第五章 實驗部分
Scheme 3-5 High-pressure reaction
第四章 結論
於 本 論 文 中 ， 依 照 文 獻 方 式 成 功 合 成 出 配 位 基 2,7-bis(2-pyridyl)-1,8-naphthyridine (bpnp) 和 5-phenyl-2,8-bis(2,2’-bipyridin-6-yl)-1,9,10-anthyridine (pbbpa)，並分別於甲醇和二氯甲烷下合成出鈀金屬錯合物 9 和 11，透過核磁共 振光譜鑑定確定其結構，兩者皆是雙金屬錯合物。
鈀金屬錯合物 9 可作為硝基苯還原反應的催化試劑，此催化系統不需額外添 加其他還原劑來活化，即可在一大氣壓氫氣下還原硝基苯，得到單一產物苯胺，其 反應相當乾淨，和文獻相比幾乎不會得到副產物氧化偶氮苯。這個催化反應容忍具 有官能基如烷基、羥基、胺基、氟基、氰基與酮基的分子；對於具立體障礙的反應
物如 1,3-二甲基-2-硝基苯和 1-硝基萘也能夠轉換成相對應的苯胺。然而，芳香雜
環如噻吩、吡啶和脂肪類之硝基物在本催化系統中無法被還原；含氯或溴之苯化物 亦會減低反應性，此乃由於鹵素基團會被活化。有趣的是氯或溴之硝基苯化物在鹼 性條件下，兩官能基皆會被還原。鈀金屬錯合物 11 在經 NaBH3CN 處理後，則能 夠在氫氣下還原硝基苯。
以各種中間體如 N-苯基羥胺、氧化偶氮苯和偶氮苯等在催化系統中的變化來 解析其反應機制。錯合物 9 的催化過程，是先將硝基苯還原成亞硝基苯與 N-苯基
羥胺，縮合成氧化偶氮苯後，藉由雙金屬的協助進行後續的還原得到苯胺 (Scheme 3-3, pathway b)；而錯合物 11 與 Pd(bpy)(TFA)2則是直接將 N-苯基羥胺還原成產物 (Scheme 3-3, pathway a)。雖然錯合物 11 是雙金屬化合物，但是兩金屬的距離約在 5 Å ，比錯合物 9 中的距離長約 2 Å ，不利於氧化偶氮苯的還原，因此錯合物 11 的 活性與單金屬較為相似，這些結果說明了雙鈀金屬錯合物 9 的協同作用，使其金 屬活性有不同的效應。
第五章 實驗部分
5.1 General part
All reagents were reagent grade and used without further purification unless
otherwise specified. MeOH was dried by refluxing over CaH2 and distilled under N2
before use. CH2Cl2 was dried by refluxing over P2O5 or CaH2 and distilled under N2
before use. THF was dried by refluxing over sodium benzophenone ketyl and distilled
under N2 before use. Acetonitrile was dried by refluxing over CaH2 and distilled under
N2 before use. Toluene was dried by passing through the molecular sieves packed drying
column under N2. Other reagents and solvents were obtained from the commercial
sources (Sigma-Aldrich Co., Acros Organics Co., Alfa Aesar Co. and Merck Co.) and
used without further purification. All non-aqueous reactions were carried out in
oven-dried glassware unless otherwise noted. Reactions were magnetically stirred and
monitored by thin-layer chromatography (TLC) on E. Merck silica gel 60 F254 aluminium
sheets. Compounds were visualized by UV, or using potassium permanganate as
visualizing agents. E. Merck silica gel 60 (60–200 μm particle sizes) were used for
column chromatography.
Infrared (IR) spectra were recorded on Varian 640-IR FT-IR spectrometer. Nuclear
magnetic resonance (NMR) spectra were obtained on Varian Advance-400 (400 MHz
NMR) spectrometers. Chemical shifts (δ) are given in parts per million (ppm) relative to δH 7.26/ δC 77.0 (central line of t) for CHCl3/CDCl3, δH 3.31/ δC 49.0 for CH3OH/CD3OD,
δH 1.94/ δC 1.32 (central line of septet) for CH3CN/CD3CN, δH 4.80 for H2O/D2O, δH 4.33
for CH3NO2/CD3NO2 and δH 2.50 (m)/ δC 39.5 (m) for (CH3)2SO/(CD3)2SO. The splitting
patterns are reported as s (singlet), t (triplet), q (quartet), dd (doublet of doublets), td
(triplet of doublets), m (multiplet), quin (quintet), septet and br (broad). Coupling
constants (J) are given in Hz. High resolution mass spectrometry (HRMS) diagrams under
electrospray ionization were obtained on a Micromass® LCT Premier™ XE instrument
or a Bruker micrOTOF-Q II instrument and were reported in mass-to-charge ratio (m/z).
5.2 Synthetic procedures and characterization of compounds
5.2.1 Synthesis of ligands and palladium(II) complexes
2-Amino-7-hydroxy-1,8-naphthyridine (1) 47
2,6-diaminopyridine (0.20 mol, 22.10 g) and malic acid (0.22 mol, 30.10 g) were
cooled in an ice bath, and then concentrated H2SO4 (100 mL) was added dropwise. The
solution was warmed up to room temperature for 30 min, and then heated to 110°C
overnight. After completion of the reaction, the mixture was poured over ice and basified
to pH = 8 with NaOH. The mixture was filtered and washed with H2O. The desired
product yielded as yellow to brown solid (29.33 g, 91%). 1H NMR (400 MHz,
DMSO-d6) δ 11.61 (s, br, 1H), 7.62 (d, J = 9 Hz, 2H), 6.81 (s, br, 2H), 6.32 (d, J = 9 Hz, 1H),
6.09 (d, J = 9 Hz, 1H).
