Acyclonucleosides: Part 1. Seco-Nucleosides

Synthesis and Cytotoxic Activity of New Thiazolopyrimidine Sugar Hydrazones and Their Derived Acyclic Nucleoside Analogues

New thienyl- or chlorophenyl-substituted thiazolopyrimidine derivatives and their derived sugar hydrazones incorporating acyclic d-galactosyl or d-xylosyl sugar moieties in addition to their per-O-acetylated derivatives were synthesized. Heterocyclization of the formed sugar hydrazones afforded the derived acyclic nucleoside analogues possessing the 1,3,4-oxadiazoline as modified nucleobase via acetylation followed by the cyclization process. The cytotoxic activity of the synthesized compounds was studied against human breast cancer MCF7 and MDA-MB-231 cell lines as well as human colorectal cancer HCT 116 and Caco-2 cell lines. High activities were revealed by compounds 1, 8, 10, 11, and 13 against Caco-2 and MCF7 cells in addition to moderate activities exhibited by other compounds against HCT116 or MDA-MB-231 cells.

Synthesis and anti-H5N1 virus activity of triazole- and oxadiazole-pyrimidine hybrids and their nucleoside analogs

New 1,2,3-triazole glycosides and 1,2,4-thioglycosides incorporating a substituted pyrimidinedione ring system were synthesized via click dipolar cycloaddition and heterocyclization of hydrazine-1-carbodithioate derivatives, respectively. The sugar hydrazine derivatives linked aminodimethyluracil were also prepared. In addition, the oxadiazoline substituted with acyclic sugar moieties linked to the pyrimidinedione as acyclic nucleoside analogs were synthesized. The antiviral activity of the synthesized compounds against avian influenza H5N1 virus was investigated and compounds 18, 13 and 19 showed good activities against the virus strains.

Synthesis of New 7-Alkylated Theophyllines by Chemical Modification of Dyphylline

Chemical modification of the propyl side chain of 7-(2,3-dihydroxyprop-1-yl)theophylline led to a variety of hetero-cyclic compounds linked to the theophylline by a methylene group.

Synthesis and in vitro evaluation of antiviral and cytostatic properties of novel 8-triazolyl acyclovir derivatives

As a part of the research aimed on identification of new nucleobase derivatives with improved biological properties, a series of novel 8-substituted acyclovir derivatives were synthesized. The 8-azidoguanosine 4 and novel 8-azidoacyclovir 9 were synthesized from commercially available guanosine 1 and acyclovir 6 which were transformed into 8-bromopurine derivatives 2 and 7 and hydrazine derivatives 3 and 8, respectively. 8-Triazolylguanosine 5 and 8-triazolylacyclovir analogs 10-12 were successfully synthesized via the Cu(I) catalyzed 1,3-dipolar cycloaddition reaction of azides 4 and 9 with propargyl alcohol, 4-pentyn-1-ol and 5-hexyn-1-ol. The novel 1,4-disubstituted 1,2,3-triazolyl compounds 5, 10-12 were evaluated for antiviral activity against selected DNA and RNA viruses and cytostatic activity against normal Madine Darby canine kidney (MDCK I) cells, and seven tumor cell lines (HeLa, CaCo-2, NCI-H358, Jurkat, K562, Raji and HuT78). While tested compounds exerted no antiviral activity at nontoxic concentrations, the 8-triazolyl acyclovir derivative 10, with the shortest alkyl substituent at the C-4 of triazole ring, was found to be the most active against the CaCo-2 cell line.

Synthesis and anticancer activity of new [(Indolyl)pyrazolyl]-1,3,4-oxadiazole thioglycosides and acyclic nucleoside analogs

New [(Indolyl)pyrazolyl]-1,3,4-oxadiazole compounds and their derived thioglycosides as well as the corresponding sugar hydrazones were synthesized. The acyclo C-nucleoside analogs of the oxadiazoline base system were also prepared by reaction of acid hydrazides with aldehydo sugars followed by one pot process encompassing acetylation and cyclization of the synthesized hydrazones. The anticancer activity of the newly synthesized compounds was studied against colorectal carcinoma (HCT116), breast adenocarcinoma (MCF7) and prostate cancer (PC3) human tumor cell lines and a number of compounds showed moderate to high activities.

