key: cord-0972244-wxcn28ws
authors: Głowacka, Iwona E.; Andrei, Graciela; Schols, Dominique; Snoeck, Robert; Gawron, Katarzyna
title: Design, Synthesis, and the Biological Evaluation of a New Series of Acyclic 1,2,3‐Triazole Nucleosides
date: 2017-08-01
journal: Arch Pharm (Weinheim)
DOI: 10.1002/ardp.201700166
sha: 0bdf8ce93686ba13580923fa56be52c57da4fcb2
doc_id: 972244
cord_uid: wxcn28ws

A new strategy for the synthesis of N (3)‐benzoylated‐ and N (3)‐benzylated N (1)‐propargylquinazoline‐2,4‐diones 30a−d and 31a−d from isatoic anhydride 41 is reported. The alkynes 30a−d and 31a−d were applied in the 1,3‐dipolar cycloadditions with azides 27 and 28 to synthesize acyclic 1,2,3‐triazole nucleosides. The obtained alkynes and 1,2,3‐triazole were evaluated for antiviral activity against a broad range of DNA and RNA viruses. The alkyne 30d showed activity against adenovirus‐2 (EC(50) = 8.3 μM), while compounds 37a and 37d were also active toward herpes simplex virus‐1 wild‐type and thymidine kinase deficient (HSV‐1 TK(−)) strains (EC(50) values in the range of 4.6–13.8 μM). In addition, compounds 30a, 30b, 37b, and 37c exhibited activity toward varicella‐zoster virus (VZV) TK(+) and TK(−) strains (EC(50) = 2.1–9.5 μM). The compound 30b proved to be the most selective against VZV and displayed marginal activity against human cytomegalovirus (HCMV). Although the compound 30a had improved anti‐HCMV activity, the increase in anti‐HCMV activity was accompanied by significant toxicity. Compounds 37a and 37d showed inhibitory effects toward the human T lymphocyte (CEM) cell line (IC(50) = 21 ± 7 and 22 ± 1 μM, respectively), while compound 35 exhibited cytostatic activity toward HMEC‐1 cells (IC(50) = 28 ± 2 μM).

Acyclic analogs of nucleosides belong to the most important class of compounds showing antiviral and antitumor activities [1, 2] . Among them, acyclovir and penciclovir exhibit activity against herpes viruses including HSV-1, HSV-2, VZV, hepatitis B virus (HBV) [3] [4] [5] [6] [7] , while ganciclovir [7, [8] [9] [10] and valganciclovir À its prodrug with significantly improved oral bioavailability [10] [11] [12] À are commonly used as anti-cytomegalovirus agents. However, in most cases, the clinical applications of nucleosides are limited due to the observed side effects. In addition, an important problem in treatment of viral infections is the emergence of drug-resistant mutant viruses. For this reason, the search for new antiviral compounds with improved activity has been continuing for decades. This is not limited to modifications of aliphatic chains, but also includes the introduction of additional groups into the structure of nucleosides with well-documented biological activity. Since the 1,2,3-triazole moiety has been recognized as bioisosteric with the amide function [13, 14] , the incorporation of this structural motive has been widely applied and resulted in a broad spectrum of pharmaceutically important molecules. Furthermore, 1,2,3-triazoles are able to form hydrogen bonds, they are not protonated at the physiological pH, and are also stable to oxidation and reduction as well as to many enzymatic reactions [15] . Several compounds of the 1,2,3-triazole family have exhibited a broad spectrum of biological activities, such as anti-inflammatory [16, 17] , anticonvulsants [18] , antiviral [19] [20] [21] [22] [23] , anticancer [24] [25] [26] [27] , antimicrobial agents [28] [29] [30] , as well as b-lactamase inhibitors [31] and dopamine D2 receptor ligands related to schizophrenia [32] . Since 1997, when the first acyclic 1,2,3-triazolenucleosides have been obtained by Lazrek et al. [33, 34] , many efforts have been made by several research groups to synthesize more potent antiviral and anticancer nucleoside analogs having both natural and modified nucleobases ( Fig. 1 ) [35] [36] [37] [38] [39] [40] [41] [42] [43] [44] [45] [46] [47] [48] [49] .

Among various heterocyclic moieties that would serve as modified nucleobase mimetics, substituted quinazoline-2,4-diones are of special interest. This structural motive was successfully attached to various biologically active compounds to provide even more active hybrids (Fig. 2 ) [50] [51] [52] [53] [54] [55] [56] .

