Facile synthesis of N-(1-alkenyl) derivatives of 2,4-pyrimidinediones

N-(1-alkenyl) derivatives of 2,4-pyrimidinediones (6-9) were prepared in a one pot synthesis from aldehydes and the nucleobases using trimethylsilyl trifluoromethanesulfonate (TfOTMS) as coupling reagent. Presilylation of the above nucleobases, and N6-benzoyladenine, with excess N,O-bis(trimethylsilyl)acetamide (BSA) followed by addition of one mol eq. TfOTMS yielded the N-(1-trimethylsilyloxyalkyl) derivatives 1-5.     

N6-Alkylthiomethyl and N6-Arylthiomethyl Derivatives of Adenosine and Their Cytokinin Activity

Five new derivatives of adenosine, N⁶-[(1-methylethyl)thiomethyl]-(1), N⁶-methyithiomethyl-(2), N⁶-phenylthiomethyl-(3), N⁶-[(3-amino-3-carboxypropyl)thiomethyl]-(4), and N⁶-[(2-amino-2-carboxyethyl)thiomethyl]adenosine (5), were synthesized and their cytokinin activity was tested in the Amaranthus betacyanin assay and the soybean callus growth.

1, 2, and 3 were active in the former assay and all five compounds were active in the latter assay. The activities of the compounds were, however, weaker than those of the reference derivatives, in which Sulfides were replaced by methylenes, N⁶-isopentyl-, N⁶-n-propyl-, N⁶-benzyl-, and N⁶-(5-amino-5-carboxypentyl)adenosine. This fact indicates that the sulfide structure introduced into the N⁶-side chains had the effect of reducing cytokinin activity.     

An Efficient Method for the Synthesis of [4–15N]Cytidine, 2′-Deoxy[4–15N]Cytidine, [6–15N]adenosine,and 2′-Deoxy [6–15N]adenosine Derivatives

Abstract

Nucleophilic substitution reactions of 4-azolyl-1 β-P-D-ribofuranosylpyrimidin-2(1H)-one and 6-azolyl-9-β-D-ribofuranosyl-9H-purine derivatives, which were converted from uridine and inosine, with [¹⁵N]phthalimide in the presence of triethylamine or DBU gave N ⁴-phthaloyl[4-¹⁵N]cytidine and N ⁶-phthaloyl[6-¹⁵N]- adenosine derivatives, respectively, in high yields. Similar reactions of those azolyl derivatives with succinimide afforded N ⁴-succinylcytidine and N ⁶-succinyladenosine derivatives in high yields. The corresponding 2′-deoxyribonucleosides were also synthesized efficiently through the same procedure.

     

Synthesis and Antitumor Activity of N-Sulfonyl Derivatives of Nucleobases and Sulfonamido Nucleoside Derivatives

Abstract

The introduction of sulfonamido group on the C-2 position of pyrimidine nucleosides was achieved by ring opening of 2,2′- and 2,3′-anhydronucleosides. N-sulfonyl derivatives of nucleobases and sulfonamido derivatives of nucleosides were assayed for in vitro antitumor activity.     

The Chemical Synthesis of E. coli tRNALys Anticodon Loop Fragment and Its Analogues

Abstract

E. coli tRNA^Lys anticodon loop fragment (Umnm⁵sUUUt⁶A) 1 and its analogues 2–6 were synthesized by the classical phosphotriester approach in solution. The preparation of suitably protected derivatives of N⁶-threonylcarbamoyladenosine 18 is also described.     

Synthesis of novel sulfonamides under mild conditions with effective inhibitory activity against the carbonic anhydrase isoforms I and II

Novel sulfonamide derivatives 6a–i, as new carbonic anhydrase inhibitors which candidate for glaucoma treatment, were synthesized from the reactions of 4-amino-N-(4-sulfamoylphenyl) benzamide 4 and sulfonyl chloride derivatives 5a–i with high yield (71–90%). The structures of these compounds were confirmed by using spectral analysis (FT-IR, ¹H NMR, ¹³C NMR, LC/MS and HRMS). The inhibition effects of 6a–i on the hydratase and esterase activities of human carbonic anhydrase isoenzymes, hCA I and II, which were purified from human erythrocytes with Sepharose®4B-l-tyrosine-p-aminobenzene sulfonamide affinity chromatography, were studied as in vitro, and IC₅₀ and K_i values were determined. The results show that newly synthesized compounds have quite powerful inhibitory properties.     

