Synthesis and characterization of novel 1,2,3-triazole-linked ... - NOPR

Indian Journal of Chemistry Vol. 53B, March 2014, pp. 311-318

Synthesis and characterization of novel 1,2,3-triazole-linked theophylline and coumarin s-triazines Penny Joshia,b, Mohit Tripathia & Diwan S Rawata* a

Department of Chemistry, University of Delhi, Delhi 110 007, India

b

Department of Chemistry, Kumaun University, Nainital 263 001, India E-mail: [email protected] Received 4 June 2013; accepted (revised) 31 October 2013

A series of novel s-triazine-1,2,3-triazole-theophylline and s-triazine-1,2,3-triazole-coumarin generation-0 dendrimers has been synthesized and characterized by FT-IR, 1H and 13C NMR, and mass-spectral methods. Some selected compounds have been evaluated for antibacterial and antifungal activity against a variety of strains and for anti-cancer activity against 60 human cancer cell lines. Keywords: s-Triazine, dendrimer, triazole, theophylline, coumarin

Among the heterocycles, triazines have played an important role in medicinal chemistry. This class of compounds was first recognized in the early 1960s for their herbicidal activity1 and from thereon, 1,3, 5-triazine (s-triazine) derivatives have been extensively studied and found to exhibit a variety of biological activities such as anti-protozoal2-4, anticancer5,6, estrogen receptor modulator7, antimalarial8,9, cyclin-dependent kinase inhibitory10, and antiviral activity11 including anti-HIV activity12. It has also been reported that s-triazine derivatives also possess potent anti-bacterial activity against gram positive and gram negative bacteria13,14. Melarsoprol (II), a triazine based arsenic containing compound is quite effective for the treatment of chronic African trypanosomiasis (Figure 1)15,16. Triazine based compounds have distinct advantages like synthetic versatility, higher yields and up-scalability, well-defined structures, high stability, possible functionalization aiding post-synthetic manipulation, and appropriate toxicity profiles17-19 that make them suitable candidates for developing dendrimer based novel drug delivery systems17. Drug delivery using dendrimers involves either the covalent or non-covalent association with the drug by utilizing multivalent sites on the surface of the dendrimer17. The latter mode comprises a variety of physicochemical interactions such as hydrogen-bonding, electrostatic interactions, van der Waals forces, and hydrophobic interactions17. Typically, triazine dendrimers involve the covalent mode of drug

association to circumvent the problem of low-drug loadings that would otherwise result if non-covalent strategies were used, particularly for hydrophobic drugs. Thus, hydrophobic anticancer drugs such as doxorubicin, paclitaxel, and camptothecin have been attached covalently to the triazine dendrimers for drug delivery17. Coumarins and xanthenes are two different classes of compounds that have been known for their wide range of biological activities. Coumarins are universally found in nature and have attracted considerable attention due to their large variety of biological activities20. Some naturally occurring coumarin antibiotics such as novobiocin (III), coumermycin A1 and chlorobiocin (IV) have been found to possess exceptional activity20 but they are not used clinically due to their poor water-solubility and side effects (Figure 2)21. Similarly, methyl xanthines such as caffeine and theophylline and their derivatives are known to possess biological activities such as bronchodilating agents, cognition enhancers, mild diuretic and anti-bacterial properties22, and there are reports that they may increase the inhibitory effects of antibacterial agents23,24. As part of our ongoing work towards the synthesis of biologically relevant molecules25, herein is reported the synthesis of triazine based generation-0 dendrimers of the coumarin and theophylline moieties with the anticipation that these macromolecules may show better biological activity profile.

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INDIAN J. CHEM., SEC B. MARCH 2014

Figure 1 — Biologically active s-triazines

Figure 2 — Some coumarin-based antibiotics

Results and Discussion Click-chemistry was employed in the synthesis of the 1,2,3-triazole linked coumarin and theophylline s-triazine dendrimers (Scheme I). Firstly, theophylline and 4-hydroxycoumarin were reacted with dibromides, Br-(CH2)n-Br (with n = 2,3,4,5) to give compounds 1a-d and 3a-d respectively. These were subsequently converted to their respective azides 2a-d and 4a-d, by reaction with sodium azide (NaN3) in N,N’-dimethylformamide (DMF) as solvent at RT for 4-6 h. On the other hand, cyanuryl chloride was reacted with excess of propargyl alcohol in presence of K2CO3 and THF under refluxing conditions to give 2,4,6-tris-prop-2-ynyloxy-[1,3,5]triazine 5 and compound 7 was prepared in a similar way from 6, which in turn was synthesized by employing low

