SYNTHESIS OF NOVEL D- AND L-3′-DEOXY-3′-C-HYDROXYMETHYL NUCLEOSIDE WITH EXOCYCLIC METHYLENE AS POTENTIAL RIBONUCLEOTIDE REDUCTASE INHIBITOR

D- and L-3′-Deoxy-3′-C-hydroxymethyl thymidine substituted with exocyclic methylene at 2′-position were synthesized, starting from D- and L-xylose as potential ribonucleotide reductase inhibitor, respectively, but they were found to be inactive against several tumor cell lines.     

PHOSPHORAMIDATE DERIVATIVES OF 2′,5′-DIDEOXYADENOSINE AS POTENTIAL INHIBITORS OF THE EDHF PHENOMENON

P-site inhibitors of adenyl cyclase, such as the dideoxynucleosides 2′,3′-ddA and 2′,5′-ddA, have been shown to attenuate EDHF phenomenon in rabbit arteries and veins. In order to present the dideoxynucleosides as pre-activated nucleotides and bypass the kinase, as well as to prevent their metabolism to dideoxyinosine by adenosine deaminase, the aryloxyphosphoramidate approach has been successfully applied, initially on the 2′,3′-ddA. In the present work a new series of 2′,5′-ddA phosphoramidates has been synthesized, representing the first example of phosphoramidate protide not at the 5′-position.     

SYNTHESIS OF CERTAIN 2′-DEOXYURIDINE DERIVATIVES CONTAINING SUBSTITUTED PHENOXY GROUPS ATTACHED TO C-5′; EVALUATION AS POTENTIAL dUTP ANALOGUES

Derivatives of 2′-deoxyuridine in which the 5′-OH group is replaced by a 2,3,6-trifluoro-5-hydroxy-4-nitrophenoxy or a 4-carboxy-2,3,6-trifluoro-5-hydroxyphenoxy group have been prepared for evaluation as possible dUTP analogues. They showed a weak ability to displace radiolabelled dUTP from a dUTP-binding antiserum. The corresponding compounds lacking the three fluorine substituents were prepared for comparison.     

SYNTHESIS OF 5-METHYLAMINO-2′-DEOXYURIDINE DERIVATIVES

Reductive amination of 3′,5′-O-(tetraisopropyldisilyloxane-1,3-diyl)-2′-deoxy-5-formyluridine with several aliphatic and aromatic amines, in various solvents, is described. In the case of aliphatic amines, the expected C-5 substituted methylamino pyrimidine nucleosides are formed along with by-products deriving from opening of the pyrimidine ring. Relative amounts of the by-products depend upon the polarity of the solvent employed.     

LARGE-SCALE SYNTHESIS OF 5′-O-PIXYL PROTECTED 2′-DEOXYNUCLEOSIDES USEFUL FOR OLIGONUCLEOTIDE SYNTHESIS

Synthesis of 5′-O-pixylated 2′-deoxynucleosides 4 has been accomplished and the products are commercially available.     

SYNTHESIS OF NOVEL 3′-DEOXY-3′-C-HYDROXYMETHYL NUCLEOSIDES WITH CONFORMATIONALLY RIGID SUGAR MOIETY AS POTENTIAL ANTIVIRAL AGENTS

Based on the fact that the ring expanded 3′-C-hydroxymethyl analogue of oxetanocin A exhibited potent antiviral activity, two types of conformationally rigid 3′-C-hydroxymethyl derivatives in which 2′-hydroxyl group is linked to the 4′-position or to the 6′-position were synthesized starting from 1,2;5,6-di-O-isopropylidene-D-glucose, respectively.     

SYNTHESIS OF A 2′-AMINO-α-L-LNA-T PHOSPHORAMIDITE

A convergent route to 2′-amino-α-L-LNA-T phosphoramidite building block 16 has been developed. Key steps include 1) introduction of a C2-azido group prior to nucleobase-coupling, 2) tandem Staudinger and intramolecular nucleophilic substitution reaction, and 3) separation of α-L- and β-L-configured intermediates.     

