A. Maercker et al. / Journal of Organometallic Chemistry 566 (1998) 143–149
147
(m.p. 128–130°C): MS (70 eV): m/z 194 (100), 181 (21),
1H-NMR (80 MHz, CDCl3): l 2.38 (s, 3 H, methyl),
179 (33), 178 (16), 167 (17), 165 (21), 129 (19), 105 (20),
103 (18), 91 (20). H-NMR (200 MHz, CDCl3): l 1.82
7.25 (m, 10 H, aromatic H).
1
(s, 6 H, methyl), 5.82 (s, 2 H, vinyl), 7.24 (m, 20 H,
aromatic H). 13C-NMR (50 MHz, CDCl3): l 28.1, 49.3,
125.8, 127.8, 127.9, 137.5, 148.6. –C30H28 (388.56):
calcd. C 92.74, H 7.26; found: C 92.60; H 7.31.
2.7. Reaction of 1,1-dibromo-2,2-diphenylethene (5)
with t-butyllithium and warming to −10°C
A sample of 3.38 g (10 mmol) 1,1-dibromo-2,2-
diphenylethene (5) were treated with 30 ml (45 mmol)
of a 1.5 M solution of t-butyllithium in pentane, as
described above. The solution was allowed to warm to
−10°C over a period of 2 h. Then the solution was
cooled down to −70°C, quenched with dimethyl sul-
phate, and the work-up was performed as usual. The
following products were detected by gas chromato-
graphic investigation: 170 mg (0.9 mmol) of 1,1-
diphenyl-1-propene (7) and 780 mg (3.5 mmol) of
(Z)-4,4-dimethyl-2,3-diphenyl-2-pentene (23).
2.5. Con6ersion of (E)-1-lithio-2-(2-lithiophenyl)-2-
phenylethene (13) into the (Z)-compound 15
The crude (E)-compound 13 was prepared from 3.4 g
(10 mmol) 1,1-dibromo-2,2-diphenylethene (5) and 0.7 g
(100 mmol) lithium dust as described above. The excess
of lithium was filtered off and the resulting solution
stirred for 2 h at −25°C. After quenching with
dimethyl sulphate and usual work-up, the resulting
slurry was recondensed in a cooled trap. In the volatile
part 5 mg (0.03 mmol) 1,1-diphenylethene (6), 5 mg
See above for spectroscopical data of 1,1-diphenyl-1-
propene (7), see next experiment for spectroscopical
data of (Z)-4,4-dimethyl-2,3-diphenyl-2-pentene (23).
(0.03 mmol)
1,1-diphenyl-1-propene
(7),
5 mg
(0.03 mmol) (E)-1-(2-methylphenyl)-1-phenyl-1-propene
(9), and 455 mg (2.2 mmol) (Z)-1-(2-methylphenyl)-1-
phenyl-1-propene (10) are obtained.
2.8. Confirming the formation of (Z)-4,4-dimethyl-2,3-
diphenyl-2-pentene (23)
A solution of 1.78 g (10 mmol) of tolane (22) in 50 ml
of THF was treated at −70°C over 30 min with 30 ml
(45 mmol) of a 1.5 M solution of t-butyllithium in
pentane. After stirring for an additional 30 min the
solution was quenched with dimethyl sulphate and
worked-up as usual. Yield: 1.35 g (5.4 mmol) (Z)-4,4-
dimethyl-2,3-diphenyl-2-pentene (23) m.p. 50.5–51°C.
MS (70 eV): m/z 250 (M+, 32), 178 (30), 157 (68), 145
(34), 115 (99), 105 (52), 91 (100), 51 (31), 41 (53), 39
(28). –C19H22 (250.38): calcd. C 91.14, H 8.86; found: C
91.32; H 8.88. 1H-NMR (80 MHz, CDCl3): (1.28 (s,
9 H, t-butyl), 2.28 (s, 3 H, methyl), 6.90 (m, 5 H,
aromatic H). The (Z)-structure was confirmed by NOE-
difference spectroscopy (t-butyl/methyl).
2.6. Reaction of 1,1-dibromo-2,2-diphenylethene (5)
with t-butyl lithium at −90°C
A solution of 3.38 g (10 mmol) of 1,1-dibromo-2,2-
diphenylethene (5) in 30 ml of THF was treated at
−90°C and over 15 min with 30 ml (45 mmol) of a
1.5 M solution of t-butyllithium in pentane. The stir-
ring was continued for an additional 30 min and then
the solution was allowed to warm up to −70°C. At
this temperature the mixture was quenched with a
solution of 5 ml (53 mmol) dimethyl sulphate in 10 ml
THF. The excess of dimethyl sulphate was destroyed by
stirring with aqueous ammonia at r.t. The organic layer
was separated, washed with 2 M hydrochloric acid,
saturated sodium hydrogencarbonate solution, and
brine. After drying over magnesium sulphate and re-
moving the solvent, the residue was recondensed in a
cooled trap. The following products were found by gas
chromatographical investigation: 56 mg (0.3 mmol) of
1,1-diphenyl-1-propene (7), 141 mg (0.9 mmol) of 1,1-
diphenyl-2-methyl-1-propene (8), 382 mg (2.2 mmol) of
tolane (22), and 870 mg (3.2 mmol) of 2-bromo-1,1-
diphenyl-1-propene (21).
2.9. Reaction of 1,1-diphenyl-2,2-bis(trimethylstannyl)-
ethene (24) with n-butyllithium
A solution of 2.53 g (5 mmol) of 1,1-diphenyl-2,2-
bis(trimethylstannyl)ethene (24) [19] in 20 ml of THF
was treated at −90° with 40 ml (65 mmol) of a 1.6 M
solution of n-butyllithium in hexane. After warming up
to −55°C, the stirring was continued for 24 h. The
solution was again cooled to −70°C. At this tempera-
ture the mixture was quenched with a solution of 10 ml
(105 mmol) of dimethyl sulphate in 20 ml of THF. The
excess of dimethyl sulphate was destroyed by stirring
with aqueous ammonia at ambient temperature. The
organic layer was separated, washed with 2 N hy-
drochloric acid, saturated sodium hydrogencarbonate
solution, and brine. After drying over magnesium sul-
See above for spectroscopical data of 1,1-diphenyl-1-
propene (7) and 1,1-diphenyl-2-methyl-1-propene (8).
Tolane (22) [17]: MS (70 eV): m/z 179 (15), 178 (M+,
100), 177 (11), 176 (22), 152 (18), 151 (12), 89 (12), 76
(16), 51 (14), 50 (14).
2-Bromo-1,1-diphenyl-1-propene (21) [18]: MS
(70 eV): m/z 274 (18) 272 (M+, 18), 193 (11), 178 (25),
165 (16), 115 (100), 91 (23), 51 (28), 50 (14), 39 (14).