

Citation: Yang Kang, Gu Huiwen, Zhang Fang, Xu Xiaojuan, Zhang Lijie, Sun Yaquan. Synthesis of 1, 2, 6-Trisubstituted Benzimidazoles[J]. Chinese Journal of Organic Chemistry, 2018, 38(8): 2130-2136. doi: 10.6023/cjoc201802027

1, 2, 6-三取代苯并咪唑的合成研究
English
Synthesis of 1, 2, 6-Trisubstituted Benzimidazoles
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Key words:
- synthesis
- / benzimidazole
- / process optimization
- / one-pot reaction
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苯并咪唑核存在于多种天然产物和药物中[1], 有多种生物活性, 如抗细菌、抗真菌、组胺受体拮抗剂、质子泵抑制剂、抗高血压、抗寄生虫、抗病毒、抗癌、镇痛等, 是新药研发的热点领域之一[2], 此外还在材料科学[3, 4]、农用化学品[5]、炸药[6]等有广泛应用.近年来, 将不同取代基引入苯并咪唑体系成为药物分子设计的重要领域[7].同时, 在苯并咪唑上引入杂原子能够有效调节唑环上的电子云密度, 进而影响其与体内多种酶和受体的相互作用方式, 从而改善化合物生物活性[8].在苯并咪唑结构的苯环上引入氰基有利于提高其生物活性[9].我们分别在苯并咪唑环的1位、2位和6位分别引入苄基、其他取代基和腈基, 合成了新型的1, 2, 6-三取代苯并咪唑衍生物, 希望筛选出高效、低毒的化合物. Wan[10]和Liu等[11]都以邻苯二胺(或邻苯二胺单取代物)和芳香醛为原料, 以水为溶剂, 分别用三甲基氯硅烷(TMSCl)和FeCl3为催化剂一步法合成了1, 2-二取代苯并咪唑衍生物, 如Eq. 1所示.但是该方法不能同时控制苯并咪唑环1位和2位取代基的种类, 应用范围非常有局限性.
(1) 此外, 三取代苯并咪唑的合成途径主要有两条, 如Scheme 1所示:途径Ⅰ为先合成二取代苯并咪唑[12~14], 再和卤代物反应生成三取代苯并咪唑[15].途径Ⅱ先由邻卤素硝基苯或邻卤素苯胺与伯胺生成仲胺, 再与醛[16]或酸[17]反应生成三取代苯并咪唑.途径(Ⅰ)中要经取代、还原、缩合的步骤, 比较繁琐, 而且反应时间较长. Yang等[18]在途径(Ⅱ)中采用一锅法得到了三取代苯并咪唑, 但反应时间太长(22 h).因此, 我们先对途径(Ⅱ)进行工艺探索和优化, 在最优条件下合成了21个1, 2, 6-三取代苯并咪唑化合物.具体合成方法见Scheme 2.
图式 1
图式 2
1. 结果与讨论
1.1 化合物1的合成
文献中并无化合物1a~1c合成方法, 分别参照Yang[18]、Kanhed[19]和Zhang[20]的方法, 以3-氟-4-硝基苄腈和苄胺为原料合成1a为例, 结果见表 1.
表 1
从表 1可以看出, 加入K2CO3后, 反应时间缩短, 反应温度降低, 收率提高.原因在于K2CO3在反应中既是碱, 催化反应进行, 还可以吸收反应生成的HF, 促进反应向正反应方向进行[20].与传统加热方法相比, 微波法制备化合物1a~1c有一定的优势.
1.2 目标化合物2a~2u的合成工艺优化
除了化合物2d, 其他均为未见文献报道的新化合物.先参照Yang等[18]的方法以二甲基亚砜(DMSO)- EtOH为溶剂“一锅法”合成, 发现反应时间过长且后处理会形成黏稠状液体, 提纯困难.于是采用分步合成, 先合成化合物1, 再与醛反应生成化合物2.以化合物1a和对氯苯甲醛为原料, 合成目标化合物2m为例, 考察了反应溶剂、保险粉用量、反应温度、原料物质的量比和溶剂体积比对产物产率的影响, 实验结果见表 2.
