Citation: Teng Qiaoling, Xu Lulu, Cheng Dongping, Xu Xiaoliang. Synthesis of 10-Phenanthrenol Derivatives via Visible Light Catalyzed Itramolecular Cycloaromatization[J]. Chinese Journal of Organic Chemistry, 2020, 40(12): 4258-4266. doi: 10.6023/cjoc202005077
可见光催化分子内环芳构化合成10-菲酚衍生物
English
Synthesis of 10-Phenanthrenol Derivatives via Visible Light Catalyzed Itramolecular Cycloaromatization
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菲衍生物广泛存在于自然产物中, 是一类重要的多环芳烃化合物[1].由于具有抗癌[2]、抗疟疾[3]、抗过敏[4]、抗菌[5]等多种生物活性, 菲衍生物在药物化学研究中备受关注.此外, 该类化合物还具有显著的光导、光化学和电致发光性质, 使其成为材料科学中常见的结构基序[6].在过去几十年中, 菲衍生物的合成方法得到了不断发展, 大致可分为两类.第一类主要是以二苯乙烯衍生物为起始原料发生分子内环烷化反应[7]、缩合反应[8]、光化学环化反应[9]等得到目标产物.其中Mallory反应是以二苯乙烯衍生物发生氧化光环化制备菲衍生物最常用的方法之一, 该反应涉及使用催化量的碘氧化二氢菲中间体生成菲的过程[10].另外顺式2-碘二苯乙烯的自由基环化[11]和双(N-对甲苯磺酰腙)的卡宾二聚反应[12]也是合成菲衍生物的有效方法.第二种是以联苯衍生物为起始原料来合成, 如2, 2'-二羰基联苯的McMurry反应[13]、2, 2'-二乙烯基联苯的烯烃复分解反应[14]、联苯与内炔的分子间环加成反应[15]等.此外以2-乙炔基联苯衍生物为起始原料, 通过过渡金属催化[16]、碱催化[17]、亲电环化[18]合成菲衍生物的反应也得到了广泛研究.尽管上述方法可以有效合成菲衍生物, 但是有些反应仍然存在效率低、区域选择性差、反应条件苛刻等缺点.鉴于菲衍生物在许多领域中的重要性, 开发更方便、更温和、更高效的菲衍生物制备方法仍然具有重要意义.
近几年来, 可见光光催化因其符合绿色化学的要求取得了巨大的研究进展[19], 已经被成功地应用于脱羧、脱硼、烷基化、环加成、还原、氧化、聚合等反应.最近Wang等[20]报道了N-溴代丁二酰亚胺(NBS)诱导的2-芳基苯甲酰乙酸衍生物发生分子内环化反应.该反应为自由基历程, 需要使用过量的氧化剂叔丁基过氧化氢(TBHP).基于我们长期以来对可见光催化反应的关注[21], 在此报道可见光催化2-芳基苯甲酰乙酸衍生物发生分子内环芳构化反应, 生成一系列的10-菲酚衍生物.
1. 结果与讨论
首先, 选择2-苯基苯甲酰乙酸乙酯(1a)作为模型底物, 以Ir[dF(CF3)ppy]2(dtbbpy)PF6为可见光催化剂, O2为氧化剂, N-甲基吡咯烷酮(NMP)为溶剂, 在LED蓝光照射下进行反应(表 1, Entry 1), 成功地分离得到目标产物2a, 尽管产率只有18%.接着考察了不同可见光催化剂对反应的影响(Entries 2~4).当使用Ru(bpy)3(PF6)2、曙红Y、Ir(ppy)3作为可见光催化剂时, 通过薄层色谱(TLC)检测发现原料未减少, 基本没有产物生成, 这可能与可见光催化剂的氧化还原电位有关.考虑反应中加入碱是否能提高收率, 我们改变反应条件为以Na2CO3为碱, Na2S2O8为氧化剂, N, N-二甲基甲酰胺(DMF)为溶剂, 在氮气保护下进行反应, 以20%的收率得到目标产物2a (Entry 5).在筛选的单一溶剂中, 以甲苯或乙醇为溶剂时收率较高.考虑到反应中添加剂的溶解度, 还筛选了混合溶剂, 当甲苯/乙醇(V:V=5:1)用作溶剂时, 反应以33%的收率得到产物2a (Entries 6~10).当把反应中的氧化剂换成K2S2O8或(NH4)2S2O8时, 收率并没有得到提高(Entries 11~12). Wang等报道的工作表明少量的NBS可以诱导2-芳基苯甲酰乙酸衍生物实现分子内环芳构化.当在反应中添加少量的NBS, 反应收率略微提升至41% (Entry 13), NBS在可见光催化体系下并没有起到好的效果.令人惊喜的是, 当添加催化量的KI时, 反应以75%的收率获得2a (Entries 14~16).随后对碱进行了筛选, 结果表明K2HPO4在反应中效果最佳, 2a的收率可以达到79% (Entries 17~19).控制实验表明反应在黑暗条件下无产物2a生成, 证明可见光对该反应是必不可少的(Entry 20).当反应体系不加可见光催化剂时, 产物2a的收率降至22% (Entry 21).最终确定了表 1中的Entry 17为最优条件.
