Efficient mono- and dilithiation of 2-bromo-1,1-diphenylethene with n-butyllithium/tetramethylethylenediamine

Article abstract of DOI:10.1055/s-2002-20963

Lithiation of 2-bromo-1,1-diphenylethene (2) with n-butyllithium or tert-butyllithium/tetramethylethylenediamine (TMEDA) in pentane at -100°C effects a halogen-lithium exchange to give 2-lithio-1,1-diphenylethene (3) exclusively, which reacts with electrophiles to provide 2-substituted-1,1-diphenylethenes 5-8 in high yields. Further lithiation of the monolithium derivative 3 with n-butyllithium/TMEDA results in the direct ortho-lithiation of Z-located phenyl ring to give dilithium derivative 9, which forms disubstituted ethenes 11-13 or heterocycles 15-17 on treatment with electrophiles, tert-Butyllithium/TMEDA is ineffective for the second lithiation step.

Full text of DOI:10.1055/s-2002-20963

PAPER
491
Efficient Mono- and Dilithiation of 2-Bromo-1,1-diphenylethene with
n-Butyllithium/Tetramethylethylenediamine
Efficient
M
ono
e
-
and
D
ilit
r
hiation
o
g
f
2-Bromo-
1
e
,1,diphenyl
i
ethene M. Korneev,*a,1 Dieter E. Kaufmannb
a
Institute of Chemistry, St. Petersburg State University, University Pr.2, 198504 St. Petersburg, Russia
E-mail: sergei.korneev@gmx.de
b
Institute of Organic Chemistry, Technical University of Clausthal, Leibnizstr.6, 38678 Clausthal-Zellerfeld, Germany
Received 10 September 2001; revised 2 January 2002
The second possibility is halogen–metal exchange
(Scheme 1, route b) to give the vinyllithium C.5,11,12 This
way is more distinctive for bromo- and iodo-derivatives
(X = Br, I) and provides a versatile synthetic tool for the
Abstract: Lithiation of 2-bromo-1,1-diphenylethene (2) with n-bu-
tyllithium or tert-butyllithium/tetramethylethylenediamine (TME-
DA) in pentane at –100 °C effects a halogen–lithium exchange to
give 2-lithio-1,1-diphenylethene (3) exclusively, which reacts with
electrophiles to provide 2-substituted-1,1-diphenylethenes 5–8 in preparation of 2-substituted 1,1-diarylethene D. Unfortu-
high yields. Further lithiation of the monolithium derivative 3 with
n-butyllithium/TMEDA results in the direct ortho-lithiation of Z-lo-
cated phenyl ring to give dilithium derivative 9, which forms disub-
stituted ethenes 11–13 or heterocycles 15–17 on treatment with
nately, this halogen-metal exchange is accompanied usu-
ally by the formation of acetylenes that reduce the
synthetic scope of the reaction.12,13
We wish to report here improved conditions for selective
and efficient halogen–lithium exchange in 2-bromo-1,1-
diphenylethene (2) in the presence of TMEDA, which re-
sult in the formation of 1,1-diphenylethylene derivatives
on treatment of the intermediate vinyllithium compound 3
with electrophiles. Alternatively, the vinyllithium com-
pound 3 can undergo further lithiation of the phenyl ring.
electrophiles. tert-Butyllithium/TMEDA is ineffective for the sec-
ond lithiation step.
Key words: halides, lithiation, organometallic reagents, complex-
es, regioselectivity
Two different reaction pathways are known for the lithia-
tion of 2-halo-1,1-diphenylethenes.2,3 The first path in-
cludes proton removal (Scheme 1, route a) under the
action of a strong base with the formation of 1-halo-1-
lithioethene A. In the case of the chloro derivative
(X = Cl) this intermediate is sufficiently stable at low tem-
perature (–100 to –85 °C) to react with electrophiles, like
CO2 or Br2, resulting in the formation of 1-substituted 1-
halo-2,2-diphenylethenes in moderate yields.4–6 At higher
temperature or in the cases of bromo and iodo derivatives
(X = Br, I), which are significantly more reactive, A
readily rearranges into diarylacetylene B.5–9 This classical
example of the anionic rearrangement was discovered in
189410 and recognised as a very suitable way for the syn-
thesis of diarylacetylenes.7,8
Lithiation of 2-bromo-1,1-diphenylethene (2) with 3
equivalents of n-BuLi or t-BuLi in pentane in the presence
of 3 equivalents of TMEDA results in complete halogen-
lithium exchange at –100 °C already within 20 minutes
(Scheme 2). Product distribution at different temperatures
were investigated by treatment of the reaction mixture
with iodine (Table 1). At –100 °C the iodide 5 together
with a small amount of ethene 1 were identified as the
only products along with traces of the starting bromide 2
(<2%). When the reaction was allowed to warm to 0 °C
during 1 h, further deactivation of the lithium derivative 3
to ethene 1 was observed. No rearranged tolane 4 was de-
tected not only after instant warming up, but also on keep-
ing the reaction mixture at 20 °C during 10 hours.
TMEDA is of great importance for this reaction since only
5% of bromide 2 underwent Br–Li exchange to form lith-
ium derivative 3 and 95% of the starting bromide 2 were
recovered in the absence of TMEDA. On the one hand,
TMEDA accelerates Br–Li exchange in bromoethene 2,
and on the other hand it stabilises the intermediate vinyl-
lithium compound 3 in a form of a complex up to room
temperature and prevents its deactivation to ethene 1.
Ar
Ar
Li
X
route a
Ar
Ar
Ar
Ar
H
X
A
C
B
D
base
Ar
Ar
H
Y
Ar
Ar
H
route b
Li
Since the yield of the lithium derivative 3 under original
conditions was nearly quantitative, it was of interest to ex-
amine its reaction with various electrophiles. The lithium
derivative 3 was readily converted into substituted
ethenes 5–8 in high yields (93–96%) by treatment with io-
dine, methanol-d4, deuterium oxide, dimethyl sulfate or
chlorotrimethylsilane, respectively (Table 2). Products
were identified by MS, NMR and IR spectra and by com-
parison with the data reported in the literature.
Scheme 1 X = Cl, Br, I.
Synthesis 2002, No. 4, 15 03 2002. Article Identifier:
1437-210X,E;2002,0,04,0491,0496,ftx,en;T08801SS.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881

