Melting points were determined on a Yanaco MF-500 V
melting point apparatus. UV-irradiation was used with a
SAN-EI UVF-203S Hg–Xe lamp filtered by a band-path glass
filter (330 ꢁ 70 nm, UV-D33S; Toshiba) and water filter
(optical path: 3 cm).
2.7 mmol), 1,3,5-tris(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-
benzene (274 mg, 0.6 mmol), K2CO3 (1.24 g, 9.0 mmol),
Pd(PPh3)4 (208 mg, 0.18 mmol) were mixed in degassed DMF
(30 mL), and stirred at 90 1C under argon for 24 h. Solvent was
removed under reduced pressure, and the residue was poured into
water and extracted with CHCl3. The organic layer was washed
with water and brine, and dried over MgSO4, followed by the
removal of the solvent under reduced pressure. The crude product
was purified by column chromatography (silica gel, CH2Cl2
DFT calculations were carried out using the Gaussian 03
program package.17 The structure was optimized using the
B3LYP level of the theory with the LANL2DZ basis sets for
Pt, and 6-31G* basis set for the other atoms.
then CH2Cl2–MeOH 30
: 1) to give 6 as white solid
(309 mg, yield; 78%); mp 177–179 1C; 1H NMR (500 MHz,
CDCl3, r.t.) d (ppm) = 8.69 (d, J = 5.8 Hz, 6H, PyHa), 7.13
(d, J = 5.8 Hz, 6H, PyHb), 7.00 (s, 3H, PhH), 2.17 (s, 18H, Me),
1.95 (s, 18H, Me). 13C NMR (125 MHz, CDCl3, r.t.) d (ppm) =
151.2 (Cq), 150.0 (CH), 142.7 (Cq), 141.8 (Cq), 138.5 (Cq), 132.0
(Cq), 130.9 (Cq), 128.7 (CH), 125.0 (CH), 18.1 (CH3),
18.0 (CH3). MALDI-TOF MS (dithranol matrix); m/z = 706
[6 + H]+. IR (KBr, cmꢂ1); 2990, 2922 (br), 1596, 1541, 1457,
1409, 1204, 1132, 1013, 990, 896, 855, 812, 788, 640, 616.
Syntheses
2,3,5,6-Tetramethyl-1,4-bis(pyridin-4-yl)benzene
(4d).
1,4-Diiodo-2,3,5,6-tetramethylbenzene (386 mg, 1 mmol),
4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (615 mg,
3 mmol), K2CO3 (1.38 g, 10 mmol), Pd(PPh3)4 (231 mg,
0.2 mmol) were mixed in degassed DMF (20 mL), and stirred
at 90 1C under argon for 24 h. Solvent was removed under
reduced pressure, and the residue was poured into water and
extracted with CHCl3. The organic layer was washed with water
and brine, and dried over MgSO4, followed by the removal
of the solvent under reduced pressure. The crude product was
purified by column chromatography (silica gel, CH2Cl2, then
CH2Cl2–MeOH 50 : 1), followed by recrystallization from ethyl
acetate to give 4d as a white powder (233 mg, yield; 81%); mp
4210 1C (sublimed); 1H NMR (500 MHz, CDCl3, r.t.) d (ppm)
= 8.70 (dd, J = 6.0 Hz, 1.6 Hz, 4H, PyHa), 7.13 (dd, J = 6.0 Hz,
1.6 Hz, 4H, PyHb), 1.93 (s, 12H, Me). 13C NMR (125 MHz,
CDCl3, r.t.) d (ppm) = 150.7 (Cq), 150.1 (CH), 139.3 (Cq), 131.4
(Cq), 124.8 (CH), 17.9 (CH3). EI-MS; m/z = 288 [4d]+. IR
(KBr, cmꢂ1); 3028, 2927 (br), 1593, 1542, 1408, 1215, 1070, 988,
870, 812, 753, 640. Elemental analysis: calc. for C20H20N2:
C, 83.30; H, 6.99; N, 9.71; found: C, 83.03; H, 7.11; N, 9.51%.
Pt(II)-linked ring 3a. A D2O solution (0.5 mL) of (en)Pt(NO3)2
(1, 3.79 mg, 0.01 mmol) was added to a 1,4-dioxane-d8 (0.5 mL)
solution of 1,2-bis(4-pyridyl)ethane (2a, 1.84 mg, 0.01 mmol), and
the solution was put in the UV quarts cell and irradiated at room
temperature under aerobic condition. The reaction was monitored
by 1H NMR, and 3a was almost quantitatively formed after 4 h.
1H NMR (500 MHz, D2O–1,4-dioxane-d8 1 : 1, r.t.) d (ppm) =
8.63 (d, J = 6.5 Hz, 8H, PyHa), 7.50 (d, J = 6.5 Hz, 8H, PyHb),
3.42 (s, 8H, CH2), 2.93 (s, 8H, en). 13C NMR (125 MHz, D2O–
1,4-dioxane-d8 1 : 1, r.t.) d (ppm) = 154.6 (Cq), 151.5 (CH), 127.5
(Cq), 47.6 (en), 33.0 ꢂ(CH2). CSI-MS (H2O–MeOH–DMF): ꢂm/z =
329.1 [3a ꢂ (NO3
)
+ (dmf)6]4+, 347.3 [3a ꢂ (NO3
) +
4
4
(dmf)7]4+
,
365.6 [3a
ꢂ
(NO3
)
4
+
(dmf)8]4+
,
410.7
ꢂ
[3a ꢂ (NO3ꢂ)3 + (dmf)4]3+, 435.1 [3a ꢂ (NO3ꢂ)3 + (dmf)5]3+
,
+
+
4-(4-Iodo-2,3,5,6-tetramethylphenyl)pyridine.