In continuation of our involvement in the search for new biologically active acyclic nucleoside analogs [57] [58] [59] [60] [61] [62] [63] [64] [65] [66] , a new series of 1,2,3-triazole nucleosides containing the substituted quinazoline-2,4-dione at C4 was designed (compounds 32-37, Scheme 1). Based on the previous observations on analogous heterocyclic conjugates 24-26 synthesized in our research group (Fig. 3 ) [57, 58, 67] , functionalized benzyl and benzoyl groups were carefully selected as suitable substituents to be attached at C3 in the quinazolinone-2,4-dione framework. The synthetic strategy for our new series 1,2,3-triazolenucleosides is presented in Scheme 1.

The starting 3-azidopropanol 27 was prepared from 3chloropropanol in 90% yield according to the literature procedure [68] . Reaction of 3-azidopropanol 27 with benzyl bromide gave 28 in 80% yield [69, 70] . Initially, we considered the respective N 3 -benzoylated quinazoline-2,4-diones as convenient substrates for the preparation of N 3 -benzoyl-N 1propargylquinazoline-2,4-diones 30a (Scheme 2). The N 3benzoylquinazoline-2,4-dione 40 was previously obtained from 2-benzoylaminobenzoxazinone, although with low (less than 5%) overall yield [71] Recently, we reported [57] the synthesis of N 3 -benzoyl-N 1 -propargylquinazoline-2,4-diones 30a from quinazoline-2,4-dione 38 in 19% overall yield (Scheme 2).

However, this procedure suffers from several steps including benzoylation of 38 to N 1 ,N 3 -dibenzoylquinazoline-2,4dione 39, requires a selective N 1 -debenzoylation and finally propargylation. Unfortunately, in this method, the selective N 1 -debenzoylation step appeared less effective and tedious. For this reason, another strategy for the synthesis of N 3benzoyl-N 1 -propargylquinazoline-2,4-diones 30a was devised (Scheme 3). It started from propargylation of commercially available isatoic anhydride 41 followed by the reaction of the compound 42 with urea [72] to give N 1 -propargylquinazoline-2,4-dione 29. Finally, the key compound 29 could be transformed into substituted both N 3 -benzoyl-and N 3 -benzyl-N 1propargylquinazoline-2,4-diones 30aÀd and 31aÀd via the reaction with the respective benzoyl chlorides and benzyl bromides (Scheme 3). The standard benzoylation of N 1 -propargylquinazoline-2,4dione 29 with benzoyl chlorides in the presence of triethylamine led to the formation of N 3 -benzoylated N 1 -propargylquinazoline-2,4-diones 30aÀd in moderate to good yields without formation of by-products. At first, attempts at benzylation of N 1 -propargylquinazoline-2,4-dione 29 following the strategy previously described [67] for the synthesis of N 1 -allylated N 3 -benzoylquinazoline-2,4-dione were undertaken. Treatment of 29 with benzyl bromide in the presence of potassium hydroxide at 105°C for 4 h or 60°C for 48 h led to the formation of ca. a 50:50 mixture of an alkyne 31a and an allene 43a in 79% total yield. Unfortunately, several attempts at elaborating the efficient procedure to separate N 3 -benzyl-N 1 -propargylquinazoline-2,4-diones 31a from N 3 -benzyl-N 1 -(propa-1,2-dien-1-yl)quinazoline-2,4-diones 43a on silica gel columns or by crystallization proved fruitless. Fortunately, we were able to chromatographically isolate a small amount of pure allene 43a. Attempts to optimize a procedure for benzylation of 29, thereby avoiding formation of allenes 43 were undertaken. Thus, the treatment of N 1 -propargylquinazoline-2,4-dione 29 with benzyl bromide in the presence of potassium carbonate in DMF at room temperature for 48 h afforded pure N 3 -benzyl-N 1 -propargylquinazoline-2,4-dione 31a and no traces of the allene 43a were observed.