temperature (~0ºC) mono-chloro substitution of cyanuryl chloride with aniline (Scheme II). Finally, four sets of triazine based macromolecules were synthesized via the Click reaction of 2a-d with 5; 4a-d with 5; 2a-d with 7; and 4a-d with 7; to yield the respective tris-(theophylline-1,2,3-triazole)s-triazines 8a-d; tris-(coumarin-1,2,3-triazole)s-triazines 9a-d; bis-(theophylline-1,2,3-triazole)s-triazine-anilines 10a-d; and bis-(coumarin-1,2,3-triazole)s-triazin-anilines 11a-d. The reaction was performed regioselectively by employing copper sulfate and sodium ascorbate to give 1,2,3-triazoles through Cu(I)-catalyzed azidealkyne cycloaddition. The synthesized macromolecules were 1 13 characterized by spectral (IR, H NMR and C NMR) methods and some of them were screened for their

JOSHI et al.: THEOPHYLLINE AND COUMARIN s-TRIAZINES 2a-d

Me N

O Me N

+

4a-d

5

O

N ( )n N N N

N N O

O

N N

N N ( )n

Me N N

Na-ascorbate, CuSO4..5H2O H2O, t-BuOH (1:1), 45 oC

O Me

O

O

N

O ( )n N N N O

O

O

N N

O N N N ( )n

O O

N O

O N N N ( )n N

O

5

+


N N

313

N N N ( )n O

8a-d

9a-d O O

N Me N

N Me

O

2a-d

Me N

O Me N

+

4a-d

7

N N


Na-ascorbate, CuSO4..5H2O H2O, t-BuOH (1:1), 45 oC O

N ( )n N N N

O

O

N N

N N N N ( )n

Me N N

7

+

O Me

O

N

O

O ( )n N N N O

O

O

N N

O N N N ( )n

O O

N

HN

HN 10a-d

11a-d

Scheme I — Synthesis of triazole linked coumarin and theophylline s-triazines

antibacterial and antifungal activity against a variety of strains viz. Gram-positive bacteria [S. aureus (MTCC96), S. epidermidis (MTCC435)], Gramnegative bacteria [E. coli DH5α and P. aeruginosa (MTCC434)] and fungal strains [G. candidum, C. galbrata, and C. albicans] at different concentrations. Some of the compounds (8c, 9a) showed moderate antifungal activities (% killing of 83% and 84% respectively) at higher concentrations (250 µM) but these two compounds showed very moderate activity against the bacterial strains. Two representative compounds (8a, 11a) were selected by the US National Cancer Institute’s 60 human cancer cell line (NCI 60) panel for evaluation

of in vitro cytotoxicity and selectivity (differential cytotoxicity) across diverse histologies: leukemia, melanoma, and cancers of lung, colon, kidney, ovary, breast, prostate, and the central nervous system (CNS)26,27. Details of the NCI 60 human tumour cell line screening methodology are described at http://dtp.nci.nih.gov/branches/btb/ivclsp.html. The single dose screening results (at 10 µM concentration of compounds) showed that various cancer cell lines were largely insensitive to the compounds with no appreciable killing or growth-inhibition. However, interestingly, highly selective growth inhibition was observed against UO-31 (renal cancer) and UACC-257 (melanoma) cell lines by both the


