张 盼,封云倩,田小龙,邹泰爽,罗国勇
(贵州中医药大学药学院,贵州 贵阳 550025)
2-芳基苯并呋喃类化合物在自然界中广泛存在,同时具有多样的生物活性,如抗肿瘤、抗病毒、抗真菌、抗氧化、腺苷A1拮抗、抗心肌缺血、抗炎、免疫抑制等[1-2]。2-芳基苯并呋喃类成分表现出巨大的药用价值,极具开发潜力,长期以来备受关注[3]。Iteafuranal A(图1)是从民族药冬青叶鼠刺中分离鉴定的2-芳基苯并呋喃类化合物[4]。同时,进一步的活性评价发现其表现出显著的抗氧化和抗肝癌活性,可作为先导结构进一步开发[4-5]。
肼与羰基的缩合反应即为腙化反应,是基于羰基开展结构修饰的常用策略,可达到提升活性、降低毒性、发现新用途等目的[6-9]。基于此,本研究以iteafuranal A为原料,合成了7个全新的苯腙衍生物,以期为后续先导结构的发现奠定基础。
图1 Iteafuranal A的结构图Fig.1 Structure of iteafuranal A
Bruker Ascend 400 核磁共振仪(TMS为内标,德国布鲁克公司);Waters Xevo G2-S QTOF质谱仪(美国Waters公司);ZF-7暗箱三用紫外分光仪(上海嘉鹏科技有限公司); N-1300D旋转蒸发仪(东京理化器械株式会社);柱层析硅胶和 GF 254 薄层层析硅胶(青岛海洋化工有限公司);所有试剂均为分析纯,并经蒸馏处理后使用。
参照现有方法进行合成[10],具体步骤如下(图2,以苯肼为例进行描述):称取iteafuranal A (1)30 mg(0.1 mmol),置于50 mL圆底烧瓶,以5 mL甲醇溶解。完毕,搅拌下加入苯肼32 mg(0.15 mmol)。接着,用胶头滴管加入两滴冰乙酸,60℃搅拌反应。用TLC监测反应原料的反应情况,直至反应结束。通过硅胶柱层析,以二氯甲烷/甲醇(30∶1)洗脱得产物2a。2b-2g均参照此方法合成得到。
图2 化合物2a-2g的合成方法Fig.2 Synthetic routine of compounds 2a-2g
4-(4-hydroxy-3-((E)-(2-phenylhydrazono)methyl)-5-((E)-prop-1-en-1-yl)benzofuran-2-yl)benzene-1,2-diol(2a)深黄色粉末;产率:70%;1H NMR(400 MHz,MeOH-d4)δ8.18(s,1H),7.34(d,J= 8.6 Hz,1H),7.26(dd,J=8.6,7.3 Hz,2H),7.15(d,J=2.1 Hz,1H),7.07(dd,J=8.3,2.1 Hz,1H),7.01 -6.97(m,2H),6.92(d,J=8.2 Hz,1H),6.86(d,J=8.5 Hz,1H),6.85 -6.79(2H,m),6.16(dq,J=15.9,6.6 Hz,1H),1.90(dd,J=6.6,1.8 Hz,1H);13C NMR(100 MHz,MeOH-d4)δ155.04,154.63,148.28,146.87,145.44,144.54,133.84,129.02,125.94,124.08,122.91,121.54,120.25,119.42,118.75,115.30,114.77,114.38,112.09,111.97,101.74,17.63;HR-MS(ESI)m/z 399.13632 [M-H]-(cacld for C24H19N2O4,399.135031),err 3.2 ppm。
4-(4-hydroxy-5-((E)-prop-1-en-1-yl)-3-((E)-(2-(2,4,6-trichlorophenyl)hydrazono)methyl)benzofuran-2-yl)benzene-1,2-diol(2b)黄色粉末;产率:60%;1H NMR(400 MHz,MeOH-d4)δ8.30(s,1H),7.46(s,2H),7.29(d,J=8.6 Hz,1H),7.14(d,J=2.1 Hz,1H),7.04(dd,J=8.2,2.1 Hz,1H),6.90(d,J=8.2 Hz,1H),6.84(d,J=8.5 Hz,1H),6.69(dd,J=15.9,1.9 Hz,1H),6.08(dq,J=16.0,6.5 Hz,1H),1.83(dd,J=6.6,1.8 Hz,3H);13C NMR(100 MHz,MeOH-d4)δ157.62,156.00,149.55,148.47,146.86,139.73,138.33,131.53,131.38,129.94,127.28,125.53,124.29,122.54,121.71,120.31,116.65,116.16,115.43,112.96,103.00,19.03;HR-MS(ESI)m/z 501.01971 [M-H]-(cacld for C24H16Cl3N2O4,501.018114),err 3.2 ppm。
