Chinese Chemical Letters  2014, Vol.25 Issue (11):1469-1472   PDF    
Synthesis and biological activities of dithiocarbamates containing 1,2,3-triazoles group
Qing-Han Li , Yong Ding, Neng-Wang Huang    
College of Chemistry and Environmental Protection Engineering, Southwest University for Nationalities, Chengdu 610041, China
Abstract: Twelve novel dithiocarbamates containing 1,2,3-trizaoles group were prepared via one step starting from organic halides, dithiocarbamic acid prop-2-ynyl ester, and sodium azide, using a very simple catalytic system composed of copper(Ⅰ) chloride and water at 70℃. The structures of the new compounds were characterized and screened for their in vitro anti-tumor. Four of the compounds displayed varying levels of anti-tumor activity against the CDC25B.
Key words: Dithiocarbamates     1,2,3-Trizaoles     Synthesis     Antitumor activity    
1. Introduction

Organic dithiocarbamates have received considerable attention due to their numerous biological activities [1, 2, 3] and their pivotal role in agriculture [4, 5, 6]. They have often been used as protection groups in peptide synthesis [7],as linkers in solid-phase organic synthesis [8, 9],and recently in the synthesis of ionic liquids [10]. Because they have a strong metal binding capacity,they also can act as inhibitors of enzymes and have a profound effect on biological systems. Furthermore,dithiocarbamates are also widely used in medicinal chemistry and have been used in cancer treatment [11, 12, 13]. Therefore,the synthesis of dithiocarbamates has attracted a lot of attention recently.

1,2,3-Trizaole and its derivatives have attracted interest over the past few years as they have been widely used in pharmaceuticals,agrochemicals,dyes,photographic materials,corrosion inhibition,etc. [14]. They are also associated with a wide range of biological properties such as antiviral,antiepileptic,antiallergic [15],anticancer [16, 17],anti HIV [18],and antimicrobial activities against gram positive bacteria [19]. In general,1,2,3-trizaoles compounds are prepared through the reaction between alkynes and azides at high temperatures [20, 21, 22],and by using solid supports [23]. In recent years,several different methods have been reported for the synthesis of trizaoles [24, 25, 26, 27, 28, 29, 30, 31, 32]. As a result,the numerous 1,2,3-trizaole and its derivatives were synthesized. Although there have been a lot of reports about the syntheses of 1,2,3-trizaoles and their pharmacological properties [33, 34, 35, 36, 37], insufficient efforts have been made to study dithiocarbamates containing 1,2,3-trizaoles group and their biological activities.

Thus,on the basis of the above findings,and in order to discover new dithiocarbamates with broad spectrum and good activities and to explore the relationship between their structures and biological activities,herein we wish to report the design,synthesis and bioactive evaluation for a series of novel dithiocarbamates containing 1,2,3-trizaoles group. To the best of our knowledge,this is the first report on the synthesis of dithiocarbamates containing 1,2,3-trizaoles group and their applications. 2. Experimental

Melting points were determined with an XRC-1 micro melting point apparatus and uncorrected. IR spectra were determined as KBr pellets on an FT-IR169 spectrophotometer. 1H NMR spectra were recorded using a Varian 400 MHz spectrometer in CDCl3with tetramethylsilane as internal standard. Mass spectra were carried out on a Finnigan MAT-4510 spectrometer (ESI). Elemental analyses were performed on a PE-2400 elemental analyzer. Compounds 1(a-c) were prepared following the reported procedure [38]. Other reagents were commercially available and used as received.

General procedure for the compounds 3(a-l) in water: Under an atmosphere of nitrogen,CuCl (4.95 mg,0.05 mmol),compound 2(1 mmol) and NaN3(72 mg,1.1 mmol) were placed in a 25 mL round-bottomed flask in H2O (4 mL). Sequentially,benzyl halide 1 (1 mmol) was added. The reaction mixture was warmed to 70℃ and monitored by TLC until conversion of the starting materials was satisfactory. After completion of the reaction,water (30 mL) was added to the resulting reaction mixture followed by extraction with EtOAc (10 mL×4). The collected organic phases were dried with Na2SO4,and the solvent was removed under vacuum to give the desired products. The crude product was subjected to flash column chromatography on silica gel (hexane or ethyl acetate/ hexane = 100/1) to afford the corresponding compounds 3(a-l).