SYNTHESIS OF A NEW 5′-O-TRIPHOSPHATE ANALOG OF 5-METHYL 2′-O-DEOXYCYTIDINE. PRELIMINARY IN VITRO LABELING FOR NON-RADIOACTIVE DETECTION OF DNA

We report the synthesis of the triphosphate of 5-methyl 4-N-[6-(p-bromobenzamido)hex-1-yl]-2′-O-deoxycytidine 3A . We also analyzed the formation of intramolecular H-bonds of 5-methyl 4-N-{n-[6-(p-bromobenzamido) caproyl amino]alk-1-yl}-2′-deoxycytidine compounds, and confirmed their presence by ¹H-NMR studies. In vitro DNA labeling with modified nucleotides is preliminarily evaluated.     

SYNTHESIS OF 2′-C-METHYL-4′-THIO RIBONUCLEOSIDES

Starting from 2-C-methyl-ribonolactone, 1,2,3,5-tetra-O-acetyl-2-C-methyl-4-thioribofuranose was synthesized and condensed with heterocyclic bases to afford 2′-C-methyl-4′-thioribonucleosides.     

SYNTHESIS AND EVALUATION OF ANTI-HSV ACTIVITY OF NEW 5-ALKYNYL-2′-DEOXYURIDINES

Eight 5-alkynyl-2′deoxyuridines containing different bulky substituents have been prepared and tested against HSV-1 in Vero cells. The compounds show positive antiviral activity. There is no obvious correlation between activity and substituent size. The nature of the linker between uracil and a substituent appears to be more important for antiviral properties: nucleosides containing arylethynyl groups show higher activity.     

SYNTHESIS OF 3′-THIOAMIDO-MODIFIED 3′-DEOXYTHYMIDINE-5′-TRIPHOSPHATES AND THEIR USE AS CHAIN TERMINATORS IN SANGER-DNA SEQUENCING

The thioamide derivatives 3′-deoxy-5′-O-(4,4′-dimethoxytrityl)-3′-[(2-methyl-1-thioxo-propyl)amino]thymidine 1 and 3′-deoxy-5′-O-(4,4′-dimethoxytrityl)-3′-{{6-{[(9H-(fluo-ren-9-ylmethoxy)carbonyl]-amino}-1-thioxohexyl}amino} thymidine 2 were synthesized by regioselective thionation of their corresponding amides 7 and 8 with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphet-ane-2,4-disulfide (Lawesson's reagent). The thioamides were converted into the corresponding 5′-triphosphates 3 and 4. Compound 3 was chosen for DNA sequencing experiments and 4 was further labelled with fluorescein.     

STRUCTURE-ACTIVITY RELATIONSHIP OF 5′-SUBSTITUTED FLUORO-NEPLANOCIN A ANALOGUES AS POTENT INHIBITORS OF S-ADENOSYLHOMOCYSTEINE HYDROLASE

Four 5′-substituted fluoro-neplanocin A analogues 1a–d were designed and synthesized, and the inhibitory activity against SAH was in the following order: NH₂ > SH > F, N₃, indicating a hydrogen bonding donor is essential for inhibitory activity.     

SYNTHESIS OF 2′,3′-DIDEOXY-2′,3′-DIDEHYDRO NUCLEOSIDES VIA A SERENDIPITOUS ROUTE

This paper describes a “green” synthesis of 2′,3′-unsaturated 2′,3′-dideoxynucl-eosides via an electrochemical reaction. Using this approach d4T, d4U, ddA and ddI can be synthesized in high yields.     

CHEMICAL STABILITY OF 2′-DEOXY-5-METHYLISOCYTIDINE DURING OLIGODEOXYNUCLEOTIDE SYNTHESIS AND DEPROTECTION

ABSTRACT

Previous studies have encountered difficulties with degradation of some isocytidine derivatives during solid-phase synthesis and deprotection of oligonucleotides. Here we investigate the degradation of a commonly used derivative, 2′-deoxy-5-methylisocytidine, during oligodeoxynucleotide synthesis and deprotection. A small, but detectable amount of hydrolytic deamination occurred at ca. 0.5% of 2′-deoxy-5-methyliso-cytidine residues using routine synthesis and deprotection conditions. Depyrimidination, or cleavage of the glycosylic bond, occurred to a far lesser extent during alkaline deprotection than previously suggested. In contrast to model studies of nucleoside monomers, significant depyrimidination was not observed, even at extended incubation times.     