表 2
Entry Temperature/℃ n(1a):n(p-ClC6H4CHO):n(Na2S2O4) Solventa Time/h Yieldb/% 1 80 1:1:10 EtOH 4 37.93 2 80 1:1:10 DMSO 3 60.72 3 80 1:1:10 DMSO-EtOH 12 78.32 4 80 1:1:10 EtOH-H2O 3 25.97 5 80 1:1:10 CH3CN-H2O 3.5 64.28 6 80 1:1:10 DMSO-H2O 2 79.84 7 80 1:1:10 DMF-H2O 5 11.66 8 80 1:1:10 PhH >40 — 9 80 1:1:3 DMSO-H2O 6 74.03 10 80 1:1:6 DMSO-H2O 3 80.66 11 80 1:1:9 DMSO-H2O 2 87.93 12 80 1:1:12 DMSO-H2O 1.5 84.51 13 80 1:1:15 DMSO-H2O 1.5 83.74 14 60 1:1:9 DMSO-H2O 5 79.32 15 70 1:1:9 DMSO-H2O 3 83.62 16 90 1:1:9 DMSO-H2O 1.5 84.38 17 100 1:1:9 DMSO-H2O 1.5 83.88 18 80 1:1.2:9 DMSO-H2O 2 82.97 19 80 1:1.4:9 DMSO-H2O 2 83.15 20 80 1:1.6:9 DMSO-H2O 2 83.18 21 80 1:1.8:9 DMSO-H2O 2 83.13 22 80 1:2:9 DMSO-H2O 2 83.10 a V(有机溶剂):V(H2O)=3:2; b重结晶后产率. 由表 2可以看出, 反应的最佳条件是:反应温度80 ℃, 反应时间2 h, 原料及保险粉的物质的量比为n(3-(苄基氨基)-4-硝基苄腈):n(对氯苯甲醛):n(保险粉)=1:1:9, 反应溶剂为DMSO和H2O, 体积比为V(DMSO):V(H2O)=3:2.化合物2m的收率为87.93%, 纯度为99.8% (Entry 11).溶剂的极性越大, 反应时间越短, 收率越高.在DMSO中加入水可缩短反应时间, 提高产物收率, 原因在于保险粉在该反应中起还原环化作用, 而其在有机溶剂中溶解度小, 但易溶于水.保险粉用量越多, 产率越高, 以9 equiv.为宜.对氯苯甲醛用量增加时, 会发生一定的副反应, 产率有所降低.
1.3 目标化合物2a~2u的合成
利用上述实验条件合成化合物2a~2u.从表 3可以发现:化合物1a与吡啶甲醛反应分别生成2a, 2b, 2c, 反应时间稍长, 产率相对较低.脂肪醛(2r, 2s)收率较低.相同取代基在苯环上不同位置时, 邻位产率最低, 对位产率最高, 可能因为在2位时空间位阻大, 在4位时空间位阻小, 反应易进行.当不同取代基在苯环上相同位置时, F、CH3产率较高.化合物1a与硝基苯甲醛反应分别生成2n和2o时, 反应时间较长且产率较低.在反应过程中硝基苯甲醛上的硝基也会被保险粉还原成氨基. 2n和2o红外光谱图分别在3442, 3439 cm-1处有N—H的伸缩振动峰.质谱表征结果也印证该结论. n的值越大, 即苯并咪唑环1位取代基碳链越长(2d, 2t, 2u), 相应的产物产率越高, 可能因为碳链越长, 位阻越小, 反应越易发生.
表 3
表 3 1, 2, 6-三取代苯并咪唑化合物2a~2u的实验结果Table 3. Experimental results of 1, 2, 6-trisubstituted benzimidazole compounds 2a~2uCompd. n R Time/h Yield/% 2a 1 2-Py 2.5 69.25 2b 1 3-Py 2.5 55.91 2c 1 4-Py 2.5 61.02 2d 1 Ph 1.5 84.33 2e 1 C6H4(CH2)2 2.0 93.64 2f 1 m-F-C6H4 2.5 82.19 2g 1 p-F-C6H4 2.5 84.94 2h 1 o-Me-C6H4 2.0 76.40 2i 1 m-Me-C6H4 2.0 80.54 2j 1 p-Me-C6H4 2.0 83.25 2k 1 o-Cl-C6H4 2.0 67.21 2l 1 m-Cl-C6H4 2.5 76.44 2m 1 p-Cl-C6H4 2.0 87.93 2n 1 o-H2N-C6H4 4.0 71.45 2o 1 p-H2N-C6H4 4.0 71.67 2p 1 2-Furyl 2.5 82.76 2q 1 2-Thienyl 2.0 80.19 2r 1 Et 2.0 43.51 2s 1 n-Butyl 1.5 45.24 2t 2 Ph 1.5 87.17 2u 3 Ph 1.5 91.62 2. 结论
以3-氟-4-硝基苄腈、芳香胺和多种醛为原料, 经过两步反应合成了21个1, 2, 6-三取代苯并咪唑衍生物2a~2u.该方法原料易得, 工艺成本低, 毒性小, 操作简便, 反应条件温和, 时间短, 以芳香醛为底物时产率较高, 但以脂肪醛为底物时产率较低.
3. 实验部分
3.1 仪器与试剂
美国CEM Discover Lab-Mate微波合成仪; 美国Waters e2695高效液相色谱仪; 德国Bruker Vertex80/RamanII傅里叶变换红外光谱仪, KBr压片; 德国Bruker Advance 400MHz核磁共振仪, CDCl3或DMSO- d6为溶剂, TMS为内标; 美国Agilent 1100MSD液相色谱质谱联用仪.美国METTLER TOLEDO MP90熔点仪(温度计未校正).所用试剂均为分析纯.