314 O

H3C O

N N CH3

O

H N

Br(CH2)nBr

N

K2CO3, DMF

H3C O

n = 2,3,4,5

O

( )nBr NaN3, DMF N

N

H3C

rt, 4-6 hrs

N N CH3

O

1a-d

Br ( )n

O

N N CH3

O

Br(CH2)nBr O

N

2a-d

O

OH

( )nN3 N

N3 ( )n

NaN3, DMF

K2CO3, DMF

O

O

rt, 4-6 hrs

O

O

n = 2,3,4,5 4a-d

3a-d

O

O

N N

N O

OH

Cl N

K2CO3, THF reflux

Cl

N N

PhNH2,NaHCO3 THF, 0 oC

Cl

5

Cl

Cl

N N

HN

N

OH

O N

K2CO3, THF reflux

6

N

O N

HN

7

Scheme II — Synthesis of precursors for Azide-Alkyne cycloaddition reaction

compounds. Furthermore, it was observed that 8a also inhibited TK-10 (renal cancer) and SNB-75 (CNS cancer) while 11a inhibited NCI-H522 (non-small lung cancer) cell line (Table I). Experimental Section All the chemicals used in the synthesis were purchased from Sigma-Aldrich and were used as recieved. Thin layer chromatography was used to monitor the progress of the reactions. Melting points were determined in an open-capillary melting point apparatus and are uncorrected. IR (KBr) and IR (Nujol) spectra were recorded using Perkin-Elmer FT-IR spectrophotometer and the values are expressed as νmax cm−1. Mass spectral data were recorded on a Jeol (Japan) JMS-DX303 micromass LCT, Mass Spectrometer/Data system. The 1H NMR spectra were recorded on Bruker Spectrospin spectrometer at 400 MHz, 300 MHz, 200 MHz and 60 MHz and 13C NMR were recorded on Bruker Spectrospin spectrometer at 100 MHz, 75 MHz and 50.32 MHz respectively using TMS as an internal standard. Synthesis of 2,4,6-tris-prop-2-ynyloxy-[1,3,5]triazine, 5. Propargyl alcohol (4.5 mL) was added slowly to a suspension of cyanuric chloride (1.00 g, 5.4 mmol) in 15 mL THF at RT followed by K2CO3

(2.99 g, 21.6 mmol). Reaction was stirred at 80°C for 14 h. The reaction mixture was filtered, excess of solvent was removed and the residue was dissolved in 50 mL CHCl3 and washed multiple times with water followed by brine solution. The chloroform layer was dried over anhydrous Na2SO4 and excess of solvent was removed under vacuum to give 5 as a white solid, which was purified by crystallization from ethanol. Yield 1.15 g (87%); m.p. 69°C; IR (Film): 3270, 2999, 2938, 2131, 1571, 1451, 1416, 1332, 1272, 1135 cm-1; 1H NMR (60 MHz, CDCl3): δ 2.65 (t, 3H, 3 × CH), 5.20 (d, 6H, 3 × CH2); ESI-MS: m/z 244.1 (M++H). Synthesis of 4,6-dichloro-N-phenyl-1,3,5-triazin2-amine, 6. A suspension of cyanuric chloride (2.00 g, 10.84 mmol) was stirred with aniline (1.00 mL, 10.84 mmol) in THF (40 mL), and NaHCO3 (2.73 g, 32.40 mmol) was added to maintain the pH of 6.6-7.0 for 1-2 h at 0-5°C. The product was isolated by filtration and washed with ice cold water to yield 6. Yield 81%; m.p. 198°C; IR (Nujol): 3350, 1610, 1552, 1514, 1390, 1324, 1218, 1511, 1018, 868, 751 cm-1; 1 H NMR (60 MHz, CDCl3): δ 7.50-7.80 (m, 5H, Ph), 8.00 (brs, 1H, NH); ESI-MS: m/z 241.1 (M++H). Synthesis of benzyl-(4,6-bis-prop-2-ynyloxy[1,3,5]triazin-2-yl)-amine, 7. Propargyl alcohol (0.9 mL, 15.67 mmol) was added slowly to a suspension of

JOSHI et al.: THEOPHYLLINE AND COUMARIN s-TRIAZINES

Table I — Single dose in vitro screening results of compounds 8a and 11a against NCI-60 DTP Human Tumor Cell Lines Panel at 10µM concentration Cancer Cell Line Leukemia CCRF-CEM HL-60(TB) K-562 MOLT-4 RPMI-8226 SR Non-Small Cell Lung Cancer A549/ATCC HOP-62 NCI-H226 NCI-H23 NCI-H322M NCI-H460 NCI-H522 Colon Cancer COLO 205 HCC-2998 HCT-116 HCT-15 HT29 KM12 SW-620 CNS Cancer SF-268 SF-295 SF-539 SNB-19 SNB-75 U251 Melanoma MALME-3M M14 MDA-MB-435 SK-MEL-28 UACC-257 UACC-62 Ovarian Cancer IGROV1 OVCAR-3 OVCAR-4 OVCAR-5 OVCAR-8 NCI/ADR-RES SK-OV-3 Renal Cancer 786-0 A498 ACHN CAKI-1 SN12C TK-10 UO-31 Prostate Cancer PC-3 DU-145 Breast Cancer MCF7 MDA-MB-231/ATCC HS 578T BT-549 T-47D MDA-MB-468