The H€ uisgen reaction of the azide 27 with the alkyne 29 could be accomplished within 21 days when the reaction mixture was heated at 45°C. However, when the reaction was performed at the same temperature under microwave irradiation, the azide was consumed in less than 30 min. For this reason, all cycloadditions of azides 27 and 28 with N 1 -propargylquinazoline-2,4-dione 29, N 3 -benzoylated N 1propargylquinazoline-2,4-diones 30aÀd, and N 3 -benzylated N 1 -propargylquinazoline-2,4-diones 31aÀd were carried out in a microwave oven (Scheme 4) and disappearance of the starting azide was monitored by IR spectroscopy. All compounds were purified chromatographically and by crystallization. Structures and purity of all 1,2,3-triazole nucleosides were established by 1 H, 13 C NMR, and IR techniques as well as by elemental analysis. 

ND: not determined. a) Required to reduce virus-induced cytopathogenicity by 50%.

Required to cause a microscopically detectable alteration of normal cell morphology. compared to the reference compound UDA against human corona virus was measured (EC 50 of 18.5 mM and 1.8 mM, respectively). Moreover, several synthesized quinazoline-2,4-diones inhibited the replication of both TK þ and TK À VZV strains at EC 50 in the 2-70 mM range (Table 2 ). In particular, alkynes 30a (EC 50 ¼ 6.5 mM), 30b (EC 50 ¼ 9.5 mM), and 30d (EC 50 ¼ 5.9 mM) as well as 1,2,3-triazoles 36a (EC 50 

as well as 37b (EC 50 ¼ 8.2 mM) showed marked activity toward TK À VZV strain, which was higher than that of the reference drugs acyclovir and brivudin (EC 50 ¼ 40.7 and 32.0 mM, respectively). However, they were significantly less active than the reference anti-VZV drugs against the TK þ VZV strain Oka. Except for 36c, these derivatives had a minimum cytotoxic concentration !100 mM. However, compounds 30a (CC 50 ¼ 11.3 mM) and 30d (CC 50 ¼ 9.1 mM) as well as 36a (CC 50 ¼ 10.6 mM) and 36b (CC 50 ¼ 12.5 mM) reduced cell growth (as measured by the 50% cytostatic concentration, i.e., CC 50 ) at lower concentrations than acyclovir and brivudin (CC 50 > 350 mM), resulting in low selectivity (ratio CC 50 /EC 50 ). Interestingly, 30b emerged as the most selective anti-VZV quinazoline-2,4-diones since it did not inhibit growth of HEL cells up to a concentration of 100 mM.

All synthesized compounds were also subjected to antiviral screening against HCMV, and among them, 36a (EC 50 ¼ 10.8-14.5 mM) and 36d (EC 50 ¼ 12.6 and 8.9 mM) showed some activity; however, at the same time, 36a showed cytotoxicity toward HEL cells (CC 50 ¼ 10.6 mM).

The cytostatic activity of the tested compounds was defined as the 50% cytostatic inhibitory concentration (IC 50 ) causing a 50% decrease in cell proliferation and was determined against the transformed cells murine leukemia L1210, human lymphocyte CEM, human cervix carcinoma HeLa compared to human dermal microvascular endothelial HMEC-1 cells.

In these series, several compounds showed inhibitory activity against the proliferation of tumor cell lines (Table 3) . 

The N 3 -benzoylated-and N 3 -benzylated N 1 -propargylquinazoline-2,4-diones 30a-d and 31aÀd were efficiently synthesized from isatoic anhydride 41.

The copper(I)-catalyzed 1,3-dipolar cycloadditions of the azides 27 and 28 with the selected N 3 -benzoylated-and N 3 -benzylated N 1 -propargylquinazoline-2,4-diones 30aÀd and 31aÀd under microwave irradiation led to the formation of 1,2,3-triazole acyclonucleosides 32, 35 and 33-34aÀd as well as 36-37aÀd in good yields.