表 1
Entry Photocatalyst Oxidant Base Additives Solvent Yieldb/% 1f, g PC(1) O2 — — NMP 18 2e, f, g PC(2) O2 — — NMP — 3f, g, PC(3) O2 — — NMP Trace 4e, f, g PC(4) O2 — — NMP — 5g PC(1) Na2S2O8 Na2CO3 — DMF 20 6g PC(1) Na2S2O8 Na2CO3 — Toluene 22 7g PC(1) Na2S2O8 Na2CO3 — EtOH 25 8g PC(1) Na2S2O8 Na2CO3 — Toluene/EtOH (V:V=1:1) 27 9g PC(1) Na2S2O8 Na2CO3 — Toluene/EtOH (V:V=2:1) 25 10g PC(1) Na2S2O8 Na2CO3 — Toluene/EtOH (V:V=5:1) 33 11g PC(1) K2S2O8 Na2CO3 — Toluene/EtOH (V:V=5:1) 25 12g PC(1) (NH4)2S2O8 Na2CO3 — Toluene/EtOH (V:V=5:1) 18 13c PC(1) Na2S2O8 Na2CO3 NBS Toluene/EtOH (V:V=5:1) 41 14 PC(1) Na2S2O8 Na2CO3 NaI Toluene/EtOH (V:V=5:1) 35 15 PC(1) Na2S2O8 Na2CO3 KI Toluene/EtOH (V:V=5:1) 75 16 PC(1) Na2S2O8 Na2CO3 NH4I Toluene/EtOH (V:V=5:1) 56 17 PC(1) Na2S2O8 K2HPO4 KI Toluene/EtOH (V:V=5:1) 79 18 PC(1) Na2S2O8 K3PO4 KI Toluene/EtOH (V:V=5:1) 37 19 PC(1) Na2S2O8 NaOAc KI Toluene/EtOH (V:V=5:1) 49 20d, e PC(1) Na2S2O8 K2HPO4 KI Toluene/EtOH (V:V=5:1) — 21 — Na2S2O8 K2HPO4 KI Toluene/EtOH (V:V=5:1) 22 a Reaction conditions: 1a (0.3 mmol), oxidant (1.2 equiv.), base (1.2 equiv.), iodide (5 mol%), photocatalyst (1 mol%), solvent (3.0 mL), reaction time (12~48 h), 45 W blue LEDs irradiation under N2 atmosphere at ambient temperature. PC(1): Ir[dF(CF3)ppy]2(dtbbpy)PF6: 4, 4'-di-tert-butyl-2, 2'-bipyridine)bis[3, 5-difluoro-2-(5-trifluoromethyl-2-pyridinyl-kN)phenyl-kC]iridium(Ⅲ) hexafluorophosphate; PC(2): Ru(bpy)3(PF6)2: tris(2, 2'-bipyridine)ruthenium(Ⅱ) hexafluorophosphate; PC(3): Eosin Y: 2', 4', 5', 7'-tetrabromo-3', 6'-dihydroxyspiro(isobenzofuran-1(3H), 9'-(9H)xanthen)-3-one; PC(4): Ir(ppy)3: tris(2-phenylpyridine)iridium(Ⅲ). b Isolated yields by silica gel column chromatography. c NBS (20 mol%). d Without light irradiation. e Substrate 1a remained unreacted. f Without base. g Without additive. 在最优化反应条件下, 考察了各种取代2-芳基苯甲酰乙酸酯及其衍生物在该反应体系中的适用性(表 2).实验结果表明, Ar2环上取代基为吸电子基团或给电子基团都可以成功发生分子内环芳构化反应, 以中等至良好的收率分离得到相应产物(2b~2p).其中Ar2环的对位有取代基的底物反应效果最好(2b~2e和2i~2l), 可能由于取代基的电子效应及空间位阻效应对反应的影响. 3, 5-二甲基取代的底物仅以43%的收率得到2p.有趣的是, 邻位异丙基取代的底物1h在反应中没有发生异丙基的裂解, 并以63%的收率转化为产物2h.值得注意的是, 乙烯基或甲硫基取代的底物1j和1n也可以顺利发生反应, 均以30%的收率获得产物.当Ar2环上为间甲基取代时, 得到2m和2m'的混合物产率为48%, 两种产物极性相近, 使用柱层析和大板均未分开. Ar2环上为萘基取代的底物1q和1r经环芳构化得到多环芳烃化合物2q和2r, 产率分别为51%和33%.在标准反应条件下, N-苯酰胺取代底物1s可以发生环化反应, 产物2s的收率为32%.此外, 在Ar1环的不同位置氟或甲氧基取代的底物也能顺利反应(2t~2w), 其中对位氟取代底物2t收率最高, 为85%.遗憾的是, 甲磺酰或氰基取代的底物1x和1y在这个反应体系中没有相应的目标产物生成.
表 2
aReaction conditions: 1a (0.3 mmol), Na2S2O8 (1.2 equiv.), K2HPO4 (1.2 equiv.), KI (5 mol %), Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol%), toluene/EtOH (V:V=5:1 (3.0 mL), blue LEDs irradiation under N2 atmosphere at ambient temperature. bIsolated yields by silica gel column chromatography. c KI (10% mol). 为了初步探索反应机理, 进行了一系列探究实验(Scheme 1).首先在反应体系中加入2 equiv. 2, 2, 6, 6-四甲基哌啶-1-氧基(TEMPO), 只能得到痕量的产物2a, 表明该反应可能涉及自由基历程.在不添加Na2S2O8、KI和光催化剂的条件下, 往反应体系中加入等物质的量的I2, 以61%的收率分离得到产物2a.结果表明, 该反应可能发生了原位碘化.令人遗憾的是, 我们无法捕获或表征反应过程中可能存在的碘化物中间体.