Growth Percent 8a 11a 99.35 95.51 114.54 97.7 106.29 99.1

98.16 94.17 101.63 103.14 101.52 91.71

94.99 122.45 96.18 106.91 107.25 103.42 104.21

101.26 106.41 96.55 102.86 98.05 102.32 81.84

114.58 106.85 101.34 100.6 104.79 108.24 99.1

113.81 127.09 109.88 97.47 103.34 97.53 109.44

102.08 98.66 100.84 106.95 85.09 93.49

98.35 98.58 94.8 99.41 99.17 98.88

92.95 104.21 95.18 99.86 85.49 110.89

96.81 105.26 98.1 107.93 91.39 108.99

105.39 102.01 113.38 96.96 98.99 116.48 113.29

109.87 111.97 113.2 100.07 101.63 121.71 112.91

100.29 105.68 99.77 99.28 103.72 84.96 85.85

101.2 90.81 91.37 96.8 106.93 103.77 83.43

101.56 108.05

103.72 112.62

99.45 123.19 122.97 102.9 109.71 101.49

101.67 123.72 100.98 106.39 103.56 100.16

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benzyl-(4,6-dichloro-[1,3,5]triazin-2-yl)-amine (6, 1.00 g, 3.92 mmol) in THF at RT followed by K2CO3 (2.16 g, 15.67 mmol). Reaction was heated to 60°C overnight and thereafter it was filtered. After evaporation of solvent, the residue was dissolved in CHCl3 and washed with saturated brine solution. The chloroform layer was dried over anhydrous Na2SO4 and excess of solvent was removed under vacuum to give 7 as a white solid, which was purified over SiO2 column. Yield 1.01 g (88%); m.p. 140-41°C; IR (Film): 3295, 3141, 3001, 2131, 1637, 1585, 1556, 1448, 1333, 1118 cm-1; 1H NMR (60 MHz, CDCl3): δ 2.50 (s, 4H, 2 × CH2), 3.15 (s, 1H, NH), 4.25 (t, 2H, 2 × CH), 5.00 (s, 2H, NCH2Ph), 7.40 (s, 5H, Ph). Synthesis of 7,7',7''-((4,4',4''-(((1,3,5-triazine2, 4, 6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3triazole-4,1-diyl))tris(ethane-2,1-diyl))tris(1, 3-dimethyl-1H-purine-2,6(3H,7H)-dione), 8a. To a vigorously stirred solution of 7-(2-azido-ethyl)-1,3dimethyl-3,7-dihydro-purine-2,6-dione (0.31 g, 1.23 mmol) 2a and 2,4,6-tris-prop-2-ynyloxy[1,3,5]triazine (5, 0.10 g, 0.41 mmol) in tert-butanol (5 mL), a solution of CuSO4.5H2O (0.02 g, 0.09 mmol) and sodium ascorbate (0.03 g, 0.16 mmol) in distilled water (5 mL), was added. The resulting deep yellow mixture was stirred vigorously at 45°C and progress of the reaction was monitored by thin layer chromatography. After 10 h, reaction was completed and the crude mixture was extracted with CHCl3 and dried over anhydrous Na2SO4. Excess of solvent was removed under vacuum. The crude reaction mixture was purified over silica-column (60-120 mesh, MeOH/CHCl3 as mobile phase) to yield compound 8a. Yield 0.23 g (58%); m.p. 224°C; IR (KBr): 3449, 3109, 2957, 1703, 1657, 1551, 1475, 1361, 1134, 1027 cm-1; 1H NMR (200 MHz, CDCl3): δ 3.35 (s, 9H, 3 × NCH3), 3.46 (s, 9H, 3 × NCH3), 4.76-4.80 (m, 12H, 3 × CH2CH2), 5.43 (s, 6H, 3 × OCH2), 7.16 (s, 3H, 3 × CH), 7.50 (s, 3H, 3 × CH); 13C NMR (50.32 MHz, CDCl3): δ 28.01 (CH3), 29.82 (CH3), 46.53 (CH2), 50.01 (CH2), 63.84 (OCH2), 106.24 (Cquat), 124.83 (CH), 141.87 (CH), 142.40 (Cquat), 149.28 (Cquat), 151.39 (Cquat), 155.24 (Cquat), 172.52 (Cquat); ESI-MS: m/z 991.4 (M++H). Using the similar procedure, compounds 8b-d and 9a-d were synthesized by reacting 2b-d and 4a-d with 5 respectively. Similarly, 10a-d and 11a-d were synthesized by reacting 2a-d and 4a-d with 7 respectively. Synthesis of 7,7',7''-((4,4',4''-(((1,3,5-triazine2, 4, 6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3triazole-4, 1-diyl))tris(propane-3,1-diyl))tris(1, 3-di-