All synthesized compounds were tested for their antiviral activities against DNA and RNA viruses as well as cytostatic activity and cytotoxicity. Among all tested compounds, 30d (EC 50 ¼ 7.6 mM) showed activity against adenovirus-2 comparable to that of the reference compounds cidofovir, alovudine, and zalcitabine. Compounds 30d, 36a, and 36d proved equally active against HSV-1 and VZV TK þ and TK À strains. In addition, the derivatives 30a, 30b, and 36b were also inhibitory for TK þ and TK À VZV strains. The highest selectivity (ratio cytostatic effect [CC 50 ]/antiviral activity [EC 50 ]) was found for the compound 30b (CC 50 ! 100 mM and MCC ¼ 100). The selectivity for the compounds 30a, 30d, 36a, and 36b was low as they reduced cell growth (CC 50 Among all tested quinazoline-2,4-diones, compounds 36a and 36d were the most inhibitory toward the human T-lymphocyte (CEM) cell line and they showed inhibitory effects (IC 50 ¼ 21 AE 7 and 22 AE 1 mM, respectively) comparable to that of the reference compound 5-fluorouracil (IC 50 ¼ 18 AE 5 mM). The compound 35 exhibited also cytostatic activity (IC 50 : 28 AE 2 mM) toward HMEC-1 cell line. Table 3 . Inhibitory effects of the tested compounds against the proliferation of murine leukemia cells (L1210), human T-lymphocyte cells (CEM), human cervix carcinoma cells (HeLa), and human dermal microvascular endothelial cells (HMEC-1). The following adsorbents were used: column chromatography, Merck silica gel 60 (70-230 mesh); analytical TLC, Merck TLC plastic sheets silica gel 60 F 254 . TLC plates were developed in chloroform-methanol solvent systems. Visualization of spots was effected with iodine vapors. All solvents were purified by methods described in the literature.

All microwave irradiation experiments were carried out in a microwave reactor Plazmatronika RM 800.

3-Azidopropan-1-ol 27 [68] , (3-azidopropoxy)methylbenzene 28 [69, 70] , N 1 -(prop-2-yn-1-yl)isatoic anhydride [73] , and N 3 -benzoyl-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 30a [57] were obtained according to the literature procedures.

The InChI codes of the investigated compounds together with some biological activity data are provided as Supporting Information.

To a solution of the N 1 -(prop-2-yn-1-yl)isatoic anhydride 42 , CH 2 C À À À À À À CH), 3.29 (t, J ¼ 2.4 Hz, 1H, CH 2 C À À À À À À CH); 13 General procedure for benzoylation of N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29

To a suspension of the N 1 -(prop-2-yn-1-yl)quinazoline-2,4dione 29 (1.00 mmol) in dry acetonitrile (6 mL), benzoyl chloride (2.20 mmol) and TEA (3.00 mmol) were added. The mixture was stirred at room temperature for 48 h. The solvent was removed and the residue was suspended in dichloromethane (20 mL) and extracted with water (3 Â 20 mL). The organic phase was dried (MgSO 4 ), concentrated, and chromatographed and/or crystallized to give pure 30aÀd. According to the general procedure from N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29 (0.10 g, 0.50 mmol) and 3-fluorobenzoyl chloride (0.13 mL, 1.10 mmol), N 3 -(3-fluorobenzoyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 30c (0.089 g, 55%) was obtained as a white solid after purification on a silica gel column with dichloromethane and crystallization from a chloroform-diethyl ether mixture. M. , CH 2 C À À À À À À CH), 2.38 (t, J ¼ 2.4 Hz, 1H, CH 2 C À À À À À À CH); 13 General procedure for benzylation of N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29: Method A To a suspension of N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29 (0.50 mmol) and potassium hydroxide (1.5 mmol) in anhydrous acetonitrile (35 mL), benzyl bromide (0.55 mmol) was added. The mixture was stirred at 105°C for 4 h or 60°C for 48 h, then the solvent was removed by vacuum evaporation. The residue was suspended in dichloromethane and extracted with water (3 Â 20 mL). The organic phase was dried (MgSO 4 ) and concentrated to give a crude product as a mixture of an alkyne 31a and an allene 43a (50:50). Then purification on a silica gel column with chloroform and crystallization from a chloroform-diethyl ether mixture gave a mixture of 31a and 43a (0.149 g, 53%) and pure 43a (0.026 g, 9%) as a white powder. General procedure for benzylation of N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29: Method B To a suspension of N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29 (0.50 mmol) and anhydrous potassium carbonate (0.50 mmol) in anhydrous DMF (5 mL), substituted benzyl bromide (0.60 mmol) was added. The mixture was stirred at room temperature for 48 h. Then water (10 mL) was added and the mixture was extracted with dichloromethane (3 Â 10 mL). The organic phases were combined, dried (MgSO 4 ), and concentrated. The crude products were purified by chromatography on the silica gel columns and crystallized to give 31aÀd.

