ARTICLES

Design, Synthesis and Antibacterial Activities of Isoxzoleamide Derivatives Containing Phosphonate Fragment

  • Huixian She ,
  • Qing Wang ,
  • Qin Zha ,
  • Jiaqiang Yang , *
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  • Guizhou Provincial Key Laboratory of Innovation and Manufacturing for Pharmaceuticals, School of Pharmacy, Zunyi Medical University, Zunyi, Guizhou 563000
* E-mail:

Received date: 2025-12-03

  Revised date: 2026-01-11

  Online published: 2026-02-12

Supported by

Guizhou Provincial Science and Technology Plan(Qiankehe Foundation ZK[2024]265)

National College Students’ Innovation and Entrepreneurship Training Program(202510661273)

Abstract

In order to obtain antibacterial candidate compounds, eighteen isoxazoleamide derivatives containing phosphonate fragment were designed and synthesized by combining methylisoxazole and phosphonate via amide bonds based on molecular hybridization strategy. Their structures were confirmed by 1H NMR, 13C NMR and elemental analysis. Antibacterial activity tests revealed that these derivatives exhibited varying degrees of inhibition against the tested bacteria, with particularly significant activity against Gram-negative bacteria. Diethyl ((3-(2-chloro-6-fluorophenyl)-5-methylisoxazole-4-carboxamido) (4-hydroxyphenyl)methyl)phosphonate (Ⅲl) stood out as the most potent, showing minimum inhibitory concentrations (MIC) of 2 μg/mL against both E. coli and fluoroquinolone-resistant E. coli (FREC), outperforming the control drug gentamicin. Additionally, compound Ⅲl demonstrated a low tendency to induce resistance. Time-kill curve analysis indicated that at concentrations≥1 MIC, compound Ⅲl exhibited bactericidal effects throughout the growth cycle of E. coli, with the most pronounced effect observed at 4 MIC. Intracellular bactericidal assays confirmed that compound Ⅲl possesses intracellular antibacterial activity against E. coli-infected macrophages. Furthermore, compound Ⅲl showed no toxicity toward murine mononuclear macrophages, suggesting its potential as a promising lead compound for further antibacterial development.

Cite this article

Huixian She , Qing Wang , Qin Zha , Jiaqiang Yang . Design, Synthesis and Antibacterial Activities of Isoxzoleamide Derivatives Containing Phosphonate Fragment[J]. Chinese Journal of Organic Chemistry, 2026 , 46(5) : 2059 -2066 . DOI: 10.6023/cjoc202512004

随着抗菌药物的大量使用, 细菌耐药性问题持续加剧, 以至于现有药物临床疗效逐渐下降乃至失效[1-2]. 面对“后抗生素时代”与“超级细菌”的威胁, 加速新型抗菌药物的研发已成为一项紧迫任务.
异噁唑作为五元双杂芳香环, 结构中的O和N使该环具有良好的亲电性及氢键结合能力, 在药物设计中常作为“优势结构”被广泛应用, 其衍生物呈现多种医用和农用活性[3-8]. 尤其是甲基异噁唑片段在抗菌药物的设计与改造中发挥重要作用, 既能增强与靶标的作用 力[9-11], 如在β-内酰胺类药物的结构改造中, 引入异噁唑环的苯唑西林能有效提升对青霉素结合蛋白(PBPs)的亲和力, 并提高对细菌β-内酰胺酶的稳定性, 不易产生耐药性; 还能显著改善药物分子的药代动力学性 质[12-13], 如氯唑西林、磺胺甲基异噁唑等抗菌药物.
磷作为生命体的必需元素, 广泛参与能量转移、细胞信号传导及生物大分子合成等关键生理过程[14-16]. 含磷化合物凭借其独特的结构特征与可修饰性, 已成为药物设计与结构优化的重要部分. 目前上市的含磷药物大多以磷(膦)酸(酯)结构呈现, 该类结构不仅能模拟天然磷酸化过渡态, 增强与靶标结合力, 还可显著改善药物的水溶性与代谢稳定性, 进而提高其选择性与生物利用度[17-18]. 其中, 在抗菌药物的研发中, 磷修饰策略显示出重要的应用价值, 如克林霉素磷酸酯和头孢洛林酯结构中的磷酰基有效提高抗菌活性和改善药代动力学性质. 近年来, 该方向研究持续取得进展. 2023年, Yang 等[19]设计合成的一系列香豆素膦酸酯衍生物, 在体内外均展现出显著抗MRSA (methicillin-resistance S. aureus)活性, 且细胞毒性较低, 具备良好的成药潜力; 2025年, 本课题组[20]将膦酸酯骨架引入到天然产物蛇床子素结构中, 得到的部分衍生物对耐药菌MRSA和FREC (fluoroquinolone-resistant E. coli)抑制作用显著, 且不易产生耐药, 有成为候选化合物的潜力, 膦酸酯骨架的引入显著改善了该类化合物的抗菌活性和脂水分配系数.
基于此, 运用分子杂合策略, 将抗菌活性结构甲基异噁唑与膦酸酯通过酰胺键组合, 设计合成系列新型含膦酸酯结构的异噁唑酰胺衍生物, 进行抗菌活性评价和构效关系研究. 设计思路见图1, 合成路线如Scheme 1.
图1 目标化合物的设计思路

