Synthesis and antiviral activity of 1,5- and 1,3-dialkyl-1,2,4-triazole C-nucleosides derived from 1-(chloroalkyl)-1-aza-2-azoniaallene salts.

Reactions of alpha,alpha'-dichloroazo compounds 2 with SbCl5 gave 1-(chloroalkyl)-1-aza-2-azoniaallene salts 3 as reactive intermediates. Cycloadditions of 3 with the ribofuranosyl cyanide 4 afforded the beta-D-ribofuranosyl-1,2,4-triazolium salts 5, which rearranged spontaneously to salts 6. Hydrolysis of 6 gave the 1,2,4-triazole C-nucleosides 7, which yielded the free nucleosides 8 after deblocking. Analogously, 12 was prepared from the cycloaddition of 4 with the alpha-chloroazo compound 10 in the presence of SbCl5. Deblocking of 12 with sodium methoxide afforded 13. Compounds 8a,b,e,f and 13 were tested against HIV-1, HIV-2, HSV-1 and HSV-2 and were found to be inactive.     

Microwave-Assisted Synthesis and Anti-HIV Activity of New Acyclic C-Nucleosides of 3-(D-Ribo-Tetritol-1-yl)-5-Mercapto-1,2,4-Triazoles. Part 1

Microwave-assisted synthesis of novel acyclic C-nucleosides of 6-alkyl/aryl-3-(1,2-O-isopropylidene-D-ribo-tetritol-1-yl)[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (5–12) and the 6-aryl-thiomethyl analogues 25–27 has been described. Deblocking of 5–12 and 25–27 afforded the free acyclic C-nucleosides 13–20, and 28–30, respectively. All of the synthesized compounds showed no inhibition against HIV-1 and HIV-2 replication in MT-4 cells. However, 6-(3,4-dichlorophenyl)-3-(1,2-O-isopropylidene-D-ribo-tetritol-1-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole (6) is a potent inhibitor, in vitro, of the replication of HIV-2. These results suggest that compound 6 should be considered as a new lead in the development of antiviral agent.     

Syntheses of 1-[(2-Hydroxyethoxy)methyl]- and 1-[(1,3-Dihydroxy-2-Propoxy)methyl]- Derivatives of 5-Substituted-2,4-difluorobenzene: Unnatural Acyclo Thymidine Mimics for Evaluation as Anticancer and Antiviral Agents

Abstract

A group of 1-[(2-hydroxyethoxy)methyl]- (12) and 1-[(1,3-dihydroxy-2-propoxy)methyl]- (13) derivatives of 2,4-difluorobenzene possessing a variety of C-5 substituents (R = Me, H, I, NO₂) were designed with the expectation that they may serve as acyclic 5-substituted-2′-deoxyuridine (thymidine) mimics. Compounds 12 and 13 (R = Me, H, I) were inactive as anticancer agents (C₅₀ = 10^?3 to 10^?4 M range), whereas the 5-nitro compounds (12d, 13d) exhibited weak-to-moderate cytotoxicity (CC₅₀ = 10^?5 to 10^?6 M range) against a variety of cancer cell lines. All compounds prepared (12a-d, 13a-d) were inactive as antiviral agents in a broad-spectrum antiviral screen that also included the human immunodeficiency virus (HIV-1 and HIV-2) and herpes simplex virus (HSV-1 and HSV-2).     

Novel Regioselective Formation of S- and N-Hydroxyl-Alkyls of 5-(3-Chlorobenzo[b]Thien-2-yl)-3-Mercapto-4H-1,2,4-Triazole and A Facile Synthesis of Triazolo-Thiazoles and Thiazolo-Triazoles. Role of Catalyst and Microwave

Regioselective alkylation of 5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole (1) with hydroxy alkylating agents 2, 3, 13, and the 2,3-O-isopropylidene-1-O-(p-tolylsulfonyl)-glycerol (10) afforded the corresponding S-alkylated derivatives 6, 7, 11, and 14 under both conventional and microwave irradiation conditions; bentonite as a solid support gave better results, with no change in regioselectivity. A facile intramolecular dehydrative ring closure of 6, 7, 11, and 14 using K₂CO₃ in DMF afforded the corresponding fused triazolo-thiazines and thiazolo-triazole 17–19. The isopropylidenes and acetyl derivatives of the products were prepared.     