Synthesis of bis-acyclonucleoside analogues bearing benzothienyl-1,2,4-Triazol-3-Yl-disulfide under conventional and microwave methods

The oxidation of 5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole-3-thiol (1) with a solution of iodine and potassium iodide at room temperature afforded [5-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole-3-yl]disulfide (2). In contrast, when the reaction mixture was heated or irradiated by MW, an unexpected additional product was obtained and identified as 3-(3-chlorobenzo[b]thien-2-yl)-4H-1,2,4-triazole (3); the ratio of products was 3:1. The preferred conformer of 2 was deduced from the theoretical calculation. The alkylation of compounds 2 and 3 with epichlorohydrin and hydroxyalkylating agents gave the corresponding N,N-bis- and N-acyclonucleosides analogues 8-15.

Synthesis of 1,4-disubstituted mono and bis-triazolocarbo-acyclonucleoside analogues of 9-(4-hydroxybutyl)guanine by Cu(I)-catalyzed click azide-alkyne cycloaddition

A series of novel mono-1,2,3-triazole and bis-1,2,3-triazole acyclonucleoside analogues of 9-(4-hydroxybutyl)guanine was prepared via copper(I)-catalyzed 1,3-dipolar cycloaddition of N-9 propargylpurine, N-1-propargylpyrimidines/as-triazine with the azido-pseudo-sugar 4-azidobutylacetate under solvent-free microwave conditions, followed by treatment with K(2)CO(3)/MeOH, or NH(3)/MeOH. All compounds studied in this work were screened for their antiviral activities [against human rhinovirus (HRV) and hepatitis C virus (HCV)] and antibacterial activities against a series of Gram positive and negative bacteria.

Synthesis of acyclovir and HBG analogues having nicotinonitrile and its 2-methyloxy 1,2,3-triazole

Reaction of pyridin-2(1H)-one 1 with 4-bromobutylacetate (2), (2-acetoxyethoxy)methyl bromide (3) gave the corresponding nicotinonitrile O-acyclonucleosides, 4 and 5, respectively. Deacetylation of 4 and 5 gave the corresponding deprotected acyclonucleosides 6 and 7, respectively. Treatment of pyridin-2(1H)-one 1 with 1,3-dichloropropan-2-ol (8), epichlorohydrin (10) and allyl bromide (12) gave the corresponding nicotinonitrile O-acyclonucleosides 9, 11, and 13, respectively. Furthermore, reaction of pyridin-2(1H)-one 1 with the propargyl bromide (14) gave the corresponding 2-O-propargyl derivative 15, which was reacted via [3+2] cycloaddition with 4-azidobutyl acetate (16) and [(2-acetoxyethoxy)methyl]azide (17) to give the corresponding 1,2,3-triazole derivatives 18 and 19, respectively. The structures of the new synthesized compounds were characterized by using IR, (1)H, (13)C NMR spectra, and microanalysis. Selected members of these compounds were screened for antibacterial activity.

Synthesis and in vitro antitumor activity of new substituted thiopyrimidine acyclic nucleosides and their thioglycoside analogs

Some new thiopyrimidine acyclic nucleosides and thioglycoside derivatives 3a-c, 4a-c, 6a,b, and 7a,b were synthesized. The cytotoxicity and antitumor evaluation of all prepared compounds have been tested in vitro against Ehrlich's ascites carcinoma cell line and their activity against glutathione peroxidase and catalase were reported. The role of the prepared compounds as free radical regulators and the therapeutic antitumor effect of a balanced generation of free radicals are discussed. Compounds 2, 3b, 3c, 4a, and 4c inhibited significantly in a dose dependent manner the growth of Ehrlich ascites carcinoma cells while the other compounds did not show any antitumor activity even at higher concentrations.

Short synthesis and antiviral activity of acyclic phosphonic acid nucleoside analogues

An efficient route for synthesizing novel allylic and cyclopropanoid phosphonic acid nucleoside analogues is described. The condensation of the bromine derivatives 6 and 18 with nucleoside bases (A, U, T, C, G) under standard nucleophilic substitution and deprotection conditions, afforded the target phosphonic acid nucleoside analogues. These compounds were evaluated for their antiviral properties against various viruses. Cyclopropanoid phosphonic adenine nucleoside analogue 23 showed significant anti-HIV activity.