Compound 3a. Pale yellow solid,mp 86-87℃; 1H NMR (400 MHz,CDCl3): δ 7.61 (s,1H,trizaole),7.36-7.39 (m,3H, ArH),7.27-7.29 (m,2H,ArH),5.50 (s,2H,NCH2),4.71 (s,2H,SCH2), 4.29 (br,2H,NCH2),3.87 (br,2H,NCH2),1.70 (br,6H,NCH2(CH2)3). IR (KBr,cm-1 ):v3040 (55C-H,Ph),2929 (C-H,CH2),1605,1551, 1481,1452 (C55C,Ph),1222 (C55S). ESI-MS (m/z) (%): 686 [(2M + Na-H)+ ,100],332 [M+ ,7]. Anal. Calcd. for C16H20N4S2:C 57.80,H 6.06,N 16.85; found: C 57.42,H 6.42,N 16.47.

Compound 3b. Pale yellow solid,mp 53-55℃; 1HNMR (400 MHz,CDCl3): δ7.56 (s,1H,trizaole),7.22 (d,2H,J= 6.8 Hz, ArH),6.88 (d,2H,J= 8.4 Hz,ArH),5.41 (s,2H,NCH2),4.67 (s,2H, SCH2),4.27 (br,2H,NCH2),3.82 (br,2H,NCH2),3.80 (s,3H,OCH3), 1.68 (br,6H,NCH2(CH2)3). IR (KBr,cm-1 ):v3031 (55C-H,Ph),2932 (C-H,CH2),1612,1541,1514,1475 (C55C,Ph),1242 (C55S). ESI-MS (m/z) (%): 746 [(2M + Na-H)+ ,100],362 [M+ ,6]. Anal. Calcd. for C17H22N20S2: C 56.32,H 6.12,N 15.46; found: C 56.41,H 6.43,N 15.31.

Compound 3c. Pale yellow solid,mp 67-69℃; 1H NMR (400 MHz,CDCl3): δ 7.63 (s,1H,trizaole),7.31-7.32 (m,1H, ArH),7.01-7.05 (m,2H,ArH),6.90-6.93 (m,1H,ArH),5.46 (s,2H, NCH2),4.68 (s,2H,SCH2),4.25 (br,2H,NCH2),3.83 (br,2H,NCH2), 1.67 (br,6H,NCH2(CH2)3). IR (KBr,cm-1 ):v3061 (55C-H,Ph),2934 (C-H,CH2),1590,1537,1482,1450 (C55C,Ph),1226 (C55S). ESI-MS (m/z) (%): 722 [(2M + Na-H)+,100],350 [M+ ,5]. Anal. Calcd. for C16H19FN4S2: C 54.83,H 5.46,N 15.99; found: C 54.52,H 5.53,N 15.64.

Compound 3d. Pale yellow solid,mp 75-76℃; 1HNMR (400 MHz,CDCl3): δ 7.67 (s,1H,trizaole),7.44 (d,1H,J= 8.0 Hz, ArH),7.35-7.38 (m,1H,ArH),7.08-7.11 (m,1H,ArH),5.44 (s,2H, NCH2),4.70 (s,2H,SCH2),4.28 (br,2H,NCH2),3.84 (br,2H,NCH2), 3.80 (s,3H,OCH3),1.70 (br,6H,NCH2(CH2)3). IR (KBr,cm-1 ):v3027 (55C-H,Ph),2924 (C-H,CH2),1601,1553,1506,1464 (C55C,Ph), 1220 (C55S). ESI-MS (m/z) (%): 824 [(2M + Na + H) + ,100],402 [M + + 2,10]. Anal. Calcd. for C16H18N4S2: C 47.52,H 4.52,N 13.96; found: C 47.52,H 4.36,N 13.57.