2,7-Dihydroxy-1,8-naphthyridine (2) 47
Compound 1 (63 mmol, 10.16 g) and NaNO2 (78 mmol, 5.41 g) were cooled in an
ice bath, and concentrated H2SO4 (100 mL) was added dropwise. The mixture was stirred
in an ice bath until NO2 evolution stopped, and warmed up to room temperature overnight.
After completion of the reaction, the mixture was poured into ice water and neutralized
to pH = 7 with NaOH. The mixture was filtered and washed with H2O. The desired
product was obtained in ca. 100% yield as brown solid. 1H NMR (400 MHz, DMSO-d6) δ 7.67 (d, J = 8 Hz, 2H), 6.13 (d, J = 8 Hz, 2H).
2,7-Dichloroxy-1,8-naphthyridine (3) 47
The mixture of 2 (11.79 g) and phosphoryl chloride (60 mL) was refluxed overnight.
The solution was poured into ice water and neutralized to pH = 7 with NaOH. After
filtration, the resulting dark brown solid was purified by Soxhlet extraction with CH2Cl2.
The solvent was removed and the desired product yielded as pale yellow solid (7.27 g,
58%). 1H NMR (400 MHz, CDCl3) δ 8.13 (d, J = 8.5 Hz, 2H), 7.51 (d, J = 8.5 Hz, 2H).
2,7-Bis(2-pyridyl)-1,8-naphthyridine (bpnp) 46
Compound 3 (2.5 mmol, 502 mg), 2-tributylstannylpyridine (4 mL) and
PdCl2(PPh3)2 (0.12 mmol, 85 mg) were degassed and filled with N2, and then dried
toluene (40 mL) was added. The reaction mixture was refluxed for 48 h. After removal
of the solvent, the residue was filtered and washed with hexane. The filtrate was
concentrated and purified by column chromatography on silica gel using CH2Cl2: acetone
(3:1) as eluent to provide the desired product as golden solid (498 mg, 70%). 1H NMR
(400 MHz, CDCl3) δ 8.80 (d, J = 7 Hz, 2H), 8.67 (d, J = 5 Hz, 2H), 8.64 (d, J = 8 Hz,
2H), 8.25 (d, J = 8 Hz, 2H), 7.82 (t, J = 7 Hz, 2H), 7.31 (dd, J = 7, 5 Hz, 2H).
2-Amino-6-chloro-4-phenylpyridine-3,5-dicarbonitrile (4) 49
To a solution of trimethyl orthobenzoate (27.4 mmol, 5.00 g) and malononitrile (57.5
mmol, 3.80 g) was added pyridine (55.6 mmol, 4.40 g). The resulting mixture was heated
to 100°C overnight. After the reaction mixture returned to room temperature,
concentrated HCl (15 mL) was added dropwise under ice bath. The solution was heated
at 100°C for 2 h. After filtration and drying, the desired product was obtained as brown
solid (1.60 g, 23%). 1H NMR (400 MHz, DMSO-d6) δ 8.66 (s, br, 1H), 8.18 (s, br, 1H),
7.60 – 7.53 (m, 5H).
2,6-Diamino-4-phenylpyridine-3,5-dicarbonitrile (5) 49
A mixture of NH4OH (80 mL) and acetone (20 mL) was slowly added to 4 (6.3
mmol, 1.61 g) in a 120 mL autoclave. The autoclave was sealed tightly and heated to
100°C for 24 h. After removal of acetone, the residue was filtered to obtain desired
product as beige solid (1.32 g, 89%). 1H NMR (400 MHz, DMSO-d6) δ 7.52 – 7.50 (m,
3H), 7.47 – 7.44 (m, 2H), 7.24 (s, br, 4H).
2,6-Diamino-4-phenylpyridine-3,5-dicarbaldehyde (6) 49
Compound 5 (2.1 mmol, 500 mg), Pd/C (75 mg, 15 wt%) and 2 M HCl (60 mL)
were stirred for 15 min and purged with N2 for 2 h. The resulting mixture was degassed
by water pump and filled with H2 for 30 min. It was stirred vigorously and heated at 40°C
for 12 h. After filtration, NH4OH (20 mL) was added to the filtrate. The desired product
precipitated as white solid (128 mg, 25%) in the basified solution. 1H NMR (400 MHz,
DMSO-d6) δ 9.05 (s, 2H), 8.69 (s, br, 2H), 7.92 (s, br, 2H), 7.53 – 7.51 (m, 3H), 7.44 –
7.41 (m, 2H).
1-(6-Bromopyridin-2-yl)ethanone (7) 21
To a solution of 2,6-dibromopypridine (12.7 mmol, 3.00 g) in dried Et2O (30 mL)
was added n-BuLi (14.0 mmol, 8.7 mL, 1.6 M in hexane) dropwise at -78°C. The resulting
mixture was stirred for 30 min at -78°C. Dimethylacetamide (22.9 mmol, 2.1 mL) was
slowly added to the solution. The solution was kept at -78°C for 15 min, and then stirred
under room temperature for 12 h. The mixture was quenched by saturated NH4Cl aqueous
solution (40 mL) and stirred for 1 h. After extraction with Et2O (30 mL × 3) and removal
of solvent, the residue was purified by column chromatography on silica gel using Hexane:
EA (19:1) as eluent. The desired product yielded as pale yellow solid (1.39 g, 55%). 1H
NMR (400 MHz, CDCl3) δ 7.96 (m, 1H), 7.71 – 7.63 (m, 2H), 2.69 (m, 3H).