图式 1
根据上述结果和相关文献报道[20-22], 提出了可能的反应机理(Scheme 2). Muniz等[22]的工作证实了微量的水可以引发分子碘发生歧化反应, 快速生成次碘酸盐, 同时Ishihara等[23]报道的相关工作也表明次碘酸盐具有催化作用.由此, 我们推测在本反应中, 催化量的KI被Na2S2O8氧化为I2, 通过歧化反应转化为HOI和HI.活化的次碘酸盐引发底物1a发生原位碘化, 生成中间体A.在蓝光LED照射下, A发生C—I键均裂生成B, 从而引发自由基循环. B发生分子内自由基环化得到C. C脱质子得到自由基阴离子D, 随后D被A氧化得到目标产物2a和[A]·-. [A]·-脱去I-重新得到B(路线Ⅰ).或者C被A氧化生成E, 随后E脱去质子得到目标产物2a(路线Ⅱ).
图 2
2. 结论
报道了可见光催化2-芳基苯甲酰乙酸衍生物的分子内环芳构化反应, 该反应条件温和, 以中等至良好的收率合成10-菲酚衍生物, 为菲衍生物的合成提供一条路线, 同时拓宽可见光催化在有机合成中的应用.起始原料联苯衍生物可以通过Suzuki-Miyaura偶联反应高效合成.
3. 实验部分
3.1 仪器与试剂
1H NMR和13C NMR由Bruker VANCE Ⅲ (500 MHz)核磁共振仪测定, 内标为四甲基硅烷(TMS), 溶剂为氘代氯仿或氘代二甲基亚砜; ESI低分辨和高分辨质谱由Varian 1200质谱分析仪测定; 熔点由精松X-4显微熔点仪测定, 温度计未校正; 其他使用的仪器为Synthware MS-H-Pro+磁力搅拌器、Heidolph ML/HB/G3旋转蒸发仪、25 mL Schlenk tube.
所有试剂均为市售的分析纯试剂, 直接使用.甲苯、过硫酸钠、过硫酸钾、过硫酸铵、磷酸三钾均购于国药集团化学试剂有限公司, 无水碳酸钠购于太仓美达试剂有限公司, N-溴代丁二酰亚胺购于上海化学试剂采购供应五联化工厂, 碘化铵、磷酸氢二钾购于阿拉丁, 碘化钠购于浙江海川化学品有限公司, 无水乙酸钠购于温州润华化工实业公司.柱层析硅胶(200~300目)购于青岛鼎康硅胶有限公司, 展开剂使用重蒸工业级石油醚(PE)和乙酸乙酯(EA). 2-芳基苯甲酰乙酸衍生物(化合物1)按照文献方法制备[24-27].
3.2 化合物2a~2w的合成
在氮气保护下, 将化合物1 (0.3 mmol)、K2HPO4 (0.36 mmol)、Na2S2O8 (0.36 mmol)、KI (0.015 mmol, 5 mol%)、Ir[dF(CF3)ppy]2(dtbbpy)PF6 (0.003 mmol, 1 mol%)、甲苯(2.5 mL)和乙醇(0.5 mL)分别加入25 mL干燥的Schlenk反应管.将反应混合物放置在距离45 W Blue LED灯约5 cm处, 并在室温下搅拌5~48 h, 用TLC板追踪反应.待反应结束用旋转蒸发仪除去溶剂, 将残渣与硅胶混合干法上柱.以石油醚/乙酸乙酯(V/ V=20/1)为洗脱剂, 在硅胶(200~300目)上进行柱色谱纯化, 得到纯产物2a~2w.
10-羟基菲-9-羧酸乙酯(2a): 62.8 mg, 产率79%.白色固体, m.p. 103~104 ℃(文献值[20] 109~110 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.40 (s, 1H), 8.82~8.80 (d, J=8.5 Hz, 1H), 8.59~8.54 (m, 3H), 7.77~7.74 (m, 1H), 7.67~7.57 (m, 2H), 7.51~7.48 (m, 1H), 4.64~4.60 (q, J=7.2 Hz, 2H), 1.59~1.56 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.78, 162.63, 133.52, 130.21, 129.34, 127.40, 126.63, 125.91, 125.84, 125.11, 124.81, 124.02, 122.67, 122.25, 101.39, 61.86, 14.21; MS (ESI) m/z: 289.1 [M+Na]+.
10-羟基-7-甲基菲-9-羧酸乙酯(2b): 64.5 mg, 产率77%.白色固体, m.p. 101~102 ℃(文献值[20] 106~107 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.28 (s, 1H), 8.61 (s, 1H), 8.56~8.52 (m, 2H), 8.46~8.44 (d, J=8.4 Hz, 2H), 7.77~7.73 (m, 1H), 7.63~7.60 (m, 1H), 7.33~7.31 (m, 1H), 4.64~4.60 (q, J=7.3 Hz, 2H), 2.56 (s, 3H), 1.60~1.57 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.87, 162.69, 137.20, 133.72, 130.29, 129.53, 126.33, 125.95, 125.67, 124.90, 124.86, 123.87, 122.69, 122.19, 101.37, 61.91, 22.11, 14.25; MS (ESI) m/z: 303.1 [M+Na]+.