Compound 3e. Pale yellow solid,mp 73-74℃; 1H NMR (400 MHz,CDCl3): δ 7.61 (s,1H,trizaole),7.36-7.39 (m,3H, ArH),7.23-7.25 (m,2H,ArH),5.49 (s,2H,NCH2),4.69 (s,2H,SCH2), 3.93 (t,2H,J= 4.8 Hz,NCH2),3.64 (t,2H,J= 6.4 Hz,NCH2),2.04- 2.11 (m,4H,2NCH2CH2). IR (KBr,cm-1 ):v3048 (55C-H,Ph),2952 (C-H,CH2),1601,1547,1460,1452 (C55C,Ph),1153 (C55S). ESI-MS (m/z) (%): 658 [(2M + Na-H)+ ,100],318 [M+ ,25]. Anal. Calcd. for C15H18N4S2: C 56.57,H 5.70,N 17.59; found: C 56.29,H 5.46,N 17.25.

Compound 3f. Pale yellow solid,mp 73-75℃; 1H NMR (400 MHz,CDCl3): δ 7.60 (s,1H,trizaole),7.23 (d,2H,J= 8.8 Hz, ArH),6.91 (d,2H,J= 8.8 Hz,ArH),5.42 (s,2H,NCH2),4.68 (s,2H, SCH2),3.93 (t,2H,J= 6.8 Hz,NCH2),3.82 (s,3H,OCH3),3.64 (t,2H, J= 6.4 Hz,NCH2),1.95-2.11 (m,4H,2NCH2CH2). IR (KBr,cm-1 ):v 3067 (55C-H,Ph),2923 (C-H,CH2),1610,1559,1511 (C55C,Ph), 1245 (C55S). ESI-MS (m/z) (%): 370 [(M + Na + H) +,100],348 [M+ ,4]. Anal. Calcd. for C16H20N4OS2: C 55.14,H 5.78,N 16.08; found: C 55.32,H 5.55,N 16.33.

Compound 3g. Pale yellow solid,mp 82-83℃; 1H NMR (400 MHz,CDCl3): d 7.65 (s,1H,trizaole),7.32-7.37 (m,1H, ArH),7.03-7.08 (m,2H,ArH),6.94-6.98 (m,1H,ArH),5.49 (s,2H, NCH2),4.71 (s,2H,SCH2),3.94 (t,2H,J= 6.4 Hz,NCH2),3.64 (t,2H, J= 6.4 Hz,NCH2),1.96-2.12 (m,4H,2NCH2CH2). IR (KBr,cm-1 ):v 3116 (55C-H,Ph),2964 (C-H,CH2),1610,1589,1504,1436 (C55C, Ph),1249 (C55S). ESI-MS (m/z) (%): 358 [(M + Na-H)+,100],336 [M+ , 7]. Anal. Calcd. for C15H17FN4S2: C 53.55,H 5.09,N 16.65; found: C 53.23,H 5.41,N 16.26.

Compound 3h. Pale yellow solid,mp 100-101 ℃; 1H NMR (400 MHz,CDCl3): δ 7.69 (s,1H,trizaole),7.46 (d,1H,J= 8.4 Hz, ArH),7.37 (s,1H,ArH),7.11 (d,1H,J= 6.4 Hz,ArH),5.45 (s,2H, NCH2),4.71 (s,2H,SCH2),3.94 (t,2H,J=6.8 Hz,NCH2),3.65 (t,2H, J= 6.8 Hz,NCH2),1.96-2.12 (m,4H,2NCH2CH2). IR (KBr,cm-1 ):v 3067 (55C-H,Ph),2923 (C-H,CH2),1598,1558,1466 (C55C,Ph), 1154 (C55S). ESI-MS (m/z) (%): 796 [(2M + Na-H)+ ,100],386 [M+ , 7]. Anal. Calcd. for C15H16Cl2N4S2: C 46.51,H 4.16,N 14.46; found: C 46.42,H 4.35,N 14.31.

Compound 3i. Pale yellow solid,mp 43-45℃; 1H NMR (400 MHz,CDCl3): δ 7.60 (s,1H,trizaole),7.34-7.36 (m,3H, ArH),7.23-7.25 (m,2H,ArH),5.47 (s,2H,NCH2),4.65 (s,2H,SCH2), 4.01 (q,2H,J= 4.2 Hz,CH2CH3),3.70 (q,2H,J= 3.8 Hz,CH2CH3), 1.23-1.26 (m,6H,2CH2CH3). IR (KBr,cm-1 ):v3040 (55C-H,Ph), 2980 (C-H,CH2),1610,1543,1494,1451 (C55C,Ph),1203 (C=S). ESI-MS (m/z) (%): 662 [(2M + Na-H)+,100],320 [M+ -H,7]. Anal. Calcd. for C15H20N4S2: C 56.22,H 6.29,N 17.48; found: C 56.26,H 6.56,N 17.23.