Figure 1 Design strategy for target compounds

图式1 目标化合物的合成路线

Scheme 1 Synthetic routes of target compounds

1 结果与讨论

1.1 化合物的合成

首先, 化合物Ⅰ的制备采用一锅法, 以芳香醛、亚磷酸二乙酯和乙酸铵为原料, 三氟甲磺酸铝为催化剂, 在100 ℃下, 无溶剂反应30~40 min, 收率可达55%~78%; 接着, 化合物Ⅱ的制备以2-氯-6-氟苯甲醛为原料, 经肟化、氯化、环化和水解等步骤制得; 最后, 化合物Ⅱ经酰氯化, 再与化合物Ⅰ缩合制得化合物Ⅲ.

1.2 化合物的结构表征

以目标物Ⅲa为例, 在1H NMR中, δ 7.50~7.56处多重峰和δ 7.41处二重峰以及δ 7.10~7.24处多重峰为芳香环上的信号峰, δ 6.25处二重双峰为酰胺NH上信号峰, δ 5.40处二重双峰为与磷原子相连的CH上的信号峰, δ 3.56~3.92处多重峰为两个OCH2的信号峰, δ 2.74处单峰为异噁唑环上CH3的信号峰, δ 1.18和δ 1.01处的三重峰为磷酸酯上两个CH3的信号峰. 在13C NMR中, δ 175.09为异噁唑环上连接CH3处碳的信号峰, δ 162.08为酰胺键中连接氧处碳的信号峰, δ 159.57为4-氯-3-氟苯环上连接氟的碳信号峰, δ 152.85处为异噁唑上连接4-氯-3-氟苯环处碳信号峰, 芳环上其余碳的信号峰在δ 115.03~135.43之间, δ 111.52为异噁唑环上连接酰胺处的碳信号峰, δ 62.87和63.36为2个OCH2的碳信号峰, δ 50.78是与磷原子相连的CH碳信号峰, 3个CH3的碳信号峰在δ 13.17~16.28之间.

1.3 化合物的抗菌活性评价

1.3.1 最小抑菌浓度(MIC)

由表1可以看出, 化合物Ⅲa~Ⅲr对所测细菌有不同程度的抗菌活性. 对于革兰氏阳性菌(S. aureus和MRSA): 化合物Ⅲg、Ⅲi、Ⅲl和Ⅲr呈现较好的活性, MIC≤16 μg/mL; 而化合物Ⅲb、Ⅲh、Ⅲj和Ⅲo的活性最差, MIC>128 μg/mL. 对于革兰氏阴性菌(E. coli和FREC): 化合物Ⅲg、Ⅲl、Ⅲn和Ⅲr的活性较突出, MIC≤16 μg/mL, 而化合物Ⅲb、Ⅲh、Ⅲj和Ⅲo几乎无活性. 对于耐药菌(MRSA和FREC): 化合物Ⅲg、Ⅲi、Ⅲl、Ⅲn和Ⅲr等多个化合物对两者的活性优于对照药庆大霉素, 表明该类化合物可能具有克服某些耐药机制的潜力, 尤其是Ⅲl和Ⅲg对MRSA和FREC的MIC值较低. 综合看来, 化合物Ⅲl对所测细菌均有较显著的活性, 对S. aureus、E. coli、MRSA和FREC的MIC值分别为4、2、4和2 μg/mL, 尤其是对革兰氏阴性菌(E. coli和FREC)的优于对照药.
表1 目标化合物Ⅲa~Ⅲr的抗菌活性