10-羟基-7-甲氧基菲-9-羧酸乙酯(2c): 69.4 mg, 产率78%.白色固体, m.p. 144~145 ℃(文献值[20] 138~139 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.46 (s, 1H), 8.52~8.50 (m, 1H), 8.45~8.44 (d, J=8.9 Hz, 2H), 8.32~8.31 (d, J=2.6 Hz, 1H), 7.74~7.71 (m, 1H), 7.58~7.55 (m, 1H), 7.11~7.09 (m, 1H), 4.62~4.57 (q, J=7.1 Hz, 2H), 3.94 (s, 3H), 1.58~1.56 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.95, 163.62, 159.05, 133.84, 130.97, 130.49, 125.74, 124.99, 124.23, 124.16, 121.89, 120.20, 113.54, 108.06, 101.13, 61.90, 55.11, 14.31; MS (ESI) m/z: 319.1 [M+Na]+.
10-羟基-7-叔丁基菲-9-羧酸乙酯(2d): 80.7 mg, 产率83%.白色固体, m.p. 127~128 ℃(文献值[20] 130~131 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.43 (d, J=1.2 Hz, 1H), 8.92 (d, J=1.9 Hz, 1H), 8.59~8.51 (m, 3H), 7.78~7.75 (m, 1H), 7.65~7.58 (m, 2H), 4.66~4.62 (q, J=7.1 Hz, 2H), 1.64~1.61 (t, J=7.1 Hz, 3H), 1.51 (s, 9H); 13C NMR (126 MHz, CDCl3) δ: 173.14, 162.89, 150.22, 133.61, 130.31, 129.24, 126.37, 124.99, 124.81, 123.82, 122.53, 122.31, 122.21, 101.66, 61.88, 35.18, 31.46, 14.38; MS (ESI) m/z: 345.1 [M+Na]+.
10-羟基-7-正丁基菲-9-羧酸乙酯(2e): 86.7 mg, 产率90%.白色固体, m.p. 61~62 ℃(文献值[20] 63~64 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.32 (s, 1H), 8.65 (s, 1H), 8.57~8.53 (m, 2H), 8.48~8.47 (d, J=8.4 Hz, 1H), 7.77~7.73 (m, 1H), 7.64~7.61 (m, 1H), 7.35~7.33 (m, 1H), 4.65~4.60 (q, J=7.1 Hz, 2H), 2.85~2.82 (t, J=7.6 Hz, 2H), 1.81~1.75 (m, 2H), 1.61~1.58 (t, J=7.1 Hz, 3H), 1.51~1.46 (q, J=7.4 Hz, 2H), 1.05~1.02 (t, J=7.3 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.91, 162.70, 142.05, 133.72, 130.24, 129.46, 126.27, 125.34, 125.05, 124.88, 124.85, 124.05, 122.63, 122.17, 101.43, 61.84, 36.06, 33.39, 22.35, 14.20, 13.97; MS (ESI) m/z: 345.1 [M+Na]+.
10-羟基-5-甲基菲-9-羧酸乙酯(2f): 39.2 mg, 产率47%.淡黄色固体, m.p. 52~53 ℃(文献值[20] 53~54 ℃); 1H NMR (500 MHz, CDCl3) δ: 12.91 (s, 1H), 8.66~8.61 (m, 3H), 7.75~7.72 (m, 1H), 7.67~7.64 (m, 1H), 7.49~7.45 (t, J=7.8 Hz, 1H), 7.38~7.37 (d, J=7.1 Hz, 1H), 4.64~4.60 (q, J=7.2 Hz, 2H), 3.05 (s, 3H), 1.57~1.54 (t, J=7.2 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.59, 161.32, 135.07, 134.37, 130.78, 129.02, 128.73, 127.61, 126.57, 126.43, 126.33, 126.16, 124.47, 123.85, 102.57, 61.98, 27.19, 14.34; MS (ESI) m/z: 303.1 [M+Na]+.
10-羟基-5-甲氧基菲-9-羧酸乙酯(2g): 82.9 mg, 产率47%.白色固体, m.p. 101~102 ℃(文献值[20] 100~101 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.06 (s, 1H), 9.62~9.61 (d, J=8.7 Hz, 1H), 8.66~8.64 (d, J=8.2 Hz, 1H), 8.41~8.40 (d, J=8.7 Hz, 1H), 7.80~7.77 (m, 1H), 7.68~7.65 (t, J=7.5 Hz, 1H), 7.53~7.49 (t, J=8.2 Hz, 1H), 7.05~7.03 (d, J=7.7 Hz, 1H), 4.64~4.60 (q, J=7.2 Hz, 2H), 4.09 (s, 3H), 1.57~1.54 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.60, 161.97, 158.52, 133.21, 131.72, 129.84, 128.43, 127.07, 126.02, 125.40, 124.06, 118.50, 116.77, 106.65, 102.01, 61.93, 55.56, 14.23; MS (ESI) m/z: 319.1 [M+Na]+.