New Sulphonamide and Carboxamide Derivatives of Acyclic C-Nucleosides of Triazolo-Thiadiazole and the Thiadiazine Analogues. Synthesis,Anti-HIV,and Antitumor Activities. Part 2

A new series of acyclic C-nucleosides 1′,2′-O-isopropylidene-D-ribo-tetritol-1-yl)[1,2,4] triazolo[3,4-b][1,3,4]thiadiazoles bearing arylsulfonamide (5–8) and arylcarboxamide (9–12) residues have been synthesized under microwave irradiation. Thiadiazines 13–15 have been analogously prepared, and upon acid hydrolysis, afforded the free nucleosides 16–18. The new synthesized compounds were assayed against HIV-1 and HIV-2 in MT-4 cells. Compound 7 was also screened against a panel of tumor cell lines consisting of CD4 human T-cells.     

SYNTHESIS AND BIOLOGICAL EVALUATION OF SOME 4-SUBSTITUTED 1-[1-(4-HYDROXYBUTYL)-1,2,3-TRIAZOL-(4 & 5)-YLMETHYL]-1H-PYRAZOLO-[3,4-d]PYRIMIDINES

The synthesis of 1-[1-(4-hydroxybutyl)-1,2,3-triazol-(4 and 5)-ylmethyl] -1H-pyrazolo[3,4-d]pyrimidines 11a,b, 12a,b and 13–17 as carboacyclic nucleosides is described. The compounds 8a,b were condensed, separately, with compound 7 via 1,3-dipolar cycloaddition reaction to afford, after separation and deprotection, 1,4-regioisomers 11a,b and 1,5-regioisomers 12a,b. The deprotected carboacyclic nucleosides 11a served as precursor for the preparation of 4-amino 13, 4-methylamino 14, 4-benzylamino 15, 4-methoxy 16 and 4-hydroxy 17 analogues. All deprotected carboacyclic nucleosides were evaluated for their inhibitory effects against the replication of HIV-1(III_B), HIV-2(ROD), various DNA viruses, a variety of tumor-cell lines and tuberculosis. No marked biological activity was found.     

SYNTHESIS AND BIOLOGICAL ACTIVITY OF 4-SUBSTITUTED 1-[1-(2-HYDROXYETHOXY)- METHYL-1,2,3-TRIAZOL-(4 & 5)-YLMETHYL]-1H-PYRAZOLO[3,4-d]PYRIMIDINES

The chemical synthesis of some 4-substituted 1-[1-(2-hydroxyethoxy)methyl-1,2,3-triazol-(4 and 5)-ylmethyl]-1H-pyrazolo[3,4-d]pyrimidines 12a,b, 13a,b and 14–23 as acyclic nucleosides is described. Treatment of (2-acetoxyethoxy)methylbromide with sodium azide afforded (2-acetoxyethoxy)methylazide 9. The heterocycles 6a,b were alkylated, separately, with propargyl bromide to obtain, regioselectively, 4-(methyl and benzyl)thio-1-(prop-2-ynyl)-1H-pyrazolo[3,4-d]pyrimidines 7a,b. These N₁-alkylated products were condensed with compound 9 via a 1,3-dipolar cycloaddition reaction to obtain, after separation and deprotection, 1,4 and 1,5-regioisomers 12a,b and 13a,b. The deprotected acyclic nucleosides 12a and 13a served as precursors for the preparation of 4-amino (14 and 15), 4-methylamino (16 and 17), 4-benzylamino (18 and 19), 4-methoxy (20 and 21) and 4-hydroxy (22 and 23) analogues. Compounds 7a,b and all deprotected acyclic nucleosides were evaluated for their inhibitory effects against the replication of HIV-1(III_B) and HIV-2(ROD) in MT-4 cells and for their anti-tumor activity. No marked activity was found. However, initial evaluation of 6a,b, 7a,b, 12a,b, 13a,b and 14–23 showed that compound 7b has marked activity against M. tuberculosis.     