Synthesis of 3′-Deoxy-3′-[4-(pyrimidin-1-yl)methyl-1,2,3-triazol-1-yl]thymidine via 1,3-Dipolar Cycloaddition

Abstract

The synthesis of new 3′-deoxy-3′-[4-(pyrimidin-1-yl)methyl-1,2,3-triazol-1-yl]thymidine 6a–f, from 3′-azido-3′-deoxy-5′-O-monomethoxytrityl-thymidine is described. The key step is the 1,3-dipolar cycloaddition between the azido group of the protected AZT 3 and N-1-propargylpyrimidine derivatives 2a–f. All new derivatives 6a–f were evaluated for their inhibitory effects against the replication of HIV-1 (IIIB), HIV-2 (ROD). No marked activity was found.     

13C CP/MAS NMR Spectral Analysis of 6-O-Tosyl, 6-Deoxy-6-iodo,and 6-Deoxy Derivatives of N-Acetylchitosan in a Solid State

6-O-Tosyl (1, d.s. 0.94, 80% yield), 6-deoxy-6-iodo (2, d.s. 0.49, 86% yield) and 6-deoxy (3, d.s. 0.49, 50% yield) derivatives of N-acetylchitosan were prepared, and a ¹³C CP/MAS NMR spectral analysis was performed because no suitable solvent for 3 was found. The ¹³C signal for CH₃ at C-6 in 3 was detected at 18.9 ppm, and that for C-4 in 1–3 appeared at 72.2–72.7 ppm, which is in a higher magnetic field than those (82.5–86.0 ppm) in N-acetylchitosan, 6-O- (ethylthio), 6-O-(benzylthio)- and 6-O-(methylthio)-thiocarbonyl derivatives, chitosan, and chitin. This strongly suggests a different molecular conformation for 1–3.     

Synthesis and in vitro antimicrobial activity of novel N-(6-chlorobenzo[d]thiazol-2-yl) hydrazine carboxamide derivatives of benzothiazole class

In this study, a series of novel 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole (6a–g) and 1,3,4-oxadiazole (7a–g, 8) were synthesized from N-(6-chlorobenzo[d]thiazol-2-yl) hydrazine carboxamide derivatives of benzothiazole class. Antimicrobial properties of the title compound derivatives were investigated against one Gram (+) bacteria (Staphylococcus aureus), three Gram (?) bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and five fungi (Candida albicans, Aspergillus niger, Aspergillus flavus, Monascus purpureus and Penicillium citrinum) using serial plate dilution method. The investigation of antibacterial and antifungal screening data revealed that all the tested compounds showed moderate to good inhibition at 12.5–100?µg/mL in DMSO. It has been observed that triazolo-thiadiazole derivatives are found to be more active than 1,3,4-oxadiazole derivatives against all pathogenic bacterial and fungal strains.     

Nucleosides. IX. Synthesis of Purine N 3,5′‐Cyclonucleosides and N 3,5′‐Cyclo‐2′,3′‐seconucleosides via Mitsunobu Reaction as TIBO‐like Derivatives

The Mitsunobu reaction was applied to prepare, in one step, purine N ³,5′‐cyclonucleosides 10a–d. A subsequent ring opening in the ribose moiety of the resultant N ³,5′‐nucleosides by sodium periodate led to the corresponding N ³,5′‐cyclo‐2′,3′‐seconucleosides. These products consist of 5‐, 6‐, and 7‐membered tricyclic system which is the basic skeleton of TIBO derivatives, known antiviral agents.     

Synthesis of 1-Deazaadenosine Analogues of (2′→5′) ApApA

Abstract

Synthesis of (2′ → 5′)ApApA analogues containing 1-deazaadenosine at different positions is described (32–34). The approach used the phosphotrieer methodology in solution and utilized 3′-O-benzoylated derivatives of the N⁶-protected 5′-O-monomethoxytrityl-1-deazaadenosine as starting material.