Synthesis and antiviral evaluation of novel 2,3-dihydroxypropyl nucleosides from 2- and 4-thiouracils

Regioselective alkylation of 2-thiouracils 1a-c and 4-thiouracils 7a,b with 2,3-O-isopropylidene-2,3-dihydroxypropyl chloride (2) afforded 2-[[(2,2-Dimethyl-1,3-dioxolan-4-yl) methyl]thio]pyrimidin-4(1H)-ones 3a-c and 4-[[(2,2-Dimethyl-1,3-dioxolan-4-yl)methyl]thio] pyrimidin-2(1H)-ones 8a,b, respectively. Further alkylation with 2 and/or 2,3-O-isopropylidine-1-O-(4-toluenesulfonyl)-glycerol (4) gave the acyclo N-nucleosides 5a-c and 9a,b whose deprotection afforded 6a-c and 10a,b. 2-(Methylthio)pyrimidin-4(1H)-ones 11a-c and 4-(methylthio)pyrimidin-2(1H)-ones 14a,b were treated with 2 and/or 4 to give 12a-c and 15a,b which were deprotected to give 13a-c and 16a,b. Pyrimidine-2,4(1H,3H)-dithiones 17a-c were treated with two equivalents of 2 to give 2,4-bis[[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl]thio] pyrimidines 18a-c. Deprotection of compounds 18a-c gave 2,4-bis[(2,3-dihydroxypropyl)thio]pyrimidines 19a-c. The activity of the deprotected nucleosides against Hepatitis B virus was evaluated and showed moderate inhibition activity against HBV with mild cytotoxicity.

Synthesis and activity against HBV of novel Tetra-seconucleoside analogues of dyphlline having the acyclic chains of ACV and HBG

Selective alkylation of dyphylline (1) with (2-acetoxyethoxy)methyl bromide (2a) or 4-acetoxybutyl bromide (2b) afforded 3'-O-[(acetoxyethoxy)methyl]dyphylline (3a) and 3'-O-(4-acetoxybutyl)-dyphylline (3b), respectively. A trans esterification process rather than alkylation of the dihydroxy-propyl side chain in 1 had taken place during the reaction with 2-p-toluoyloxy)ethyl chloride (5) to afford the respective 3'-toluoyloxy derivative 7 and not the anticipated 3'-O-[(p-toluoyloxy)ethyl]-dyphylline (6). Deacylation of 3a,b and 7 afforded 4a,b and 1, respectively. Viral screening of selected compounds against HBV has been investigated.

New acyclic quinoxaline nucleosides. Synthesis and anti-hiv activity

A series of acyclonucleosides substituted 1-(4,5-dihydroxypentyl) (13-8) and 2-(4,5-dihydroxypentyloxy)quinoxalines (19-24) were synthesized by the sharpless asymmetric dihydroxylation of the derivatives 1-6 and 7-12, respectively. Treatment of the quinoxaline base 26 with (R)-2,2-dimethyl-1,3-dioxolan-4-ylmethyl-p-toluenesulfonate (27) in the presence of NaH/DMF furnished 28. Acid hydrolysis of 28 gave 1-(2,3-dihydroxypropyl)-6,7-dimethyl-quinoxaline-2-one (29). Alternatively, 29 was prepared by sharpless dihydroxylation of 30. All the compounds were evaluated for their in vitro anti-HIV-1 and HIV-2 in MT-4 cell and found inactive, except 29, which showed inhibition of HIV-1 with EC50 value of 0.15 +/- 0.1 microg/ml and a therapeutic index (SI) of 73.

Acyclonucleosides: Part 2. diseco-Nucleosides

This chapter is the second of a sequence of three chapters that appears in successive volumes of this series dealing with the chemistry of acyclonucleosides. The first chapter appeared in the previous volume [97AHC391] and dealt with seco-nucleosides (one bond disconnection). This chapter deals with diseco-nucleosides (two bond disconnections). The final chapter of this series will deal with tri-, tetra-, and pentaseco-nucleosides, as well as contain an appendix of the literature that appeared after the three chapters were prepared.

