkylation with p-toluene-sulfonyloxymethyldiethylphosphonate yielded bis-trityl-protected diethyl-(S)-HPMPA 4. De-protection and ester cleavage gave (S)-HPMPA 1.     

Aldol Reaction of Nucleoside 5′-Carboxaldehydes with Acetone. Synthesis of 5′-C-Chain Extended Thymidine Derivatives

Abstract

Reaction of 3′-0-(t-butyldimethylsilyl)-2′-deoxythymidine-5′-carboxaldehyde and 2′,3′-dideoxythymidine-5′-carboxaldehyde with acetone afforded a 3:2 mixture of the two (5′R)- and (5′S)-5′-acetonylthymidine derivatives.     

2′,3′-Dideoxyadenosine Analogs of the Nucleoside Antibiotics Tubercidin,Toyocamycin and Sangivamycin

Abstract

Application of previously described methodologies, for the synthesis of 2′,3′-dideoxy-2′,3′-didehydro nucleosides from the parent ribonucleosides, to the antibiotics tubercidin (1), toyocamycin (6) and sangivamycin (10) has provided the corresponding 2′,3′-unsaturated nucleosides 4, 9, and 13. A reduction of the 2′,3′-unsaturated moiety has afforded the 2′,3′-dideoxynucleoside antibiotics 5, 14, and 15.     

Synthesis of 3′-Fluoro-3′-Deoxyribonucleosides; Anti-HIV-1 and Cytostatic Properties

Abstract

It has generally proven difficult to synthesize ribonucleosides with sugar modifications at the 3′ position. We now present a practical route for the synthesis of ribonucleosides with a 3′ fluorine substituent. Nucleosides with the xylo configuration were prepared by sugar-base condensation. Tritylation of the unprotected nucleosides gave a mixture of 2′,5′ and 3′,5′ bistritylated nucleosides which were difficult to characterize. Therefore the necessary precursors were synthesized in a step-wise fashion, starting with selective deprotection of the 2′-acyl group, followed by tritylation. This gave the 2′,5′-tritylated xylonucleosides in good yield. Reaction with diethylaminosulfur trifluoride and deprotection with 80 % acetic acid provided the 3′-fluoro-3′-deoxyribonucleosides 1, 2 and 4. The cytidine derivative was synthesized from 1 by reaction with trifluoromethanesulfonic anhydride followed by ammonia. Treatment of 4 with adenosine deaminase yielded 5.     

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.     

Improved Synthesis of Adenosine Cyclic 3′, 5′-Phosphoramidates via Anhydrides. Preparation of Adenosine Cylic 3′, 5′-(Rp) - and (p)-N-Methylphosphoramidate

Abstract

The two-step method for the preparation of adenosine cyclic 3′,5′-phosphoramidate diastereoisomers, which involves the activation of adenosine cyclic 3′,5′-monophosphate (1) with an acid chloride and in situ aminolysis of the anhydride intermediate (Bentrude, W.G.; Tomsaz, J. Synthesis 1984, 27; Bottka, S.; Tomasz, J. Tetrahedron Lett. 1985, 24, 2909), has been improved. The best yields were attained when 1 was reacted with 4.4 molar equivalents of phosphorus oxychloride in trimethyl phosphate at O°C for 3 h, and the solution of phosphorus oxychloride in trimethyl phosphate was pretreated with 0.5 molar equivalent of water at room temperature for 20 min. R _p and S _p diastereoisomers of adenosine cyclic 3′,5′-N-methyphosphoramidate and N,N-dimethylphosphoramidate have been synthesized under these experimental conditions.     

A Facile Synthesis of the Phosphoramidites of 2-N-Methyl-2′-deoxy (or 2′-O-allyl)-ψ-isocytidine, 1, 3-Dimethyl-2′-deoxy-ψ-uridine and N1-Methyl-2′-O-allyl-ψ-uridine as Synthons Suitable for Oligonucleotide Synthesis

Abstract

An efficient and facile syntheses of 5′-O-(4, 4′-dimethoxytrityl)-3′-[2-cyanoethyl bis(1-methylethyl)]phosphoramidites of 2-N-methyl-2′-deoxy-ψ-isocytidine (6), 2-N-methyl-2′-deoxy-α-ψ-isocytidine (13), 2-N-methyl-2′-O-allyl-ψ-isocytidine (11), 1, 3-dimethyl-2′-deoxy-ψ-uridine (4) and N1-methyl-2′-O-allyl-ψ-uridine (19) have been accomplished in good overall yields. The pyrimidine-pyrimidine transformation reaction was found to be useful for the preparation of 2-N-methyl-2′-O-allyl-ψ-isocytidine (10). The utility of these novel phosphoramidites is demonstrated by their incorporation into oligonucleotides via solid-support, oligonucleotide methodology.     

Studies on Nucleosides: Part XXVIII1. Synthesis of 4-Amino (or Hydroxy)-6-Methylthio-1-(3′-Deoxy-β- D-ribofuranosyl)-1-H-pyrazolo[3, 4-d]Pyrimidines

Abstract

4-Amino-6-methylthio-1-(3′-deoxy-β-D-ribofuranosyl)-1H-pyrazolo-[3, 4-d]pyrimidine (11) and 6-methylthio-4(5H)-oxo-1-(3′-deoxy-β-D-ribofuranosyl)-1H-pyrazolo[3, 4-d]pyrimidine (12) have been synthesized from 1, 2-di-O-acetyl-5-O-benzoyl-3-deoxyribofuranose (5) and 4, 6-bis (methylthio)-1H-pyrazolo-[3, 4-d]pyrimidine (6). in a convergent fashion. Structural proofs are based on MS, IR, ¹H NMR, ¹³C NMR and elemental analyses.     

Metabolism of Pyridine Coenzymes in Microorganisms

NADP and NADP analog were phosphorylated to NAD diphosphate and NADP analog phosphate, respectively, by an enzyme preparation of Proteus mirabilis (IFO 3849). The degradation products from NAD-diphosphate and NADP analog phosphate by the snake venom nucleotide pyrophosphatase were identical with nicotinamide riboside diphosphate and adenosine 2′(3′), 5′-diphosphate.