1,4-Diiodo-
ꢂ
ꢂ
ꢂ
459.4 [3a ꢂ (NO3
)
3
+ (dmf)6]3+, 483.7 [3a ꢂ (NO3
)
3
2,3,5,6-tetramethylbenzene (4.63 g, 12 mmol), 4-(4,4,5,5-tetra-
methyl-1,3,2-dioxaborolan-2-yl)pyridine (820 mg, 4 mmol),
K2CO3 (6.68 g, 48.3 mmol), Pd(PPh3)4 (462 mg, 0.4 mmol)
were mixed in degassed DMF (50 mL), and stirred at 90 1C
under argon for 10 h. Solvent was removed under reduced
pressure, and the residue was poured into water and extracted
with CHCl3. The organic layer was washed with water and
brine, and dried over MgSO4, followed by the removal of the
solvent under reduced pressure. The crude product was
purified by column chromatography (silica gel, hexane–
CH2Cl2 1 : 1, then CH2Cl2) to give the title compound as a
(dmf)7]3+, 501.1 [3a ꢂ (NO3ꢂ)2]2+, 537.6 [3a ꢂ (NO3
)
2
dmf]2ꢂ+, 574.1 [3a ꢂ (NO3
)
2
+ (dmf)2]2+, 610.6 [3a ꢂ
ꢂ
ꢂ
(NO3
)
2
+ (dmf)3]2+, 647.1 [3a ꢂ (NO3
) ,
+ (dmf)4]2+
2
1064.2 [3a ꢂ NO3ꢂ]+.
Pt(II)-linked ring 3b.
A D2O solution (0.5 mL) of
(en)Pt(NO3)2 (1, 3.79 mg, 0.01 mmol) was added to a
1,4-dioxane-d8 (0.5 mL) solution of 2,3,5,6-tetrafluoro-1,4-bis-
(4-pyridylmethyl)benzene (2b, 3.32 mg, 0.01 mmol), and the
solution was put in the UV quarts cell and irradiated at room
temperature under aerobic conditions. The reaction was moni-
tored by 1H NMR, and 3b was almost quantitatively formed after
3 h. 1H NMR (500 MHz, D2O–1,4-dioxane-d8 1 : 1, r.t.) d (ppm)
= 8.93 (d, J = 6.6 Hz, 8H, PyHa), 7.63 (d, J = 6.6 Hz, 8H,
PyHb), 4.44 (s, 8H, CH2), 2.96 (s, 8H, en). 13C NMR (125 MHz,
D2O–1,4-dioxane-d8 1 : 1, r.t.) d (ppm) = 152.3 (CH), 152.1 (Cq),
145.2 (d, J = 241 Hz, CF), 127.1 (CH), 115.6 (CH), 47.7 (en), 27.3
1
white powder (1.16 g, yield; 86%); mp 192–193 1C; H NMR
(500 MHz, CDCl3, r.t.) d (ppm) = 8.67 (dd, J = 6.0 Hz,
1.6 Hz, 2H, PyHa), 7.06 (dd, J = 6.0 Hz, 1.6 Hz, 2H, PyHb),
2.55 (s, 6H, Me), 1.98 (s, 6H, Me). 13C NMR (125 MHz,
CDCl3, r.t.) d (ppm) = 150.4 (Cq), 150.1 (CH), 139.5 (Cq),
137.9 (Cq), 131.7 (Cq), 124.6 (CH), 111.7 (Cq), 27.8 (CH3) 19.8
(CH3). EI-MS; m/z = 337 [M]+. IR (KBr, cmꢂ1); 3005, 2916
(br), 1593, 1541, 1444, 1409, 1382, 1223, 1213, 1070, 987,
862, 811, 641, 611. Elemental analysis: calc. for C15H16NI:
C, 53.43; H, 4.78; N, 4.15; found: C, 53.38; H, 4.88; N,
3.93%.
(CH2). CSI-MS (H2O–MeOH–DMF): m/z
=
403.3
[3b ꢂ (NO3ꢂ)4 + (dmf)6]4+, 421 [3b ꢂ (NO3ꢂ)4 + (dmf)7]4+
,
+
ꢂ
ꢂ
)
3
439.8 [3b ꢂ (NO3
)
4
+ (dmf)8]4+, 509.7 [3b ꢂ (NO3
ꢂ
(dmf)4]3+
,
534.1 [3b
ꢂ
ꢂ
(NO3
)
3
+
(dmf)5]3+
,
558.4
[3b ꢂ (NO3
)
3
+ (dmf)6]3+, 649.6 [3b ꢂ (NO3ꢂ)2]2+, 686.1
1,3,5-Tris[2,3,5,6-tetramethyl-4-(pyridin-4-yl)phenyl]benzene
[3b ꢂ (NO3ꢂ)2 + dmf]2+, 722.6 [3b ꢂ (NO3ꢂ)2 + (dmf)2]2+
,
(6). 4-(4-Iodo-2,3,5,6-tetramethylphenyl)pyridine (910 mg,
1361.2 [3b ꢂ NO3ꢂ]+.
ꢀc
This journal is The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2009
268 | New J. Chem., 2009, 33, 264–270