3.2 测试条件
液相色谱条件: XBridgeTM C18色谱柱(4.6 mm×250 mm, 5 μm), 检测器波长293 nm, 流速0.8 mL/min, 进样5 μL, 柱温25 ℃, 溶剂甲醇, 流动相为甲醇+0.2%乙酸铵溶液(体积比80:20, 文中所述物质纯度皆为面积归一化法所确定).
3.3 化合物1a~1c的合成
以3-氟-4-硝基苄腈和苄胺合成化合物1a为例.
微波加热方法[20]:在装有回流冷凝管的100 mL烧瓶中加入1.66 g (10 mmol) 3-氟-4-硝基苄腈1.07 g (10 mmol)苄胺、2.07 g (15 mmol)碳酸钾和60 mL乙腈, 置于微波合成仪中.在250 W、83 ℃回流条件下反应15 min(保持时间).降至常温后, 加入100 mL纯水, 0 ℃下搅拌2 h后过滤, 20 mL纯水洗涤, 真空干燥, 得橘黄色固体2.47 g, 产率97.63%, 纯度99.4%.
传统加热方法:向100 mL烧瓶中加入1.66 g (10 mmol) 3-氟-4-硝基苄腈、1.07 g (10 mmol)苄胺、2.07 g (15 mmol)碳酸钾和60 mL乙腈, 83 ℃下搅拌反应3 h, 后处理同上.得橘黄色固体2.46 g, 收率97.23%, 纯度99.3%.
3-(苄基氨基)-4-硝基苄腈(1a):橘黄色固体, 产率97.63%. m.p. 151.5~152.6 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.42 (d, J=6.2 Hz, 1H), 8.28 (d, J=8.7 Hz, 1H), 7.44~7.38 (m, 2H), 7.38~7.31 (m, 3H), 7.13 (d, J=1.6 Hz, 1H), 6.90 (dd, J=8.7, 1.7 Hz, 1H), 4.55 (d, J=5.6 Hz, 2H); 13C NMR (101 MHz, CDCl3) δ: 144.55, 136.00, 134.03, 129.25, 128.25, 127.92, 127.08, 119.29, 118.70, 117.70, 117.41, 47.29; IR (KBr) ν: 3393, 3100, 2929, 2226, 1617, 1489, 1412, 1322 cm-1; HRMS calcd for C14H12N3O2 [M+H]+ 254.0924, found 254.0926.
4-硝基-3-(苯乙基氨基)苄腈(1b):橘黄色固体, 产率97.45%. m.p. 131.0~131.5 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.22 (dd, J=8.8, 2.0 Hz, 1H), 8.07 (d, J=5.4 Hz, 1H), 7.41~7.32 (m, 2H), 7.27 (d, J=6.7 Hz, 3H), 7.11 (s, 1H), 6.84 (d, J=8.8 Hz, 1H), 3.57 (q, J=6.6, 5.8 Hz, 2H), 3.04 (td, J=6.9, 1.9 Hz, 2H); 13C NMR (101 MHz, CDCl3) δ: 144.60, 137.67, 133.62, 129.01, 128.74, 127.92, 127.16, 119.24, 118.41, 117.46, 117.16, 44.61, 35.12; IR (KBr) ν: 3382, 3092, 2867, 2234, 1618, 1406 cm-1; HRMS calcd for C15H14N3O2 [M+H]+ 268.1081, found 268.1086.
4-硝基-3-(3-苯丙基氨基)苄腈(1c):橘黄色固体, 产率97.52%. m.p. 93.2~94.7 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.24 (dd, J=8.7, 2.0 Hz, 1H), 8.05 (d, J=5.4 Hz, 1H), 7.37~7.29 (m, 2H), 7.23 (dd, J=15.7, 7.0 Hz, 3H), 7.06 (s, 1H), 6.85 (dd, J=8.9, 1.7 Hz, 1H), 3.30 (q, J=6.7, 6.3 Hz, 2H), 2.79 (td, J=7.4, 2.0 Hz, 2H), 2.09 (pd, J=7.2, 1.9 Hz, 2H); 13C NMR (101 MHz, CDCl3) δ: 144.70, 140.36, 133.59, 128.73, 128.37, 127.97, 126.46, 119.27, 118.40, 117.47, 117.01, 42.32, 32.98, 30.08; IR (KBr) ν: 3377, 3023, 2929, 2228 1617, 1443 cm-1; HRMS calcd for C16H16N3O2 [M+H]+ 282.1237, found 282.1237.
3.4 化合物2a~2u的合成通法
向250 mL反应瓶中加入1 mmol化合物1, 1 mmol合适的醛, 15 mL DMSO, 9 mmol保险粉溶解在10 mL水中形成的溶液.在80 ℃下反应薄层色谱(TLC)跟踪反应至结束.降至室温, 加入50 mL纯水、0 ℃搅拌1.5~4 h、过滤、20 mL纯水洗涤滤饼, 丙酮重结晶, 真空干燥.