     

Synthesis of N6-Substituted 9-[3-(Phosphonomethoxy)Propyl]Adenine Derivatives As Possible Antiviral Agents

A number of N ⁶ -substituted 9-[3-(phosphonomethoxy)propyl]adenine derivatives having hydroxymethyl at C-1′-position were prepared from the appropriate 6-chloroadenine derivative. The syntheses of the corresponding prodrugs of these compounds are also reported. These compounds showed poor activity against HCV in replicon assay.     

Nucleosides Having Quinolone Derivatives as Nitrogenated Base: Regiospecific and Stereospecific Ribosylation of 3-Carbethoxy-1,4-dihydro-4-oxoquinolines

Abstract

Ribosylation reactions of previously silylated 3-carbethoxy-8-methyl-1,4-dihydro-4-oxoquinoline (6a) and 3-carbethoxy-6-methyl-1,4-dihydro-4-oxoquinoline (6b) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (7), under Lewis acid catalysis, were studied. The method using hexamethyldisilazane (HMDS)/trimethylchlorosilane (TMCS) mixture for silylation and anhydrous stannic chloride as catalyst for ribosylation failed to give any nucleoside product. On the other hand, the protected nucleoside 3-carbethoxy-6-methyl-1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-1,4-dihydro-4-oxoquinoline (8b) was obtained in good yields using bis(trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% of TMCS and the same catalyst. Compound 8b was more easily isolated in higher yields with an improvement of the later method by replacing stannic chloride with trimethylsilyl trifluoromethanesulfonate (TMSOTf).

De-O-benzoylation of 8b with methanolic sodium hydroxide solution afforded the free riboside 3-carbomethoxy-6-methyl-1-β-D-ribofuranosyl-1,4-dihydro-4-oxoquinoline (9b). The structures of the obtained products were confirmed by their LTV, MS, IR, ¹H and ¹³C-NMR data.     

The Synthesis of New Polymer Derivatives of ATP by Radical Copolymerization and Their Coenzymic Activity

Three polymerizable ATP derivatives, N⁶-[N-(6-methacrylamidohexyl)carbamoylmethyl]-, N⁶-[N -[2-[N -(2-methacrylamidoethyl)carbamoyl]ethyl]carbamoylmethyl]-, and N⁶ -[N -[N -(2-hydroxy- 3-methacrylamidopropyl)carbamoylmethyl]carbamoylmethyl]-ATP, were synthesized and radically copolymerized with comonomers [acrylamide, N -(2-hydroxyethyl)-, N -ethyl-, N, N - diethylacrylamide, acrylic acid, and 6-methacrylamidohexylammonium chloride] to obtain 18 new polymer derivatives of ATP. The molecular weight distributions were controlled by appropriate initiator concentrations. The monomeric and polymeric ATP derivatives were all coenzymically active against both hexokinase and glycerol kinase. The observed coenzymic activities (Km and V_max) are discussed in connection with the structures of the derivatives.     

An Efficient Method for the Synthesis of β-d-Ribonucleosides Catalyzed by Metal Iodides

Abstract

Several β-d-ribonucleosides were synthesized in high yields under mild conditions by N-glycosylations of methyl 2,3,5-tri-O-benzoyl-β-d-ribofuranosyl carbonate (1) with trimethylsilylated nucleoside bases in acetonitrile using a catalytic amount of metal iodide such as SnI₂, SbI₃ or TeI₄. A deprotection of N⁶ -benzoyl group of coupling product took place to a considerable extent when N⁶ -benzoyl-N⁶ , N⁹ -bis(trimethylsilyl)adenine was employed as a nucleoside base using SnI₂ or SnCI₂ as a catalyst while it was minimized when SbI₃ or TeI₄ was used. Further, the N-glycosylation of 1 with 7-trimethylsilyltheophylline in the presence of a catalytic amount of metal iodide was more effectively achieved in nitrile solvents other than acetonitrile.

     

Synthesis and anticandidal evaluation of new benzothiazole derivatives with hydrazone moiety

In this study, we have performed the synthesis of new N′-(arylidene)-4-[(benzothiazol-2-yl)thio]butanoylhydrazide derivatives (3a–s) bearing azole moiety and hydrazone group in a lipophilic structural framework. The target compounds were prepared by a three step synthetic procedure starting from 2-mercaptobenzothiazole. The structures of the target compounds were elucidated by IR, ¹H NMR, ¹³C NMR spectra and elemental analysis. The antifungal activity of the obtained compounds has been determined against a number of clinic and fluconazole-resistant Candida strains by using microdilution method. Compounds (3a–3s) exhibited anticandidal activity in different ratios varying between the range of MIC: 50 and 200?µg/mL.     