316


methyl-1H-purine-2,6(3H,7H)-dione), 8b. Yield 69%; m.p. 123°C; IR (KBr): 3449, 3102, 2926, 1669, 1658, 1554, 1418, 1323, 1147, 1028 cm-1; 1H NMR (200 MHz, CDCl3): δ 2.49-2.56 (m, 6H, 3 × CH2CH2CH2), 3.40 (s, 9H, 3 × NCH3), 3.59 (s, 9H, 3 × NCH3), 4.30-4.41 (m, 12H, 3 × CH2CH2CH2), 5.60 (s, 6H, 3 × OCH2), 7.70 (s, 3H, 3 × CH), 7.84 (s, 3H, 3 × CH); ESI-MS: m/z 1033.3 (M++H). Synthesis of 7,7',7''-((4,4',4''-(((1,3,5-triazine2,4,6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3-triazole-4,1-diyl))tris(butane-4,1-diyl))tris(1,3-dimethyl1H-purine-2,6(3H,7H)-dione), 8c. Yield 54%; m.p. 135°C; IR (KBr): 3454, 3113, 2954, 1676, 1687, 1566, 1487, 1323, 1147 cm-1; 1H NMR (200 MHz, CDCl3): δ 1.71-1.81 (m, 12H, 3 × NCH2CH2CH2CH2N), 3.25 (s, 9H, 3 × NCH3), 3.42 (s, 9H, 3 × NCH3), 4.10 (t, 6H, 3 × NCH2CH2CH2CH2N), 4.21 (t, 6H, 3 × NCH2CH2CH2CH2N), 5.42 (s, 6H, 3 × OCH2), 7.39 (s, 3H, 3 × CH), 7.60 (s, 3H, 3 × CH); ESI-MS: m/z 1075.6 (M++H). Synthesis of 7,7',7''-((4,4',4''-(((1,3,5-triazine2,4,6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3-triazole-4,1-diyl))tris(pentane-5,1-diyl))tris(1,3-dimethyl1H-purine-2,6(3H,7H)-dione), 8d. Yield 49%; m.p. 155-56°C; IR (KBr): 3450, 3108, 2957, 1705, 1656, 1551, 1456, 1412, 1321, 1131 cm-1; 1H NMR (300 MHz, CDCl3): δ 1.15-1.25 (m, 12H, 3 × CH2CH2CH2), 1.50-1.75 (m, 6H, 3 × CH2 (CH2)2CH2CH2), 3.35 (s, 9H, 3 × NCH3), 3.46 (s, 9H, 3 × NCH3), 4.50-5.00 (m, 12H, 3 × NCH2(CH2)2CH2CH2N), 5.43 (s, 6H, 3 × OCH2), 7.16 (s, 3H, 3 × CH), 7.50 (s, 3H, 3 × CH); ESI-MS: m/z 1117.3 (M++H). Synthesis of 4,4',4''-(((4,4',4''-(((1,3,5-triazine2,4,6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3-triazole-4, 1-diyl))tris(ethane-2,1-diyl))tris(oxy))tris(2Hchromen-2-one), 9a. Yield 69%; m.p. 155°C; IR (KBr): 3449, 3089, 2957, 1718, 1626, 1569, 1414, 1364 cm-1; 1H NMR (200 MHz, CDCl3): δ 4.49 (t, J = 6Hz, 6H, 3 × CH2CH2O), 4.86 (t, J = 6Hz, 6H, 3 × CH2CH2O), 5.52 (s, 6H, 3 × OCH2), 5.62 (s, 3H, 3 × CH), 7.22-7.25 (m, 6H), 7.60-7.64 (m, 6H), 7.83 (s, 3H, 3 × CH); ESI-MS: m/z 937.2 (M++H). Synthesis of 4,4',4''-(((4,4',4''-(((1,3,5-triazine2,4,6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3-triazole-4,1-diyl))tris(propane-3,1-diyl))tris(oxy))tris(2Hchromen-2-one), 9b. Yield 65%; m.p. 110°C; IR (KBr): 3447, 3088, 2955, 1718, 1623, 1563, 1415, 1362, 1239, 1139 cm-1; 1H NMR (200 MHz, CDCl3): δ 2.50 (quintet, 6H, 3 × CH2CH2O), 4.11 (t, J = 6 Hz,