1-(2,2′-Bipyridin-6-yl)ethanone (8) 21
A mixture of 7 (5.0 mmol, 1.00 g), 2-tributylstannylpyridine (10 mmol, 3.66 g), and
PdCl2(PPh3)2 (0.25 mmol, 175 mg, 5 mol %) in dried toluene (10 mL) was heated under
reflux for 24 h. After removal of solvent, the mixture was extracted with CH2Cl2 (15 mL
× 3). Further purification by column chromatography on silica gel with elution of
hexane/ethyl acetate (3:2) provide the desired compound as white solids (0.63 g, 64%).
1H NMR (400 MHz, CDCl3) δ 8.68 (d, J = 4.8 Hz, 1H), 8.60 (dd, J = 8, 1 Hz, 1H), 8.52
(d, J = 8 Hz, 1H), 8.04 (dd, J = 7.7, 1 Hz, 1H), 7.94 (t, J = 8 Hz, 1H), 7.85 (td, J = 7.7, 1
Hz, 1H), 7.34 (ddd, J = 7.7, 4.8, 1 Hz, 1H), 2.82 (s, 3H).
5-Phenyl-2,8-bis(2,2’-bipyridin-6-yl)-1,9,10-anthyridine (pbbpa) 21
A mixture of 7 (0.42 mmol, 100 mg) and 9 (0.91 mmol, 180 mg) in ethanol (4 mL)
was heated at 60°C for 2 h. Then 10% KOH in ethanol (0.1 mL) was added to the above
solution. The resulting mixture was heated to reflux for 12 h. The reaction mixture was
washed with ethanol (5 mL × 3). After drying under vacuum, the desired compound was
obtained as yellow solids (189 mg, 80%). 1H NMR (400 MHz, CDCl3) δ 9.10 (d, J = 7
Hz, 2H), 8.88 (d, J = 9.0 Hz, 2H), 8.71 (d, J = 4.8 Hz, 2H), 8.61 (d, J = 7.8 Hz, 2H), 8.57
(d, J = 7.8 Hz, 2H), 8.30 (d, J = 9.0 Hz, 2H), 8.08 (t, J = 7 Hz, 2H), 7.84 (t, J = 7.8 Hz,
2H), 7.68 (m, 3H), 7.56 – 7.51 (m, 2H), 7.33 (dd, J = 7, 4.8 Hz, 2H).
Pd2(bpnp)(TFA)3(OH) (9)
To a stirred solution of bpnp (0.044 mmol, 12.5 mg) and Pd(OAc)2 (0.090 mmol,
20.2 mg) in MeOH (1 mL) was added CF3COOH (0.25 mL). The reaction was then heated
to 50°C for 30 min. After removal of MeOH, the residue was washed with Et2O (1 mL ×
3) to get desired product as yellow solid (32.0 mg, 98%). 1H NMR (400 MHz,
DMSO-d6) δ 9.38 (d, J = 8.4 Hz, 2H), 9.13 (d, J = 8.4 Hz, 2H), 8.90 (d, J = 8 Hz, 2H), 8.56 (t, J
= 8 Hz, 2H), 8.29 (s, br, 2H), 8.20 – 7.85 (m, 2H), 4.68 (s, br, 1H); 19F NMR (375 MHz,
DMSO-d6) δ -73.43 (s, br); 13C NMR (125 MHz, DMSO-d6) δ 163.73, 156.45, 151.40,
150.26 (q, J = 23 Hz), 149.24, 146.46, 142.81, 129.61, 128.69, 126.45, 124.06, 40.48 (q,
J = 2000 Hz). HRMS (ESI) m/z [M – CF3COO]+ calculated for C22H13F6N4O5Pd2:
740.8869, found: 740.8892. Elemental analysis calculated for [9 + 2H2O]: C, 32.42; H,
1.93; N, 6.30, found: C, 32.30; H, 1.57; N, 6.01.
Pd(bpnp)(TFA)2 (10)
To a stirred solution of bpnp (0.044 mmol, 12.5 mg) and Pd(OAc)2 (0.045 mmol,
10.1 mg) in MeOH (1 mL) was added CF3COOH (0.25 mL). The reaction was then stirred
at room temperature overnight. After removal of MeOH, the residue was washed with
Et2O (1 mL × 3) to get desired product as pale yellow solid (25.7 mg, 100%). 1H NMR
(400 MHz, CD3CN) δ 10.39 (d, J = 7.9 Hz, 1H), 9.20 (d, J = 5.7 Hz, 1H), 8.66 (d, J = 8.6
Hz, 1H), 8.53 (d, J = 7.6 Hz, 1H), 8.49 – 8.41 (m, 3H), 8.37 (d, J = 8.6 Hz, 1H), 7.93 (t,
J = 6.0 Hz, 1H), 7.77 (t, J = 7.6, 1H), 7.72 (t, J = 5.7 Hz, 1H), 6.93 (d, J = 6.3 Hz, 1H);
13C NMR (100 MHz, CD3CN) δ 163.20, 162.98, 160.78 (q, J = 68 Hz), 159.46, 157.89,
153.23, 151.80, 150.69, 148.25 (q, J = 470 Hz), 146.08, 144.29, 142.22, 141.53, 130.51,
127.96, 127.64, 126.69, 125.71, 125.26, 122.58, 62.74(q, J = 915 Hz). m/z [M –
CF3COO]+ calculated for C20H12F3N4O2Pd: 502.9950, found: 503.0006.
