(dd, J = 7.8, 0.6 Hz, 1H), 7.81–7.83 (m, 2H), 7.44–7.47 (m,
2H), 7.27–7.35 (m, 4H), 4.88 (s, 2H). 13C-NMR (75 MHz,
CDCl3): δ (ppm) 167.8, 155.1, 150.1, 145.3, 137.1, 136.4,
132.9, 132.5, 132.0, 128.7, 128.6, 127.8, 123.8, 123.5, 121.7,
121.0, 41.7. IR (film): ν (cm−1) 3029, 2930, 1766, 1699, 1617,
1584, 1422, 1387, 1341, 1304, 1155, 1106, 1067, 949, 786, 740,
695, 623. HRMS calcd for C20H15N2O2 (M + H)+ 315.1128,
found 315.1124.
48 h. The solvent was removed in vacuo, the crude product sub-
jected to silica gel chromatography using a gradient of CH2Cl2–
MeOH 100 : 1 to 35 : 1. The combined product eluents were
dried in vacuo and 4-(pyridin-2-yl)phthalimide (2c) was
1
obtained as a white solid (10 mg, 65%). H-NMR (300 MHz,
DMSO-d6): δ (ppm) 11.43 (s, 1H), 8.74 (ddd, J = 4.8, 1.8, 0.9
Hz, 1H), 8.54 (dd, J = 7.9, 1.5 Hz, 1H), 8.47 (dd, J = 1.5, 0.6
Hz, 1H), 8.19 (dt, J = 8.0, 0.9 Hz, 1H), 7.98 (td, J = 7.7, 1.8 Hz,
1H), 7.93 (dd, J = 7.8, 0.6 Hz, 1H), 7.47 (ddd, J = 7.5, 4.8, 1.0
Hz, 1H). 13C-NMR (63 MHz, DMSO-d6): δ (ppm) 168.94,
168.91, 153.9, 149.8, 144.3, 137.6, 133.5, 132.6, 132.2, 123.9,
123.4, 121.3, 120.6. IR (film): ν (cm−1) 2926, 2722, 1717,
1655, 1587, 1430, 1351, 1303, 1177, 1141, 1102, 1059, 996,
833, 783, 737, 687, 634. HRMS calcd for C13H9N2O2 (M + H)+
225.0659, found 225.0659.
N-(tert-Butyldimethylsilyl)-4-(pyridin-2-yl)phthalimide (2b).
N-(tert-Butyldimethylsilyl)-4-bromophthalimide (1b) (1.10 g,
2.98 mmol) and 2-(trimethylstannyl)pyridine (0.74 g,
3.06 mmol) were dissolved in m-xylene (10 mL) and the solu-
tion was purged with nitrogen for 20 min. Tetrakis(triphenylpho-
sphine)palladium(0) (40 mg, 35 μmol) was added and the
solution heated to reflux under nitrogen for 48 h. The solution
was cooled to ambient temperature, water (50 mL) was added,
the organic phase was separated, and the aqueous phase was
extracted with CH2Cl2 twice. The combined organic layers were
washed with brine, dried using Na2SO4, filtered, and the solvent
removed in vacuo. The crude product was subjected to silica gel
chromatography with first CH2Cl2 and then CH2Cl2–MeOH
50 : 1. The combined product eluents were dried in vacuo and
N-(tert-butyldimethylsilyl)-4-(pyridin-2-yl)phthalimide (2b) was
obtained as a light yellow solid (490 mg, 49%). 1H-NMR
(300 MHz, CDCl3): δ (ppm) 8.75 (dt, J = 4.8, 1.3 Hz, 1H), 8.43
(d, J = 7.8, 1.5 Hz, 1H), 8.37–8.38 (m, 1H), 7.90 (dd, J = 7.8,
0.6 Hz, 1H), 7.81–7.84 (m, 2H), 7.31–7.35 (m, 1H), 1.00 (s,
9H), 0.55 (s, 6H). 13C-NMR (75 MHz, CDCl3): δ (ppm) 155.5,
150.3, 145.4, 137.3, 135.0, 134.1, 132.8, 123.6, 123.5, 121.5,
121.2, 26.5, 19.2, −4.1. IR (film): ν (cm−1) 2951, 2926, 2880,
2854, 1759, 1693, 1620, 1585, 1465, 1418, 1350, 1296, 1249,
1155, 1057, 849, 838, 787, 746, 673. HRMS calcd for
C19H23N2O2Si (M + H)+ 339.1523, found 339.1516.
Half-sandwich complex 4. N-Benzyl-4-(pyridin-2-yl)phthali-
mide (2a) (20 mg, 64 μmol) was dissolved in methanol (4 mL).