Table 1 Antibacterial activities of target compounds Ⅲa~Ⅲr

Compd. R MIC/(μg∙mL-1)
S. aureus E. coli MRSA FREC
Ⅲa C6H5 128 128 >128 >128
Ⅲb 2-CH3C6H4 >128 128 >128 >128
Ⅲc 4-CH3C6H4 64 32 128 64
Ⅲd 2-CH3OC6H4 128 64 128 64
Ⅲe 4-CH3OC6H4 64 64 64 128
Ⅲf 2-FC6H4 32 32 64 32
Ⅲg 4-FC6H4 8 8 8 8
Ⅲh 2-ClC6H4 >128 128 >128 >128
Ⅲi 4-ClC6H4 32 16 16 32
Ⅲj 2-BrC6H4 128 >128 >128 >128
Ⅲk 4-BrC6H4 128 32 64 64
Ⅲl 4-HOC6H4 4 2 4 2
Ⅲm 3,4,5-F3C6H2 32 16 64 32
Ⅲn 3,4,5-(CH3O)3C6H2 64 16 64 16
Ⅲo 2-Furyl >128 128 >128 128
Ⅲp 4-CH3-2-furyl 64 32 128 32
Ⅲq 2-Thienyl 64 64 128 64
Ⅲr 4-CH3-2-thienyl 32 16 64 16
Gentamycin 1 4 128 64
构效关系分析表明: (1)取代基的位置. 对位取代通常优于邻位取代. 如Ⅲc (4-CH3C6H4)对S. aureus的MIC为64 μg/mL, 而Ⅲb (2-CH3C6H4)的MIC>128 μg/mL; Ⅲi (4-ClC6H4)对E. coli的MIC为16 μg/mL, 而Ⅲh (2-ClC6H4)的MIC>128 μg/mL. 这可能是由于邻位取代基引入空间位阻, 妨碍化合物与细菌靶点的结合, 而对位取代则允许更佳的分子取向. (2)取代基的性质. 吸电子基团在对位时能增强活性, 如Ⅲg (4-FC6H4)对所测细菌的MIC为8 μg/mL, 活性较显著, Ⅲi (4-ClC6H4)对MRSA和E. coli的MIC为16 μg/mL, 活性较好; 供电子基团在对位时活性中等, 如Ⅲc (4-CH3C6H4)和Ⅲe (4-CH3OC6H4)的MIC值在32~128 μg/mL之间; 羟基在对位时活性最强, 如Ⅲl (4-OHC6H4), 可能由于其羟基能形成氢键, 增强了与靶点的相互作用; 卤素原子的大小也影响活性, 如F和Cl取代活性较好, 而Br取代活性一般, 可能与大原子带来的立体效应有关. (3)多取代基效应. 多氟取代的Ⅲm (3,4,5-F3C6H2)不及单取代Ⅲg (4-FC6H4)的活性强, 而多甲氧基取代的Ⅲn [3,4,5- (CH3O)3C6H2]对E. coli和FREC的活性较单取代Ⅲe (4-CH3OC6H4)的活性好. (4)芳香杂环体系. 噻吩环比呋喃环更有利于活性, 如Ⅲq (2-thienyl)和Ⅲr (4-CH3-2- thienyl)对E. coli的MIC分别小于Ⅲo (2-furyl)和Ⅲp (4- CH3-2-furyl).

1.3.2 化合物Ⅲl的时间-杀菌曲线

由图2可知, 化合物Ⅲl在0.5 MIC时, 与对照组的E. coli生长趋势一致, 几乎无杀菌作用; 在1 MIC时, 在4~12 h有一定的杀菌作用, 12 h后杀菌作用不显著; 在2 MIC时, 在0~4 h杀菌作用不显著, 但在4~16 h表现出显著杀菌作用; 在4 MIC时, 在0~16 h对E. coli有快速杀菌作用, 在20 h后完全杀死细菌. 上述结果表明, 化合物Ⅲl在浓度≥1 MIC时, 对E. coli整个生长周期均有杀菌作用, 尤其是在4 MIC, 效果最为显著.
图2 化合物Ⅲl对大肠杆菌的时间杀菌曲线

Figure 2 Time-kill growth curves of compound Ⅲl to E. coli

1.3.3 化合物Ⅲl的胞内杀菌作用

从图3可以看出, 化合物Ⅲl在3 h以后, 能明显降低MAC-T细胞内E. coli的菌落数, 具有显著的胞内杀菌作用. 表明该化合物较传统的氨基糖苷类抗生素具有更好的细胞内渗透能力, 能较好地穿过细胞膜并灭杀细胞内部的细菌.
图3 化合物Ⅲl对大肠杆菌的胞内杀菌作用

Figure 3 Bactericidal effect of compound III1 against intracellular E. coli

1.4 化合物Ⅲl的细胞毒性

化合物Ⅲl对RAW 264.7的细胞毒性如图4所示. 化合物Ⅲl在浓度为32 μg/mL及以下, 小鼠单核巨噬细胞(RAW 264.7)的存活率达90%以上, 在浓度为64和128 μg/mL时, 存活率达86%以上, 对所测细胞无明显毒性.
图4 化合物Ⅲl对RAW 264.7的细胞毒性

Figure 4 Cytotoxicity of compound Ⅲl on RAW264.7 cell

2 结论

基于分子杂合策略, 设计合成了系列含膦酸酯结构的异噁唑酰胺衍生物, 部分目标物对所测细菌表现出显著的抗菌活性. 该类化合物的抗菌活性受R基团的影响较大, 苯环对位有吸电子基团或羟基取代时, 活性最强; 邻位取代通常降低活性; 在杂环体系中, 噻吩环比呋喃环更优. 这些构效关系结果为后续设计更有效的抗菌化合物提供了研究基础, 尤其对耐药菌株. 其中, 化合物Ⅲl可作为先导化合物, 进一步结构优化和深入抗菌机制研究.