[Pd2(pbbpa)Cl2](PF6)2 (11)
A mixture of pbbpa (0.11 mmol, 60 mg) and Pd(MeCN)2Cl2 (0.23 mmol, 60 mg) in
dried CH2Cl2 (15 mL) was stirred at room temperature under N2 for 3 h. KPF6 (1.1 mmol,
210 mg) was then added to the reaction mixture and the mixture was stirred overnight.
The solvent was evaporated and CH3CN (ca. 20 mL) was added. The suspension was
passed through a pad of Celite® and concentrated to ca. 5 mL. The solution was added to
Et2O to provide the yellow solid. The solid was washed with MeOH (5 mL × 3) and dried
in vacuo to obtain the desired product as brown solid (99 mg, 82%). 1H NMR (400 MHz,
CD3CN) δ 9.02 (d, J = 4.8 Hz, 2H), 8.42 (t, J = 8.0 Hz, 2H), 8.37 (t, J = 8 Hz, 2H), 8.33 – 8.28 (m, 2H), 8.26 (d, J = 8.0 Hz, 2H), 8.22 (d, J = 8.0 Hz, 2H), 8.09 – 8.02 (m, 2H),
7.89 (d, J = 8.0 Hz, 2H), 7.86 – 7.80 (m, 2H), 7.48 – 7.42 (m, 5H); 13C NMR (125 MHz,
CD3CN) δ 159.5, 156.8, 156.4, 156.2, 153.1, 146.7, 143.9, 143.9, 143.7, 130.0, 129.9,
129.9, 129.8, 129.6, 129.3, 127.3, 126.2, 125.8, 125.5, 120.2; HRMS (ESI) m/z [M –
2PF6]2+ calculated for C37H23Cl2N7Pd2: 424.4729, found: 424.4712; m/z [M – 2PF6 – Cl
+ OH]2+ calculated for C37H24ClN7OPd2: 415.4901, found: 415.4940. Elemental analysis
calculated for [11 + 6H2O]: C, 35.63; H, 2.83; N, 7.86, found: C, 35.42; H, 2.78; N, 7.37.
[Pd2(bpnp)Cl2(OH)](TFA) (12)
A mixture of 9 (0.03 mmol, 25.4 mg) and KCl (0.06 mmol, 5.0 mg) in dried CH3CN
(2 mL) was stirred at room temperature under N2 for 3 h. The solution was centrifuged,
washed with Et2O and dried under vacuum to provide the yellow solid (18.8 mg, 90%).
1H NMR (400 MHz, DMSO-d6) δ 9.34 (d, J = 8 Hz, 2H), 9.09 (d, J = 8 Hz, 2H), 8.93 –
8.74 (m, 4H), 8.45 (t, J = 8 Hz, 2H), 7.83 (t, J = 7 Hz, 2H); 19F NMR (375 MHz,
DMSO-d6) δ -73.84 (s); 13C NMR (100 MHz, DMSO-d6) δ 162.7, 156.5, 151.9, 149.9, 145.6,
141.8, 128.8, 128.2, 126.2, 123.6; HRMS (ESI) m/z [M – TFA]+ calculated for
C18H13Cl2N4OPd2: 584.8532, found: 584.8597.
[Pd2(bpnp)Br2(OH)](TFA) (13)
A mixture of 9 (0.03 mmol, 25.4 mg) and KBr (0.06 mmol, 7.0 mg) in dried CH3CN
(2 mL) was stirred at room temperature under N2 for 3 h. The solution was centrifuged,
washed with CH3CN and dried under vacuum to provide the yellow solid (17.0 mg, 72%).
1H NMR (400 MHz, DMSO-d6) δ 9.38 (d, J = 8 Hz, 2H), 9.12 (d, J = 8 Hz, 2H), 9.07 (s,
br, 2H), 8.84 (d, J = 8 Hz, 2H), 8.43 – 8.48 (m, 2H), 7.80 (s, br, 2H); 19F NMR (375 MHz,
DMSO-d6) δ -73.84 (s); 13C NMR (100 MHz, DMSO-d6) δ 163.0, 159.9, 157.1, 154.8,
145.9, 142.1, 141.7 (q, J = 70 Hz), 129.6, 128.8, 126.5, 124.1, 53.1 (q, J = 2700); HRMS
(ESI) m/z [M – TFA]+ calculated for C18H13Br2N4OPd2: 674.7513, found: 674.7503.
[Pd(tpy)Cl](PF6) 57
A mixture of 2,2':6',2''-terpyridine (0.20 mmol, 47 mg,) and Pd(MeCN)2Cl2 (0.23
mmol, 59 mg) in dried MeCN (8 mL) was stirred at room temperature under N2 for 30
min. KPF6 (0.57 mmol, 104 mg) was then added to the reaction mixture and the mixture
was heated to 50°C for 3 h. After cooled to room temperature, the solvent was evaporated
and CH3NO2 (ca. 10 mL) was added. The suspension was passed through a pad of Celite®
and concentrated to ca. 3 mL. The solution was added to Et2O to provide the pink
precipitate. The solid was filtered and washed with MeOH and Et2O, and dried in vacuo
to provide the desired product as white solid (94 mg, 90%). 1H NMR (400 MHz, CD3NO2) δ 8.90 – 8.79 (m, 2H), 8.53 (dd, J = 8.6, 7.8 Hz, 1H), 8.42 – 8.32 (m, 6H), 7.88 – 7.77 (m,
2H).
