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mmol), 1-chloroisoquinoline (1.1 g, 6.1 mmol), and imidazole (0.42 g,
6.2 mmol) was refluxed in 80 mL of degassed toluene for 20 h. The
yellow suspension was filtered and evaporated to dryness. The residue
was purified by alumina chromatography using 20% EtOAc/hexanes as
the eluent, and the final product was a yellow solid (0.39 g, 2.0 mmol,
115.92, 113.62, 44.81, 27.95. Anal. Calcd for C27H24N6F12P2: C, 44.89;
H, 3.35; N, 11.63. Found: C, 44.79; H, 3.09; N, 11.51. ESI-HRMS
([M]+) m/z calcd for C27H24N6PF6 577.1699, found 577.1703.
Bis(2-(benzimidazolylmethyl)pyridinyl)propane Hexafluorophos-
phate (Prbbimpic, 4b). The synthesis of 4b followed the procedure of
1b, starting with 0.17 g (0.82 mmol) of 2-(benzimidazolylmethyl)-
pyridine, 41 μL of 1,3-dibromopropane (0.081 g, 0.40 mmol), and
0.134 g of NH4PF6 (0.82 mmol) to yield a white product (0.10 g, 0.14
mmol, 34%). 1H NMR (500 MHz, CD3CN) δ 9.20 (s, 2H), 8.50 (d, J
= 2.5 Hz, 2H), 7.97 − 7.79 (m, 6H), 7.73−7.68 (m, 4H), 7.60 (d, J =
7.8 Hz, 2H), 7.38 (dd, J = 7.7, 4.7 Hz, 2H), 5.78 (s, 4H), 4.65 (t, J =
7.5 Hz, 4H), 2.70 (quin, J = 7.5 Hz, 2H). 13C NMR (125 MHz,
CD3CN): δ 152.23, 149.89, 137.66, 131.81, 131.33, 127.42, 127.32,
124.01, 123.31, 113.96, 113.38, 51.63, 44.29, 28.16. Anal. Calcd for
C29H28N6F12P2: C, 46.41; H, 3.86; N, 11.20. Found: C, 46.33; H, 3.54;
N, 11.11. ESI-HRMS ([M]+) m/z calcd for C27H24N6 PF6 605.2012,
found 605.2014.
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33%). H NMR (500 MHz, CDCl3) δ 8.44 (d, J = 5.6 Hz, 1H), 8.09
(s, 1H), 8.04 (d, J = 8.6 Hz, 1H), 7.95 (d, J = 8.2 Hz, 1H), 7.79 (ddd, J
= 8.2, 6.9, 1.1 Hz, 1H), 7.74 (d, J = 5.7 Hz, 1H), 7.61 (ddd, J = 8.2, 6.9,
1.1 Hz, 1H), 7.54 (s, 1H), 7.30 (s, 1H). 13C NMR (125 MHz,
CDCl3): δ 148.31, 141.24, 138.50, 137.73, 131.18, 129.84, 128.73,
127.28, 124.39, 122.62, 121.43. EI-HRMS ([M]+) m/z calcd for
C12H9N3 195.0796, found 195.0798.
2-(Benzimidazolyl)pyridine (3a). A solution of CuI (0.33 g, 1.7
mmol), N-hydroxysuccinimide (0.46 g, 4.0 mmol), and NaOMe (2.20
g, 40 mmol) was stirred in 35 mL of DMSO for 15 min in a 150-mL
round-bottom pressure flask. Benzimidazole (3.23 g, 30 mmol) and 2-
bromopyridine (2.7 mL, 4.4 g, 28 mmol) were added, and the flask
was sealed and heated to 110 °C for 18 h. Water (25 mL) was added
to the brown solution, and the mixture was filtered to remove solid
particles. The filtrate was then extracted with EtOAc (3 × 50 mL), and
the organics were combined, washed with water, and dried with
Na2SO4. The solution was evaporated to dryness, and the residue was
purified by silica chromatography using 2% MeOH/CH2Cl2 as the
eluent. The final product was a light-brown oil (1.63 g, 8.3 mmol,
[Ni(Prbimiq1)](PF6)2 (1c). A solution of 1b (0.044 g, 0.061 mmol)
and excess Ag2O in 4 mL of CH3CN was stirred for 8 h, and the
resulting solution was centrifuged to remove fine precipitate. To the
colorless filtrate, Ni(DME)Cl2 (0.014 g, 0.064 mmol) was added and
stirred for 8 h. The resulting solution was centrifuged, and the filtrate
was evaporated to obtain a red solid. Salt metathesis was performed by
adding NaPF6 (0.010 g, 0.060 mmol) and stirred for 18 h. The
resulting solution was centrifuged, and the filtrate was evaporated to
obtain a yellow solid (0.037 mg, 0.047 mmol, 78%). Single crystals
were obtained by diffusing Et2O into a concentrated solution of 1c in
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27%). H NMR (500 MHz, CDCl3): δ 8.63 (d, J = 4.5 Hz, 1H), 8.59
(s, 1H), 8.07 (d, J = 7.4 Hz, 1H), 7.95 (t, J = 8 Hz, 1H), 7.88 (d, J =
7.5 Hz, 1H), 7.60 (d, J = 8.1, 1H), 7.43 − 7.34 (m, 2H), 7.32 (dd, J =
4.5, 2.5 Hz, 1H). 13C NMR (125 MHz, CDCl3): δ 149.87, 149.47,
144.68, 141.36, 138.99, 132.13, 124.24, 123.32, 121.88, 120.64, 114.34,
112.68. Anal. Calcd for C12H9N3: C, 73.83; H, 4.65; N, 21.52. Found:
C, 73.41; H, 4.41; N, 21.16. EI-HRMS ([M]+) m/z calcd for C12H9N3
195.0796, found 195.0800.