6H, 3 × CH2CH2CH2O), 4.58 (t, J = 6Hz, 6H, 3 × CH2CH2CH2O), 5.47 (s, 6H, 3 × OCH2), 5.54 (s, 3H, 3 × CH), 7.24-7.25 (m, 6H), 7.44-7.52 (m, 3H), 7.627.63 (m, 3H), 7.79 (s, 3H, 3 × CH); ESI-MS: m/z 979.2 (M++H). Synthesis of 4,4',4''-(((4,4',4''-(((1,3,5-triazine2,4,6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3-triazole-4,1-diyl))tris(butane-4,1-diyl))tris(oxy))tris(2Hchromen-2-one), 9c. Yield 46%; m.p. 66°C; IR (KBr): 3448, 3088, 2952, 1717, 1622, 1563, 1414, 1364, 1322, 1239 cm-1; 1H NMR (300 MHz, CDCl3): δ 1.80-2.09 (m, 6H, 3 × CH2CH2O), 2.17-2.22 (m, 6H, 3 × NCH2CH2), 4.16 (t, J = 6Hz, 6H, 3 × NCH2CH2), 4.50 (t, J = 6Hz, 6H, 3 × CH2CH2O), 5.59 (s, 6H, 3 × OCH2), 5.66 (s, 3H, 3 × CH), 7.25-7.79 (m, 12H), 7.85 (s, 3H, 3 × CH); ESI-MS: m/z 1021.2 (M++H). Synthesis of 4,4',4''-(((4,4',4''-(((1,3,5-triazine2,4,6-triyl)tris(oxy))tris(methylene))tris(1H-1, 2, 3-triazole-4, 1-diyl))tris(pentane-5,1-diyl))tris(oxy))tris(2Hchromen-2-one), 9d. Yield 53%; m.p. 112°C; IR (KBr): 3450, 3090, 2958, 1718, 1622, 1563, 1419, 1364, 1237 cm-1; 1H NMR (200 MHz, CDCl3): δ 1.862.01 (m, 18H, 3 × CH2CH2CH2CH2O), 4.06 (t, J = 6Hz, 6H, 3 × NCH2CH2), 4.36 (t, J = 6Hz, 6H, 3 × CH2CH2O), 5.50 (s, 6H, 3 × OCH2), 5.58 (s, 3H, 3 × CH), 7.45-7.48 (m, 6H), 7.68-7.70 (m, 6H), 7.72 (s, 3H, 3 × CH); ESI-MS: m/z 1063.7 (M++H). Synthesis of 7,7'-(2,2'-(4,4'-(6-(benzylamino)1, 3, 5-triazine-2,4-diyl)bis(oxy)bis(methylene)bis(1H1, 2, 3-triazole-4,1-diyl))bis(ethane-2,1-diyl)bis(1, 3-dimethyl-1H-purine-2,6(3H,7H)-dione), 10a. Yield 74%; m.p. 116°C; IR (KBr): 3423, 2926, 2957, 1703, 1657, 1582, 1547, 1458, 1227, 1120 cm-1; 1H NMR (300 MHz, CDCl3): δ 3.42 (s, 6H, 2 × NCH3), 3.53 (s, 6H, 2 × NCH3), 4.62 (d, 2H, NCH2Ph), 4.75-5.00 (m, 8H, 2 × CH2CH2), 5.42 (d, 4H, 2 × OCH2), 6.39 (bs, 1H, NH), 7.19-7.34 (m, 5H), 7.36 (s, 2H, 2 × CH), 7.51 (s, 2H, 2 × CH); ESI-MS: m/z 793.1 (M++H). Synthesis of 7,7'-(3,3'-(4,4'-(6-(benzylamino)1, 3, 5-triazine-2,4-diyl)bis(oxy)bis(methylene)bis(1H1,2,3-triazole-4,1-diyl))bis(propane-3,1-diyl))bis(1,3dimethyl-1H-purine-2,6(3H,7H)-dione), 10b. Yield 48%; m.p. 115-18°C; IR (KBr): 3423, 2953, 1703, 1658, 1581, 1447, 1323, 1124, 1027 cm-1; 1H NMR (200 MHz, CDCl3): δ 2.40-2.60 (m, 4H, 2 × CH2CH2CH2), 3.42 (s, 6H, 2 × NCH3), 3.60 (s, 6H, 2 × NCH3), 4.20-4.45 (m, 8H, 2 × CH2CH2CH2), 4.69 (d, 2H, NCH2Ph), 5.54 (d, 4H, 2 × OCH2), 5.83 (s, 1H, NH), 7.32 (s, 5H), 7.69 (s, 2H, 2 × CH), 7.78 (s, 2H, 2 × CH); ESI-MS: m/z 821.2 (M++H).