Pd(bpy)(TFA)258
Pd(OAc)2 (0.044 mmol, 9.9 mg) and 2,2'-bipyridine (0.053 mmol, 8.3 mg) were
dissolved in MeOH at room temperature under N2 for 30 min, and an excess of CF3COOH (100 μL) was added. Precipitate was filtered off, washed with cold MeOH and dried in
vacuo to get the desired product as pale yellow solid (15 mg, 70%). 1H NMR (400 MHz,
DMSO-d6) δ 8.60 (d, J = 8 Hz, 2H), 8.44 (t, J = 8 Hz, 2H), 8.09 (s, br, 2H), 7.85 (t, J = 8
Hz, 2H).
Pd(bpy)Cl259
A mixture of 2,2'-bipyridine (0.34 mmol, 53 mg) and PdCl2 (0.28 mmol, 50 mg) in
dried MeOH (2 mL) was stirred at room temperature under N2 for 18 h. The resulting
solid was filtered and washed with MeOH, CHCl3 and Et2O. The solid was dried in vacuo
to provide the desired product as pale yellow solid (70 mg, 74%). 1H NMR (400 MHz,
DMSO-d6) δ 9.12 (d, J = 6.9 Hz, 2H), 8.58 (d, J = 6.9 Hz, 2H), 8.36 (t, J = 6.9 Hz, 2H),
7.81 (t, J = 6.9 Hz, 2H).
[Pd(dien)Cl]Cl 60
A mixture of diethylenetriamine (0.64 mmol, 66 mg) and PdCl2 (0.29 mmol, 51 mg)
in H2O (2 mL) was stirred at 70°C until a yellow solution resulted (ca. 1 h). The solution
was acidified with conc. HCl, and half of the solvent was evaporated. To the residue was
added EtOH (10 mL). The resulting solid was filtered and washed with cold EtOH and
Et2O. The solid was dried in vacuo to provide the desired product as tan solid (51 mg,
71%). 1H NMR (400 MHz, D2O) δ 3.22 – 3.08 (m, 2H), 3.08 – 2.93 (m, 4H), 2.80 – 2.69
(m, 2H).
5.2.2 Reduction of Nitroarenes
General procedure for reduction of nitroarenes
A mixture of nitroarene (0.5 mmol) and 9 (0.0025 mmol, 2.1 mg) was degassed and
refilled with H2 in a test tube. To the mixture was added dried MeOH (0.5 mL) and the
mixture was stirred at 50°C under H2 for 12 h. After completion of the reaction, the
reaction mixture was diluted with MeOH or CH2Cl2 and passed through a pad of Celite®.
The residue was concentrated and purified by column chromatography on silica gel to
provide the desired product if needed.
General procedure for reduction of aryl halides
A mixture of aryl halide (0.5 mmol), 9 (0.0025 mmol, 2.1 mg) and DABCO (1.0
mmol, 112 mg) was degassed and refilled with H2 in a test tube. To the mixture was added
dried MeOH (0.5 mL) and the mixture was stirred at 50°C under H2 for 12 h. After
completion of the reaction, the mixture was cooled to room temperature and small amount
of dimethyl sulfone was added as the internal standard to determined conversion and
yields by 1H NMR spectroscopy.
Procedure of multiple rounds of 9-catalyzed reduction of nitroarenes
9 (0.0025 mmol, 2.1 mg) was degassed and refilled with H2 in a test tube.
Nitrobenzene (0.50 mmol) and dried MeOH (0.5 mL) were added and the mixture was
stirred at 50°C under H2 for 3 h. Another 0.50 mmol of nitrobenzene was added. After 3
h, the third portion of nitrobenzene (0.50 mmol) was added and the mixture was stirred
overnight. After completion of the reaction, the reaction mixture was diluted with MeOH
or CH2Cl2 and passed through a pad of Celite®. The residue was concentrated to get
desired product.
High-pressure reaction
9 (0.0025 mmol, 2.1 mg) was degassed and refilled with H2 in a short test tube
capped with a silicone stopper. Nitrobenzene (5.0 mmol) and dried MeOH (0.5 mL) were
added and then the test tube was placed in an autoclave reactor with silicone oil inside. A
needle was pierced through the silicone stopper to enable gas exchange and the autoclave
reactor was quickly closed. After that the reactor was repeated degraded and refilled with
H2 for 3 times. After stirred at 50°C for 36 h, the reaction mixture was diluted with MeOH
or CH2Cl2 and passed through a pad of Celite®. The residue was concentrated to get
desired product.
Aniline (20a)
Yield: 95%. Brown liquid. 1H NMR (400 MHz, CDCl3) δ 7.24 – 7.14 (m, 2H), 6.84 –
6.75 (m, 1H), 6.75 – 6.66 (m, 2H), 3.52 (s, br, 2H); 13C NMR (100 MHz, CDCl3) δ
146.3, 129.2, 118.5, 115.0.
4-Toluidine (20b)
Yield: 96%. Yellow solid. 1H NMR (400 MHz, CDCl3) δ 7.02 (d, J = 8.3 Hz, 2H), 6.65
(d J = 8.3 Hz, 2H), 3.50 (s, br, 2H), 2.30 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 143.7,
129.6, 127.6, 115.2, 20.3.