3 实验部分

3.1 仪器与试剂

X-4B显微熔点仪检测熔点; Agilent-400核磁共振仪测试核磁共振谱; Vario EL Ⅲ元素分析仪测定元素分析. 所有试剂均为分析纯.

3.2 实验方法

3.2.1 α-氨基膦酸二乙酯(Ⅰ)的合成

α-氨基膦酸二乙酯(Ⅰ)参照文献[20]方法合成.

3.2.2 3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酸(Ⅱ)的合成

依次称取2-氟-6-氯苯甲醛6 mmol、盐酸羟胺7.2 mmol和体积分数为50%的乙醇溶液10 mL, 加入反应瓶中, 室温搅拌反应, 薄层色谱跟踪. 1 h反应完毕, 饱和食盐水洗涤, 二氯甲烷萃取. 合并有机相, 无水硫酸钠干燥, 浓缩溶剂, 得2-氟-6-氯苯甲醛肟, 无需纯化, 直接用于下一步反应.
将上述制得的2-氟-6-氯苯甲醛肟、N-氯代丁二酰亚胺5 mmol和N,N-二甲基甲酰胺5 mL加入反应瓶中, 室温搅拌反应, 薄层色谱跟踪. 5 h反应完毕后, 饱和食盐水洗涤, 乙酸乙酯萃取. 合并有机相, 无水硫酸钠干燥, 浓缩溶剂, 得2-氯-6-氟苯甲肟氯, 无需纯化, 直接用于下一步反应.
将上述得到的2-氯-6-氟苯甲肟氯、乙酰乙酸乙酯6.4 mmol和乙醇8 mL加入反应瓶中, 再滴加质量分数为30%的乙醇钠乙醇溶液, 室温搅拌反应, 薄层色谱跟踪. 5 h反应完毕, 浓缩溶剂, 再加入质量分数为30%的氢氧化钠溶液10 mL, 加热回流, 薄层色谱跟踪. 4 h反应完毕, 冷却, 用质量分为10%的HCl调节pH至3. 减压过滤, 粗品用酸碱法反复纯化, 得淡黄色固体3-(2- 氯-6-氟苯基)-5-甲基异噁唑-4-甲酸(Ⅱ), 收率68%. m.p. 199~200 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.35~7.43 (m, 1H), 7.25~7.29 (m, 1H), 7.07 (t, J=9.2 Hz, 1H), 2.80 (s, 3H).