Triethylamine (6.4 μL, 77 μmol) was added, followed by [Ru-
(η5-C5H5)(CO)(MeCN)2]PF6 (40 mg, 96 μmol), and the solution
was stirred for 2 h at 55 °C. The solution was cooled to ambient
temperature, CH2Cl2 (20 mL) was added, and the solution was
washed with brine twice. The organic phase was dried using
MgSO4, filtered, and evaporated to dryness in vacuo. The crude
product was subjected to silica gel chromatography with
CH2Cl2. The combined product eluents were dried in vacuo and
the half-sandwich complex 4 was obtained as an orange solid
(25 mg, 70%). 1H-NMR (300 MHz, CDCl3): δ (ppm) 8.95 (ddd,
J = 5.7, 1.5, 0.7 Hz, 1H), 7.94 (d, J = 7.7 Hz, 1H), 7.91–7.94
(m, 1H), 7.77 (td, J = 7.8, 1.6 Hz, 1H), 7.55 (d, J = 7.5 Hz, 1H),
7.46–7.48 (m, 2H), 7.27–7.36 (m, 3H), 6.99–7.04 (m, 1H), 5.10
(s, 5H), 4.87 (s, 2H). 13C-NMR (75 MHz, CDCl3): δ (ppm)
177.8, 170.8, 165.3, 157.6, 153.7, 137.4, 136.7, 132.8, 128.7,
128.6, 127.6, 127.0, 121.7, 120.1, 117.3, 84.8, 41.5. IR (film) ν
(cm−1) 3114, 2942, 1906, 1755, 1696, 1590, 1390, 1326, 1267,
1104, 943, 807, 779, 749, 699. HRMS calcd for C26H19N2O3Ru
(M + H)+ 509.0441, found 509.0427.
4-(Tri-n-butylstannyl)phthalimide (3). N-(tert-butyldimethyl-
silyl)-4-bromophthalimide (2b) (100 mg, 294 μmol) was dis-
solved in toluene (5 mL) and the solution was degassed for
20 min. Hexa-n-butylditin (342 μL, 676 μmol) was added fol-
lowed by the addition of tetrakis(triphenylphosphine)palladium
(0) (102 mg, 88 μmol) and the solution was heated to reflux for
5 days. The solvent was removed in vacuo, the crude product
subjected to silica gel chromatography with first hexane and then
hexane–EtOAc 10 : 1. The combined product eluents were dried
in vacuo and 4-(tri-n-butylstannyl)phthalimide (3) was obtained
Iridium(III) complex 5. N-Benzyl-4-(pyridin-2-yl)phthalimide
(2a) (31 mg, 99 μmol) and PPh3 (103 mg, 395 μmol) were
placed in a flask under nitrogen. [Ir(COD)Cl]2 (33 mg, 49 μmol)
was added in the glovebox and 2-ethoxyethanol (4 mL) was
added. The solution was heated to reflux for 18 h. Upon cooling
to ambient temperature, a yellow precipitate was formed that was
filtered off and washed three times with methanol. The resulting
yellow solid was recrystallized from hexane–CHCl3 10 : 1 to
afford iridium(III) complex 5 as a yellow powder (70 mg, 67%).
1H-NMR (500 MHz, CDCl3): δ (ppm) 9.07 (d, J = 5.4 Hz, 1H),
7.63 (d, J = 8.1 Hz, 1H), 7.59 (s, 1H), 7.48–7.51 (m, 1H),
7.34–7.39 (m, 16H), 7.27–7.30 (m, 1H), 7.07–7.09 (m, 18H),
6.83–6.85 (m, 1H), 6.61 (s, 1H), 4.70 (s, 2H), −16.58 (t, J =
16.5 Hz, 1H). 13C-NMR (125 MHz, CDCl3): δ (ppm) 169.5,
168.0, 165.43, 165.37, 163.6, 150.5, 146.6, 138.3, 137.3, 136.4,
133.93, 133.89, 133.8, 131.6, 131.4, 131.3, 131.2, 129.3, 128.5,
128.3, 127.6, 127.51, 127.47, 127.4, 122.4, 122.2, 118.5, 116.3,
41.0. 31P-NMR (121 MHz, CDCl3): δ (ppm) 5.4. IR (film): ν
(cm−1) 3047, 2926, 2117, 1758, 1696, 1601, 1481, 1431, 1380,
1340, 1184, 1092, 820, 790, 744, 693. HRMS calcd for
C56H44ClIrN2O2P2Na (M + Na)+ 1089.2088, found 1089.2087.
1
as a colourless oil (60 mg, 47%). H-NMR (300 MHz, CDCl3):
δ (ppm) 8.27 (s, 1H), 7.96–7.97 (m, 1H), 7.86 (dd, J = 7.3,
0.5 Hz, 1H), 7.77 (dd, J = 7.2, 0.7 Hz, 1H), 1.47–1.56 (m, 6H),
1.28–1.36 (m, 6H), 1.10–1.15 (m, 6H), 0.88 (t, J = 7.3 Hz, 9H).
13C-NMR (63 MHz, CDCl3): δ (ppm) 169.3, 168.9, 152.9,
142.2, 132.1, 131.2, 130.9, 122.2, 28.9, 27.3, 13.6, 9.9. IR
(film): ν (cm−1) 3253, 2955, 2921, 2853, 1773, 1720, 1459,
1411, 1338, 1294, 1105, 1060, 741, 674. HRMS calcd for
C20H32NO2Sn (M + H)+ 438.1453, found 438.1450.
4-(Pyridin-2-yl)phthalimide (2c). 4-(Tri-n-butylstannyl)phtha-
limide (3) (30 mg, 69 μmol) and 2-bromopyridine (7.4 μL,
76 μmol) were dissolved in 3 mL m-xylene and purged with
nitrogen for 15 min. Tetrakis(triphenylphosphine)palladium(0)
(8 mg, 6.9 μmol) was added and the mixture heated to reflux for
9344 | Dalton Trans., 2012, 41, 9337–9348
This journal is © The Royal Society of Chemistry 2012