492
S. M. Korneev, D. E. Kaufmann
PAPER
In principle, only 2 equivalents14 of n-BuLi are required
for the successful Br–Li exchange under the same condi-
tions, and only traces of the rearranged tolane 4 (<1%)
were detected in the reaction mixture by GC in this case.
Diethyl ether increases deactivation of the lithium deriva-
tive 3 resulting in the formation of 5–10% of ethene 1
when used as a co-solvent to pentane (Table 1).
Ph
Ph
Ph
Ph
4
a
Br
Ph
Ph
* TMEDA
2
Li
3
It is interesting, that further metalation of the lithium de-
rivative 3 in the ortho-position of the Z-located phenyl
ring took place at temperatures higher than 0 °C when 3
equivalents of n-BuLi/TMEDA were used. The reaction
was monitored by treatment with iodine, as before
(Scheme 3, Table 1). More than 90% of vinyllithium 3
turned to the dilithium derivative 9 after 4 hours stirring at
20 °C. Further keeping of the reaction mixture at this tem-
perature or under reflux caused deactivation of 9 with the
formation of the vinyllithium derivative 3 and ethene 1.
No rearranged tolane 4 was detected also in this case by
GC and 13C NMR analysis.
b
Ph
Ph
Ph
+
X
Ph
1
5 - 8 (93-96%)
X =
I
D
Me SiMe3
________________________
5
6
7
8
Scheme 2 Reagents and conditions: a) n-BuLi (3 equiv) or t-BuLi
(3 equiv), TMEDA (3 equiv), pentane, –100 °C, 20 min; b) electro-
phile, –90 °C.
Ph
Ph
Table 1 Reaction Conditions and Products Distribution from the
Lithiation of 2 Followed by I2-Quencha
b
I
Li
* 2 TMEDA
I
Li
Base/Reaction
Conditions
Products
9
11 (90%)
2
5
11
1
4
a
n-BuLi
c
Ph
Ph
Ph
Ph
d
3
–100 °C
<2 (<2) 89 (95)
– (–)
5 (–)
11 (<1)
11 (4)
7 (3)
– (–)
Sn
e
f
–25 °C
– (–)
– (–)
– (–)
– (–)
– (–)
– (–)
95b
84 (95)
70 (95)
57 (17)
7 (6)
– (–)
– (–)
– (–)
10 (52%)
1
0 °C
20 (–)
35 (78)
81 (90)
70 (91)
20 (92)
–
Scheme 3 Reagents and conditions: a) n-BuLi, TMEDA, pentane,
20 °C; b) I2, –100 °C; c) n-BuLi, TMEDA, THF, 20 °C; d) Me2SnCl2,
THF, –100 °C; e) t-BuLi, TMEDA, pentane, 20 °C; f) Al2O3, chroma-
tography, 100%.
20 °C, 0.5 h
20 °C, 4 h
20 °C, 10 h
Reflux, 2 h
20 °C, 10 h
t-BuLi
4 (<1)
<1 (<1) – (–)
12 (5)
25 (3)
4
6 (<1)
34 (<1)
–
– (–)
– (<1)
–
Unexpectedly t-BuLi/TMEDA was ineffective for further
metalation of 3 to 9, and formation of ethene 1 was the
only process on stirring the reaction mixture at 20 °C over
a 4 h period. Upon refluxing the reaction mixture for 2 h,
the formation of rearranged tolane 4 became essential
(11%), and dilithium derivative 9 was formed only in tra-
ces (<3%) together with the formation of ethene 1 (60%).
The use of THF as alternative to pentane in the reaction
carried out under the standard conditions gave also only