3.2.3 目标化合物Ⅲ的合成

依次称取0.3 mmol化合物Ⅱ和二氯化亚砜1.5 mmol加入反应瓶中, 加热回流5 h. 反应完毕, 减压浓缩溶剂, 得浅黄色固体3-(2'-氯-6'-氟苯基)-5-甲基异噁唑-4-甲酰氯, 无需纯化, 直接用于下一步反应.
将上述所得酰氯、0.25 mmol中间体Ⅰa、0.4 mmol三乙胺和10 mL二氯甲烷依次加入反应瓶中, 于5~10 ℃搅拌反应, 薄层色谱跟踪. 反应结束后, 浓缩溶剂, 石油醚重结晶纯化, 得白色固体化合物Ⅲa. 化合物Ⅲb~Ⅲr由类似方法可制得.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(苯基)甲基)膦酸酯(Ⅲa): 白色固体, 产率75%. m.p. 198~199 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.50~7.56 (m, 1H), 7.41 (d, J=8.1 Hz, 1H), 7.19~7.24 (m, 4H), 7.10~7.12 (m, 2H), 6.25 (dd, J=9.2, 5.1 Hz, 1H), 5.40 (dd, J=20.7, 9.1 Hz), 3.56~3.92 (m, 4H), 2.74 (s, 3H), 1.18 (t, J=7.0 Hz, 3H), 1.01 (t, J=7.0 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.17, 16.03, 16.28, 50.78, 62.87, 63.36, 111.52, 115.03, 126.09, 126.13, 127.53, 127.59, 128.16, 128.59, 132.83, 132.92, 134.55, 135.43, 152.85, 159.57, 162.08, 175.09. Anal. calcd for C22H23ClFN2O5P: C 54.95, H 4.82, N 5.83; found C 55.16, H 4.95, N 5.70.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(邻甲苯基)甲基)膦酸酯(Ⅲb): 白色固体, 产率76%. m.p. 221~222 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.52~7.56 (m, 1H), 7.42 (d, J=8.1 Hz, 1H), 7.01~7.26 (m, 4H), 6.81~6.83 (m, 1H), 6.31 (dd, J=9.0, 4.8 Hz, 1H), 5.66 (dd, J=20.9, 8.9 Hz, 1H), 3.45~4.00 (m, 4H), 2.74 (s, 3H), 2.42 (s, 3H), 1.22 (t, J=7.0 Hz, 3H), 0.96 (t, J=7.0 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.19, 15.97, 16.33, 19.63, 46.80, 62.83, 63.39, 111.48, 115.17, 126.13, 126.18, 126.69, 128.01, 130.52, 132.87, 132.96, 133.32, 135.44, 136.56, 152.84, 159.56, 162.08, 175.09. Anal. calcd for C23H25ClFN2O5P: C 55.82, H 5.09, N 5.66; found C 55.65, H 5.15, N 5.73.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(对甲苯基)甲基)膦酸酯(Ⅲc): 白色固体, 产率51%. m.p. 235~236 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.51~7.56 (m, 1H), 7.41 (d, J=8.1 Hz, 1H), 7.19~7.24 (m, 1H), 7.06~7.12 (m, 2H), 6.83~6.99 (m, 2H, ArH), 6.21 (dd, J=9.1, 5.3 Hz, 1H), 5.36 (dd, J=20.5, 9.1 Hz, 1H), 3.57~3.93 (m, 4H), 2.74 (s, 3H), 2.28 (s, 3H), 1.18 (t, J=7.1 Hz, 3H), 1.03 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.17, 16.07, 16.29, 21.12, 48.94, 62.82, 63.30, 111.54, 115.13, 126.08, 126.12, 127.40, 127.46, 129.28, 131.47, 132.80, 132.90, 135.44, 137.96, 152.84, 159.56, 162.08, 175.08. Anal. calcd for C23H25ClFN2O5P: C 55.82, H 5.09, N 5.66; found C 55.69, H 4.97, N 5.78.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(邻甲氧苯基)甲基)膦酸酯(Ⅲd): 白色固体, 产率74%. m.p. 207~208 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.46~7.53 (m, 1H), 7.37 (d, J=8.6 Hz, 1H), 7.14~7.23 (m, 2H), 6.81~6.92 (m, 3H), 6.48 (dd, J=9.5, 4.5 Hz, 1H), 5.91 (dd, J=21.2, 9.4 Hz, 1H), 3.57~3.96 (m, 7H), 2.74 (s, 3H), 1.21 (t, J=7.2 Hz, 3H), 0.99 (t, J=7.2 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.10, 16.02, 16.33, 45.77, 55.79, 62.66, 63.06, 111.07, 111.92, 114.79, 115.00, 116.32, 120.74, 123.00, 125.95, 129.36, 132.56, 135.47, 153.04, 156.98, 159.52, 162.09, 174.55. Anal. calcd for C23H25ClFN2O6P: C 54.07, H 4.93, N 5.48; found C 54.32, H 5.11, N 5.59.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(对甲氧苯基)甲基)膦酸酯(Ⅲe): 白色固体, 产率85%. m.p. 223~225 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.50~7.56 (m, 1H), 7.41 (d, J=8.1 Hz, 1H), 7.18~7.24 (m, 1H), 7.03~7.06 (m, 2H), 6.78~6.81 (m, 2H), 6.19 (dd, J=9.1, 5.3 Hz, 1H), 5.34 (dd, J=20.4, 9.0 Hz, 1H), 3.51~3.99 (m, 7H), 2.74 (s, 3H), 1.19 (t, J=7.1 Hz, 3H), 1.03 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.16, 16.09, 16.30, 50.11, 55.24, 62.80, 63.31, 111.55, 114.00, 114.91, 116.29, 126.08, 126.55, 128.77, 128.83, 132.80, 132.90, 135.41, 152.84, 159.38, 159.54, 162.07, 175.04. Anal. calcd for C23H25ClFN2O6P: C 54.07, H 4.93, N 5.48; found C 53.88, H 5.06, N 5.29.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(邻氟苯基)甲基)膦酸酯(Ⅲf): 白色固体, 产率88%. m.p. 203~204 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.50~7.56 (m, 1H), 7.40 (d, J=8.2 Hz, 1H), 7.19~7.25 (m, 2H), 6.97~7.06 (m, 3H), 6.35 (dd, J=9.2, 5.0 Hz, 1H), 5.74 (dd, J=21.3, 9.2 Hz, 1H), 3.61~4.06 (m, 4H), 2.75 (s, 3H, CH3), 1.22 (t, J=7.1 Hz, 3H), 1.03 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.20, 16.00, 16.27, 43.63, 63.09, 63.38, 111.43, 114.91, 115.61, 116.15, 122.06, 124.31, 126.07, 129.02, 129.85, 132.80, 135.42, 152.89, 159.07, 161.59, 162.09, 175.17. Anal. calcd for C22H22ClF2N2O5P: C 52.97, H 4.45, N 5.62; found C 52.76, H 4.61, N 5.47.