Compound 3j. Pale yellow solid,mp 86-88℃; 1H NMR (400 MHz,CDCl3): δ 7.56 (s,1H,trizaole),7.22 (d,2H,J= 8.8 Hz, ArH),6.89 (d,2H,J= 8.8 Hz,ArH),5.42 (s,2H,NCH2),4.65 (s,2H, SCH2),4.02 (q,2H,J= 4.4 Hz,CH2CH3),3.81(s,3H,OCH3),3.71 (q, 2H,J= 4.2 Hz,CH2CH3),1.24-1.28 (m,6H,2CH2CH3). IR (KBr, cm-1 ): v3131 (55C-H,Ph),2974 (C-H,CH2),1612,1551,1504, 1452 (C55C,Ph),1256 (C55S). ESI-MS (m/z) (%): 372 [(2M+Na-H)+ , 100],351 [M+ + H,7]. Anal. Calcd. for C16H22N4OS2: C 54.83,H 6.33, N 15.98; found: C 54.35,H 6.53,N 15.43.

Compound 3k. Pale yellow solid,mp 52-53℃; 1H NMR (400 MHz,CDCl3): δ 7.64 (s,1H,trizaole),7.32-7.34 (m,1H, ArH),7.03-7.07 (m,2H,ArH),6.93-6.96 (m,1H,ArH),5.50 (s,2H, NCH2),4.69 (s,2H,SCH2),4.03 (q,2H,J= 4.2 Hz,CH2CH3),3.72 (q, 2H,J= 3.4 Hz,CH2CH3),1.26-1.29 (m,6H,2CH2CH3). IR (KBr, cm-1 ): v3055 (55C-H,Ph),2976 (C-H,CH2),1590,1535,1494, 1451 (C55C,Ph),1203 (C55S). ESI-MS (m/z) (%): 698 [(2M + Na-H)+ , 100],338 [M+ ,10]. Anal. Calcd. for C15H19FN4S2: C 53.23,H 5.66,N 16.55; found: C 53.37,H 5.48,N 16.12.

Compound 3l. Pale yellow solid,mp 61-62℃; 1HNMR (400 MHz,CDCl3): δ 7.68 (s,1H,trizaole),7.46 (d,1H,J= 8.4 Hz, ArH),7.37 (s,1H,ArH),7.11 (d,1H,J= 6.0 Hz,ArH),5.46 (s,2H,NCH2), 4.70 (s,2H,SCH2),4.04 (q,2H,J= 3.2 Hz,CH2CH3),3.81 (s,3H,OCH3), 3.72 (q,2H,J= 3.2 Hz,CH2CH3),1.286-1.30 (m,6H,2CH2CH3). IR (KBr,cm-1 ):v3073 (55C-H,Ph),2974 (C-H,CH2),1557,1481,1453, 1430 (C55C,Ph),1256 (C55S). ESI-MS (m/z) (%): 800 [(2M + Na + H) + , 100],388 [M+ ,7]. Anal. Calcd. for C15H18Cl2N4S2: C 46.27,H 4.66,N 14.39; found: C 46.45,H 4.51,N 14.56. 3. Results and discussion

