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4.2. Preparation of 2-chloro-1-(n-N,N-dimethylamino-
phenyl)ethenes (1–3). General procedure
Isomer E-3. IR (KBr, cmK1): 2810, 1600, 1360, 960, 830.
1H NMR (CDCl3): d 7.17–6.66 (m, 4H), 6.73 (d, 1H,
JZ13.7 Hz), 6.42 (d, 1H, JZ13.7 Hz), 2.96 (s, 6H). EM
(70 eV): 181 (MC, 75), 180 (100), 165 (25), 144 (12), 130
(4). C10H12NCl (181.66). Anal. Calcd: C 66.12, H 6.66, N
7.71. Found: C 66.35, H 6.41, N 7.50.
A solution of n-butyllithium 1.6 M in hexane (90 mL,
144 mmol) was slowly added to a suspension of chloro-
methylen(triphenyl)phosphonium ylide (38 g, 109 mmol) in
210 mL of dry THF, under argon atmosphere at 0 8C. The
mixture was stirred for 30 min until an intense red colour,
and then n-N,N-dimethylaminobenzene carboxaldehyde
(11 g, 73 mmol) was added with stirring at room tempe-
rature overnight. After, the solvent was evaporated to leave
a brown oil, that was purified by silica gel column
chromatography, to give the 2-chloroethenyl derivative.
4.3. Homocoupling reactions with tris(triphenylphos-
phine)nickel prepared from dichlorobis(triphenylphos-
phine)nickel. General procedure
To a suspension of dichlorobis(triphenylphosphine) nickel
(719 mg, 1.1 mmol), tetrabutylammonium iodide (407 mg,
1.1 mmol) and powdered zinc (107 mg, 1.65 mmol) in 5 mL
of dry THF, under argon atmosphere, was stirred for 30 min
until the mixture becomes dark red. Then a solution of the
chloroethenyl derivative 1–3 (200 mg, 1.1 mmol) in 2 mL
of dry THF was added and stirred at room temperature for
24 h. Then, hexane was added to the mixture, filtered and
the solvent removed. The crude product was purified by
chromatography on a silica gel column, using dichloro-
methane as the eluent.
4.2.1. 2-Chloro-1-(o-N,N-dimethylaminophenyl)ethene
(1). Toluene was used as the eluent, giving both isomers
as a yellow oil, 12.68 g (Z/E, 3:2). The Z and E isomers were
isolated using hexane–toluene (2/1): (Z)-1, 7.66 g (60%) as
a pale-yellow oil; (E)-1, 5.02 g (40%) as a pale-yellow oil.
1
Isomer (Z)-1. IR (film, cmK1): 2800, 1600, 740, 660. H
NMR (CDCl3): d 7.84–7.80 (m, 1H), 7.24–7.13 (m, 1H),
7.06–6.90 (m, 2H), 6.85 (d, 1H, JZ7.9 Hz), 6.28 (d, 1H,
JZ7.9 Hz, 1H), 2.70 (s, 6H). EM (70 eV): 181 (MC, 14), 166
(2), 146 (72), 131 (100). C10H12NCl (181.66). Anal. Calcd: C
66.12, H 6.66, N 7.71. Found: C 65.97, H 6.55, N 7.65.
4.3.1. 1,4-Di(o-N,N-dimethylaminophenyl)-1,3-buta-
diene (4). Following the general method, three isomers
were separated as yellow oils: (1Z,3Z)-1,4-di(o-N,N-
dimethylaminophenyl)-1,3-butadiene (4a), 35 mg (22%);
(1Z,3E)-1,4-di(o-N,N-dimethylaminophenyl)-1,3-butadiene
(4b), 70 mg (40%); (1E,3E)-1,4-di(o-N,N-dimethylamino-
phenyl)-1,3-butadiene (4c), 55 mg (34%).
1
Isomer (E)-1. IR (film, cmK1): 2800, 1600, 960, 740. H
NMR (CDCl3): d 7.33–7.18 (m, 2H), 7.12 (d, 1H,
JZ13.7 Hz), 7.07–6.93 (m, 2H), 6.62 (d, 1H, JZ
13.7 Hz), 2.73 (s, 6H). EM (70 eV): 181 (MC, 6), 166
(10), 146 (88), 131 (100). C10H12NCl (181.66). Anal. Calcd:
C 66.12, H 6.66, N 7.71. Found: C 66.06, H 6.37, N 7.54.
(1Z,3Z)-1,4-Di(o-N,N-dimethylaminophenyl)-1,3-butadiene
(4a). IR (film, cmK1): 2800, 1600, 1500, 770, 700. 1H NMR
(CDCl3): d 7.56–7.52 (m, 2H), 7.26–7.17 (m, 2H), 7.07–
6.99 (m, 4H), 6.70–6.52 (m, 4H), 2.81 (s, 12H). EM
(70 eV): 292 (MC, 100), 277 (12), 248 (14), 233 (3), 172
(24), 158 (29), 145 (48). C20H24N2 (292.42). Anal. Calcd: C
82.15, H 8.27, N 9.58. Found: C 82.01, H 8.42, N 9.62.