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CH3CN. H NMR (500 MHz, CD3CN) δ 9.34 (s, 2H), 8.39 (d, J =
8.3 Hz, 2H), 8.33 (s, 1H), 8.19 (d, J = 8.3 Hz, 2H), 8.10 (t, J = 8.2 Hz,
2H), 8.05 (d, J = 2.2 Hz, 2H), 7.90 (t, J = 8.4, 2H), 7.50 (d, J = 2.2 Hz,
1H), 4.41 (br s, 2H), 4.06 (s, 4H), 2.31 (quin, J = 5.6 Hz, 2H). 13C
NMR (125 MHz, CD3CN): δ 163.70, 155.21, 14460, 137.80, 135.08,
129.63, 129.25, 127.95, 127.08, 126.27, 107.80, 45.99, 29.66. Anal.
Calcd for C27H24N6NiF12P2: C, 41.62; H, 2.85; N, 10.79. Found: C,
40.05; H, 2.90; N, 10.50. ESI-HRMS ([M]+) m/z calcd for
C27H24N6NiPF6 633.0896, found 633.0911.
Bis(3-(imidazolyl)isoquinolinyl)propane Hexafluorophosphate
(Prbimiq1, 1b). A solution of 1a (0.070 g, 0.36 mmol) and 1,3-
dibromopropane (18 μL, 0.026 g, 0.18 mmol) in 8 mL of THF was
heated to 110 °C for 2 d in a sealed 35-mL tube pressure flask. White
precipitate was collected by vacuum filtration and dissolved in water.
Ammonium hexafluorophosphate (0.060 g, 0.37 mmol) was added,
and the white precipitate was collected by vacuum filtration and
[Ni(Prbimiq2)](PF6)2 (2c). The synthesis of 2c followed the
procedure of 1c with quantitative conversion, starting with 0.035 g
(0.048 mmol) of 2b, 0.011 g (0.050 mmol) of Ni(DME)Cl2, and
0.008 g (0.048 mmol) of NaPF6 to yield a yellow product. Single
crystals were obtained by diffusing Et2O into a concentrated solution
of 2c in CH3CN. 1H NMR (500 MHz, CD3CN) δ 8.65 (d, J = 8.7 Hz,
2H), 8.45 (d, J = 2.3 Hz, 2H), 8.36 (d, J = 6.3 Hz, 2H), 8.24 (d, J = 8.3
Hz, 2H), 8.12−8.06 (m, 4H), 7.98 (t, J = 7.2, 2H), 7.56 (d, J = 2.3 Hz,
1H), 4.40−4.20 (br m, 4H), 2.32 (quin, J = 6.0 Hz, 2H). 13C NMR
(125 MHz, CD3CN): δ 162.81, 150.18, 139.88, 139.74, 134.12,
130.88, 126.00, 124.00, 123.16, 121.16, 46.34, 30.18. Anal. Calcd for
C27H24N6NiF12P2·H2O: C, 40.68; H, 3.03; N, 10.54. Found: C, 40.36;
H, 2.82; N, 10.39. ESI-LRMS ([M]+) m/z calcd for C27H24N6Ni
244.0624, found 244.0626.
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washed with EtOH and Et2O (0.070 g, 0.096 mmol, 54%). H NMR
(500 MHz, CD3CN) δ 9.90 (s, 2H), 9.28 (s, 2H), 8.36 (s, 2H), 8.27 −
8.16 (m, 4H), 8.08 (d, J = 8.0 Hz, 2H), 7.93 (t, J = 7.6 Hz, 2H), 7.82
(t, J = 8.6 Hz, 2H), 7.77 (d, J = 2.5 Hz, 2H), 4.54 (t, J = 7.1 Hz, 4H),
2.73 (quin, J = 7.9 Hz, 2H). 13C NMR (125 MHz, CD3CN): 153.12,
141.54, 136.99, 134.51, 132.62, 129.10, 128.85, 128.23, 127.15, 123.70,
119.74, 110.15, 47.13, 29.64. Anal. Calcd for C27H24N6F12P2: C, 44.89;
H, 3.35; N, 11.63. Found: C, 44.56; H, 3.06; N, 11.45. ESI-HRMS
([M]+) m/z calcd for C27H24N6 PF6 577.1699, found 577.1709.