To investigate the formation of dithiocarbamates containing 1,2,3-trizaoles group,a set of reactions was carried out. Initially,we selected the compound 1a(1 mmol) with benzyl bromide 2a (1 mmol) and NaN3(1.1 mmol) as the model reaction. Treatment of 1a with benzyl bromide (2a) and NaN3in the absence of metal in water at 70℃ did not yield the dithiocarbamates (3a) (Table 1, entry 1). When 5 mol% of CuI was used as the catalyst,the reaction of 1a with benzyl bromide (2a) and NaN3 produced the dithiocarbamates (3a) with 53% yield (Table 1,entry 2). Encouraged by this result,we further investigated other copper salts such as CuBr,CuCl2,CuBr2,Cu,and CuCl for this reaction,and the results are listed in Table 1 (entries 3-6). The desired product 3a was formed in 93% yield in 4 h when 5 mol% of CuCl was used as catalyst (Table 1,entry 7). However,the reaction of 1a with benzyl bromide (2a) and NaN3performed in the presence of 5 mol% of CuCl2or CuBr2did not yield the dithiocarbamates (3a) (Table 1, entries 4,5). To further improve the reactivity,the amount of catalyst and temperature were optimized (Table 1,entries 8-11). It was found that the reaction was sensitive to the amount of catalyst and temperature. When the amount of CuCl was lowered from 5 mol% to 2.5 mol%,there was a drop in the yield (Table 1,entry 8). When the amount of CuCl was increased from 5 mol% to 10 mol%, product 3a yield was not changed (Table 1,entry 9). Nevertheless, further lowering or increasing the reaction temperature dramatically decreased the yield (Table 1,entries 10,11). Extensive screening showed that the optimized conditions were 5 mol% CuCl, 1.0 mmol 1a,1.0 mmol 2a,and 1.1 mmol NaN3in water at 70℃ (Table 1,entry 7).

Table 1
Effect of the catalyst and temperature in the reaction of compounds1awith benzyl bromide 2aand NaN3 a

Using the optimized conditions (Table 1,entry 7),the substrate scope of this reaction was then examined (Table 2). Compounds 1(a-c)reacted with a series of benzyl halide 2(a-d) and NaN3in water at 70℃ smoothly to provide the corresponding products 3(a-l) in good to excellent yields (78%-94%,Table 2,entries 1-12). From Table 2,it was found that the reaction was not significantly affected by the electronic properties of the substituent on the aromatic ring of the benzyl halide,both electron-rich (Table 2, entries 2,6,10) and electron-deficient substituent on the aromatic ring of the benzyl halide were effective (Table 2,entries 3,4,7,8, 11,12). Notably,benzyl chloride and benzyl bromide are all tolerated under the given reaction conditions.

Table 2
CuCl-catalyzed the reaction of compounds 1(a-c) with benzyl halide 2(a-d) and NaN3 a .

The dithiocarbamates containing 1,2,3-trizaoles group 3(a-l) were tested for theirin vitro anti-tumor activity with the CDC25B using the fluorescence spectrometry,the data are listed in Table 3. As shown in Table 3,it has been found that dithiocarbamates 3a, 3d,3h and 3l possess different inhibitory activities against CDC25B (Table 3,entries 1,4,8,12),while compound3dshowed excellent inhibitory activity against CDC25B (Table 3,entry 4). Comparing the structures of compounds 3d with3aand3h,they possess different amino groups and substituents on the aromatic ring of the benzyl halide. So,it shows that a cyclopentyl-amino group is more preferable than a cyclobutyl-amino group,and an electron-deficient substituent on the aromatic ring of the benzyl halide is conducive to enhancing dithiocarbamates3biological activities.

Table 3
he inhibition rates for CDC25B of compounds 3(a-l)in vitro a.
4. Conclusion

In summary,a straightforward synthesis of dithiocarbamates containing 1,2,3-trizaoles group has been successfully introduced from benzyl halides,dithiocarbamic acid prop-2-ynyl ester,and sodium azide,using a very simple catalytic system composed of copper(I) chloride and water at 70℃. Novel dithiocarbamates containing 1,2,3-trizaoles group were screened for their antitumor activities. Some compounds exhibited good inhibitory activity against CDC25B. So,dithiocarbamates containing 1,2,3-trizaoles group are valuable for further study. Acknowledgments

The authors are thankful to the National Centre for Drug Screening,Shanghai,China,for evaluating the inhibitory activity against CDC25B. We also thank the Fundamental Research Funds for the Central Universities,Southwest University for Nationalities (No. 12NZYTH03),the Natural Science Foundation of Southwest University for Nationalities (No. 381010),and the Postgraduate Degree Construction Project of Southwest University for Nationalities (No. 2013XWD-S0703) for financial support.

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