According to the general procedure (method B) from N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29 (0.10 g, 0.50 mmol) and benzyl bromide (0.071 mL, 0.60 mmol), the alkyne 31a (0.12 g, 80%) was obtained as colorless needles after column chromatography with dichloromethane and crystallization from a chloroform-diethyl ether mixture. M. According to the general procedure (method B) from N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29 (0.10 g, 0.50 mmol) and 3fluorobenzyl bromide (0.075 mL, 0.60 mmol), the product 31c (0.11 g, 73%) was obtained as a white powder after chromatography on a silica gel column with dichloromethane and 

According to general procedure (method B) from N 1 -(prop-2yn-1-yl)quinazoline-2,4-dione 29 (0.10 g, 0.50 mmol) and 4fluorobenzyl bromide (0.074 mL, 0.60 mmol), the product 31d (0.13 g, 81%) was obtained as a white powder after chromatography on a silica gel column with dichloromethane and crystallization from a chloroform-diethyl ether mixture. M. General procedure for the preparation of 1,2,3-triazoles 32, 33-34aÀd and 35, 36-37aÀd: Method A To a solution of 3-azidopropan-1-ol 27 (0.025 g, 0.25 mmol) in ethanol (3 mL) and H 2 O (1mL), CuSO 4 Â 5H 2 O (0.006g, 0.025 mmol), sodium ascorbate (0.010 g, 0.050 mmol), and N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29 (0.050 g, 0.25 mmol) were added. The mixture was stirred at 45°C for 21 days. After cooling, the solvent was removed by vacuum evaporation. The crude product was purified by crystallization from water to give N 1 -{[1-(3-hydroxypropyl)-1H-1,2,3-triazol-4yl]methyl}quinazoline-2,4-dione 32 (0.065 g, 85%) as colorless needles.

General procedure for the preparation of 1,2,3-triazoles 32, 33-34aÀd and 35, 36-37aÀd: Method B

To a solution of an azide (1.00 mmol) in EtOH (1 mL) and H 2 O (1 mL), CuSO 4 Â 5H 2 O (0.10 mmol), sodium ascorbate (0.20 mmol), and alkynes (1.00 mmol) were added. The suspension was irradiated in the microwave reactor (Plazmatronika RM800, 800 W) at 40À45°C for 30 min. After cooling, the solvent was removed, the residue was suspended in dry chloroform (3 mL), and filtered through a layer of Celite. The solution was concentrated in vacuo and the crude product was purified on a silica gel column with chloroform or chloroform-methanol mixtures (100:1, 50:1 or 25:1, v/v) and crystallized to give the 1,2,3-triazoles 32, 33-34aÀd and 35, 36-37aÀd. According to general procedure (method B) for the preparation of 1,2,3-triazoles from 3-azidopropan-1-ol 27 (0.051 g, 0.50 mmol) and N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 29, the 1,2,3-triazole 32 (0.14 g, 90%) was obtained as colorless needles after crystallization from water. M. According to general procedure (method B) from 3-azidopropan-1-ol 27 (0.051 g, 0.50 mmol) and N 3 -benzoyl-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 30a, the 1,2,3-triazole 33a (0.21 g, 98%) was obtained as a white powder after purification on silica gel with chloroform and crystallization from a chloroform-diethyl ether mixture. M. 

758, 696; 1 H NMR (600 MHz

H 2 O: C, 58.94

31 mmol) and N 3 -(3-fluorobenzoyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 30c (0.10 g, 0.31 mmol), the 1,2,3-triazole 33c (0.12 g, 95%) was obtained as a white powder after purification on silica gel with chloroformmethanol (50:1 to 25:1, v/v) and crystallization from a chloroform-diethyl ether mixture. M.p.: 134À136°C; IR (KBr, cm À1 ) n max : 3549

39 (dt, J ¼ 8.5 Hz, J ¼ 2.1 Hz, 1H), 7.33 (t, J ¼ 7.9 Hz, 1H, H6), 4.49 (t, J ¼ 6.8 Hz, 2H, CH 2 CH 2 CH 2 OH), 3.64 (t, J ¼ 6.8 Hz, 2H, CH 2 CH 2 CH 2 OH), 2.12 (qu

1 to 25:1, v/v) and crystallization from a chloroform-diethyl ether mixture. M.p.: 148À150°C; IR (KBr, cm À1 ) n max : 3546

g, 0.52 mmol) and N 3 -benzyl-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 31a (0.15 g, 0.52 mmol), the 1,2,3-triazole 34a (0.19 g, 96%) was obtained as white needles after purification on silica gel with chloroform-methanol (50:1 to 25:1

