农药学学报  2016, Vol. 18 Issue (3): 291-298   PDF    
引用本文
万莹莹, 魏巍, 陈有为, 刘敬波, 程丹丹, 熊丽霞, 于淑晶, 李玉新, 李正名 . 新型含苯并咪唑的(S,S)-2,8-二氮杂双环[4.3.0]壬烷类衍生物的合成及生物活性[J]. 农药学学报, 2016, 18(3): 291-298,doi: 10.16801/j.issn.1008-7303.2016.0040   
WAN Yingying, WEI Wei , CHEN Youwei , LIU Jingbo , CHENG Dandan , XIONG Lixia , YU Shujing , LI Yuxin , LI Zhengming . Synthesis and bioactivity of (S, S)-2,8-diazabicyclo[4.3.0]nonane containing benzimidazole moiety[J]. Chinese Journal of Pesticide Science, 2016, 18(3): 291-298, doi:10.16801/j.issn.1008-7303.2016.0040   
新型含苯并咪唑的(S,S)-2,8-二氮杂双环[4.3.0]壬烷类衍生物的合成及生物活性
万莹莹1, 魏巍1, 陈有为1, 刘敬波1, 程丹丹1, 熊丽霞1, 于淑晶1, 李玉新1,2, 李正名1,2     
1. 南开大学 元素有机化学研究所/元素有机化学国家重点实验室, 天津 300071;
2. 天津化学化工协同创新中心, 天津 300071
收稿日期: 2016-02-02    录用日期: 2016-03-15.
摘要: 通过N-烷基化反应合成了一系列新型含苯并咪唑的(S,S)-2,8-二氮杂双环[4.3.0]壬烷类衍生物，中间体化合物通过环化反应和酰化反应合成得到。所有新型化合物的结构均通过熔点测定、核磁共振氢谱和高分辨质谱确认。生物活性测试结果显示，目标化合物拥有中等的抗植物真菌活性，对东方粘虫Mythimna separata Walker和蚊幼虫Culex pipiens pallens具有中等到良好的杀虫活性。其中化合物6e和6f对油菜菌核Sclerotinia sclerotiorum、马铃薯晚疫Phytophthora infestans、小麦赤霉Fusarium graminearum等真菌具有良好的抗菌活性。化合物6e和6k在200 mg/L下对东方粘虫的致死率为100%，化合物6h和6k在2 mg/L下对蚊幼虫的致死率为75%。
关键词: 苯并咪唑     (S,S)-2,8- 二氮杂双环 [4.3.0] 壬烷     抗真菌活性     杀虫活性    
Synthesis and bioactivity of (S, S)-2,8-diazabicyclo[4.3.0]nonane containing benzimidazole moiety
WAN Yingying1, WEI Wei1, CHEN Youwei1, LIU Jingbo1, CHENG Dandan1, XIONG Lixia1, YU Shujing1, LI Yuxin1,2, LI Zhengming1,2     
1. State Key Laboratory of Elemento-organic Chemistry, Institute of Elemento-organic Chemistry, Nankai University,Tianjin 300071, China;
2. Collaborative Innovatiaon Center of Chemical Science and Engineering (Tianjin), Tianjin 300071, China
Received: Feb 2, 2016    Accepted: Mar 15, 2016
Fond project: Project supported by the National Science Foundation of China (No.31370039)
Biography: WAN Yingying, female, master student, E-mail: 1012150289@qq.com *Li Yuxin, author for correspondence, female, Ph. D., associate professor, the research is focus on pesticide chemical, E-mail: liyx128@nankai.edu.cn *Li Zhengming, co-author for correspondence, male, Ph. D., academician, the research is focus on pesticide chemical, E-mail: nkzml@vip.163.com
Abstract: A series of novel (S, S)-2,8- diazabicyclo [4.3.0] nonane containing benzimidazole moiety was synthesized and their structures were determined by 1H NMR and HRMS. The biological activity results showed that these compounds possessed moderate antifungal activity to some plant pathogenous fungi and moderate insecticidal activity against Mythimna separata Walker and Culex pipiens pallens. Compounds 6e and 6f exhibited good antibacterial activity against Sclerotinia sclerotiorum, Phytophthora infestans and Fusarium graminearum. The lethality rates of compounds 6e and 6k against Mythimna separata Walker were 100% at 200 mg/L and the lethality rates of compounds 6h and 6k against C. pippiens pallens were 75% at 2 mg/L.
Key words: (S, S)-2, 8-diazabicyclo[4.3.0]nonane      benzimidazole      antifungal activity      insecticidal activity     