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(对氟苯基)甲基)膦酸酯(Ⅲg): 白色固体, 产率52%. m.p. 222~223 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.52~7.56 (m, 1H), 7.42 (d, J=8.2 Hz, 1H), 7.11~7.22 (m, 3H), 6.81~6.96 (m, 2H), 6.20 (dd, J=8.8, 5.6 Hz, 1H), 5.36 (dd, J=20.8, 8.9 Hz, 1H), 3.62~3.93 (m, 4H), 2.75 (s, 3H), 1.20 (t, J=7.1 Hz, 3H), 1.05 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.19, 16.07, 16.29, 48.59, 62.97, 63.39, 111.38, 114.94, 115.15, 115.49, 115.71, 126.09, 129.23, 129.31, 130.55, 132.88, 135.46, 152.77, 159.55, 159.78, 162.88, 175.24. Anal. calcd for C22H22Cl- F2N2O5P: C 52.97, H 4.45, N, 5.62; found C 53.18, H 4.34, N 5.73.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(邻氯苯基)甲基)膦酸酯(Ⅲh): 白色固体, 产率81%. m.p. 218~219 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.52~7.56 (m, 1H), 7.43 (d, J=8.2 Hz, 1H), 7.29~7.33 (m, 1H), 7.13~7.24 (m, 3H), 6.82~6.96 (m, 1H), 6.39 (dd, J=8.7, 6.2 Hz, 1H), 5.97 (dd, J=21.2, 8.7 Hz, 1H), 3.53~4.05 (m, 4H), 2.75 (s, 3H), 1.24 (t, J=7.2 Hz, 3H), 0.98 (t, J=7.2 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.24, 15.95, 16.28, 47.48, 63.12, 63.54, 111.32, 115.20, 126.14, 126.99, 128.43, 128.48, 129.26, 129.73, 132.91, 133.00, 133.78, 135.45, 152.81, 159.58, 162.11, 175.38. Anal. calcd for C22H22Cl2FN2O5P: C 51.28, H 4.30, N 5.44; found C 51.52, H 4.15, N 5.70.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(对氯苯基)甲基)膦酸酯(Ⅲi): 白色固体, 产率76%. m.p. 227~228 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.52~7.56 (m, 1H), 7.42 (d, J=8.3 Hz, 1H), 7.20~7.24 (m, 3H), 7.05~7.08 (m, 2H), 6.23 (dd, J=8.9, 6.0 Hz, 1H), 5.35 (dd, J=21.0, 8.8 Hz, 1H), 3.60~3.99 (m, 4H), 2.74 (s, 3H), 1.19 t, J=7.1 Hz, 3H), 1.06 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.20, 16.10, 16.36, 50.26, 63.05, 63.44, 111.35, 115.16, 126.10, 126.14, 128.78, 128.80, 128.85, 128.91, 132.89, 132.99, 133.25, 134.09, 152.76, 159.55, 162.08, 175.29. Anal. calcd for C22H22Cl2- FN2O5P: C 51.28, H 4.30, N 5.44; found C 51.08, H 4.14, N 5.59.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(邻溴苯基)甲基)膦酸酯(Ⅲj): 白色固体, 产率92%. m.p. 221~222 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.51~7.58 (m, 2H), 7.43 (d, J=8.1 Hz, 1H), 7.17~7.23 (m, 2H), 7.10~7.12 (m, 1H), 6.92~6.94 (m, 1H), 6.40 (dd, J=8.6, 6.3 Hz, 1H), 5.96 (dd, J=21.0, 8.6 Hz, 1H), 3.47~4.09 (m, 4H), 2.74 (s, 3H), 1.25 (t, J=7.1 Hz, 3H), 0.98 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.26, 15.96, 16.29, 50.00, 63.16, 63.60, 111.29, 115.00, 124.24, 126.15, 127.61, 128.50, 128.55, 129.52, 132.93, 133.03, 134.86, 135.44, 152.80, 159.57, 162.10, 175.43. Anal. calcd for C22H22BrClFN2O5P: C 47.21, H 3.96, N 5.00, found C 47.05, H 4.10, N 4.93.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(对溴苯基)甲基)膦酸酯(Ⅲk): 白色固体, 产率84%. m.p. 230~231 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.51~7.57 (m, 1H), 7.38~7.42 (m, 3H), 7.19~7.23 (m, 1H), 6.93~7.00 (m, 2H), 6.23 (dd, J=8.9, 5.9 Hz, 1H), 5.34 (dd, J=21.0, 8.8 Hz, 1H), 3.57~4.00 (m, 4H), 2.74 (s, 3H), 1.19 (t, J=7.1 Hz, 3H), 1.07 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.17, 16.08, 16.28, 50.33, 63.08, 63.47, 111.36, 115.15, 122.25, 126.09, 126.13, 129.16, 129.22, 131.72, 132.87, 132.97, 133.77, 135.39, 152.77, 161.59, 162.04, 175.25. Anal. calcd for C22H22BrClFN2O5P: C 47.21, H 3.96, N 5.00; found C 46.98, H 3.85, N 5.11.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(对羟苯基)甲基)膦酸酯(Ⅲl): 白色固体, 产率58%. m.p. 174~175 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.47~7.53 (m, 1H), 7.32~7.39 (m, 2H), 7.05~7.12 (m, 3H), 6.89~6.92 (m, 2H), 6.19 (dd, J=8.8, 5.7 Hz, 1H), 5.35 (dd, J=20.9, 8.9 Hz, 1H), 3.63~3.90 (m, 4H), 2.62 (s, 3H), 1.17 (t, J=7.1 Hz, 3H), 1.04 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.17, 16.07, 16.35, 50.22, 62.98, 63.38, 111.36, 115.04, 121.46, 125.22, 126.14, 128.63, 131.79, 132.55, 132.90, 134.99, 135.36, 152.75, 155.32, 159.50, 159.85, 175.25. Anal. calcd for C22H23ClF- N2O6P: C 53.18, H 4.67, N 5.64; found C 53.44, H 4.51, N 5.48.