1-苄基-2-(吡啶-2-基)-1H-苯并[d]咪唑-6-甲腈(2a):黄色粉末, 产率69.25%. m.p. 168.8~170.3 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.70~8.65 (m, 1H), 8.46 (d, J=8.0 Hz, 1H), 7.92~7.86 (m, 2H), 7.65 (d, J=1.4 Hz, 1H), 7.54 (dd, J=8.3, 1.4 Hz, 1H), 7.40 (ddd, J=7.7, 4.8, 1.2 Hz, 1H), 7.31~7.26 (m, 3H), 7.19~7.14 (m, 2H), 6.22 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 152.94, 149.57, 148.95, 145.54, 137.21, 136.33, 128.91, 127.91, 126.80, 126.26, 125.25, 124.76, 121.05, 119.84, 115.83, 106.26, 49.40; IR (KBr) ν: 3056, 2217, 1580, 1436, 1333 cm-1; HRMS calcd for C20H15N4 [M+H]+ 311.1291, found 311.1291.
1-苄基-2-(吡啶-3-基)-1H-苯并[d]咪唑-6-甲腈(2b):黄色粉末, 产率55.91%. m.p. 163.9~164.5 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.96 (d, J=2.2 Hz, 1H), 8.77 (dd, J=4.9, 1.7 Hz, 1H), 8.05 (dt, J=7.9, 2.0 Hz, 1H), 7.97~7.91 (m, 1H), 7.60 (d, J=8.2 Hz, 2H), 7.45 (dd, J=7.9, 4.8 Hz, 1H), 7.40~7.33 (m, 3H), 7.06 (dd, J=7.3, 2.1 Hz, 2H), 5.51 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 154.39, 151.61, 149.69, 146.02, 136.76, 135.75, 134.72, 129.54, 128.60, 126.56, 125.72, 125.48, 123.73, 121.24, 119.57, 115.57, 106.47, 48.79; IR (KBr) ν: 3039, 2215, 1567, 1453, 1329 cm-1; HRMS calcd for C20H15N4 [M+H]+ 311.1291, found 311.1292.
1-苄基-2-(吡啶-4-基)-1H-苯并[d]咪唑-6-甲腈(2c):黄色粉末, 产率61.02%. m.p. 148.1~148.9 ℃; 1H NMR (400 MHz, CDCl3) δ: 8.78 (m, 1H), 8.54 (dd, J=4.9, 1.7 Hz, 1H), 8.15 (dt, J=7.9, 2.0 Hz, 1H), 7.89~7.94 (m, 1H), 7.74 (d, J=8.5 Hz, 2H), 7.45 (dd, J=7.5, 4.5 Hz, 1H), 7.45~7.38 (m, 3H), 7.06~7.11 (m, 2H), 5.79 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 153.33, 149.80, 147.03, 137.37, 134.95, 134.02, 128.64, 127.69, 126.51, 125.73, 121.34, 120.56, 118.63, 115.74, 105.41, 50.76; IR (KBr) ν: 3024, 2216, 1523, 1450, 1313 cm-1; HRMS calcd for C20H15N4 [M+H]+ 311.1291, found 311.1289.
1-苄基-2-苯基-1H-苯并[d]咪唑-6-甲腈(2d):淡黄色粉末, 产率84.33%. m.p. 163.8~164.7 ℃(文献值[21]: 161~163 ℃); NMR、IR和HRMS数据和文献[21]相同.
1-苄基-2-苯乙基-1H-苯并[d]咪唑-6-甲腈(2e):白色粉末, 产率93.64%. m.p. 53.8~55.2 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.94 (d, J=8.3 Hz, 1H), 7.51 (d, J=8.2 Hz, 2H), 7.34~7.29 (m, 3H), 7.25~7.19 (m, 3H), 7.15~7.09 (m, 2H), 6.97~6.90 (m, 2H), 5.21 (s, 2H), 3.31 (dd, J=8.9, 6.5 Hz, 2H), 3.18 (dd, J=8.9, 6.6 Hz, 2H); 13C NMR (101 MHz, CDCl3) δ: 157.86, 139.60, 133.89, 133.83, 129.44, 128.82, 128.73, 128.41, 127.14, 126.83, 126.24, 119.44, 119.23, 115.23, 106.71, 47.69, 33.59, 29.30; IR (KBr) ν: 3030, 2216, 1611, 1502, 1331, 1251 cm-1; HRMS calcd for C21H16N3 [M+H]+ 338.1652, found 338.1648.