In recent years,due to the increasing resistance of fungi to fungicides,it is necessary to develop new environmentally friendly fungicide. Moxifloxacin is the fourth-generation fluoroquinolone drug with broad-spectrum antifungal activity,good pharmaco- kinetics property,low drug resistance,and safe to use[1-2]. It also has very broad application prospect,and huge market potential[3]. As the branched-chain,(S,S)-2,8-diazabicyclo [4.3.0] nonane is the key intermediate for the synthesis of moxifloxacin. Its special diazabicyclo structure strengthens moxifloxacin’s activity against gram-positive bacteria,and also reduces adverse reaction while keeps the original activity [4].

Heterocyclic compounds with benzimidazole moiety usually showed high biological activity[5-6],including antiparasitic,antiviral,antifungal and anticancer activity. Aromatic heterocyclic ring containing two nitrogen atoms,can form hydrogen bonds with receptors[6-7]. The synthesis of 1-substituted and 2-substituted benzimidazole derivatives has become a hot research topic recently[7-13].

Since (S,S)-2,8- diazabicyclo [4.3.0] nonane and benzimidazole have special nitrogen heterocyclic structures,we designed and synthesized a series of novel hetereocycles with 2,8-diazabicyclo [4.3.0] nonane and benzimidazole moiety by using active substructure splicing method (Scheme 1). The antifungal activity and insecticidal activity of these compounds were also evaluated.

Reagents and conditions:(i)(COCl)2, DMF, CH2Cl2, rt;(ii)ClCH2COOH, HCl, H2O, re- flux, NH3·H2O;(iii)compounds 2a-2k, Et3N, CH2Cl2, 0 ℃; reflux;(iv)(S, S)-2, 8-diazabicyclo [4.3.0] nonane, K2CO3, CH3CN, rt. Scheme1 Synthesis of compounds 6a-6l

1 Materials and methods 1.1 Instruments

All chemicals and reagents were of analytical grade. Reactions were monitored with analytical thin-layer chromatography (TLC). The melting points were determined on an X-4 binocular microscope melting point apparatus (Beijing Tech Instruments Co.,Beijing,China) and were uncorrected. 1H NMR spectra were recorded at 400 MHz on a Bruker AV 400 spectrometer in a CDCl3 solution with tetrame- thylsilane as the internal standard. High resolution mass spectrometry (HRMS) data were obtained on a Varian QFT-ESI instrument.

1.2 Synthetic procedures 1.2.1 General procedure for synthesis of compounds 2b-2k

To a solution of acid 1 (10 mmol) and oxalyl chloride (20 mmol) in dry CH2Cl2 (20 mL),0.1 mL DMF was added. The mixture was stirred at room temperature for 4 h. The reaction mixture was concentrated under reduced pressure. The crude acid chloride 2 was used in the subsequent step without further purification [16-17].

1.2.2 General synthetic procedure for compound 4

Compounds 4 were prepared according to the literature procedures [14-16].