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(3,4,5-三氟苯基)甲基)膦酸酯(Ⅲm): 白色固体, 产率43%. m.p. 186~187 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.54~7.60 (m, 1H), 7.44 (d, J=8.2 Hz, 1H), 7.22~7.26 (m, 1H), 6.75~6.79 (m, 2H), 6.20 (dd, J=8.6, 6.5 Hz, 1H), 5.28 (dd, J=21.3, 8.6 Hz, 1H), 3.75~3.96 (m, 4H), 2.75 (s, 3H), 1.20 (t, J=7.1 Hz, 3H), 1.13 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.22, 16.14, 16.29, 48.38, 63.34, 63.59, 111.09, 111.68, 115.05, 116.17, 126.19, 126.22, 133.13, 133.22, 135.19, 135.43, 152.66, 159.54, 159.99, 160.08, 162.07, 175.59. Anal. calcd for C22H20ClF4N2O5P: C 49.41, H 3.77, N 5.24; found C 49.57, H 3.95, N 5.05.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(3,4,5-三甲氧苯基)甲基)膦酸酯(Ⅲn): 白色固体, 产率96%. m.p. 184~185 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.49~7.53 (m, 1H), 7.38 (d, J=8.2 Hz, 1H), 7.16~7.21 (m, 1H), 6.39~6.42 (m, 2H), 6.19 (dd, J=8.7, 5.9 Hz, 1H), 5.30 (dd, J=20.7, 8.8 Hz, 1H), 3.65~3.89 (m, 13H), 2.77 (s, 3H), 1.19 (t, J=7.1 Hz, 3H), 1.06 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.15, 16.14, 16.30, 49.50, 51.03, 56.02, 60.81, 62.93, 63.47, 104.52, 111.27, 114.87, 116.21, 126.04, 130.09, 132.94, 133.03, 135.39, 137.70, 152.72, 153.21, 153.23, 159.54, 162.06, 175.43. Anal. calcd for C25H29ClFN2O8P: C 52.59, H 5.12, N 4.91; found C 52.50, H 5.15, N 5.00.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(呋喃-2-基)甲基)膦酸酯(Ⅲo): 白色固体, 产率32%. m.p. 133~134 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.46~7.52 (m, 1H), 7.36 (d, J=8.2 Hz, 1H), 7.28~7.29 (m, 1H), 7.15~7.19 (m, 1H), 6.28~6.29 (m, 1H), 6.22~6.23 (m, 1H), 6.05 (dd, J=9.6, 3.0 Hz, 1H), 5.61 (dd, J=20.6, 9.3 Hz, 1H), 3.80~4.01 (m, 4H), 2.76 (s, 3H), 1.20 (t, J=7.1 Hz, 3H), 1.14 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.15, 16.16, 16.31, 44.86, 63.10, 63.35, 108.74, 110.72, 111.50, 114.81, 125.98, 132.65, 132.74, 135.36, 142.68, 147.22, 152.96, 159.49, 162.01, 174.86. Anal. calcd for C20H21ClFN2O6P: C 51.02, H 4.50, N 5.95; found C 51.20, H 4.34, N 6.06.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(5-甲基呋喃-2-基)甲基)膦酸酯(Ⅲp): 白色固体, 产率38%. m.p. 167~168 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.45~7.51 (m, 1H), 7.35 (d, J=8.1 Hz, 1H), 7.14~7.18 (m, 1H), 6.09~6.12 (m, 1H), 5.99~6.01 (m, 1H), 5.85 (dd, J=3.2, 0.9 Hz, 1H), 5.54 (dd, J=20.5, 9.4 Hz, 1H), 3.81~3.99 (m, 4H), 2.75 (s, 3H), 2.19 (s, 3H), 1.19 (t, J=7.1 Hz, 3H), 1.15 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.14,13.55, 16.14, 16.31, 44.90, 62.99, 63.25, 106.67, 109.55, 111.58, 114.77, 125.92, 132.62, 132.71, 135.38, 145.20, 152.37, 152.96, 159.48, 162.03, 174.79. Anal. calcd for C21H23ClFN2O6P: C 52.02, H 4.78, N 5.78; found C 51.85, H 4.98, N 5.60.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(噻吩-2-基)甲基)膦酸酯(Ⅲq): 白色固体, 产率67%. m.p. 147~148 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.44~7.50 (m, 1H), 7.35 (d, J=8.1 Hz, 1H), 7.13~7.17 (m, 2H), 6.94~6.99 (m, 1H), 6.83~6.88 (m, 1H), 6.13 (dd, J=9.3, 4.0 Hz, 1H), 5.72 (dd, J=20.5, 9.3 Hz, 1H), 3.74~3.98 (m, 4H), 2.73 (s, 3H), 1.17 (t, J=7.1 Hz, 3H), 1.09 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.15, 16.11, 16.28, 46.24, 63.18, 63.51, 111.45, 114.85, 125.56, 126.02, 126.70, 127.03, 132.76, 132.86, 135.33, 136.72, 152.93, 159.48, 162.00, 174.93. Anal. calcd for C20H21ClFN2O5PS: C 49.34, H 4.35, N 5.75; found C 49.51, H 4.19, N 5.92.
二乙基((3-(2-氯-6-氟苯基)-5-甲基异噁唑-4-甲酰胺基)(5-甲基噻吩-2-基)甲基)膦酸酯(Ⅲr): 白色固体, 产率45%. m.p. 188~190 ℃; 1H NMR (400 MHz, CDCl3) δ: 7.45~7.51 (m, 1H), 7.36 (d, J=8.1 Hz, 1H), 7.09~7.16 (m, 1H), 6.70~6.81 (m, 1H), 6.52~6.53 (m, 1H), 6.03 (dd, J=9.3, 3.9 Hz, 1H), 5.61 (dd, J=20.4, 9.3 Hz, 1H), 3.77~3.99 (m, 4H), 2.74 (s, 3H), 2.37 (s, 3H), 1.19 (t, J=7.1 Hz, 3H), 1.12 (t, J=7.1 Hz, 3H); 13C NMR (101 MHz, CDCl3) δ: 13.15, 15.26, 16.14, 16.30, 46.37, 63.09, 63.47, 111.50, 114.84, 125.06, 126.01, 126.69, 132.70, 132.79, 133.93, 135.36, 140.28, 152.93, 159.49, 162.02, 174.90. Anal. calcd for C21H23ClFN2O5PS: C 50.35, H 4.63, N 5.59; found C 50.55, H 4.75, N 5.70.