4-Aminophenol (20c)
Yield: 99%. Yellow solid. 1H NMR (400 MHz, DMSO-d6) δ 8.36 (s, br, 1H), 6.48 (d, J
= 8.2 Hz, 2H), 6.42 (d, J = 8.2 Hz, 2H), 4.37 (s, br, 2H); 13C NMR (100 MHz, DMSO-d6)
δ 149.2, 141.6, 116.5, 116.2.
4-Phenylenediamine (20d)
Yield: 95%. Yellow solid. 1H NMR (400 MHz, CDCl3) δ 6.57 (s, 4H), 3.29 (s, br, 4H);
13C NMR (100 MHz, CDCl3) δ 138.8, 117.0
4-Fluoroaniline (20e)
Yield: 89%. Brown liquid. 1H NMR (400 MHz, CDCl3) δ 6.88 – 6.84 (m, 2H), 6.67 –
6.57 (m, 2H), 3.45 (s, br, 2H); 19F NMR (375 MHz, CDCl3) δ -127.27 (tt, J = 6.7, 4.4 Hz);
13C NMR (100 MHz, CDCl3) δ 156.4 (d, J = 235.7 Hz), 142.3, 116.1 (d, J = 7.5 Hz),
115.6 (d, J = 22.5 Hz).
4-Chloroaniline (20f)
Yield: 28%. Yellow solid. 1H NMR (400 MHz, CDCl3) δ 7.10 (d, J = 8.8 Hz, 2H), 6.60
(d, J = 8.8 Hz, 2H), 3.65 (s, br, 2H); 13C NMR (100 MHz, CDCl3) δ 145.2, 129.3, 123.4,
116.5.
4-Aminophenylacetonitrile (20h)
Yield: 100%. White solid. 1H NMR (400 MHz, CDCl3) δ 7.04 (d, J = 8.4 Hz, 2H), 6.63
(d, J = 8.4 Hz, 2H), 3.73 (s, br, 2H), 3.57 (s, 2H); 13C NMR (100 MHz, CDCl3) δ 146.2,
128.7, 119.0, 118.5, 115.3, 22.6. IR (KBr): 3453, 3370, 3223, 3035, 3007, 2909, 2248,
1629, 1518, 1438, 1415, 1284, 1201, 1182, 1129, 1087, 1015, 824, 775 cm-l.
4’-Aminoacetophenone (20i)
Yield: 88%. Yellow solid. 1H NMR (400 MHz, CDCl3) δ 7.80 (d, J = 8.7 Hz, 2H), 6.64
(d, J = 8.7 Hz, 2H), 4.13 (s, br, 2H), 2.50 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 196.8,
151.5, 130.9, 127.7, 113.8, 26.2. IR (KBr): 3395, 3323, 3218, 1652, 1603, 1566, 1513,
1438, 1361, 1305, 1281, 1231, 1178, 961, 838, 820 cm-l.
4-Aminobenzoic acid (20j)
Yield: 86%. White solid. 1H NMR (400 MHz, DMSO-d6) δ 7.64 (d, J = 8.2 Hz, 2H), 6.56
(d, J = 8.2 Hz, 2H), 5.85 (s, br, 2H); 13C NMR (100 MHz, DMSO-d6) δ 167.8, 153.1,
131.3, 117.3, 112.7.
2,6-Xylidine (20k)
Yield: 100%. Yellow liquid. 1H NMR (400 MHz, CDCl3) δ 6.97 (d, J = 7.5 Hz, 2H), 6.66
(t, J = 7.5 Hz, 1H), 3.58 (s br, 2H), 2.20 (s, 6H); 13C NMR (100 MHz, CDCl3) δ 142.6,
128.2, 121.6, 117.9, 17.6.
1-Naphthylamine (20l)
Yield: 100%. Red solid. 1H NMR (400 MHz, CDCl3) δ 7.84 – 7.81 (m, 2H), 7.51 – 7.44
(m, 2H), 7.34 – 7.33 (m, 2H), 6.79 – 6.77 (m,1H), 4.05 (s, br, 2H); 13C NMR (100 MHz,
CDCl3) δ 141.8, 134.4, 128.7, 126.4, 126.0, 125.1, 124.0, 120.9, 119.4, 110.2.
3,4-Dimethylbenzene-1,2-diamine (20m)
Yield: 99%. Yellow solid. 1H NMR (400 MHz, CDCl3) δ 6.63 (d, J = 7.8 Hz, 1H), 6.58
(d, J = 7.8 Hz, 1H), 3.48 (s, br, 4H), 2.31 (s, 3H), 2.16 (s, 3H); 13C NMR (100 MHz,
CDCl3) δ 133.6, 131.4, 128.19, 120.1, 114.3, 19.9, 12.8.
1,3-Diaminobenzene (20n)
Yield: 92%. White solid. 1H NMR (400 MHz, CDCl3) δ 6.93 (t, J = 7.9 Hz, 1H), 6.10 (d,
J = 7.9, 2H), 5.99 (s, 1H), 3.46 (s, br, 4H); 13C NMR (100 MHz, CDCl3) δ 147.4, 130.0,
105.8, 101.9.
