An Approach to Molecular Wires
1-Iod o-4-(a cetylth io)ben zen e (5). To a solution of 1,4-
diiodobenzene (3 g, 9.1 mmol) in dry ether (100 mL), cooled at
-78 °C, is added dropwise tert-butyllithium (1.7 M in hexane,
10 mL, 17 mmol). The solution is vigorously stirred at this
temperature for 10 min. Then the solution is allowed to warm,
and sulfur is added (290 mg, 1.1 mmol), as soon as the
temperature reaches -10 °C. The reaction is kept at 0 °C for
30 min and then cooled again at -78 °C before the addition of
acetyl chloride in one portion (0.9 g, 11.4 mmol). The solution
is allowed to warm to room temperature overnight. After
hydrolysis, the mixture is extracted with dichloromethane. The
combined organic layers are washed with a dilute solution of
sodium hydrogenocarbonate and dried over magnesium sul-
fate. The crude product is purified by silica gel flash chroma-
tography (eluent, hexane:ether 25:1) and then recrystallized
166.75, 157.98, 157.24, 157.06, 155.38, 154.49, 150.87, 150.70,
150.54, 149.48, 146.78, 136.97, 136.31, 136.17, 135.65, 134.59,
134.50, 132.28, 132.07, 131.96, 131.61, 130.63, 127.46, 126.87,
126.79, 126.62, 126.60, 124.58, 123.89, 123.63, 123.49, 123.46,
123.41, 123.26, 122.30, 119.59, 114.44, 104.65, 96.83, 93,80,
91.26, 90.62, 87.44, -0.76. ES-MS: 864.4 (M - PF6-). HRMS
calcd for RuC52N5SiH40 (M - PF6-): 864.20965. Found:
864.21120.
Com p lex 9: 93% yield from 8. 1H NMR (400 MHz, CD3CN)
δ: 8.48 (d, J ) 8.0 Hz, 1H), 8.40 (d, J ) 8.0 Hz, 1H), 8.33-
8.37 (m, 2H), 8.11 (d, J ) 8 Hz, 1H), 8.07 (dd, J 1 ) 6 Hz, J 2
1.2 Hz, 1H), 8.03 (d, J ) 1.6 Hz, 1H), 8.01 (td, J 1 ) 8 Hz, J 2
)
)
1.6 Hz, 1H), 7.82-7.89 (m, 3H), 7.80 (d, J ) 6 Hz, 1H), 7.73-
7.78 (m, 3H), 7.63 (d, J ) 6 Hz, 1H), 7.43-7.57 (m, 13H), 7.22-
7.28 (m, 3H), 7.00 (pseudo td, J 1 ) 5.6 Hz, J 2 ) 1.6 Hz, 1H),
6.98 (dd, J 1 ) 8 Hz, J 2 ) 1.6 Hz, 1H), 6.56 (d, J ) 8 Hz, 1H),
0.26 (s, 9H). 13C NMR (400 MHz, CD3CN) δ: 199.49, 166.81,
158.02, 157.29, 157.10, 155.42, 154.49, 150.85, 150.70, 150.53,
149.47, 146.79, 136.96, 136.30, 136.17, 135.64, 134.58, 134.49,
132.27, 132.09, 132.06, 132.03, 131.99, 131.62, 130.65, 127.44,
126.84, 126.76, 126.60, 124.62, 123.87, 123.62, 123.55, 123.52,
123.47, 123.44, 123.30, 123.22, 122.36, 119.59, 114.51, 104.67,
96.89, 93.81, 91.33, 91.07, 90.97, 90.76, 87.47, - 0.77. ES-
MS: 964.2 (M - PF6-). HRMS calcd for RuC60N5SiH44 (M -
PF6-): 964.24095. Found: 964.24143.
Com p lex 10: 56% yield from complex 7. 1H NMR (250 MHz,
CD3CN) δ: 8.46 (d, J ) 8.20 Hz, 1H), 8.38 (d, J ) 8.20 Hz),
8.32 (dd, J ) 3.4 Hz, 7.7 Hz, 2H), 8.03 (m, 4H), 7.79 (m, 7H),
7.49 (m, 10 H), 7.23 (m, 4H), 6.96 (m, 2H), 6.53 (d, J ) 7.7 Hz,
1H), 2.41 (s, 3H).13C NMR (250 MHz, CD3CN) δ: 200.17,
194.27, 167.17, 158.43, 157.69, 157.50, 155.82, 154.91, 151.38,
151.16, 151.01, 149.97, 147.24, 137.46, 136.79, 136.64, 136.12,
135.52, 135.07, 135.00, 132.87, 132.61, 132.12, 131.11, 129.81,
127.94, 127.38, 127.27, 127.12, 125.07, 124.73, 124.35, 123.94,
123.76, 122.68, 120.07, 114.84, 94.31, 91.26, 90.84, 87.90,
30.49. FAB-MS: 842(M - PF6-). HRMS calcd for RuC49N5-
SOH34 (M - PF6-): 842.15276. Found: 842.15384.