3.2.4 抗菌活性评价

MIC的测定: S. aureus、E. coli源于北京北纳创联生物技术研究院; 耐药菌株MRSA和FREC由遵义医科大学附属医院分离提供. 采用两倍稀释法测定目标物的MIC, 测试方法参照文献[21].
时间-杀菌曲线: 移取E. coli菌液于24孔板, 再分别向其加入Ⅲl的DMSO溶液, 使其终浓度为4 MIC、2 MIC、1 MIC和1/2 MIC, 以空白菌液为对照, 置37 ℃恒温箱中培养, 分别在0、4、8、12、16、20和24 h取各组菌液100 μL, 用培养液依次10倍稀释, 涂于琼脂板, 于37 ℃恒温箱培养24 h, 进行菌落计数, 以时间为横坐标, lg(CFU/mL)为纵坐标, 绘制时间-杀菌曲线.
胞内杀菌: 参照文献[22], 将MAC-T细胞平铺在6孔板中, 于恒温箱37 ℃培养过夜, 感染E. coli (1×105 CFU) 2 h后, 用磷酸盐缓冲液(PBS)洗涤细胞3次, 每孔加入1 mL庆大霉素(100 μg/mL)清除细胞外细菌. 将化合物Ⅲl (50 μg/mL)和庆大霉素与杜尔贝科改良伊格尔培养基(DMEM)-体积分数为10%的胎牛血清(FBS)培养液混合, 分别加入至6孔板中与细胞孵育. 分别在1、2、4和8 h, 用体积分数为0.1%的TritonX-100处理, 裂解物在平板上连续稀释, 以计数细胞内的活细菌.

3.2.5 细胞毒性

取对数生长期的小鼠单核巨噬细胞, 接种于96孔, 每孔100 μL, 于恒温箱培养24 h, 移除培养基, PBS清洗2次, 加入Ⅲl, 使其终浓度分别为128、64、32、16、8、4、2、1和0.5 μg/mL. 设置单独细胞及空白培养液为对照, 24 h后, 每孔加入10 μL的2-(4-碘苯)-3-(4-硝基苯)-5-(2,4-二磺基苯)-2H-四氮唑钠盐(WST-1), 置于恒温箱中孵育1 h, 酶标仪检测OD450数值, 计算细胞存活率A (%).
辅助材料(Supporting Information) 目标化合物Ⅲa~Ⅲr的1H NMR和13C NMR图谱. 这些材料可以免费从本刊网站(http://sioc-journal.cn/)上下载.
(Cheng, F.)
[1]
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