41 (s, 2H, CH 2 ), 5.32 (s, 2H, NCH 2 Ph), 4.48 (t

Found: C, 64

-Fluorobenzyl)-N 1 -{[1-(3-hydroxypropyl)-1H-1,2,3-triazol-4-yl]methyl}quinazoline-2,4-dione 34b

-fluorobenzyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 31b (0.14 g, 0.45 mmol), the 1,2,3-triazole 34b (0.18 g, 97%) was obtained as a white powder after purification on silica gel with chloroform and crystallization from a chloroform-diethyl ether mixture. M.p.: 121À123°C; IR (KBr, cm À1 ) n max : 3399

CH 2 CH 2 CH 2 OH), 3.64 (t, J ¼ 6.4 Hz, 2H, CH 2 CH 2 CH 2 OH), 2.12 (qu, J ¼ 6.4 Hz, 2H, CH 2 CH 2 CH 2 OH), 1.96 (s, 1H, OH); 13 C NMR (151 MHz

32 mmol) and N 3 -(3-fluorobenzyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 31c (0.100 g, 0.32 mmol), the 1,2,3-triazole 34c (0.12 g, 94%) was obtained as a white powder after purification on silica gel with chloroform and crystallization from a chloroform-diethyl ether mixture. M.p.: 83À85°C; IR (KBr, cm À1 ) n max : 3417

43 (s, 2H, CH 2 ), 5.30 (s, 2H, NCH 2 Ph), 4.50 (t, J ¼ 6.5 Hz, 2H, CH 2 CH 2 CH 2 OH), 3.65 (t, J ¼ 6.5 Hz, 2H, CH 2 CH 2 CH 2 OH), 2.12 (qu, J ¼ 6.5 Hz, 2H, CH 2 CH 2 CH 2 OH), 1.79 (s, 1H, OH); 13 C NMR (151 MHz

CDCl 3 ): d ¼ 162.31 (d, J ¼ 245.9 Hz, C4 0 ), 161.70 (s, C --O)

90%) was obtained as a white powder after purification on silica gel with chloroform and crystallization from a chloroform-diethyl ether mixture. M.p.: 203À205°C; IR (KBr, cm À1 ) n max : 3043, 2960, 1682, 1608, 1501, 1482, 1403; 1 H NMR (600 MHz

CDCl 3 ): d ¼ 168.66 (s, C --O)

-fluorobenzoyl)-quinazoline-2,4-dione 36b

According to general procedure (method B) from (3-azidopropoxy)methylbenzene 28 (0.065 g, 0.34 mmol) and N 3 -(2-fluorobenzoyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 30b (0.11 g, 0.34 mmol), the product 36b (0.16 g, 92%) was obtained as a white powder after purification on silica gel with chloroform and crystallization from a chloroformdiethyl ether mixture

cm À1 ) n max : 3035

61 (s, 1H, HC5 0 ), 7.36À7.29 (m, 7H), 7.11 (dd, J ¼ 8.4 Hz, 1H), 5.43 (s, 2H, CH 2 ), 4.48À4.46 (m, 4H, NCH 2 Ph, NCH 2 CH 2 CH 2 OBn), 3.46 (t, J ¼ 6.4 Hz, 2H, NCH 2 CH 2 CH 2 OBn), 2.19 (qu, J ¼ 6.4 Hz, 2H, NCH 2 CH 2 CH 2 OBn)

1H-1

According to general procedure (method B) from (3-azidopropoxy)methylbenzene 28 (0.080 g, 0.42 mmol) and N 3 -(3-fluorobenzoyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2

42 mmol), the 1,2,3-triazole 36c (0.20 g, 93%) was obtained as a white powder after purification on silica gel with chloroform and crystallization from a chloroformdiethyl ether mixture

cm À1 )

41 (s, 2H, CH 2 ), 4.48À4.46 (m, 4H, NCH 2 Ph, NCH 2 -CH 2 CH 2 OBn), 3.46 (t, J ¼ 6.4 Hz, 2H, NCH 2 CH 2 CH 2 OBn), 2.19 (qu, J ¼ 6.4 Hz, 2H, NCH 2 CH 2 CH 2 OBn); 13 C NMR (151 MHz