10-羟基-5-异丙基菲-9-羧酸乙酯(2h): 57.9 mg, 产率63%.淡黄色固体, m.p. 63~64 ℃(文献值[20] 55~56 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.05 (s, 1H), 8.62~8.57 (m, 2H), 8.35~8.33 (d, J=8.2 Hz, 1H), 7.71~7.63 (m, 2H), 7.58~7.54 (m, 2H), 4.64~4.59 (q, J=7.1 Hz, 2H), 4.17~4.12 (m, 1H), 1.57~1.54 (t, J=7.1 Hz, 3H), 1.48~1.47 (d, J=6.7 Hz, 6H); 13C NMR (126 MHz, CDCl3) δ: 172.70, 161.64, 146.53, 133.37, 130.19, 128.37, 127.58, 126.76, 126.61, 126.39, 126.26, 125.77, 124.34, 123.50, 122.73, 102.25, 61.94, 31.35, 25.60, 14.34; MS (ESI) m/z: 331.1 [M+Na]+.
9-羟基菲-2, 10-二甲酸二乙酯(2i): 78.0 mg, 产率77%.白色固体, m.p. 131~132 ℃(文献值[20] 135~136 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.45 (s, 1H), 9.56~9.56 (d, J=1.5 Hz, 1H), 8.56~8.53 (m, 3H), 8.08~8.06 (m, 1H), 7.80~7.77 (m, 1H), 7.70~7.67 (m, 1H), 4.64~4.60 (q, J=7.2 Hz, 2H), 4.49~4.44 (q, J=7.1 Hz, 2H), 1.64~1.62 (t, J=7.1 Hz, 3H), 1.49~1.46 (t, J=7.2 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.65, 166.95, 163.24, 132.85, 130.62, 129.00, 128.91, 128.23, 127.79, 126.07, 125.08, 124.27, 123.00, 122.82, 101.42, 101.42, 62.29, 61.03, 14.45, 14.17; MS (ESI) m/z: 361.1 [M+Na]+.
10-羟基-7-乙烯基菲-9-羧酸乙酯(2j): 26.0 mg, 产率30%.白色固体, m.p. 104~105 ℃(文献值[20] 113~114 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.38 (s, 1H), 8.84 (s, 1H), 8.54~8.47 (m, 3H), 7.77~7.74 (m, 1H), 7.64~7.56 (m, 2H), 6.93~6.87 (dd, J=17.6, 10.8 Hz, 1H), 5.93~5.90 (d, J=17.8 Hz, 1H), 5.39~5.37 (d, J=11.0 Hz, 1H), 4.64~4.59 (q, J=7.1 Hz, 2H), 1.61~1.58 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.87, 163.05, 137.47, 136.56, 133.50, 130.49, 129.66, 126.81, 125.70, 125.22, 125.02, 124.46, 123.09, 122.45, 121.87, 114.21, 101.46, 62.05, 14.31; MS (ESI) m/z: 315.1 [M+Na]+.
7-氯-10-羟基菲-9-羧酸乙酯(2k): 63.1 mg, 产率70%.白色固体, m.p. 121~122 ℃(文献值[20] 125~126 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.46 (s, 1H), 8.74~8.73 (d, J=2.2 Hz, 1H), 8.47~8.46 (m, 1H), 8.38~8.32 (m, 2H), 7.73~7.70 (m, 1H), 7.62~7.59 (m, 1H), 7.37~7.34 (m, 1H), 4.62~4.57 (q, J=7.1 Hz, 2H), 1.59~1.57 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.46, 163.67, 133.63, 133.01, 130.67, 130.53, 126.99, 125.47, 125.03, 124.34, 124.26, 124.09, 122.23, 100.54, 62.29, 14.21; MS (ESI) m/z: 323.0 [M+Na]+.
7-氟-10-羟基菲-9-羧酸乙酯(2l): 54.7 mg, 产率64%.白色固体, m.p. 122~123 ℃(文献值[20] 125~126 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.53 (s, 1H), 8.51~8.40 (m, 4H), 7.75~7.72 (m, 1H), 7.62~7.59 (m, 1H), 7.20~7.17 (m, 1H), 4.64~4.59 (q, J=7.1 Hz, 2H), 1.59~1.57 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.61, 163.95, 163.14, 161.20, 133.25, 131.16, 131.07, 130.66, 126.52, 125.03, 124.77, 124.69, 122.48, 122.14, 112.52, 112.34, 111.51, 111.31, 100.89, 100.87, 62.23, 14.25; MS (ESI) m/z: 307.1 [M+Na]+.