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

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 RT inhibitory activity evaluation of new pyrimidine-based seco-nucleosides

Eleven new 3',4'-seco acyclic nucleosides (4-14) were prepared by nucleophilic substitution of protected pyrimidine bases on ethyl 3,3-diethoxypropanoate (3). Structures were characterized spectroscopically and a brief analysis of their conformation in solution was performed by the vicinal coupling constants (3)JH2'aH3' and (3)JH2'bH3'. In solid state, compound 6 forms a homodimer linked by hydrogen bonding. In preliminary tests all compounds show low toxicity and gentle activity against HIV-1 RT in vitro.

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 K(2)CO(3) in DMF afforded the corresponding fused triazolo-thiazines and thiazolo-triazole 17-19. The isopropylidenes and acetyl derivatives of the products were prepared.

Novel regioselective hydroxyl-alkylation of 4,5-diphenylimidazole-2-thione and a competitive intramolecular ring closure of the S-hydroxyalkyl-imidazoles to imidazo[2,1-b]thiazines and thiazoles. Role of catalyst, microwave irradiation, and solid support

Under both conventional method (CM) and microwave (MW) irradiation (MWI) conditions, alkylation of 4,5-diphenylimidazole-2-thione (1) with halogeno-alkanols 2 or 5, chloroglycerol 11 and 2,3-O-isopropylidene-1-O-(p-tolylsulfonyl)-glycerol (8) in presence of sodium ethoxide or sodium acetate in alcohol afforded regioselectively the corresponding S-alkylated analogues 3, 6, 9, and 12; they also were obtained using MW in absence and presence of bentonite as solid support with no change in regioselectivity. In the presence of potassium carbonate in DMF, the bisalkylated analogues 4, 7, 10, and 13 were obtained except in case of compound 13 where it was accompanied with the imidazothiazine 14. A convenient approach for imidazo-[2,1-b]thiazines and thiazoles 14-16 could be achieved by intramolecular dehydrative ring closure of the S-hydroxyalkylated imidazoles 3, 6, and 12 using potassium carbonate in DMF under both conventional and microwave methods. Isopropylidenation of 12 and 13 and deprotection of 9 and 10 also were investigated.

Synthesis and antimicrobial activity of some cyclic and acyclic nucleosides of thieno[2,3-d]pyrimidines

The reaction of compounds 1, 2, 3, 4, or 13 with 2-chloroethyl methyl ether or 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl bromide, afforded some acyclic and cyclic nucleosides of thieno[2,3-d]pyrimidine derivatives. Furthermore, cyclic C-nucleosides 24 and 25 were prepared from the reaction of 20, 21 or from 26, 27 with D-glucose. The antimicrobial evaluation of some prepared products showed promising antimicrobial activity.

Synthesis and biological evaluation of some alpha-[6-(1'-carbamoylalkylthio)-1 H-pyrazolo[3,4-D]pyrimidin-4-yl]thioalkylcarboxamide acyclonucleosides

The reaction of 1H-pyrazolo[3,4-d]pyrimidin-4,6-dithione 11 with compounds 12a-c produces ethyl alpha-[6-(1'-carboethoxyalkylthio)-1 H-pyrazolo[3,4-d]pyrimidin-4-yl]thioalkylates 13a-c, respectively. These heterocycles were alkylated, separately, with alkylating agents 14, 15, and 16 to afford, predominately, the N(1)-acyclic nucleosides (17-19)a-c, which were deprotected to give the desired products (20-22)a-c. All synthetic compounds were characterized on the basis of their physical and spectroscopic properties. The acyclic nucleosides (20-22)a-c were evaluated for their inhibitory effects against the replication of varicella-zoster virus, human cytomegalovirus and M. tuberculosis. No marked biological activity was found.