Synthesis and glycosidation of 1-deoxy-1-[(2,2-diacylvinyl)amino]-d-fructoses

The reactions of 1-amino-1-deoxy-d-fructose acetate (1) with methyl 3-methoxy-2-methoxycarbonylacrylate and 5-methoxymethylene-2,2-dimethyl-1,3-dioxane-4,6-dione in the presence of a base afforded 1-deoxy-1-[(2,2-dimethoxycarbonylvinyl)amino]- (2 and 1-deoxy-1-[(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidenemethyl)amino]-d-fructose (3), respectively, in high yields. 1-Deoxy-1-[(4,4-dimethyl-2,6-dioxocyclohexylidenemethyl)amino]-d-fructose (4) was obtained (85%) by a transamination reaction between 1 and 5,5-dimethyl-2-phenylaminomethylene-1,3-cyclohexanedione in the presence of Et₃N. The isomeric composition of equilibrium solutions of 1–4 was established by ¹³C-n.m.r. spectroscopy. For all the compounds, the β-pyranose form was the main component in D₂O; the α-furanose, the β-furanose, and, for 1, the α-pyranose forms, were also present. The major constituents of 2 in (CD₃)₂SO solution were the β- and the α-furanose forms. Acetylation of 2 afforded the tetra-acetates of the α- and β-furanose forms, the 3,4,6-triacetates of the α- and β-furanose forms, the 3,4,5-triacetate of the β-pyranose form, and 2,3,4,5,6-penta-O-acetyl-1-deoxy-1-[(2,2-dimethoxycarbonylvinyl)amino]-d-arabino-hex-1-enitol. Glycosidation of 2 with MeOHHCl afforded a mixture of methyl 1-deoxy-1-[(2,2-dimethoxycarbonylvinyl)amino]-α- (11α) and -β-d-fructofuranoside (11β), and methyl 1-deoxy-1-[(2,2-dimethoxycarbonylvinyl)-amino]-β-d-fructopyranoside (13). Compounds 11α and 13 were isolated as their tri-acetates (12 and 14, respectively). Deacetylation and removal of the N-protecting group of 12 gave methyl 1-amino-1-deoxy-α-d-fructofuranoside (∼54% from 2).     

Synthesis and Antiviral Activities of Enantiomeric 1-[2-(Hydroxymethyl) Cyclopropyl] Methyl Nucleosides

Abstract

Cyclopropyl carbocyclic nucleosides have been synthesized from the key intermediate 2 which was converted to the mesylated cyclopropyl methyl alcohol 3. Condensation of compound 3 with various purine and pyrimidine bases gave the desired nucleosides. All synthesized nucleosides were evaluated for antiviral activity and cellular toxicity. Among them adenine 22 and guanine 23 derivatives showed moderate antiviral activity against HIV-1 and HBV. None of the other compounds showed any significant antiviral activities against HIV-1, HBV, HSV-1 and HSV-2 in vitro up to 100μM.     

Quinolone Nucleosides: 6,7-Dihalo-N-β- and α-Glycosyl-l 4-dihydro-4-oxo-quinoline-3-carboxylic Acids and Derivatives. Synthesis,Antimicrobial and Antiviral Activity

Abstract

Reaction of the silylated 6,7-dihaloquinoline bases 10–12 with l-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (13) gave ethyl 7-chloro-6-flouro-l,4-dihydro-4-oxo-1 -(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)quinoline-3-carboxylate (14) and the free acids 15 and 16, respectively, which led on deblocking of the sugar moiety to the free nucleosides 17, 18 and 20, respectively. Treatment of 14 with methanolic ammonia afforded the amide derivative 19. Ribosylation of 11 with l,2-di-O-acetyl-3-azido-3-deoxy-5-p-toluoyl-β-D-ribofuranose (21) afforded the azido nucleoside 22, which was again converted into the free nucleoside 23. Analogously, reaction of 11 with the chloro deoxyribose derivative 24 led to a mixture of α /β (2:1) anomers of 25. Deblocking and recrystallization of the product gave mainly the α-anomer 26. Compounds 17–19, 23 and 26 were evaluated against Escherichia coli and found inactive. Compound 16–18 and 22 were inactive aganist HIV-1 (III B) and HIV-2 (ROD) induced cytopathicity in human MT-4 lymphocyte cells.     