EFFICIENT METHODS FOR THE SYNTHESIS OF [2-15N]GUANOSINE AND 2′-DEOXY[2-15N]GUANOSINE DERIVATIVES

The nucleophilic addition–elimination reaction of 2′,3′,5′-tri-O-acetyl-2-fluoro-O ⁶-[2-(4-nitrophenyl)ethyl]inosine (8) with [¹⁵N]benzylamine in the presence of triethylamine afforded the N ²-benzyl[2-¹⁵N]guanosine derivative (13) in a high yield, which was further converted into the N ²-benzoyl[2-¹⁵N] guanosine derivative by treatment with ruthenium trichloride and tetrabutyl-ammonium periodate. A similar sequence of reactions of 2′,3′,5′-tri-O-acetyl-2-fluoro-O ⁶-[2-(methylthio)ethyl]inosine (9) and the 6-chloro-2-fluoro-9-(β-D-ribofuranosyl)-9H-purine derivative (11), which were respectively prepared from guanosine, with potassium [¹⁵N]phthalimide afforded the N ²-phthaloyl [2-¹⁵N]guanosine derivative (15; 62%) and 9-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)-6-chloro-2-[¹⁵N]phthalimido-9H-purine (17; 64%), respectively. Compounds 15 and 17 were then efficiently converted into 2′,3′,5′-tri-O-acetyl[2-¹⁵N]guanosine. The corresponding 2′-deoxy derivatives (16 and 18) were also synthesized through similar procedures.     

An Improved Synthesis of N6-(6-Aminohexyl)FAD

Abstract

We report an improved synthesis of N ⁶-(6-aminohexyl)FAD (1) using an efficient one-pot conversion of inosine to the N-trifluoroacetyl protected N ⁶-(6-aminohexyl)adenosine 3. The 5′-O-phosphorylated AMP derivative 4, activated as the imidazolide, was coupled with commercial sodium riboflavin phosphate by using 18-crown-6 in DMF.     

A Functional Screening of Adenosine Analogues at the Adenosine A2B Receptor: A Search for Potent Agonists

Abstract

Various adenosine analogues were tested at the adenosine A_2B receptor. Agonist potencies were determined by measuring the cyclic AMP production in Chinese Hamster Ovary cells expressing human A_2B receptors. 5′-.N-Substituted carboxamidoadenosines were most potent. 5′-N-Ethylcarboxamidoadenosine (NECA) was most active with an ECso value of 3.1 μM. Other ribose modified derivatives displayed low to negligible activity. Potency was reduced by substitution on the exocyclic amino function (N⁶) of the purine ring system. The most active N⁶-substituted derivative N⁶-methyl-NECA was 5 fold less potent than NECA. C8-and most C2-substituted analogues were virtually inactive. 1-Deaza-analogues had a reduced potency, 3-and 7-deazaanalogues were not active.     

Design,synthesis and pharmacological evaluation of novel azole derivatives of aryl acetic acid as anti-inflammatory and analgesic agents

A series of substituted azole derivatives (3a–e, 4a–e and 5a–e) were synthesised by the cyclisation of N¹(diphenylethanoyl)-N⁴-substituted phenyl thiosemicarbazides under various reaction conditions. These compounds were tested in vivo for their anti-inflammatory activity. The compounds which showed activity comparable to the standard drug ibuprofen, were screened for their analgesic, ulcerogenic and lipid peroxidation activities. The compounds 5-(diphenylmethyl)-N-(4-fluorophenyl)-1,3,4-oxadiazol-2-amine (3b) and 5-(diphenylmethyl)-N-(3-chloro-4-fluorophenyl)-1,3,4-oxadiazol-2-amine (3c) emerged as the most active compounds of the series, and were moderately more potent than the standard drug, ibuprofen. (This abstract was published in Inflammation Research, Supplement 2, Volume 56, page A101, 2008.)