1-苄基-2-(3-氟苯基)-1H-苯并[d]咪唑-6-甲腈(2f):白色粉末, 产率82.19%. m.p. 183.5~184.8 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.84 (dd, J=8.4, 0.7 Hz, 1H), 7.55~7.44 (m, 2H), 7.44~7.35 (m, 3H), 7.35~7.23 (m, 3H), 7.20~7.16 (m, 1H), 7.05~6.95 (m, 2H), 5.43 (s, 2H); 13C NMR (100 MHz, CDCl3) δ: 162.8 (d, 1JC-F=247.3 Hz), 155.9, 145.9, 135.6, 134.9, 131.0 (d, 3JC-F=8.2 Hz), 130.7 (d, 3JC-F=9.1 Hz), 129.4, 128.5, 126.4, 125.8, 124.9 (d, 4JC-F=4.0 Hz), 121.1, 119.6, 117.9 (d, 2JC-F=21.4 Hz), 116.6 (d, 2JC-F=23.0 Hz), 115.5, 106.2, 48.8; IR (KBr) ν: 3064, 2217, 1582, 1451, 1336, 1259 cm-1; HRMS calcd for C21H15FN3 [M+H]+ 328.1245, found 328.1241.
1-苄基-2-(4-氟苯基)-1H-苯并[d]咪唑-6-甲腈(2g):白色粉末, 产率84.94%. m.p. 137.9~139.4 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.88~7.78 (m, 1H), 7.67~7.57 (m, 2H), 7.50 (dd, J=8.4, 1.5 Hz, 1H), 7.46 (d, J=1.3 Hz, 1H), 7.35~7.26 (m, 3H), 7.17~7.05 (m, 2H), 7.05~6.92 (m, 2H), 5.40 (s, 2H); 13C NMR (100 MHz, CDCl3) δ: 164.2 (d, 1JC-F=251.2 Hz), 156.4, 145.9, 135.6, 135.0, 131.4, 131.3, 129.4, 128.4, 126.4, 125.7, 125.1 (d, 3JC-F= 3.1 Hz), 120.9, 119.7, 116.3 (d, 2JC-F=21.2 Hz), 115.4, 105.9, 48.7; IR (KBr) ν: 3027, 2218, 1607, 1457, 1334, 1231 cm-1; HRMS calcd for C21H15FN3 [M+H]+ 328.1245, found 328.1243.
1-苄基-2-(邻甲苯基)-1H-苯并[d]咪唑-6-甲腈(2h):黄色粉末, 产率76.40%. m.p. 111.9~113.4 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.85~7.76 (m, 1H), 7.49 (d, J= 7.5 Hz, 2H), 7.36 (td, J=7.5, 1.6 Hz, 1H), 7.31~7.26 (m, 2H), 7.20 (dd, J=6.7, 3.2 Hz, 4H), 6.91~6.83 (m, 2H), 5.16 (s, 2H), 2.14 (s, 3H); 13C NMR (101 MHz, CDCl3) δ: 157.17, 146.06, 138.19, 134.89, 134.45, 130.85, 130.55, 129.80, 129.11, 128.77, 128.37, 126.57, 126.03, 125.97, 120.97, 119.88, 115.50, 105.71, 48.37, 19.74; IR (KBr) ν: 3029, 2945, 2858, 1612, 1453, 1282 cm-1; HRMS calcd for C22H18N3 [M+H]+ 324.1495, found 324.1497.
1-苄基-2-(间甲苯基)-1H-苯并[d]咪唑-6-甲腈(2i):黄色粉末, 产率80.54%. m.p. 152.2 ~153.1 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.82 (dd, J=8.3, 0.7 Hz, 1H), 7.52~7.46 (m, 2H), 7.45~7.43 (m, 1H), 7.37 (dt, J= 6.7, 2.2 Hz, 1H), 7.33~7.29 (m, 2H), 7.28 (q, J=1.6, 1.0 Hz, 3H), 7.01 (dd, J=7.6, 1.9 Hz, 2H), 5.41 (s, 2H), 2.32 (s, 3H); 13C NMR (101 MHz, CDCl3) δ: 131.55, 130.20, 129.36, 128.82, 128.33, 126.29, 126.07, 125.93, 120.87, 115.43, 48.83, 21.39; IR (KBr) ν: 3062, 2218, 1615, 1453, 1336, 1290 cm-1; HRMS calcd for C22H18N3 [M+H]+ 324.1495, found 324.1490.
1-苄基-2-(对甲苯基)-1H-苯并[d]咪唑-6-甲腈(2j):黄色粉末, 产率83.25%. m.p. 182.3~183.6 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.91 (d, J=8.4 Hz, 1H), 7.66~7.60 (m, 2H), 7.57 (dd, J=8.3, 1.5 Hz, 1H), 7.52 (d, J=1.3 Hz, 1H), 7.42~7.35 (m, 3H), 7.32 (d, J=7.9 Hz, 2H), 7.13~7.03 (m, 2H), 5.50 (s, 2H), 2.44 (s, 3H); 13C NMR (101 MHz, CDCl3) δ: 146.17, 141.15, 135.69, 135.31, 129.75, 129.36, 129.20, 128.30, 126.27, 126.05, 125.88, 120.77, 119.87, 115.36, 105.59, 48.78, 21.50; IR (KBr) ν: 3059, 2957, 2915, 2214, 1610, 1455, 1293, 1186 cm-1; HRMS calcd for C22H18N3 [M+H]+ 324.1495, found 324.1498.