1.2.3 General procedure for synthesis of compounds 5a-5k

To a solution of 2-(chloromethyl)-1H-benzo [d] imidazole 4 (10 mmol) and triethylamine (15 mmol) in CH2Cl2 (20 mL),acyl chlorides 2 (10 mmol) was added dropwise at 0 ℃. The reaction mixture was allowed to warm to room temperature,and was then refluxed for 2 h. After the reaction completed,the mixture was diluted with CH2Cl2,washed with 1 mol/L HCl (50 mL×3),followed by brine (10 mL×3). The combined organic layers were dried over MgSO4,concentrated in vacuo,and purified by column chromatography on silica gel to afford 5a-5k[18].

(2-chloromethyl-benzoimidazol-1-yl)-ethanone (5a): yield 80%,a yellow solid,m. p. 80-81 ℃; 1H NMR,δ: 7.82 (dd,J = 6.4,2.6 Hz,1H,Ar-H),7.71 (dd,J = 6.7,2.4 Hz,1H,Ar-H),7.45-7.39 (m,2H,Ar-H),5.11 (s,2H,CH2),2.89 (s,3H,CH3).

(2-chloromethyl-benzoimidazol-1-yl)-phenyl-methanone (5b): yield 83%,a yellow solid,m. p. 80-81 ℃; 1H NMR,δ: 8.16 (d,J = 7.3 Hz,2H,Ar-H),7.79-7.51 (m,3H,Ar-H),7.50 (t,J = 7.7 Hz,2H,Ar-H),7.34-7.31 (m,2H,Ar-H),4.93 (s,2H,CH2).

(2-chloromethyl-benzoimidazol-1-yl)-(3-nitro-phenyl)-methanone (5c): yield 85%,a yellow solid,m. p. 128-129 ℃; 1H NMR,δ: 8.70 (s,1H,Ar-H),8.60 (d,J = 8.2 Hz,1H,Ar-H),8.11 (d,J = 7.7 Hz,1H,Ar-H),7.84-7.77 (m,2H,Ar-H),7.36 (t,J = 7.7 Hz,1H,Ar-H),7.17 (t,J = 7.8 Hz,1H,Ar-H),6.60 (d,J = 8.3 Hz,1H,Ar-H),5.10 (s,2H,CH2).

(2-chloromethyl-benzoimidazol-1-yl)-(4-chloro-phenyl)-methanone (5d): yield 80%,a yellow solid,m. p. 110-111 ℃; 1H NMR,δ: 7.79 (t,J = 8.8 Hz,3H,Ar-H),7.54 (d,J = 8.4 Hz,2H,Ar-H),7.33 (t,J = 7.7 Hz,1H,Ar-H),7.1 (t,J = 7.8 Hz,1H,Ar-H),6.71 (d,J = 8.3 Hz,1H,Ar-H),5.08 (s,2H,CH2).

(2-chloromethyl-benzoimidazol-1-yl)-(4-bromo-phenyl)-methanone (5e): yield 80%,a yellow solid,m. p. 108-109 ℃; 1H NMR,δ: 7.80 (d,J = 8.1 Hz,1H,Ar-H),7.75-7.61 (m,4H,Ar-H),7.33 (t,J = 7.5 Hz,1H,Ar-H),7.18 (t,J = 7.7 Hz,1H,Ar-H),6.71 (d,J = 8.3 Hz,1H,Ar-H),5.07 (s,2H,CH2).

(2-chloromethyl-benzoimidazol-1-yl)-p-tolyl-methanone (5f): yield 87%,a yellow solid,m. p. 73-74 ℃; 1H NMR,δ: 7.79 (d,J = 8.1 Hz,1H,Ar-H),7.72 (d,J = 7.8 Hz,2H,Ar-H),7.37-7.28 (m,3H,Ar-H),7.16 (t,J = 7.8 Hz,1H,Ar-H),6.76 (d,J = 8.3 Hz,1H,Ar-H),5.07 (s,2H,CH2),2.50 (s,3H,CH3).