Microwave-assisted synthesis and anti-HIV activity of new acyclic C-nucleosides of 3-(D-ribo-tetritol-1-yl)-5-mercapto-1,2,4-triazoles. Part 1

Microwave-assisted synthesis of novel acyclic C-nucleosides of 6-alkyl/aryl-3-(1,2-O-isopropylidene-D-ribo-tetritol-1-yl)[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles (5-12) and the 6-aryl-thiomethyl analogues 25-27 has been described. Deblocking of 5-12 and 25-27 afforded the free acyclic C-nucleosides 13-20, and 28-30, respectively. All of the synthesized compounds showed no inhibition against HIV-1 and HIV-2 replication in MT-4 cells. However, 6-(3,4-dichlorophenyl)-3-(1,2-O-isopropylidene-D-ribo-tetritol-1-yl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole (6) is a potent inhibitor, in vitro, of the replication of HIV-2. These results suggest that compound 6 should be considered as a new lead in the development of antiviral agent.     

Synthesis of Some Novel Acyclolumazine N-1 Nucleosides

Abstract

Reactjon of (2-acetoxyethoxy)methyl bromide with the silylated lumazine bases (1-6) in the presence of n-Bu₄NI leads to the formation of the nucleosides 8, 10, 12, 14, 16 and 18 respectively. Deacetylation with methanolic ammonia afforded the free nucleosides 9, 11, 13, 15, 17 and 19, respectively, in good yields. Structural proofs of the newly synthesized compounds are based on elemental analyses, UV and ¹H-NMR spactra. None of the acyclic nucleosides exhibited antiviral activity against HSV-1 in vitro.     

Halide abstraction reactions of Sb(V) chloride: Synthesis and characterisation of hexachloroantimonate salts of M(II) M = Zn,Mg; M(III) M = Cr; and M(IV) M = Ti,Sn and related Cp2M(IV) M = Ti,Zr and Hf

Reactions of SbCl₅ with various covalent metal halides in MeCN have been studied as a convenient and direct route to metal hexachloroantimonate salts via Sb(V) halide abstraction. The isolation and characterization (Ir, Vis-UV, ¹H NMR spectroscopic and microanalytical) of the complexes [Zn(MeCN)₆][SbCl₆]₂, [CrCl₂(MeCN)₄][SbCl₆], [SnCl₃(MeCN)₃][SbCl₆], [TiCl₂(MeCN)₄][SbCl₆]₂, [Cp₂M(Cl)(MeCN)_x][SbCl₆] M = ti, x = 1; M = Zr, Hf, x = 2, and [Cp₂M(MeCN)_y][SbCl₆]₂ M = Ti, y = 2; M = Zr, Hf, y = 3, is described. The reaction of MgCl₂ with SbCl₅ was carried out in EtOAC as solvent and gave [Mg(EtOAc)₆][SbCl₆]₂. ¹²¹Sb NMR, IR and UV spectroscopic measurements provide positive identification of the SbCl_6⁻ anion.     