1-苄基-2-(2-氯苯基)-1H-苯并[d]咪唑-6-甲腈(2k):黄色粉末, 产率67.21%. m.p. 95.6~96.7 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.95~7.89 (m, 1H), 7.57 (d, J= 7.5 Hz, 3H), 7.51 (dd, J=7.9, 6.4 Hz, 2H), 7.43~7.35 (m, 3H), 7.29~7.26 (m, 3H), 5.28 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 154.62, 145.65, 134.57, 134.35, 134.11, 132.12, 130.09, 129.13, 128.83, 128.49, 127.89, 127.29, 126.69, 126.22, 121.20, 119.68, 115.83, 106.28, 77.25, 48.79; IR (KBr) ν: 3030, 2218, 1593, 1447, 1285, 1168 cm-1; HRMS calcd for C21H15ClN3 [M+H]+ 344.0949, found 344.0957.
1-苄基-2-(3-氯苯基)-1H-苯并[d]咪唑-6-甲腈(2l):白色粉末, 产率76.44%, m.p. 186.4~189.1 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.84 (dd, J=8.4, 0.7 Hz, 1H), 7.68 (t, J=1.9 Hz, 1H), 7.51 (dd, J=8.4, 1.5 Hz, 1H), 7.48 (ddt, J=4.8, 2.9, 1.4 Hz, 2H), 7.44 (ddd, J=8.1, 2.1, 1.1 Hz, 1H), 7.36 (d, J=7.8 Hz, 1H), 7.34~7.28 (m, 3H), 7.04~6.95 (m, 2H), 5.41 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 155.82, 145.94, 135.70, 135.22, 134.93, 130.89, 130.74, 130.27, 129.62, 129.48, 128.53, 127.17, 126.48, 125.86, 121.16, 119.65, 115.54, 106.27, 48.84; IR (KBr) ν: 3063, 2216, 1611, 1456, 1400 cm-1; HRMS calcd for C21H15ClN3 [M+H]+ 344.0949, found 344.0959.
1-苄基-2-(4-氯苯基)-1H-苯并[d]咪唑-6-甲腈(2m):黄色粉末, 收率87.32%. m.p. 199.5~ 200.9 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.91 (d, J=8.3 Hz, 1H), 7.68~7.62 (m, 2H), 7.58 (dd, J=8.4, 1.5 Hz, 1H), 7.54 (d, J=1.3 Hz, 1H), 7.51~7.45 (m, 2H), 7.41~7.34 (m, 3H), 7.10~7.04 (m, 2H), 5.47 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 156.23, 146.00, 137.21, 135.75, 134.98, 130.58, 129.50, 129.40, 128.50, 127.42, 126.48, 125.75, 121.04, 119.71, 115.46, 106.11, 48.78; IR (KBr) ν: 3402, 3064, 2220, 1615, 1596, 1450, 1438 cm-1; HRMS calcd for C21H15ClN3 [M+H]+ 344.0949, found 344.0948.
1-苄基-2-(2-氨基苯基)-1H-苯并[d]咪唑-6-甲腈(2n):黄色粉末, 收率71.45%. m.p. 97.7~98.6 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.21 (d, J=1.4 Hz, 1H), 7.90 (d, J=8.3 Hz, 1H), 7.70 (dd, J=8.3, 1.5 Hz, 1H), 7.29 (s, 1H), 7.27 (d, J=2.1 Hz, 2H), 7.26~7.23 (m, 2H), 7.07~6.99 (m, 2H), 6.93~6.86 (m, 1H), 6.66 (td, J=7.5, 1.0 Hz, 1H), 5.56 (s, 2H); 13C NMR (101 MHz, DMSO-d6) δ: 155.97, 148.01, 145.12, 136.45, 135.05, 132.21, 130.78, 129.22, 128.22, 127.09, 126.62, 120.11, 119.89, 117.01, 116.69, 116.50, 111.30, 105.08, 48.38; IR (KBr) ν: 3442, 3032, 2222, 1615, 1452, 1329 cm-1; HRMS calcd for C21H17N4 [M+H]+ 325.1448, found 325.1448.