(2-chloromethyl-benzoimidazol-1-yl)-(4-methoxy-phenyl)-methanone (5g): yield 83%,a yellow solid,m. p. 77-78 ℃; 1H NMR,δ: 7.80 (t,J = 8.7 Hz,3H,Ar-H),7.31 (t,J = 7.7 Hz,1H,Ar-H),7.17 (t,J = 7.8 Hz,1H,Ar-H),7.02 (d,J = 8.1 Hz,2H,Ar-H),6.83 (d,J = 8.2 Hz,1H,Ar-H),5.07 (s,2H,CH2),3.93 (s,3H,CH3).

(2-chloromethyl-benzoimidazol-1-yl)-(4-fluoro-phenyl)-methanone (5h): yield 80%,a yellow solid,m. p. 77-78 ℃; 1H NMR,δ: 7.98-7.77 (m,3H,Ar-H),7.37-7.18 (m,4H,Ar-H),6.73 (d,J = 8.3 Hz,1H,Ar-H),5.11 (s,2H,CH2).

(2-chloromethyl-benzoimidazol-1-yl)-(4-nitro-phenyl)-methanone (5i): yield 85%,a yellow solid,m. p. 80-81 ℃; 1H NMR,δ: 8.44 (d,J = 7.1 Hz,2H,Ar-H),8.02 (d,J = 7.1 Hz,2H,Ar-H),7.84 (d,J = 8.1 Hz,1H,Ar-H),7.38 (t,J = 7.7 Hz,1H,Ar-H),7.20 (t,J = 7.8 Hz,1H,Ar-H),6.59 (d,J = 8.3 Hz,1H,Ar-H),5.12 (d,J = 1.5 Hz,2H,CH2).

(2-chloromethyl-benzoimidazol-1-yl)-(3-chloro-phenyl)-methanone (5j): yield 80%,a yellow solid,m. p. 87-88 ℃; 1H NMR,δ: 8.14 (t,J = 1.8 Hz,1H,Ar-H),8.08-8.00 (m,1H,Ar-H),7.65 (dt,J = 6.6,3.3 Hz,2H,Ar-H),7.60-7.57 (m,1H,Ar-H),7.44 (t,J = 7.9 Hz,1H,Ar-H),7.37-7.30 (m,2H,Ar-H),4.94 (s,2H,CH2).

(2-chloromethyl-benzoimidazol-1-yl)-(4-trifluoromethyl-phenyl)-methanone (5k): yield 86%,a yellow solid,m. p. 78-79 ℃; 1H NMR,δ: 7.97 (d,J = 8.1 Hz,2H,Ar-H),7.85 (dd,J = 10.3,8.3 Hz,3H,Ar-H),7.42-7.31 (m,1H,Ar-H),7.25-7.16 (m,1H,Ar-H),6.63 (d,J = 8.3 Hz,1H,Ar-H),5.12 (s,2H,CH2).

1.2.4 General procedure for the synthesis of compounds 6a-6l

To a mixture of (S,S)-2,8-diazabicyclo [4.3.0] nonane (10 mmol) and anhydrous K2CO3 (15 mmol) in CH3CN (20 mL),compound 5 (5 mmol) was added. After the reaction completed,the mixture was filtrated. The solvent was removed and the residue was dissolved by CH2Cl2. The mixture was washed with saturated NaHCO3 solution and water. The combined organic layers were dried over MgSO4,concentrated in vacuo,and purified by column chromatography on silica gel to afford title compounds 6a-6l[19-20].

1.3 Bioassays 1.3.1 Antifungal activity

The fungicidal activity of title compounds was tested in vitro against Physalospora piricala,Fusarium graminearum,Phytophthora infestans,Rhizoctonia cerealis,Sclerotinia sclerotiorum,Cochliobolus heterostrophus and Fusarium moniliforme,their relative inhibitory rates (%) were determined by the mycelium growth rate method[21]. Carbendazim,chlorothalonil and thiram were used as controls. After the mycelia grew completely,the diameters of the mycelia were measured and the inhibition rate was calculated according to the formula:

I/% = [(D1 - D2)/D1] × 100

In the formula,I is the inhibition rate,D1 is the average diameter of mycelia in the blank test,and D2 is the average diameter of mycelia in the presence of one of those compounds.