10-羟基-6-甲基菲-9-羧酸乙酯/10-羟基-8-甲基菲-9-羧酸乙酯=4/1(2m)[20]: 40.0 mg, 产率48%.白色固体, m.p. 88~89 ℃; 1H NMR (500 MHz, CDCl3) δ: 13.28 (s, 1H), 10.92 (s, 0.25H), 8.70~8.68 (d, J=8.7 Hz, 1H), 8.58~8.55 (m, 1.8H), 8.58~8.55 (m, 0.45H), 8.49~8.47 (m, 0.25H), 8.43~8.41 (m, 0.25H), 8.36 (s, 1H), 7.78~7.73 (m, 1H), 7.78~7.73 (m, 0.25H), 7.66~7.62 (m, 1H), 7.66~7.62 (m, 0.25H), 7.47~7.40 (m, 1.2H), 7.47~7.40 (m, 0.3H), 4.64~4.60 (q, J=7.1 Hz, 2H), 4.50~4.46 (q, J=7.2 Hz, 0.5H), 2.58 (s, 3H), 2.55 (s, 0.75H), 1.59~1.56 (t, J=7.1 Hz, 3H), 1.41~1.38 (t, J=7.2 Hz, 0.75H); 13C NMR (126 MHz, CDCl3) δ: 172.92, 171.69, 162.06, 158.22, 134.15, 133.75, 133.59, 133.44, 130.42, 130.20, 129.98, 129.15, 128.78, 127.20, 127.12, 126.82, 126.69, 126.15, 125.88, 125.35, 124.93, 124.52, 124.51, 122.72, 122.39, 120.27, 103.64, 101.54, 61.92, 61.74, 22.92, 21.45, 14.34, 14.11; MS (ESI) m/z: 303.1 [M+Na]+.
10-羟基-7-甲硫基菲-9-羧酸乙酯(2n): 28.5 mg, 产率30%.白色固体, m.p. 141~142 ℃; 1H NMR (500 MHz, CDCl3) δ: 13.46 (s, 1H), 8.66~8.65 (d, J=11.8 Hz, 1H), 8.53~8.48 (m, 2H), 8.43~8.42 (d, J=8.7 Hz, 1H), 7.76~7.73 (m, 1H), 7.62~7.59 (m, 1H), 7.37~7.35 (m, 1H), 4.63~4.59 (q, J=7.2 Hz, 2H), 2.62 (s, 3H), 1.59~1.56 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.85, 163.47, 138.18, 133.52, 130.55, 129.96, 126.48, 125.00, 124.77, 123.32, 123.09, 122.80, 122.20, 122.08, 100.82, 62.08, 15.57, 14.39; MS (ESI) m/z: 335.1 [M+ Na]+; HRMS (ESI) calcd for C18H16O3S [M+Na]+ 335.0718, found 335.0712.
5-氟-10-羟基菲-9-羧酸乙酯(2o): 50.3 mg, 产率59%.白色固体, m.p. 89~90 ℃(文献值[20] 93~94 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.26 (s, 1H), 9.03~9.01 (m, 1H), 8.60~8.54 (m, 2H), 7.80~7.77 (m, 1H), 7.68~7.65 (t, J=7.5 Hz, 1H), 7.49~7.44 (m, 1H), 7.22~7.17 (m, 1H), 4.63~4.59 (q, J=7.2 Hz, 2H), 1.57~1.54 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.51, 162.83, 162.53, 160.53, 132.00, 131.97, 131.36, 131.31, 130.75, 130.73, 127.58, 127.38, 127.35, 127.29, 127.03, 127.02, 125.64, 124.61, 121.67, 121.64, 115.67, 115.60, 111.46, 111.26, 101.49, 101.46, 62.22, 14.30; MS (ESI) m/z: 307.1 [M+Na]+.
10-羟基-6, 8-二甲基菲-9-羧酸乙酯(2p): 37.6 mg, 产率43%.淡黄色固体, m.p. 100~101 ℃(文献值[20] 119~120 ℃); 1H NMR (500 MHz, CDCl3) δ: 10.79 (s, 1H), 8.54~8.53 (d, J=8.3 Hz, 1H), 8.43~8.41 (m, 1H), 8.19 (s, 1H), 7.71~7.68 (m, 1H), 7.60~7.57 (m, 1H), 7.23 (s, 1H), 4.45~4.40 (q, J=7.1 Hz, 2H), 2.51 (s, 3H), 2.47 (s, 3H), 1.35~1.33 (t, J=7.2 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 171.74, 157.61, 133.94, 133.54, 132.03, 129.81, 127.31, 126.70, 126.53, 124.66, 124.49, 122.73, 120.32, 103.65, 61.69, 22.77, 21.43, 14.12; MS (ESI) m/z: 317.1 [M+Na]+.
5-羟基四苯-6-羧酸乙酯(2q): 48.2 mg, 产率51%.淡黄色固体, m.p. 124~125 ℃(文献值[20] 103~104 ℃); 1H NMR (500 MHz, CDCl3) δ: 11.15 (s, 1H), 8.64~8.63 (d, J=8.3 Hz, 1H), 8.58~8.51 (m, 2H), 8.03~8.01 (d, J=8.4 Hz, 1H), 7.94~7.93 (d, J=7.8 Hz, 1H), 7.89~7.88 (d, J=8.8 Hz, 1H), 7.82~7.79 (m, 1H), 7.70~7.67 (m, 1H), 7.58~7.48 (m, 1H), 4.40~4.36 (q, J=7.1 Hz, 2H), 1.18~1.15 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.46, 158.53, 133.21, 133.00, 130.05, 129.54, 128.93, 127.80, 126.73, 126.03, 125.91, 124.66, 124.27, 123.99, 122.94, 120.19, 103.78, 61.65, 13.75; MS (ESI) m/z: 339.1 [M+Na]+.