Bis(1-(imidazolyl)isoquinolinyl)propane Hexafluorophosphate
(Prbimiq2, 2b). The synthesis of 2b followed the procedure of 1b,
starting with 0.060 g (0.30 mmol) of 2a, 16 μL of 1,3-dibromopropane
(0.031 g, 0.15 mmol), and 0.055 g of NH4PF6 (0.30 mmol) to yield a
[Ni(Prbbimpy)](PF6)2 (3c). A solution of 3b (0.087 g, 0.12 mmol)
and excess Ag2O in 4 mL of CH3CN was stirred for 8 h, and the
resulting solution was centrifuged to remove fine precipitate. To the
colorless filtrate, Ni(DME)Cl2 (0.026 g, 0.12 mmol) was added and
stirred for 8 h. The resulting solution was centrifuged, and the filtrate
was evaporated to obtain a red solid identified by NMR studies and X-
ray diffraction as [Ni(Prbbimpy)Cl]PF6 (0.050 g, 0.08 mmol). Salt
metathesis was performed by adding AgPF6 (0.019 g, 0.075 mmol)
and stirred for 18 h. The resulting solution was centrifuged, and the
filtrate was evaporated to obtain a yellow solid (0.065 g, 0.08 mmol,
70% from 3b). Single crystals were obtained by diffusing Et2O into a
concentrated solution of 3c in CH3CN. 1H NMR (500 MHz,
CD3CN) δ 8.55 (d, J = 5.4 Hz, 2H), 8.45 (t, J = 8.4 Hz, 2H), 8.3 (d, J
= 8.1, 2H), 8.23 (d, J = 7.2 Hz, 2H), 7.88 (d, J = 7.8 Hz, 1H), 7.77 −
7.60 (m, 6H), 4.75 (br s, 2H), 4.24 (br s, 2H), 2.42 (quin, J = 5.6 Hz,
2H). 13C NMR (125 MHz, CD3CN): δ 151.24, 150.04, 143.56,
135.16, 130.09, 126.38, 126.11, 124.04, 113.43, 112.69, 112.43, 43.34,
27.51. Anal. Calcd for C27H24N6NiF12P2: C, 41.62; H, 2.85; N, 10.79.
Found: C, 41.83; H, 2.75; N, 11.19. ESI-HRMS ([M]+) m/z calcd for
C27H24N6NiPF6 633.0896, found 633.0915.
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white product (0.044 g, 0.061 mmol, 40%). H NMR (400 MHz,
CD3CN) δ 9.15 (s, 1H), 8.53 (d, J = 5.6 Hz, 2H), 8.21 (d, J = 8.2 Hz,
2H), 8.13 (d, J = 5.5 Hz, 1H), 8.07 − 7.93 (m, 6H), 7.87 (dd, J = 8.6,
6.8 Hz, 2H), 7.79 (t, J = 1.9 Hz, 2H), 4.51 (t, J = 7.3 Hz, 4H), 2.80 −
2.60 (quin, J = 8 Hz, 2H). 13C NMR (125 MHz, CD3CN): δ 145.23,
140.95, 138.66, 136.71, 132.16, 129.93, 127.70, 124.32, 123.76, 123.10,
122.94, 122.01, 29.92, 29.47. ESI-HRMS ([M]+) m/z calcd for
C27H24N6 PF6 577.1699, found 577.1712.
Bis(2-(benzimidazoyl)pyridinyl)propane Hexafluorophosphate
(Prbbimpy, 3b). The synthesis of 3b followed the procedure of 1b,
starting with 0.302 g (1.5 mmol) of 3a, 73 μL of 1,3-dibromopropane
(0.14 g, 0.7 mmol), and 0.252 g of NH4PF6 (1.5 mmol) to yield a
white product (0.19 g, 0.26 mmol, 34%). 1H NMR (500 MHz,
CD3CN) δ 9.60 (s, 2H), 8.76 (d, J = 4.0 Hz, 2H), 8.46 − 8.34 (m,
1H), 8.24 (td, J = 7.8, 1.9 Hz, 2H), 8.06−8.02 (m, 2H), 7.89 (d, J = 8.2
Hz, 2H), 7.86 − 7.78 (m, 4H), 7.78 − 7.67 (m, 2H), 4.79 (t, J = 7.5
Hz, 4H), 2.85 (quin, J = 7.5 Hz, 2H). 13C NMR (125 MHz, CD3CN):
δ 149.96, 147.05, 140.62, 131.88, 130.28, 128.35, 127.87, 125.59,
J
dx.doi.org/10.1021/ja4074003 | J. Am. Chem. Soc. XXXX, XXX, XXX−XXX