1.3.2 Insecticidal activity

Insecticidal activity against Mythimna separata Walker was tested in a greenhouse [22]. The bioassay was operated at (25±1) ℃ by statistical requirements. The compounds were dissolved with acetone at various concentrations,0.306 μL of the tested solution was applied to the thoracic tergite of fourth-instar larva with a platinum loop. After the treatment,the insects were observed under standard rearing conditions. Mortalities were calculated after 72 h. Each treatment was performed in triplicate.

Insecticidal activity against Culex pipiens pallens[22] was also evaluated. compounds (1 mL) was added to water (99 mL) to get the test solutions of different concentrations. 20 fourth-instar mosquito larva were transferred into 10 mL of the test solution and raised for 2 d,and the results were expressed by the lethality rate.

2 Results and discussion 2.1 Synthesis and analytical spectral data

The physical and chemical data of the title compounds 6a-6l were shown in Table 1. The 1H NMR data of the title compounds 6a-6l were shown in Table 2. The 13C NMR data of the title compounds 6d,6e,6g and 6i were shown in Table 3.

Table 1 Physical and chemical data of the title compounds 6a-6l

Table 2 1H NMR data of the title compounds 6a-6l

Table 3 13C NMR data of the title compounds 6

The synthetic route of the intermediates and title compounds are illustrated in Scheme 1. Compound 4 was prepared from o-phenylenediamine and chloroacetic acid via a cyclization reaction in the acidic environment,followed by the ammonia neutralization. It can be conveniently obtained with high yields. Compounds 5a-5l can be obtained through the acylation reaction in CH2Cl2 with Et3N as base with high yields.

It was noteworthy that the target compounds 6a-6l can’t be obtained in acetone with anhydrous K2CO3 and KI,while they were formed in the N-alkylation reaction in CH3CN. It might indicated the poor activity of the reactants in acetone.

2.2 Antifungal activity

The antifungal activities of the target compounds against seven pathogenic fungis were listed in Table 4. Most of them showed moderate activity at the concentration of 50 μg/mL. Inhibition rate against P. infestans ranged from 50.0% to 62.5% for compounds 6d-6g. Compounds 6d-6h exhibited activity toward S. sclerotiorum,however,all of them were less effective than chlorothaloni. Inhibition rates against P. piricala of compounds 6h-6i were as good as carbendazim. Compounds 6d-6l exhibited inhibition rates of 55.0%-67.6% against R. cerealis. Compounds 6d-6g were less effective than carbendazim against C. heterostrophus and F. moniliforme. However,the fungicidal activities of other title compounds are not notable.

Table 4 Anti-fungal activity (inhibition rate,%) of title compounds at 50 μg/mL

Table 5 Insecticidal activity(lethality rates,%)of title compounds

2.3 Insecticidal activity

The insecticidal activity was evaluated against M. separata and C.pipiens pallens. Chloratraniliprole was used as control. We found that the insecticidal activities of most new compounds against M. separata were over 50% at the concentration of 200 mg/L. Among them,compounds 6e and 6k showed higher activities. Most of the target compounds also exhibited insecticidal activity against C. pipiens pallens at the concentration of 2 mg/L. Compounds 6h,6i and 6k showed higher lethality rates against C. pipiens pallens.

In conclusion,a series of 2,8-diazabicyclo [4.3.0] nonane containing benzimidazole moiety has been synthesized and characterized. All 12 compounds showed moderate antifungal activity against seven pathogenic fungi and moderate insecticidal activity against M. separata and C. pipiens pallens. 2,8-Diazabicyclo [4.3.0] nonane and benzimidazole are developed and applied widely in the field of fungicide. Interestingly,to a certain extent,these novel structures exhibited insecticidal activity,which means they are worth for our further modification.

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