1H-1

CDCl 3 ): d ¼ 167.45 (s, C --O), 166.99 (d, J ¼ 258.6 Hz, C4 0 ), 161.08 (s, C --O)

H 2 O: C, 64.91

17 mmol) and N 3 -benzyl-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 31a (0.050 g, 0.17 mmol), the 1,2,3-triazole 37a (0.076 g, 91%) was obtained as a white powder after purification on silica gel with chloroformmethanol (100:1 to 50:1, v/v) and crystallization from a chloroform-diethyl ether mixture. M.p.: 143À145°C; IR (KBr, cm À1 ) n max : 3138

40 (s, 2H, CH 2 ), 5.31 (s, 2H, NCH 2 Ph), 4.46 (s, 2H, OCH 2 Ph), 4.45 (t, J ¼ 6.8 Hz, 2H, NCH 2 CH 2 CH 2 OBn), 3.45 (t

H 2 O: C, 69

According to general procedure (method B) from (3-azidopropoxy)methylbenzene 28 (0.062 g, 0.32 mmol) and N 3 -(2-fluorobenzyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 31b (0.10 g, 0.32 mmol), pure product 37b (0.15 g, 90%) was obtained as a white solid after purification on silica gel with chloroform and crystallization from a chloroform-diethyl ether mixture

41 (s, 4H, CH 2 , OCH 2 Ph), 4.46À4.45 (m, 4H, NCH 2 Ph, NCH 2 CH 2 CH 2 OBn), 3.45 (t, J ¼ 6.4 Hz, 2H, NCH 2 CH 2 CH 2 OBn), 2.18 (qu, J ¼ 6.4 Hz, 2H, NCH 2 CH 2 CH 2 OBn); 13 C NMR (151 MHz

1H-1

According to general procedure (method B) from (3-azidopropoxy)methylbenzene 28 (0.062 g, 0.32 mmol) and N 3 -(3-fluorobenzyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 31c (0.10 g, 0.32 mmol), the 1,2,3-triazole 37c (0.15 g, 91%) was obtained as a white solid after purification on silica gel with chloroform and crystallization from a chloroform-diethyl ether mixture

NCH 2 CH 2 CH 2 OBn), 3.46 (t, J ¼ 6.2 Hz, 2H, NCH 2 CH 2 CH 2 OBn), 2.18 (qu, J ¼ 6.2 Hz, 2H, NCH 2 CH 2 CH 2 OBn); 13 C NMR (151 MHz

1H-1

32 mmol) and N 3 -(4-fluorobenzyl)-N 1 -(prop-2-yn-1-yl)quinazoline-2,4-dione 31d (0.10 g, 0.32 mmol), the 1,2,3-triazole 37d (0.15 g, 95%) was obtained as a white solid after purification on silica gel with chloroform and crystallization from a chloroform-diethyl ether mixture. M.p.: 96À97°C; IR (KBr, cm À1 ) n max : 3331

NCH 2 CH 2 CH 2 OBn), 3.46 (t, J ¼ 6.2 Hz, 2H, NCH 2 CH 2 CH 2 OBn), 2.18 (qu, J ¼ 6.2 Hz, 2H, NCH 2 CH 2 CH 2 OBn); 13 C NMR (151 MHz

Modified Nucleosides in Biochemistry

Antiviral Nucleosides: Chiral Synthesis and Chemotherapy

3-Triazole Nucleosides Archiv der Pharmazie

Nucleosides Nucleotides Nucleic Acids

Klepet a rov a

3-Triazole Nucleosides Archiv der Pharmazie

The authors have declared no conflict of interest.

 50 or concentration required reducing virus-induced cytopathogenicity or viral plaque (VZV) formation by 50%. The minimal cytotoxic concentration (MCC) of the compounds was defined as the compound concentration that caused a microscopically visible alteration of cell morphology. Alternatively, cytotoxicity of the test compounds was measured based on inhibition of cell growth. HEL cells were seeded at a rate of 5 Â 10 3 cells/ well into 96-well microtiter plates and allowed to proliferate for 24 h. Then, medium containing different concentrations of the test compounds was added. After 3 days of incubation at 37°C, the cell number was determined with a Coulter counter. The cytostatic concentration was calculated as the CC 50 , or the compound concentration required reducing cell proliferation by 50% relative to the number of cells in the untreated controls.