5.2.3 Investigation of Reaction Intermediates and Mechanism
Reaction of nitrobenzene (14a)
9 (0.0025 mmol, 2.1 mg) was degassed and refilled with H2 in a test tube. To the
mixture was added nitrobenzene (0.5 mmol) and dried MeOH (0.5 mL) and the mixture
was stirred at 40°C under H2 for 6 h. Conversion and yields were determined by 1H NMR
spectroscopy using CH2Br2 as the internal standard. The reaction catalyzed by 11 was conducted similarly with 0.0025 mmol of 11 and 0.0125 mmol of NaBH3CN. 0.0050
mmol of Pd(bpy)(TFA)2 was used in the reaction catalyzed by Pd(bpy)(TFA)2.
Reaction of N-phenylhydroxylamine (16a)
A mixture of N-phenylhydroxylamine (0.5 mmol) and 9 (0.0025 mmol, 2.1 mg) was
degassed and refilled with H2 in a test tube. To the mixture was added dried MeOH (0.5
mL) and the mixture was stirred at 40°C under H2 for 6 h. Conversion and yields were
determined by 1H NMR spectroscopy using CH2Br2 as the internal standard. The reaction catalyzed by 11 was conducted similarly with 0.0025 mmol of 11 and 0.0125 mmol of
NaBH3CN. 0.0050 mmol of Pd(bpy)(TFA)2 was used in the reaction catalyzed by
Pd(bpy)(TFA)2.
Reaction of azobenzene (18a)
A mixture of azobenzene (0.25 mmol) and 9 (0.0025 mmol, 2.1 mg) was degassed
and refilled with H2 in a test tube. To the mixture was added dried MeOH (0.5 mL) and
the mixture was stirred at 40°C under H2 for 6 h. Conversion and yields were determined
by 1H NMR spectroscopy using CH2Br2 as the internal standard. The reaction catalyzed by 11 was conducted similarly with 0.0025 mmol of 11 and 0.0125 mmol of NaBH3CN.
0.0050 mmol of Pd(bpy)(TFA)2 was used in the reaction catalyzed by Pd(bpy)(TFA)2.
Kinetic study of reduction of azoxybenzene (17a)
A mixture of N-phenylhydroxylamine (0.25 mmol), nitrosobenzene (0.25 mmol) and
9 (0.0025 mmol, 2.1 mg) was degassed and refilled with H2 in a test tube. To the mixture
was added dried MeOH (0.5 mL) and the mixture was stirred at 50°C under H2. The
reaction was followed by 1H NMR spectroscopy using dimethyl sulfone as the internal
standard. Condensation of N-phenylhydroxylamine and nitrosobenzene occurred
immediately after mixing and generated azoxybenzene. Azoxybenzene was quantified by
1H NMR integration of doublets at δ 8.29 (2H) and δ 8.14 (2H); azobenzene was
quantified by 1H NMR integration of doublet at δ 7.90 (4H); hydrazobenzene was quantified by 1H NMR integration of multiplet at δ 6.79 – 6.85 (3H); aniline was
quantified by 1H NMR integration of doublet at δ 6.68 (2H). The procedure for
11-catalyzed reaction was same as 9, except that 0.0125 NaBH3CN was added to the reaction
mixture. The reaction catalyzed by Pd(bpy)(TFA)2 was conducted similarly with 0.0050
mmol of Pd(bpy)(TFA)2.
Kinetic study of reduction of p-nitrotoluene (14b)
A mixture of 14b (0.50 mmol) and 9 (0.0025 mmol, 2.1 mg) was degassed and
refilled with H2 in a test tube. To the mixture was added dried MeOH (0.5 mL) and the
mixture was stirred at 50°C under H2. The reaction was followed by 1H NMR
spectroscopy using dimethyl sulfone as the internal standard. The reaction catalyzed by Pd(bpy)(TFA)2 was conducted similarly with 0.0050 mmol of Pd(bpy)(TFA)2.
Kinetic study of reduction of 14b activated by NaBH3CN
A mixture of 14b (0.50 mmol), NaBH3CN (0.050 mmol) and 9 (0.0025 mmol, 2.1
mg) was degassed and refilled with H2 in a test tube. To the mixture was added dried
MeOH (0.5 mL) and the mixture was stirred at 50°C under H2. The reaction was followed
by 1H NMR spectroscopy using dimethyl sulfone as the internal standard. In the kinetic
study of the reaction catalyzed by Pd(bpy)(TFA)2, 0.0050 mmol of Pd(bpy)(TFA)2 was used. The reaction catalyzed by 11 was conducted similarly with 0.0025 mmol of 11 and
0.0125 mmol of NaBH3CN.
Mercury poisoning experiment
A mixture of 14b (0.50 mmol) and 9 (0.0025 mmol, 2.1 mg) was degassed and
refilled with H2 in a test tube. To the mixture was added dried MeOH (0.5 mL) and the
mixture was stirred at 50°C under H2 for 4 h. Afterward a drop of mercury was added to
the reaction mixture. The reaction was followed by 1H NMR spectroscopy using CH2Br2
as the internal standard.
參考文獻
1. Gavrilova, A. L.; Bosnich, B. Chem. Rev. 2004, 104, 349–383.
2. Tikkanen, W.; Kaska, W. C.; Moya, S.; Layman, T.; Kane, R.; Krüger, C. Inorg.
Chim. Acta 1983, 76, L29–L30.
3. He, C.; Lippard, S. J. J. Am. Chem. Soc. 2000, 122, 184–185.
4. He, C.; Barrios, A. M.; Lee, D.; Kuzelka, J.; Davydov, R. M.; Lippard, S. J. J.
Am. Chem. Soc. 2000, 122, 12683–12690.