1-苄基-2-(4-氨基苯基)-1H-苯并[d]咪唑-6-甲腈(2o):橘黄色粉末, 产率71.67%. m.p. 150.4~151.2 ℃; 1H NMR (400 MHz, DMSO-d6) δ: 8.28 (d, J=1.5 Hz, 1H), 7.91 (d, J=8.4 Hz, 1H), 7.87~7.79 (m, 1H), 7.59~7.53 (m, 2H), 7.44~7.28 (m, 4H), 7.14 (dd, J=8.5, 6.7 Hz, 2H), 6.80~6.72 (m, 2H), 5.75 (s, 2H); 13C NMR (101 MHz, DMSO-d6) δ: 156.09, 152.03, 149.40, 135.93, 134.82, 131.50, 131.02, 129.44, 128.39, 128.21, 126.88, 126.80, 119.63, 117.82, 117.37, 114.72, 106.08, 48.90; IR (KBr) ν: 3442, 3032, 2222, 1615, 1452, 1329 cm-1; HRMS calcd for C21H17N4 [M+H]+ 325.1448, found 325.1446.
1-苄基-2-(呋喃-2-基)-1H-苯并[d]咪唑-6-甲腈(2p):淡黄色粉末, 产率82.76%. m.p. 192.3~193.8 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.93~7.84 (m, 1H), 7.61~7.52 (m, 3H), 7.44~7.33 (m, 4H), 7.12 (td, J=7.1, 6.3, 2.7 Hz, 3H), 5.64 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 145.96, 135.96, 134.86, 130.87, 130.25, 129.48, 129.00, 128.42, 128.31, 126.59, 125.75, 120.70, 114.81, 105.93, 48.63; IR (KBr) ν: 3126, 2219, 1603, 1501, 1456, 1414 cm-1; HRMS calcd for C19H14N3O [M+H]+ 300.1131, found 300.1131.
1-苄基-2-(噻吩-2-基)-1H-苯并[d]咪唑-6-甲腈(2q):白色粉末, 产率80.19%. m.p. 221.9~223.4 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.86 (d, J=8.4 Hz, 1H), 7.63 (d, J= 1.7 Hz, 1H), 7.59 (d, J=1.4 Hz, 1H), 7.54 (dd, J=8.4, 1.5 Hz, 1H), 7.38~7.30 (m, 3H), 7.25 (d, J=3.6 Hz, 1H), 7.14 (d, J=2.1 Hz, 1H), 7.13 (t, J=1.8 Hz, 1H), 6.62 (dd, J=3.6, 1.8 Hz, 1H), 5.75 (s, 2H); 13C NMR (101 MHz, CDCl3) δ: 147.32, 145.98, 145.14, 144.32, 135.36, 135.23, 129.23, 128.31, 126.62, 126.25, 120.66, 119.74, 114.90, 112.46, 105.94, 48.84; IR (KBr) ν: 3109, 3056, 2214, 1611, 1454, 1283 cm-1; HRMS calcd for C19H14N3S [M+H]+ 316.0903, found 316.0907.
1-苄基-2-乙基-1H-苯并[d]咪唑-6-甲腈(2r):淡黄色粉末, 产率43.51%. m.p. 118.8~119.5 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.72 (d, J=8.4 Hz, 1H), 7.47~7.37 (m, 2H), 7.30~7.20 (m, 3H), 6.98~6.90 (m, 2H), 5.28 (s, 2H), 2.84 (q, J=7.5 Hz, 2H), 1.36 (t, J=7.5 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 158.98, 144.54, 134.03, 133.75, 128.23, 127.35, 125.05, 124.76, 119.13, 118.90, 113.25, 104.12, 46.18, 20.04, 10.39; IR (KBr) ν: 3451, 3033, 2215, 1613, 1457, 1252 cm-1; HRMS calcd for C17H16N3 [M+H]+ 262.1339, found 262.1342.
1-苄基-2-丁基-1H-苯并[d]咪唑-6-甲腈(2s):黄色固体, 产率45.24%. m.p. 127.4~128.6 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.72 (d, J=8.2 Hz, 1H), 7.46~7.37 (m, 2H), 7.31~7.22 (m, 3H), 7.02~6.84 (m, 2H), 5.29 (s, 2H), 2.94~2.68 (m, 2H), 1.89~1.63 (m, 2H), 1.34 (dt, J=14.7, 7.4 Hz, 2H), 0.85 (t, J=7.3 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 158.18, 144.57, 133.90, 133.80, 128.23, 127.36, 125.04, 124.78, 119.09, 118.91, 113.32, 104.07, 46.27, 28.40, 26.34, 21.49, 12.71; IR (KBr) ν: 3444, 3028, 2952, 2215, 1616, 1500, 1457 cm-1; HRMS calcd for C19H20N3 [M+H]+ 290.1652, found 290.1649.
1-苯乙基-2-苯基-1H-苯并[d]咪唑-6-甲腈(2t):白色粉末, 产率87.17%. m.p. 133.3~134.1 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.85 (d, J=8.3 Hz, 1H), 7.65 (s, 1H), 7.59~7.42 (m, 6H), 7.18 (d, J=7.4 Hz, 3H), 6.84 (d, J=6.9 Hz, 2H), 4.49 (t, J=7.3 Hz, 2H), 3.03 (t, J=7.3 Hz, 2H); 13C NMR (101 MHz, CDCl3) δ: 157.19, 145.83, 136.71, 135.04, 130.41, 129.25, 129.19, 128.88, 128.83, 128.58, 127.26, 126.01, 120.90, 119.92, 115.07, 105.53, 46.60, 35.91; IR (KBr) ν: 3449, 3056, 3026, 2218, 1609, 1443 cm-1; HRMS calcd for C22H18N3 [M+H]+ 324.1495, found 324.1498.