4.2.2. 2-Chloro-1-(m-N,N-dimethylaminophenyl)ethene
(2). Toluene was used as the eluent, giving the mixture of
both isomers as a yellow oil, 10.83 g (Z/E, 2:3, 82%).
Mixture (Z/E)-2. IR (film, cmK1): 2790, 1590, 990, 840,
760, 710, 690. 1H NMR (CDCl3): 7.24 (dd, 1H, JZ7.8 Hz,
Z), 7.17 (dd, 1H, JZ7.8 Hz, E), 7.09–7.07 (m, 1H, Z), 7.03–
6.99 (m, 1H, Z), 6.80 (d, 1H, JZ13.6 Hz, E), 6.73–6.65 (m,
4H, Z/E), 6.61 (d, 1H, JZ13.6 Hz, 1H, E), 6.22 (d, 1H, JZ
8.2 Hz, Z), 6.22 (d, 1H, JZ8.2 Hz, Z), 2.95 (s, 6H, Z), 2.94
(s, 6H, E). EM (70 eV): 181 (MC, 72), 180 (100), 165 (8),
144 (6), 130 (6). C10H12NCl (181.66). Anal. Calcd: C 66.12,
H 6.66, N 7.71. Found: C 65.78, H 6.74, N 7.46.
(1Z,3E)-1,4-Di(o-N,N-dimethylaminophenyl)-1,3-butadiene
(4b). IR (film, cmK1): 2800, 1600, 1500, 960, 770, 700. 1H
NMR (CDCl3): d 7.73–7.64 (m, 2H), 7.55–7.42 (m, 2H),
6.94–6.73 (m, 4H), 6.63–6.45 (m, 4H), 2.78 (s, 12H). EM
(70 eV): 292 (MC, 100), 277 (18), 248 (9), 233 (10), 172
(13), 158 (41), 145 (58). C20H24N2 (292.42). Anal. Calcd: C
82.15, H 8.27, N 9.58. Found: C 82.41, H 8.30, N 9.42.
(1E,3E)-1,4-Di(o-N,N-dimethylaminophenyl)-1,3-buta-
diene (4c). UV–vis (CH2Cl2), lmax (nm): 377 (3, 49,500).
Fluorescence (CH2Cl2), lmax (nm): 465 (fZ0.25). IR (film,
4.2.3. 2-Chloro-1-(p-N,N-dimethylaminophenyl)ethene
(3). Hexane–toluene (1/1) was used as the eluent, recovering
two fractions containing the mixture of both isomers as
yellow oils: (5.40 g, Z/E, 1:1, 40.9% and; 5.22 g, Z/E,
4:1, 39.5%). The E and Z isomer were isolated from the Z–E
(1/1) mixture toluene as eluent, giving (E)-3, 2.70 g as
a yellow oil, and (Z)-3, 2.29 g as a pale-yellow solid,
mp 37–39 8C.
1
cmK1): 2800, 1600, 1500, 960, 770. H NMR (CDCl3): d
7.49 (dd, 2H, JZ8.0, 2.0 Hz), 7.28–7.20 (m, 2H), 7.05–6.97
(m, 4H), 6.70–6.52 (m, 4H), 2.72 (s, 12H). EM (70 eV): 292
(MC, 100), 277 (12), 248 (15), 233 (9), 172 (25), 158 (45),
145 (41). C20H24N2 (292.42). Anal. Calcd: C 82.15, H 8.27,
N 9.58. Found: C 82.38, H 8.02, N 9.34.
Isomer Z-3. IR (film, cmK1): 2810, 1600, 1360, 830, 700. 1H
NMR (CDCl3): d 7.63–6.69 (m, 4H), 6.50 (d, 1H,
JZ8.1 Hz), 6.04 (d, 1H, JZ8.1 Hz), 2.99 (s, 6H). EM
(70 eV): 181 (MC, 92), 180 (100), 165 (18), 144 (9), 130
(8). C10H12NCl (181.66). Anal. Calcd: C 66.12, H 6.66, N
7.71. Found: C 66.22, H 6.57, N 7.63.
4.3.2. 1,4-Di(m-N,N-dimethylaminophenyl)-1,3-buta-
diene (5). Following the general method, were separated
two isomers: (1Z,3E)-1,4-di(m-N,N-dimethylaminophenyl)-
1,3-butadiene (5b) as an oil 69 mg (43%); (1E,3E)-1,4-
di(m-N,N-dimethylaminophenyl)-1,3-butadiene (5c), as an
oil 73 mg (45%).