Synthesis and Biological Evaluation of 1,3-Oxathiolane 5-Azapyrimidine, 6-Azapyrimidine,and Fluorosubstituted 3-Deazapyrimidine Nucleosides

Abstract

(2R,5S)-5-Amino-2-[2-(hydroxymethyl)-1,3-oxathiolan-5-y1]-1,2,4-triazine-3(2H)-one (8) and (2R,5R)-5-amino-2-[2-(hydroxymethyl)-1,3-oxathiolan-5-y1]-1,2,4-triazine-3(2H)-one (9) have been synthesized via a multi-step procedure from 6-azauridine. (2R,5S)-4-Amino-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-y1]-1,3,5-triazine-2(1H)-one (11) and (2R,5R)-4-amino-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-y1]-1,3,5-triazine-2(1H)-one (12), and the fluorosubstituted 3-deazanucleosides (19–24) have been synthesized by the transglycosylation of (2R,5S)-1-{2-[[(tert-butyldiphenylsilyl) oxy]methyl]-1,3-oxathiolan-5-y1} cytosine (2) with silylated 5-azacytosine and the corresponding silylated fluorosubstituted 3-deazacytosines, respectively, in the presence of trimethylsilyl trifluoromethanesulfonate as the catalyst in anhydrous dichloroethane, followed by deprotection of the blocking groups. These compounds were tested in vitro for cytotoxicity against L1210, B₁₆F₁₀, and CCRF-CEM tumor cell lines and for antiviral activity against HIV-1 and HBV.     

8-Aza-1-deazapurine Nucleosides as Antiviral Agents

Abstract

2′,3′-Dideoxy-8-aza-1-deazaadenosine (21) and its α-anomer (20) were synthesized via glycosylation of 7-chloro-3H-1,2,3-triazolo[4,5-b]pyridi-ne with 2,3-dideoxy-5-O-[(1, 1)-dimethylethyl)diphenylsilyl]-D-glycero-o-pen-tofuranosyl chloride. The reaction gave a mixture of α- and β-anomers of N³-, N⁴- and N¹-glycosylated regioisorners (12–15). The α- and β-anomers of the N⁴-glycosylated isomer 26 and 27 were also synthesized through the glycosylation of 8-aza-1-deazaadenine with 1-acetoxy-2,3-dideoxy-5-O-f(1,1-di-methylethyl)dimethylsilyl]-D-glycero-pentouranose. These dideoxynucleo-sides and a series of previously synthesized 8-aza-1-deazapurine nucleosidcs were tested for activity against several DNA and RNA viruses, HIV-1 included. The α- and β-anomers of 7-chloro-3-(2-deoxy-D-erythro-pentofuranosyl)-3H-1,2,3-triazolo[4,5-b]pyridine (3a and 4) showed activities against Sb-1 and Coxs viruses. The α- and β-anomers of 2′,3′-dideoxy-8-aza-1-deazaadenosine (20 and 21) were found active as inhibitors of adenosine deaminase.     

Nucleosides. II. Synthesis and Properties of 3,4-Diaryl-4,5-dihydro-1-(β-D-ribofuranosyl)-1,2,4-triazole-5-thiones

Abstract

3,4-Diaryl-4,5-dihydro-1,2,4-triazole-5-thiones (1a-c) were silylated to give compounds (2a-c) which were condensed with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (3) in the presence of trimethylsilyl trifluoromethane sulfonate to afford the corresponding nucleosides 4a-c. Treatment of 4a-c with sodium methoxide in methanol at room temperature afforded the debenzoylated nucleosides 5a-c. The reaction of 5a with acetone in the presence of p-toluenesulfonic acid gave the 2′, 3′-isopropylidene derivative (6a). Phosphorylation of 6a with phosphoryl chloride and triethylphosphate followed by treatment with barium hydroxide afforded barium 3,4-diphenyl-4,5-dihydro(β-D-ribofuranosyl)-1,2,4-triazole-5-thione-5′- monophosphate, which gave after lyophilization the free acid (7a)     