5-羟基苯并[c]菲-6-羧酸乙酯(2r): 31.2 mg, 产率33%.淡黄色固体, m.p. 95~96 ℃(文献值[20] 102~103 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.01 (s, 1H), 8.91~8.85 (m, 2H), 8.78~8.76 (d, J=9.1 Hz, 1H), 8.67~8.65 (m, 1H), 7.99~7.97 (m, 1H), 7.90~7.77 (m, 1H), 7.76~7.67 (m, 1H), 7.66~7.56 (m, 2H), 4.67~4.63 (q, J=7.2 Hz, 2H), 1.59~1.56 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.62, 161.70, 133.21, 131.76, 129.93, 129.35, 128.44, 128.34, 127.91, 127.85, 127.50, 126.20, 125.95, 125.69, 125.29, 124.51, 123.97, 122.74, 102.68, 62.18, 14.37; MS (ESI) m/z: 339.1 [M+Na]+.
10-羟基-N-苯基菲-9-甲酰胺(2s): 29.8 mg, 产率32%.白色固体, m.p. 193~194 ℃(文献值[20] 111~112 ℃); 1H NMR (500 MHz, DMSO-d6) δ: 10.57 (s, 1H), 10.11 (s, 1H), 8.88~8.86 (d, J=8.0 Hz, 1H), 8.81~8.79 (d, J=8.1 Hz, 1H), 8.43~8.41 (d, J=8.2 Hz, 1H), 7.86~7.85 (d, J=7.8 Hz, 2H), 7.80~7.72 (m, 3H), 7.62~7.54 (m, 2H), 7.40~7.37 (t, J=7.8 Hz, 2H), 7.14~7.11 (t, J=7.4 Hz, 1H); 13C NMR (126 MHz, DMSO) δ: 165.99, 147.19, 139.58, 130.95, 130.00, 128.66, 127.87, 127.40, 126.78, 126.10, 125.52, 124.33, 124.19, 123.45, 123.17, 123.01, 119.63, 116.73; MS (ESI) m/z: 336.1 [M+Na]+.
2-氟-10-羟基菲-9-羧酸乙酯(2t): 85.3 mg, 产率85%.白色固体, m.p. 94~95 ℃(文献值[20] 97~98 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.21 (s, 1H), 8.75~8.74 (d, J=8.4 Hz, 1H), 8.47~8.39 (m, 2H), 8.11~8.09 (m, 1H), 7.56~7.53 (t, J=7.7 Hz, 1H), 7.48~7.42 (m, 2H), 4.64~4.59 (q, J=7.1 Hz, 2H), 1.59~1.56 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.62, 162.44, 161.43, 161.41, 160.48, 130.02, 128.80, 127.27, 126.68, 126.61, 125.95, 125.58, 124.78, 124.72, 124.36, 122.50, 119.06, 118.87, 109.68, 109.50, 102.31, 62.14, 14.26; MS (ESI) m/z: 307.1 [M+Na]+.
3-氟-10-羟基菲-9-羧酸乙酯(2u): 67.6 mg, 产率79%.白色固体, m.p. 111~112 ℃(文献值[20] 97~98 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.37 (s, 1H), 8.75~8.73 (d, J=8.6 Hz, 1H), 8.48~8.45 (m, 1H), 8.31~8.29 (d, J=8.2 Hz, 1H), 8.06~8.04 (d, J=11.1 Hz, 1H), 7.57~7.54 (t, J=7.7 Hz, 1H), 7.45~7.42 (t, J=7.6 Hz, 1H), 7.32~7.27 (m, 1H), 4.63~4.58 (q, J=7.2 Hz, 2H), 1.59~1.56 (t, J=7.2 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.78, 165.12, 163.13, 162.33, 135.84, 135.77, 129.93, 128.11, 127.83, 127.75, 125.99, 125.18, 125.15, 124.13, 122.92, 121.78, 115.62, 115.44, 107.79, 107.61, 100.88, 62.02, 14.29; MS (ESI) m/z: 307.1 [M+Na]+.
1-氟-10-羟基菲-9-羧酸乙酯(2v): 48.3 mg, 产率57%.白色固体, m.p. 117~118 ℃(文献值[20] 121~122 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.46~13.45 (d, J=3.2 Hz, 1H), 8.70~8.68 (m, 1H), 8.50~8.48 (d, J=8.1 Hz, 1H), 8.36~8.35 (d, J=8.4 Hz, 1H), 7.69~7.64 (m, 1H), 7.59~7.56 (m, 1H), 7.49~7.46 (m, 1H), 7.30~7.26 (m, 1H), 4.64~4.60 (q, J=7.2 Hz, 2H), 1.57~1.54 (t, J=7.2 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 172.52, 162.16, 162.12, 160.08, 136.18, 130.66, 130.58, 129.57, 128.09, 125.76, 125.21, 124.45, 123.31, 118.45, 118.41, 114.71, 114.65, 113.91, 113.72, 102.63, 102.61, 62.13, 14.26; MS (ESI) m/z: 307.1 [M+Na]+.
10-羟基-2-甲氧基菲-9-羧酸乙酯(2w): 30.7 mg, 产率35%.白色固体, m.p. 121~122 ℃(文献值[20] 111~112 ℃); 1H NMR (500 MHz, CDCl3) δ: 13.35 (s, 1H), 8.81~8.79 (m, 1H), 8.50~8.48 (d, J=9.2 Hz, 2H), 7.90 (d, J=2.8 Hz, 1H), 7.55~7.47 (m, 2H), 7.40~7.38 (dd, J=9.1, 2.8 Hz, 1H), 4.65~4.61 (q, J=7.2 Hz, 2H), 4.01 (s, 3H), 1.59~1.56 (t, J=7.1 Hz, 3H); 13C NMR (126 MHz, CDCl3) δ: 173.04, 162.02, 158.64, 128.36, 127.95, 126.61, 126.48, 126.19, 125.94, 124.25, 124.18, 122.33, 121.10, 104.65, 101.98, 62.05, 55.54, 14.36; MS (ESI) m/z: 319.1 [M+Na]+.