Synthesis of 2-bromomethyl-3-hydroxy-2-hydroxymethyl-propyl pyrimidine and theophylline nucleosides under microwave irradiation. Evaluation of their activity against hepatitis B virus

Alkylation of 2-methylthiopyrimidin-4(1H)-one (1a) and its 5(6)-alkyl derivatives 1b-d as well as theophylline (7) with 2,2-bis(bromomethyl)-1,3-diacetoxypropane (2) under microwave irradiation gave the corresponding acyclonucleosides 1-[(3-acetoxy-2-acetoxymethyl-2-bromomethyl)prop-1-yl]-2-methyl-thio pyrmidin-4(1H)-ones 3a-d and 7-[(3-acetoxy-2-acetoxymethyl-2-bromomethyl)prop-1-yl]theophylline (8), which upon further irradiation gave the double-headed acyclonucleosides 1,1 '-[(2,2-diacetoxymethyl)-1,3-propylidene]-bis[(2-(methylthio)-pyrimidin-4(1H)-ones] 4a-c, and 7,7 '-[(2,2-diacetoxymethyl)-1,3-propylidene]-bis(theophylline) (9). The deacetylated derivatives were obtained by the action of sodium methoxide. The activity of deacetylated nucleosides against Hepatitis B virus was evaluated. Compound 5b showed moderate inhibition activity against HBV with mild cytotoxicity.

Double-headed acyclo C-nucleoside analogues. Functionalized 1,2-bis-(1,2,4-triazol-3-yl)ethane-1,2-diol

Reaction of L-tartaric acid with thiocarbohydcrazide afforded (1R, 2S)-1,2-bis(4-amino-5-mercapto-1,2,4-triazol-3-yl)-ethane-1,2-diol (3). The functional groups in 3 allowed the construction of fused heterocycles on the 1,2,4-triazole rings, mainly of the 1,2,4-triazolo[3,4-b][1,3,4]thiadiazine type as in 4, 5, 7, 10, 13 and 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole type as in 14.

Synthesis of novel acyclonucleosides analogs of pyridothienopyrimidine as antiviral agents

Nucleoside analogs of pyridothienopyramidines were prepared by condensing the sodium salt 2a,b with an acyclic side chain in the form of acetylated haloalkoxyalcohol, and subsequent removal of the protecting acetyl group in ammonia/methanol afforded 4a,b. The O-tosyl derivative of 4a could then be modified to azido- and amino derivatives. Reaction of the sodium salt of 2b with halo-ether, benzyl halo-ether and/or halo-thioether gave N- and S-alkylated products, 8 and 9, respectively. Coupling of 10 with the sodium salt of 2a,b gave the corresponding dioxolane derivatives 11, 13, and 14, which were treated with 80% acetic acid at room temperature to give diols 12, 15, and 16. Treatment of 16 with tosyl chloride afforded the ditosylate 17 and this could then be modified to diazido and diamino derivatives. Some of the products were screened for their biological activity.

First synthesis of double headed 1,3,4-oxadiazino[6,5-b]indole acyclo C-nucleosides

Condensation of 1,3-dihydro-2,3-dioxo-2H-indoles (la-c) with galactaric acid bis hydrazide (2) gave the corresponding galactaric acid bis[2-(1,2-dihydro-2-oxo-3H-indol-3-ylidene)hydrazides] (3a-c). Acetylation of the latter compounds with acetic anhydride in the presence of pyridine at ambient temperature gave the 2,3,4,5-tetra-O-acetylgalactaric acid bis[2-(1,2-dihydro-2-oxo-1-substituted-3H-indol-3-ylidene)hydrazides] (4b-d). Heterocyclization of the tetra-O-acetates 4b-d by heating with thionyl chloride afforded the double headed acyclo C-nucleosides: 1,2,3,4-tetra-O-acetyl- 1,4-bis[9-substituted-1,3,4-oxadiazino[6,5-b]indol-2-yl-1-ium]-galacto-tetritol dichlorides (5b-d). Structures of the prepared compounds were elucidated from their spectral properties.

A divergent chemoenzymatic route to an intermediate for nucleoside analogues

Two regioisomeric isoxazoline monoacetates 1 and 2 were synthesized from the corresponding diacetate 3 via PPL or PLE catalyzed hydrolysis. With both the enzymes, the initial regioselectivity (approximately 3-4:1) was offset by an intramolecular acyl transfer. In addition to a non-enzymatic catalysis for the acyl transfer, preliminary experiments do suggest a definite but minor role of enzyme for this intramolecular acyl transfer. Compounds 1 and 2 may serve as intermediates for nucleoside analogues.