5. He, C.; DuBois, J. L.; Hedman, B.; Hodgson, K. O.; Lippard, S. J. Angew. Chem.
Int. Ed. 2001, 40, 1484–1487.
6. Cheng, T.-P.; Liao, B.-S.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Dalton Trans.
2012, 41, 3468–3473.
7. Tsai, B.-C.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Eur. J. Inorg. Chem. 2016, 2016, 2783–2790.
8. Evens, G.; Caluwe, P. Macromolecules 1979, 12, 803–808.
9. Binamira-Soriaga, E.; Keder, N. L.; Kaska, W. C. Inorg. Chem. 1990, 29, 3167–
3171.
10. Tikkanen, W. R.; Binamira-Soriaga, E.; Kaska, W. C.; Ford, P. C. Inorg. Chem.
1983, 22, 1147–1148.
11. Tikkanen, W. R.; Binamira-Soriaga, E.; Kaska, W. C.; Ford, P. C. Inorg. Chem.
1984, 23, 141–146.
12. Tikkanen, W. R.; Krueger, C.; Bomben, K. D.; Jolly, W. L.; Kaska, W.; Ford, P.
C. Inorg. Chem. 1984, 23, 3633–3638.
13. Liao, B.-S.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Dalton Trans. 2012, 41, 1158–
1164.
14. Lan, Y.-S.; Liao, B.-S.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Eur. J. Org. Chem.
2013, 2013, 5160–5164.
15. Hung, M.-U.; Liao, B.-S.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Appl. Organometal.
Chem. 2014, 28, 661–665.
16. Yang, F.-M.; Chen, P.-Y.; Lee, C.-C.; Liu, Y.-H.; Peng, S.-M.; Chou, P.-T.; Liu, S.-T. Dalton Trans. 2012, 41, 5782–5784.
17. Liao, B.-S.; Liu, Y.-H.; Peng, S.-M.; Reddy, K. R.; Liu, S.-H.; Chou, P.-T.; Liu, S.-T. Dalton Trans. 2014, 43, 3557–3562.
18. Hirahara, M.; Nagai, S.; Takahashi, K.; Saito, K.; Yui, T.; Yagi, M. Inorg. Chem.
2015, 54, 7627–7635.
19. Hirakawa, S.; Koizumi, T.-A. Inorg. Chem. 2014, 53, 10788–10790.
20. Huang, D.-W.; Lo, Y.-H.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Organometallics 2013, 32, 4009–4015.
21. Huang, D.-W.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Organometallics 2016, 35, 151–158.
22. Huang, D.-W.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. Dalton Trans. 2016, 45, 8265–
8271.
23. Lo, Y.-H.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. J. Chin. Chem. Soc. 2013, 60, 839–
845.
24. Ullmann, F.; Gerhartz, W.; Yamamoto, Y. S.; Campbell, F. T.; Pfefferkorn, R.;
Rounsaville, J. F. In Ullmann's Encyclopedia of Industrial Chemistry; Vedag Chemie: Weinheim, New York, 1985; Vol. A2, pp. 303–312.
25. Ullmann, F.; Gerhartz, W.; Yamamoto, Y. S.; Campbell, F. T.; Pfefferkorn, R.;
Rounsaville, J. F. In Ullmann's Encyclopedia of Industrial Chemistry; Vedag Chemie: Weinheim, New York, 1991; Vol. A19, pp. 405–410.
26. Ullmann, F.; Gerhartz, W.; Yamamoto, Y. S.; Campbell, F. T.; Pfefferkorn, R.;
Rounsaville, J. F. In Ullmann's Encyclopedia of Industrial Chemistry; Vedag Chemie: Weinheim, New York, 1991; Vol. A17, pp. 9–55.
27. Downing, R. S.; Kunkeler, P. J.; van Bekkum, H. Catal. Today 1997, 37, 121–
136.
28. Kricsfalussy, Z.; Stammann, G.; Waldmann, H. Chem. Ing. Tech. 1994, 66, 832–
834.
29. Alper, H.; Vampollo, G. Tetrahedron Lett. 1992, 33, 7477–7480.
30. Wiener, H.; Blum, J.; Sasson, Y. J. Org. Chem. 1991, 56, 4481–4486.
31. Blaser, H. U.; Steiner, H.; Studer, M. ChemCatChem 2009, 1, 210–221.
32. Corma, A.; Serna, P.; Concepción, P.; Calvino, J. J. J. Am. Chem. Soc. 2008, 130, 8748–8753.
33. Abley, P.; Jardine, I.; McQuillin, F. J. J. Chem. Soc. C 1971, 840–844.
34. Mukherjee, D. K.; Palit, B. K.; Saha, C. R. J. Mol. Catal. 1994, 88, 57–70.
35. Alper, H.; Amaratunga, S. Tetrahedron Lett. 1980, 21, 2603–2604.
36. Hashem, K. E.; Petrignani, J.-F.; Alper, H. J. Mol. Catal. 1984, 26, 285–287.
37. Januszkiewicz, K.; Alpar, H. J. Mol. Catal. 1983, 19, 139–143.
38. Watanabe, Y.; Ohta, T.; Tsuji, Y.; Hiyoshi, T.; Tsuji, Y. Bull. Chem. Soc. Jpn.
38. Watanabe, Y.; Ohta, T.; Tsuji, Y.; Hiyoshi, T.; Tsuji, Y. Bull. Chem. Soc. Jpn.