3.3 克级规模实验
在氮气保护下, 将化合物1 (3 mmol)、K2HPO4 (3.6 mmol)、Na2S2O8 (0.36 mmol)、KI (0.15 mmol, 5 mol%)、Ir[dF(CF3)ppy]2(dtbbpy)PF6 (0.03 mmol, 1 mol%)、甲苯(25 mL)和乙醇(5 mL)分别加入50 mL干燥的Schlenk反应管.将反应混合物放置在距离45 W Blue LED灯约5 cm处, 并在室温下搅拌48 h后, 用旋转蒸发仪除去溶剂, 将残渣与硅胶混合干法上柱.以石油醚/乙酸乙酯(V:V=20:1)为洗脱剂, 在硅胶(200~300目)上进行柱色谱纯化, 以40%的收率得到纯产物2a.
辅助材料(Supporting Information)所合成目标化合物的1H NMR和13C NMR谱.这些材料可以免费从本刊网站(http://sioc-journal.cn/)上下载.
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[1]
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表 1 反应条件优化a
Table 1. Optimization of the reaction conditions
Entry Photocatalyst Oxidant Base Additives Solvent Yieldb/% 1f, g PC(1) O2 — — NMP 18 2e, f, g PC(2) O2 — — NMP — 3f, g, PC(3) O2 — — NMP Trace 4e, f, g PC(4) O2 — — NMP — 5g PC(1) Na2S2O8 Na2CO3 — DMF 20 6g PC(1) Na2S2O8 Na2CO3 — Toluene 22 7g PC(1) Na2S2O8 Na2CO3 — EtOH 25 8g PC(1) Na2S2O8 Na2CO3 — Toluene/EtOH (V:V=1:1) 27 9g PC(1) Na2S2O8 Na2CO3 — Toluene/EtOH (V:V=2:1) 25 10g PC(1) Na2S2O8 Na2CO3 — Toluene/EtOH (V:V=5:1) 33 11g PC(1) K2S2O8 Na2CO3 — Toluene/EtOH (V:V=5:1) 25 12g PC(1) (NH4)2S2O8 Na2CO3 — Toluene/EtOH (V:V=5:1) 18 13c PC(1) Na2S2O8 Na2CO3 NBS Toluene/EtOH (V:V=5:1) 41 14 PC(1) Na2S2O8 Na2CO3 NaI Toluene/EtOH (V:V=5:1) 35 15 PC(1) Na2S2O8 Na2CO3 KI Toluene/EtOH (V:V=5:1) 75 16 PC(1) Na2S2O8 Na2CO3 NH4I Toluene/EtOH (V:V=5:1) 56 17 PC(1) Na2S2O8 K2HPO4 KI Toluene/EtOH (V:V=5:1) 79 18 PC(1) Na2S2O8 K3PO4 KI Toluene/EtOH (V:V=5:1) 37 19 PC(1) Na2S2O8 NaOAc KI Toluene/EtOH (V:V=5:1) 49 20d, e PC(1) Na2S2O8 K2HPO4 KI Toluene/EtOH (V:V=5:1) — 21 — Na2S2O8 K2HPO4 KI Toluene/EtOH (V:V=5:1) 22 a Reaction conditions: 1a (0.3 mmol), oxidant (1.2 equiv.), base (1.2 equiv.), iodide (5 mol%), photocatalyst (1 mol%), solvent (3.0 mL), reaction time (12~48 h), 45 W blue LEDs irradiation under N2 atmosphere at ambient temperature. PC(1): Ir[dF(CF3)ppy]2(dtbbpy)PF6: 4, 4'-di-tert-butyl-2, 2'-bipyridine)bis[3, 5-difluoro-2-(5-trifluoromethyl-2-pyridinyl-kN)phenyl-kC]iridium(Ⅲ) hexafluorophosphate; PC(2): Ru(bpy)3(PF6)2: tris(2, 2'-bipyridine)ruthenium(Ⅱ) hexafluorophosphate; PC(3): Eosin Y: 2', 4', 5', 7'-tetrabromo-3', 6'-dihydroxyspiro(isobenzofuran-1(3H), 9'-(9H)xanthen)-3-one; PC(4): Ir(ppy)3: tris(2-phenylpyridine)iridium(Ⅲ). b Isolated yields by silica gel column chromatography. c NBS (20 mol%). d Without light irradiation. e Substrate 1a remained unreacted. f Without base. g Without additive. 表 2 底物拓展a
Table 2. Scope of the substrates
aReaction conditions: 1a (0.3 mmol), Na2S2O8 (1.2 equiv.), K2HPO4 (1.2 equiv.), KI (5 mol %), Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol%), toluene/EtOH (V:V=5:1 (3.0 mL), blue LEDs irradiation under N2 atmosphere at ambient temperature. bIsolated yields by silica gel column chromatography. c KI (10% mol).
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