4-(4-hydroxy-3-((E)-(2-(perfluorophenyl)hydrazono)methyl)-5-((E)-prop-1-en-1-yl)benzofuran-2-yl)benzene-1,2-diol(2c) 红褐色粉末;产率:45%;1H NMR(400 MHz,MeOH-d4)δ8.40(s,1H),7.31(d,J=8.5 Hz,1H),7.14(d,J=2.1 Hz,1H),7.06(dd,J=8.2,2.2 Hz,1H),6.91(d,J=8.2 Hz,1H),6.85(d,J=8.5 Hz,1H),6.74(br.d,J=15.8 Hz,1H),6.12(dq,J=15.7,6.5 Hz,1H),1.87(dd,J=6.7,1.7 Hz,3H);19F NMR(376 MHz,MeOH-d4)δ-157.82(d,J=21.3 Hz),-166.51(td,J=21.0,4.6 Hz),-170.67(tt,J=21.1,4.7 Hz);13C NMR(101 MHz,MeOH-d4)δ158.24,155.86,149.26,148.47,146.75,141.40,140.71(m),138.16(m),135.16(m),127.19,125.47,124.33,122.38,121.95,121.77(overlap),120.29,116.54,116.20,115.11,112.36,103.00,19.04;HR-MS(ESI)m/z 489.08915 [M-H]-(cacld for C24H14F5N2O4,489.087922),err 2.5 ppm。
4-(3-((E)-(2-(2,4-dinitrophenyl)hydrazono)methyl)-4-hydroxy-5-((E)-prop-1-en-1-yl)benzofuran-2-yl)benzene-1,2-diol(2d)黑色粉末;产率:82%;1H NMR(400 MHz,DMSO-d6)δ11.90(s,1H),11.27(s,1H),9.78(s,1H),9.44(s,1H),9.06(s,1H),8.83(d,J=2.7 Hz,1H),8.48(dd,J=9.6,2.8 Hz,1H),7.49(d,J=9.5 Hz,1H),7.43(d,J=8.5 Hz,1H),7.21(d,J=2.1 Hz,1H),7.16(dd,J=8.2,2.2 Hz,1H),7.05(d,J=8.5 Hz,1H),6.96(d,J=8.2 Hz,1H),6.73(d,J=15.3 Hz,1H),6.45 - 6.05(m,1H),1.87(d,J=6.2 Hz,1H);13C NMR(101 MHz,DMSO-d6)δ159.89,154.27,148.70,147.92,147.82,146.23,143.73,137.45,130.70,130.20,125.85,125.13,124.42,123.50,121.32,119.86,119.27,116.56,115.98,115.57,114.09,110.78,103.08,19.18;HR-MS(ESI)m/z 489.10602 [M-H]-(cacld for C24H17N4O8,489.105187),err 1.9 ppm。
4-(3-((E)-(2-(3,5-bis(trifluoromethyl)phenyl)hydrazono)methyl)-4-hydroxy-5-((E)-prop-1-en-1-yl)benzofuran-2-yl)benzene-1,2-diol(2e)黄色粉末;产率57%;1H NMR(400 MHz,MeOH-d4)δ8.22(s,1H),7.38(d,J=1.4 Hz,2H),7.29(d,J=8.6 Hz,1H),7.26(s,1H),7.12(d,J=2.1 Hz,1H),7.03(dd,J=8.2,2.1 Hz,1H),6.90(d,J=8.1 Hz,1H),6.84(d,J=8.6 Hz,1H),6.71(dd,J=15.9,1.9 