2-苯基-1-(3-苯丙基)-1H-苯并[d]咪唑-6-甲腈(2u):黄色粉末, 产率91.62%. m.p. 132.7~134.1 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.87 (dd, J=8.2, 2.0 Hz, 1H), 7.65 (d, J=7.4 Hz, 2H), 7.60~7.44 (m, 5H), 7.33~7.27 (m, 2H), 7.25 (d, J=6.6 Hz, 1H), 7.09 (d, J=7.3 Hz, 2H), 4.26 (td, J=7.8, 2.0 Hz, 2H), 2.68~2.57 (m, 2H), 2.23~2.09 (m, 2H); 13C NMR (101 MHz, CDCl3) δ: 156.67, 145.61, 139.72, 135.13, 130.63, 129.21, 129.12, 129.04, 128.77, 128.31, 126.66, 126.13, 120.83, 119.85, 114.96, 105.63, 44.30, 32.67, 31.04; IR (KBr) ν: 3446, 3025, 3026, 2929, 2217, 1611, 1446 cm-1; HRMS calcd for C23H20N3 [M+H]+ 338.1652, found 338.1653.
辅助材料(Supporting Information) 化合物1a~1c和2a~2u的1H NMR, 13C NMR, IR和HRMS谱图.这些材料可以免费从本刊网站(http://sioc-journal.cn/)上下载.
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表 1 不同反应条件下生成化合物1a的结果
Table 1. Results of compound 1a formation under different reaction conditions
表 2 影响化合物2m产率的因素
Table 2. Effects of some factors on the yields of compound 2m
Entry Temperature/℃ n(1a):n(p-ClC6H4CHO):n(Na2S2O4) Solventa Time/h Yieldb/% 1 80 1:1:10 EtOH 4 37.93 2 80 1:1:10 DMSO 3 60.72 3 80 1:1:10 DMSO-EtOH 12 78.32 4 80 1:1:10 EtOH-H2O 3 25.97 5 80 1:1:10 CH3CN-H2O 3.5 64.28 6 80 1:1:10 DMSO-H2O 2 79.84 7 80 1:1:10 DMF-H2O 5 11.66 8 80 1:1:10 PhH >40 — 9 80 1:1:3 DMSO-H2O 6 74.03 10 80 1:1:6 DMSO-H2O 3 80.66 11 80 1:1:9 DMSO-H2O 2 87.93 12 80 1:1:12 DMSO-H2O 1.5 84.51 13 80 1:1:15 DMSO-H2O 1.5 83.74 14 60 1:1:9 DMSO-H2O 5 79.32 15 70 1:1:9 DMSO-H2O 3 83.62 16 90 1:1:9 DMSO-H2O 1.5 84.38 17 100 1:1:9 DMSO-H2O 1.5 83.88 18 80 1:1.2:9 DMSO-H2O 2 82.97 19 80 1:1.4:9 DMSO-H2O 2 83.15 20 80 1:1.6:9 DMSO-H2O 2 83.18 21 80 1:1.8:9 DMSO-H2O 2 83.13 22 80 1:2:9 DMSO-H2O 2 83.10 a V(有机溶剂):V(H2O)=3:2; b重结晶后产率. 表 3 1, 2, 6-三取代苯并咪唑化合物2a~2u的实验结果
Table 3. Experimental results of 1, 2, 6-trisubstituted benzimidazole compounds 2a~2u
Compd. n R Time/h Yield/% 2a 1 2-Py 2.5 69.25 2b 1 3-Py 2.5 55.91 2c 1 4-Py 2.5 61.02 2d 1 Ph 1.5 84.33 2e 1 C6H4(CH2)2 2.0 93.64 2f 1 m-F-C6H4 2.5 82.19 2g 1 p-F-C6H4 2.5 84.94 2h 1 o-Me-C6H4 2.0 76.40 2i 1 m-Me-C6H4 2.0 80.54 2j 1 p-Me-C6H4 2.0 83.25 2k 1 o-Cl-C6H4 2.0 67.21 2l 1 m-Cl-C6H4 2.5 76.44 2m 1 p-Cl-C6H4 2.0 87.93 2n 1 o-H2N-C6H4 4.0 71.45 2o 1 p-H2N-C6H4 4.0 71.67 2p 1 2-Furyl 2.5 82.76 2q 1 2-Thienyl 2.0 80.19 2r 1 Et 2.0 43.51 2s 1 n-Butyl 1.5 45.24 2t 2 Ph 1.5 87.17 2u 3 Ph 1.5 91.62 -

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