Reaction of sugars with 2-hydrazinopyridine, precursors for seco C-nucleosides of 1,2,4-triazolo[4,3-a]pyridine

Reaction of 2-hydrazinopyridine (1) with D-xylose, D-galactose, D-glucose and D-fructose afforded the corresponding hydrazones mainly in the acyclic forms 2, 3, 6 and 11 with minor amounts of the cyclic structures. Oxidative cyclization of the hydrazones with bromine in methanol resulted in the formation of the 3-(polyhydroxyalkyl)-1,2,4-triazolo[4,3-a]pyridine derivatives 13-15 whose acetylation afforded the acetylated derivatives 16-18. Assignment of 1D and 2D NMR spectral data in addition to 15N NMR experiments led to complete characterization of the products.

Synthesis and anti-HBV activity of thiouracils linked via S and N-1 to the 5-position of methyl beta-D-ribofuranoside

Reverse nucleoside derivatives of 2-(methylsulfanyl)uracils 6a-d were prepared by treating of the sodium salt of 2-(methylsulfanyl)uracils (5a-d) with methyl 2,3-O-isopropylidene-5-O-p-toluenesulfonyl-beta-D-ribofuranoside (2). The alkylation of 2-thiouracils 4a-d with methyl 5-deoxy-5-iodo-2,3-O-isopropylidene-D-ribofuranoside (3) afforded the corresponding S-ribofuranoside derivatives 8a-d. Deisopropylidenation of 6a-d and 8a-d afforded the corresponding deprotected derivatives 7a-d and 9a-d, respectively. The Anti-HBV activity of selected compounds was studied.

A novel synthesis of acyclonucleosides via allylation of 3-[1-(phenylhydrazono)-l-threo-2,3,4-trihydroxybut-1-yl]quinoxalin-2(1H)one

The allylation of 3-[1-(phenylhydrazono)-L-threo-2,3,4-trihydroxybut-1-yl]quinoxalin-2(1H)one (1) gave, in addition to the anticipated 1-N-allyl derivative (2), a dehydrative cyclized product, 1-N-allyl-3-[5-(hydroxymethyl)-1-phenylpyrazol-3-yl]quinoxalin-2-one (4) and its isomeric O-allyl derivative 3. The O-allyl group in 3 underwent acetolysis under acetylation conditions, in addition to the acetylation of the hydroxyl group, to afford 2-acetoxy-3-[5-(acetoxymethyl)-1-phenylpyrazol-3-yl]quinoxaline (8) instead of the O-acetyl derivative of 3. Allylation of the tri-O-acetyl derivative of 1 caused the elimination of a molecule of acetic acid in addition to N-allylation to give 1-N-allyl-3-[3,4-di-O-acetyl-2-deoxy-1-(phenylhydrazono)but-2-en-1-yl]quinoxalin-2-one (11). Hydroxylation of the allyl group gave a glycerol-1-yl acyclonucleoside which can be alternatively obtained by a displacement reaction of the tosyloxy group in 2,3-O-isopropylidene-1-O-(p-tolylsulfonyl)glycerol (14), followed by deisopropylidenation. 1-N-(2,3-Dibromopropyl)-3-[5-(hydroxymethyl)-1-(4-bromophenyl)pyrazol-3-yl]quinoxalin-2-one (15) underwent azidolysis to give a 2,3-diazido derivative. The assigned structures were based on spectral analysis. The activity of compounds 2, 4, 6, and 15 against hepatitis B virus was studied.

Synthesis and structural characterization of 1-(d-glycosyloxy)phthalazines

Coupling of the trimethylsilyl derivative of (2H)phthalazin-1-one with 1,2,3,4,6-penta-O-acetyl-alpha-D-glucopyranose and 1,2,3,4,6-penta-O-acetyl-alpha-D-galactopyranose in the presence of stannic chloride gave the respective glycosides, 2-(per-O-acetyl-D-glycosyloxy)phthalazines, which upon deacetylation gave the respective unprotected analogues. Under the same conditions 1,2,3,5-tetra-O-acetyl-beta-D-ribofuranose gave 1-(2,3,5-tri-O-acetyl-alpha-D-ribofuranosyloxy)phthalazine. Electrospray mass spectrometry aided the structural characterization of this series of 1-(D-glycosylyloxy)phthalazines. Low energy collisionally-induced dissociation tandem mass spectrometry of the protonated molecules confirmed the MS fragmentation routes and the structural identities of this novel series of glycosides.