NOVEL SYNTHESIS OF seco TYPE OF ACYCLO C-NUCLEOSIDES OF 1,2,4-TRIAZOLE AND 1,2,4-TRIAZOLO[3,4-b][1,3,4]THIADIAZINE

The seco C-nucleosides 3-(1,2,3,4,5-penta-O-acetyl-D-gluco- and D- galacto-pentitol-1-yl)-1H-1,2,4-triazoles (8 and 9) were obtained in a one pot by deamination and dethiolation of 4-amino-3-(D-gluco- and D-galacto-pentitol-1-yl)-5-mercapto-1,2,4-triazoles (1 and 2), respectively, using sodium nitrite in orthophosphoric acid and subsequent acetylation. Condensation of 1, 2, and 4-amino-3-(D-glycero-D-gulo-hexitol-1-yl)-5-mercapto-1,2,4-triazole (12) with phenacylbromide (11) afforded the corresponding 3-(D-gluco-, D-galacto-pentitol-1-yl) and 3-(D-glycero-D-gulo-hexitol-1-yl)-6-phenyl-7H-1,2,4- triazolo[3,4-b][1,3,4] thiadiazines (15, 16, and 17). Acetylation of 15–17 gave the penta- and hexa-O-acetyl derivatives 18–20, respectively. The structures were confirmed by using ¹H, ¹³C, and 2D NMR spectra, DQFCOSY, HMQC, and HMBC experiments. The favored conformational structures were deduced from the vicinal coupling constants of the protons.     

Synthesis of AZT analogues: 7-(3-azido-2hydroxypropyl)-, 7-(3-amino-2-hydroxypropyl)-, 7-(3-triazolyl-2-hydroxypropyl)theophyllines

Nucleophilic displacement of the tosyloxy group in 7-(2-hydroxy-3-p-toluenesulfonyloxypropyl)theophylline (1) with azide anion afforded 7-(3-azido-2-hydroxypropyl)theophylline (2). Reduction of the 3-azido group in 2 with Ph₃P/Py/NH₄OH afforded the 3-amino derivative 4, alternatively obtained by regioselective amination of 7-(2,3-epoxypropyl)theophylline (3). Selective acetylation of 4 gave the N-acetyl derivative 5. 1,3-Dipolar cycloaddition of the azide group in 2 with N¹-propargyl thymine (6) afforded the regioisomeric triazole 7.     

Synthesis and Evaluation of Antimicrobial Activity of Some Pyrimidine Glycosides

Reaction of ethyl 4-thioxo-3,4-dihydropyrimidine-5-carboxylate derivatives 1a,b and ethyl 4-oxo-3,4-dihydropyrimidine-5-carboxylate 1c with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide in KOH or TEA afforded ethyl 2-aryl-4-(2′,3′,4′,6′-tetra-O-acetyl-β-D-glucopyranosylthio or/ oxy)-6-methylpyrimidine-5-carboxylate 6a-c. The glucosides 6a and 6b were obtained by the reaction of 1a and 1b with peracetylated glucose3 under MW irradiation. Mercuration of 1a followed by reaction with acetobromoglucose gave the same product 6a. The reaction of 1a-c with peracetylated ribose 4 under MW irradiation gave ethyl 2-aryl-4-(2′,3′,5′-tri-O-acetyl-β-D-ribofuranosylthio)-6-methylpyrimidine-5-carboxylate 8a–c. The deprotection of 6a–c and 8a–c in the presence of methanol and TEA/H₂O afforded the deprotected products 7a–c and 9a–c. The structure were confirmed by using ¹H and ¹³CNMR spectra. Selected members of these compounds were screened for antimicrobial activity.     

Synthesis and evaluation of arylpiperazines derivatives of 3,5-dioxo-(2H,4H)-1,2,4-triazine as 5-HT1AR ligands

5-HT_1AR agonist or partial agonists are established drug candidates for psychiatric and neurological disorders. We have reported the synthesis and evaluation of a series of high affinity 5-HT_1AR partial agonist PET imaging agents with greater selectivity over α-1AR. The characteristic of these molecules are 3,5-dioxo-(2H,4H)-1,2,4-triazine skeleton tethered to an arylpiperazine unit through an alkyl side chain. The most potent 5-HT_1AR agonistic properties were found to be associated with the molecules bearing C-4 alkyl group as the linker. Therefore development of 3,5-dioxo-(2H,4H)-1,2,4-triazine bearing arylpiperazine derivatives may provide high affinity selective 5-HT_1AR ligands. Herein we describe the synthesis and evaluation of the binding properties of a series of arylpiperazine analogues of 3,5-dioxo-(2H,4H)-1,2,4-triazine.