1
in pentane to provide 1.58 g of a white solid. Yield: 62%. H
NMR (250 MHz, CDCl3 ) δ: 7.73 (d, J ) 8.6 Hz, 2H), 7.12 (d,
J ) 8.6 Hz, 2H), 2.42 (s, 3H). MS (CI, NH3) m/z: 279.0 (M +
H+), 296.0 (M + NH4+), 313.0 (M + N2H7+).
Gen er a l P r oced u r e for th e Dep r otection of th e Tr im -
eth ylsilyl Gr ou p (7-9). To a solution of 0.2 mmol of the
silylated complex either in methanol (12 mL) (7) or in a 1:1
dichloromethane:methanol mixture (6 mL/6 mL) (8 and 9) is
added 270 mg (2.0 mmol, 10 equiv) of potassium carbonate.
The solution is stirred at room temperature for 2 h under
argon. After evaporation of the solvents, the excess potassium
carbonate is eliminated by filtration in dichloromethane. The
crude product is not purified.
Gen er a l P r oced u r e for Son oga sh ir a Cr oss-Cou p lin g
(7-9). To 2 mL of a DMF solution containing the deprotected
alkyne (typically 0.2 mmol) are added the required p-iodo
derivative 2 or 4 (2 equiv), Pd(PPh3)4 (0.05 equiv), CuI (0.1
equiv), and 1 mL of distilled diisopropylamine. The solution
is stirred at room temperature under argon for 10 h. After
evaporation of the solvents, the crude product is purified by
silica gel chromatography (eluent, dichloromethane:acetonitrile
98:2).
Com p lex 11: 50% yield from complex 8. 1H NMR (250 MHz,
DMF-d7) δ: 8.88 (d, J ) 8.2 Hz, 1H), 8.80 (d, J ) 8.2 Hz, 1H),
8.74 (m, 2H), 8.39 (d, J ) 8.2 Hz, 1H), 8.17 (m, 3H), 7.89 (m,
4H), 7.65 (m, 16H), 7.46 (m, 4H), 7.16 (m, 1H), 7.02 (dd, J )
1.6 Hz, J ) 7.8 Hz, 1H), 6.60 (d, J ) 7.6 Hz, 1H), 2.49 (s, 3H).
1H NMR (250 MHz, DMSO-d6) δ: 8.77 (d, J ) 8.2 Hz, 1H),
8.69 (d, J ) 8.2 Hz, 1H), 8.63 (dd, J ) 3.3 Hz, J ) 8.2 Hz, 2H),
8.29 (d, J ) 8.7 Hz, 1H), 8.09 (m, 2H), 7.77 (m, 3H), 7.58 (m,
18 H), 7.39 (m, 4H), 7.10 (m, 1H), 6.94 (dd, J ) 1.2 Hz, J )
7.6 Hz, 1H), 6.46 (d, J ) 7.6 Hz, 1H) 2.45 (s, 3H). 13C NMR
(250 MHz, DMF-d7) δ: 200.36, 193.46, 167.07, 158.38, 157.67,
157.42, 155.74, 154.70, 151.13, 150.96, 150,88, 149.78, 147.16,
137.48, 136.77, 136.26, 135.25, 135.10, 134.98, 132.82, 132.53,
132.44, 132.01, 130.90, 129.88, 129.47, 128.09, 127.46, 127.28,
127.15, 127.09, 124.93, 124.53, 124.21, 124.05, 123.80, 123.43,
122.46, 120.11, 114.51, 84.53, 91.88, 91.25, 91.06, 87.84. ES-
MS: 942.3 (M - PF6-). HRMS calcd for RuC57N5SOH38 (M -
PF6-): 942.18406. Found: 942.18340.
Com p lex 12: 52% yield from complex 9. 1H NMR (250 MHz,
DMF-d7) δ: 8.88 (d, J ) 8.4 Hz, 1H), 8.80 (d, J ) 8.4 Hz, 1H),
8.74 (m, 2H), 8.39 (d, J ) 8.1 Hz, 1H), 8.17 (m, 3H), 7.89 (m,
4H), 7.65 (m, 20H), 7.45 (m, 4H), 7.16 (m, 1H), 7.02 (dd, J )