JOSHI et al.: THEOPHYLLINE AND COUMARIN s-TRIAZINES

Synthesis of 7,7'-(4,4'-(4,4'-(6-(benzylamino)1, 3, 5-triazine-2,4-diyl)bis(oxy)bis(methylene)bis(1H1,2,3-triazole-4,1-diyl))bis(butane-4,1-diyl))bis(1,3dimethyl-1H-purine-2,6(3H,7H)-dione), 10c. Yield 0.14 g (48%); m.p. 54°C; IR (KBr): 3426, 2957, 2926, 1704, 1658, 1581, 1459, 1323, 1115, 1025 cm-1; 1 H NMR (200 MHz, CDCl3): δ 1.81-1.93 (m, 8H, 4 × CH2), 3.34 (s, 6H, 2 × NCH3), 3.52 (s, 6H, 2 × NCH3), 4.14-4.32 (m, 8H, 2 × NCH2CH2CH2CH2N), 4.59 (d, 2H, NCH2Ph), 5.45 (d, 4H, 2 × OCH2), 5.85 (s, 1H, NH), 7.25 (s, 5H), 7.48 (s, 2H, 2 × CH), 7.61 (s, 2H, 2 × CH); ESI-MS: m/z 849.3 (M++H). Synthesis of 7,7'-(5,5'-(4,4'-(6-(benzylamino)1, 3, 5-triazine-2,4-diyl)bis(oxy)bis(methylene)bis(1H1, 2, 3-triazole-4,1-diyl))bis(pentane-5,1-diyl))bis(1,3dimethyl-1H-purine-2,6(3H,7H)-dione), 10d. Yield 43%; m.p. 140°C; IR (KBr): 3423, 3110, 2956, 1703, 1657, 1583, 1548, 1457, 1227, 1027 cm-1; 1H NMR (200 MHz, CDCl3): δ 1.50-1.65 (m, 12H, 2 × CH2CH2CH2), 3.44 (s, 6H, 2 × NCH3), 3.54 (s, 6H, 2 × NCH3), 4.65 (d, 2H, NCH2Ph), 4.70-4.80 (m, 8H, 2 × CH2CH2CH2), 5.45 (d, 4H, 2 × OCH2), 5.63 (s, 1H, NH), 7.30 (s, 5H), 7.36 (s, 2H, 2 × CH), 7.50 (s, 2H, 2 × CH); ESI-MS: m/z 877.4 (M++H). Synthesis of 4,4'-(2,2'-(4,4'-(6-(benzylamino)1,3,5-triazine-2,4-diyl) bis(oxy)bis(methylene)bis(1H1,2,3-triazole-4,1-diyl))bis(ethane-2,1-diyl))bis(oxy)bis(2H-chromen-2-one), 11a. Yield 53%; m.p. 13638°C; IR (KBr): 3423, 2956, 2367, 1703, 1657, 1457, 1227, 1027 cm-1; 1H NMR (200 MHz, CDCl3): δ 4.424.49 (m, 8H, 2 × CH2CH2O), 4.77 (d, 2H, NCH2Ph), 5.46 (d, 4H, 2 × OCH2), 5.60 (s, 2H, 2 × CH), 5.93 (s, 1H, NH), 7.22-7.24 (m, 5H), 7.47 (s, 2H, 2 × CH), 7.58-7.70 (m, 8H); ESI-MS: m/z 757.4 (M++H). Synthesis of 4,4'-(3,3'-(4,4'-(6-(benzylamino)1, 3, 5-triazine-2,4-diyl)bis(oxy)bis(methylene)bis(1H1,2,3-triazole-4,1-diyl))bis(propane-3,1-diyl))bis(oxy)bis(2H-chromen-2-one), 11b. Yield 46%; m.p. 9798°C; IR (KBr): 3443, 2957, 2332, 1712, 1645, 1345, 1227, 1127 cm-1; 1H NMR (200 MHz, CDCl3): δ 2.302.60 (m, 4H, 2 × CH2CH2O), 4.12 (t, 4H, 2 × CH2CH2CH2O), 4.45-4.60 (m, 4H, 2 × CH2CH2CH2O), 4.61 (d, 2H, NCH2Ph), 5.45 (d, 4H, 2 × OCH2), 5.60 (s, 2H, 2 × CH), 5.83 (s, 1H, NH), 7.30 (s, 5H), 7.40 (s, 2H, 2 × CH), 7.45-7.85 (m, 8H); ESI-MS: m/z 785.1 (M++H). Synthesis of 4,4'-(4,4'-(4,4'-(6-(benzylamino)1, 3, 5-triazine-2,4-diyl)bis(oxy)bis(methylene)bis(1H1,2,3-triazole-4,1-diyl))bis(butane-4,1-diyl))bis(oxy)bis(2H-chromen-2-one), 11c. Yield 0.19 g (70%); m.p. 250°C; IR (KBr): 3426, 2926, 2365, 1718, 1622,