SYNTHESIS AND PROPERTIES OF A NOVEL BRIDGED NUCLEIC ACID ANALOGUE, 5′-AMINO-3′,5′-BNA

An oligonucleotide P3′?N5′ phosphoramidate (5′-amino-DNA) attracts much attention because of its potential for application to DNA sequencing; however, its ability to hybridize with complementary strands is low. To overcome this drawback of the 5′-amino-DNA, we have designed and successfully synthesized a novel nucleic acid analogue having a P3′?N5′ phosphoramidate linkage and a constrained sugar moiety, 5′-amino-3′-C,5′-N-methylene bridged nucleic acid (5′-amino-3′,5′-BNA). The binding affinity of the 5′-amino-3′,5′-BNA towards complementary DNA and RNA strands was investigated by UV melting experiments. The melting temperature (Tm) of the duplex comprising the 5′-amino-3′,5′-BNA and its complementary strand was much higher than that of the duplex containing the corresponding 5′-amino-DNA.     

SYNTHESIS OF 6-FORMYLURIDINE 5′-MONOPHOSPHATE: 6-FORMYL-UMP

A synthesis of 6-formyluridine 5′-monophosphate (6-formylUMP) in 6 steps starting from uridine is described. This approach should be applicable to the preparation of other O5′-phosphorylated 6-formylUrds such as 6-formylUDP and 6-formylUTP.     

SYNTHESIS AND ENZYMATIC CHARACTERIZATION OF METHYLENE ANALOGS OF ADENOSINE 5′-TETRAPHOSPHATE (P4A)

A new methodology for synthesis of biologically important nucleoside tri- and tetraphosphates containing a bisphosphonate moiety instead of the terminal pyrophosphate bond is described. The series consists of tri- and tetraphosphate analogs of adenosine, guanosine and 7-methylguanosine (characteristic for mRNA cap). We have adopted a two-step procedure that allowed us to insert a methylene bridge into the phosphate chain. Nucleoside mono- or diphosphates were first activated (as imidazole derivatives) and then used in coupling reactions with organic salts of bisphosphonate. The resulting synthetic method enabled us to obtain the desired compounds with high yields and does not require any protective groups. This makes it very useful for the synthesis of labile compounds such as those containing the 7-methylguanosine ring. The structures of the synthesized compounds were confirmed by NMR spectroscopy. They were tested as potential substrates and inhibitors of several hydrolases.     

SYNTHESIS AND BIOLOGICAL ACTIVITY OF 4′-C-HYDROXYMETHYL-2′-FLUORO-D-ARABINOFURANOSYLPURINE NUCLEOSIDES

A series of 4′-C-hydroxymethyl-2′-fluoro-D-arabinofuranosylpurine nucleosides was prepared and evaluated for cytotoxicity in human tumor cell lines. A convenient synthesis of the carbohydrate precursor 4-C-hydroxymethyl-3,5-di-O-benzoyl-2-fluoro-α-D-arabinofuranosyl bromide (13) was developed. Coupling of 13 with the sodium salt of 2,6-dichloropurine led to five target purine nucleosides.     

SYNTHESIS OF 5-CHLORO-1-(2,3-DIDEOXY-3-FLUORO-β-D-GLYCERO-HEX-2-ENOPYRANOSE-4-ULOSYL)URACIL AS POTENTIAL ANTICANCER/ANTIVIRAL AGENT

Peracetylated α-D-glucose was coupled with silylated 5-chlorouracil. The product (2) was deacetylated and 4′,6′-hydroxyls were then protected with 4′,6′-O-isopropylidene group. Fluorine was introduced at the 3′-position, followed by acetylation, deprotection, tritylation, oxidation and deritylation of subsequent compounds gave the target compound (10).