1.4 Hz, J ) 7.7 Hz, 1H), 6.59 (d, J ) 7.7 Hz, 1H), 2.49 (s, 3H).
1H NMR (250 MHz, DMSO-d6) δ: 8.76 (d, J ) 8.5 Hz, 1H),
8.68 (d, J ) 8.5 Hz, 1H), 8.63 (dd, J ) 3.0 Hz, J ) 8.5 Hz, 2H),
8.29 (d, J ) 8.5 Hz, 1H), 8.10 (m, 2H), 7.77 (m, 3H), 7.59 (m,
22 H), 7.38 (m, 4H), 7.09 (m, 1H), 6.93 (d, J ) 8.5 Hz, 1H),
6.46 (d, J ) 7.6 Hz, 1H).13C NMR (250 MHz, DMF-d7) δ:
200.36, 193.45, 167.07, 158.38, 157.67, 157.41, 155.73, 154.70,
151.12, 150.95, 150.88, 149.81, 147.16, 137.48, 136.77, 136.26,
136.17, 135.25, 135.11, 134.98, 133.85, 132.82, 132.50, 132.01,
130.90, 129.88, 128.09, 127.47, 127.28, 127.14, 127.09, 124.93,
124.52, 124.21, 124.05, 123.80, 123.71, 123.61, 123.56, 123.49,
122.46, 120.11, 114.51, 94.53, 94.44, 91.87, 91.61, 91.24, 91.07,
Gen er a l P r oced u r e for Son oga sh ir a Cr oss-Cou p lin g
(10-12). To 3 mL of a 2:1 mixture of DMF:THF containing
the deprotected alkyne (typically 0.2 mmol) are added the
S-protected derivative 5 (2 equiv), Pd(PPh3)2Cl2 (0.05 equiv),
CuI (0.1 equiv), and 1 mL of distilled diisopropylethylamine
(Hunig’s base). The solution is stirred at room temperature
under argon for 12 h. After evaporation of the solvents, the
crude product is purified by silica gel chromatography (eluent,
dichloromethane:acetonitrile 98:2).
Com p lex 7: 87% yield from 7. 1H NMR (400 MHz, CD3-
CN) δ: 8.48 (d, J ) 8.0 Hz, 1H), 8.40 (d, J ) 8.0 Hz, 1H), 8.33-
8.37 (m, 2H), 8.10 (d, J ) 8.4 Hz, 1H), 8.06 (dd, J 1 ) 4.8 Hz,
J 2 ) 1.2 Hz, 1H), 8.02 (d, J ) 1.6 Hz, 1H), 8.01 (td, J 1 ) 6 Hz,
J 2 ) 1.6 Hz, 1H), 7.81-7.89 (m, 3H), 7.79 (d, J ) 6 Hz, 1H),
7.73-7.77 (m, 3H), 7.63 (d, J ) 5.6 Hz, 1H), 7.43-7.47 (m,
5H), 7.22-7.28 (m, 3H), 7.00 (pseudo td, J 1 ) 5.6 Hz, J 2 ) 1.6
Hz, 1H), 6.98 (dd, J 1 ) 8 Hz, J 2 ) 1.6 Hz, 1H), 6.56 (d, J ) 8
Hz, 1H), 0.26 (s, 9H). 13C NMR (400 MHz, CD3CN) δ: 199.43,
166.80, 158.02, 157.29, 157.10, 155.42, 154.49, 150.85, 150.70,
150.53, 149.46, 146.78, 136.95, 136.29, 136.15, 135.63, 134.57,
134.48, 132.22, 131.51, 130.63, 127.44, 126.84, 126.75, 126.59,
124.60, 123.87, 123.61, 123.47, 123.44, 123.21, 122.52, 119.57,
114.49, 104.89, 96.37, 93.69, 87.31, 62.71, -0.75. ES-MS: 764.1
(M - PF6-). HRMS calcd for RuC44N5SiH36 (M - PF6-):
764.17835. Found: 764.17881.
Com p lex 8: 92% yield from 6. 1H NMR (400 MHz, CD3CN)
δ: 8.48 (d, J ) 8.0 Hz, 1H), 8.40 (d, J ) 8.0 Hz, 1H), 8.33-
8.37 (m, 2H), 8.10 (d, J ) 8 Hz, 1H), 8.06 (dd, J 1 ) 5.6 Hz, J 2
) 1.6 Hz, 1H), 8.03 (d, J ) 1.6 Hz, 1H), 8.01 (td, J 1 ) 8 Hz, J 2
) 1.6 Hz, 1H), 7.81-7.89 (m, 3H), 7.79 (d, J ) 5.6 Hz, 1H),
7.73-7.78 (m, 3H), 7.63 (d, J ) 5.6 Hz, 1H), 7.43-7.57 (m,
9H), 7.22-7.28 (m, 3H), 7.00 (pseudo td, J 1 ) 5.6 Hz, J 2 ) 1.6
Hz, 1H), 6.98 (dd, J 1 ) 8 Hz, J 2 ) 1.6 Hz, 1H), 6.56 (d, J ) 8
Hz, 1H), 0.26 (s, 9H). 13C NMR (400 MHz, CD3CN) δ: 199.59,
J . Org. Chem, Vol. 68, No. 6, 2003 2173