317

1324, 1109 cm-1; 1H NMR (200 MHz, CDCl3): δ 1.801.90 (m, 4H, 2 × CH2CH2O), 2.05-2.20 (m, 4H, 2 × NCH2CH2), 4.08 (t, 4H, 2 × CH2CH2CH2O), 4.304.45 (m, 4H, 2 × CH2CH2CH2O), 4.59 (d, 2H, NCH2Ph), 5.47 (d, 4H, 2 × OCH2), 5.59 (s, 2H, 2 × CH), 5.81 (s, 1H, NH), 7.19-7.22 (m, 5H), 7.48-7.54 (m, 4H), 7.54-7.69 (m, 4H), 7.70 (s, 2H, 2 × CH); ESI-MS: m/z 813.3 (M++H). Synthesis of 4,4'-(5,5'-(4,4'-(6-(benzylamino)1, 3, 5-triazine-2,4-diyl)bis(oxy)bis(methylene)bis(1H1, 2, 3-triazole-4,1-diyl))bis(pentane-5,1-diyl)bis(oxy)bis(2H-chromen-2-one), 11d. Yield 66%; IR (KBr): 3424, 2927, 2365, 1717, 1625, 1227, 1129 cm-1; 1H NMR (200 MHz, CDCl3): δ 1.44-1.55 (m, 4H, 2 × CH2CH2CH2O), 1.88-1.98 (m, 8H, 2 × NCH2CH2CH2CH2CH2O), 4.04 (t, 4H, 2 × NCH2CH2), 4.25-4.37 (m, 4H, 2 × CH2CH2CH2O), 4.57 (d, 2H, NCH2Ph), 5.43 (d, 4H, 2 × OCH2), 5.57 (s, 2H, 2 × CH), 5.73 (s, 1H, NH), 7.21-7.24 (m, 5H), 7.48 (s, 2H, 2 × CH), 7.61-7.94 (m, 8H); ESI-MS: m/z 841.1 (M++H). Conclusions To summarise, a total of sixteen novel 1,2,3-triazole linked coumarin and theophylline s-triazine based macromolecules were synthesised in good yields with regioselective Cu(I) catalysed Huisgen cycloaddition being the key step to form the triazole linkage between the respective coumarin or theophylline moieties and triazine nucleus. All the compounds were well characterised by IR, 1H and 13 C NMR, and mass spectral methods. Biological activity evaluation of some selected compounds was performed and some compounds (8c, 9a) showed anti-fungal activity at higher concentrations (250 µM) but very moderate anti-bacterial activities. Screening results for the two representative compounds (8a, 11a) by NIH 60 cancel cell-line panel showed highly selective inhibitory effects against UO-31 (renal cancer) and UACC-257 (melanoma) cell lines while individually 8a inhibited TK-10 (renal cancer) and SNB-75 (CNS cancer) and 11a inhibited NCI-H522 (non-small lung cancer) cell lines. Acknowledgement DSR thanks the University Grants Commission (41-202/2012(SR)), New Delhi, India and University of Delhi, Delhi, India for financial support. MT is thankful to DST for the award of INSPIRE-JRF. The authors thank USIC-CIF, University of Delhi for analytical data.

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