Hz,1H),6.22(dq,J=15.9,6.6 Hz,1H),1.87(dd,J=6.5,1.7 Hz,3H);19F NMR(376 MHz,MeOH-d4)δ-64.80;13C NMR(101 MHz,MeOH-d4)δ156.72,154.43,148.20,147.19,145.79,145.50,137.23,132.43(q,J=32.9 Hz),125.86,124.65,123.56(q,J=270 Hz),123.34,121.04,120.39,118.79,115.21,114.79,114.12,111.28,111.20(m),101.77,17.76;HR-MS(ESI)m/z 535.11144 [M-H]-(cacld for C26H17F6N2O4,535.109800),err 3.1 ppm。
4-(3-((E)-(2-(2,6-dichlorophenyl)hydrazono)methyl)-4-hydroxy-5-((E)-prop-1-en-1-yl)benzofuran-2-yl)benzene-1,2-diol(2f)黄色粉末;产率:65%;1H NMR(400 MHz,MeOH-d4)δ8.25(s,1H),7.44(d,J=8.1 Hz,2H),7.32(d,J=8.5 Hz,1H),7.18 -7.11(m,2H),7.04(dd,J=8.2,2.2 Hz,1H),6.89(d,J=8.3 Hz,1H),6.86(d,J=8.6 Hz,1H),6.71(dd,J=15.9,2.0 Hz,1H),6.11(dq,J=15.8,6.5 Hz,1H),1.85(dd,J=6.6,1.8 Hz,3H);13C NMR(100 MHz,MeOH-d4)δ157.28,155.98,149.61,148.37,146.81,138.90,138.88,131.37,130.14,127.49,127.30,125.48,124.22,122.61,121.66,120.24,116.62,116.12,115.49,113.06,102.95,19.02;HR-MS(ESI)m/z 467.05854 [M-H]-(cacld for C24H17Cl2N2O4,467.057086),err 3.1 ppm。
4-(3-((E)-(2-(2,6-difluorophenyl)hydrazono)methyl)-4-hydroxy-5-((E)-prop-1-en-1-yl)benzofuran-2-yl)benzene-1,2-diol(2g)黄色粉末;产率:53%;1H NMR(400 MHz,Acetone-d6)δ11.28(s,1H),9.20(s,1H),8.57(d,J=1.4 Hz,1H),8.44(s,2H),7.42(d,J=8.5 Hz,1H),7.25(d,J=2.1 Hz,1H),7.16(dd,J=8.2,2.1 Hz,1H),7.13 -7.04(m,3H),7.01(d,J=8.2 Hz,1H),6.93(d,J=8.5 Hz,1H),6.81(dd,J=16.0,1.8 Hz,1H),6.18(dq,J=15.9,6.5 Hz,1H),1.87(dd,J=6.6,1.8 Hz,3H);19F NMR(376 MHz,Acetone-d6)δ126.83;13C NMR(100 MHz,Acetone-d6)δ157.01,155.56,154.57(dd,J=244.9,5.9 Hz),149.73,147.90,146.35,139.71,127.06,125.33,123.76,122.91(t,J=9.8 Hz),122.69(t,J=13.2 Hz),122.30,121.69,119.91,116.60,116.14,115.18,113.06,112.86(dd,J=17.3,10.6 Hz),102.73,19.01;HR-MS(ESI)m/z 435.11761[M-H]-(cacld for C24H17F2N2O4,435.116187),err 3.3 ppm。
Iteafuranal A是从民族药月月青分离得到的天然产物,具有3-醛基-2-芳基苯并呋喃的基本骨架,并表现出显著的抗肝癌活性。其抗肝癌活性可能与靶向抑制RAS/ERK信号通路密切相关,为新型靶向抗肝癌药物的开发提供了新的先导结构[5]。本研究基于其C-3位醛基官能团展开结构修饰研究,共合成了7个全新的苯腙衍生物,为进一步的活性评价奠定坚实基础。