mono vinyllithium 3. Nearly 10% of starting bromide 2
were recovered and traces (5%) of the dilithium derivative
9 in the form of the diiodide 11 were detected together
with iodoethene 5 (65%) when the reaction mixture in
THF was derivatized by iodine. Alternatively bis(2,2-
diphenylethenyl)dimethylstannane (10) (52%) was
formed in the reaction with dichlorodimethylstannane
(DCDMST) (Scheme 3).
–100 °C
<2
–
90
67
57
51
38
16
5
–
–
–
–
–
–
3
10
28
39
43
55
73
60
–
–25 °C
–
0 °C
–
–
20 °C, 0.5 h
20 °C, 4 h
20 °C, 10 h
Reflux, 2 h
–
–
–
–
–
–
–
11
a Ratio n-BuLi or t-BuLi/TMEDA/2 = 3:3:1; solvent: pentane–Et2O
(1:1), in parenthesis for pentane only; reaction mixture was quenched
with I2; analysis of the crude reaction mixture by 1H NMR and GC-
MS; yields are determined by GC.
Dilithium derivative 9 obtained by the action of n-BuLi/
TMEDA on 3 in pentane was treated with methanol-d4
and dimethyl sulfate and the corresponding bis-deriva-
b Reaction without TMEDA.
Synthesis 2002, No. 4, 491–496 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Efficient Mono- and Dilithiation of 2-Bromo-1,1,diphenylethene
493
zothiophene 17 and silaindene 15 were obtained in 84 and
88% yields, respectively. Similarly, treatment of 9 with
dichlorodimethylstannane gave stannaindene 16 in 74%
yield. It is interesting to note that, the treatment of dilithi-
um derivative 9 with chlorotrimethylsilane results in the
formation of cyclic silaindene 15 together with some
amount of mono-substituted ethene 8, and no disilylated
ethene 14 was identified by NMR and GC-MS analysis in
the reaction mixture. Nearly the same cyclization was re-
ported earlier, when the reaction of 2,2 -bislithiobiphenyl
with chlorotrimethylstannane afforded 5,5-dime-
thyldibenzostannole in 34% yield instead of the expected
2,2 -bis(trimethylstannyl)biphenyl.15
Table 2 Reaction of Lithium Derivatives 3 and 9 with Electro-
philes
Product
X
I
Electrophile Yielda (%) Other Products,b (%)
5
I2
93
82c
65d
96
88
93
94
1 (2)
1 (10)
2 (10), 11 (5), 1 (8)
1(5)
6
D
CD3OD
D2O
7
8
Me
DMS
SiMe3
SnMe2
I
CTMS
In conclusion, TMEDA selectively accelerated Br–Li ex-
change in bromoethene 2 resulting in the formation of
mono- and dilithium derivatives 3 and 9 in high yields.
They serve as key intermediates for the facile and conve-
nient preparation of 1-substituted-2,2-diphenylethenes 5–
8 and disubstituted ethenes 11–13 and various heterocyles
15–17 in good yields.
10
11
12
13
14
15
16
17
DCDMST 52d
I2
90
86
86
–
1 (3), 5 (6)
D
CD3OD
DMS
1 (3), 6 (3)
Me
1 (3), 7 (5)
SiMe3
SiMe2
SnMe2
S
CTMS
DCDMS
15 (82),a 8 (9), 1 (3)
All procedures were carried out under N2. Pentane, Et2O, THF and
TMEDA were dried and distilled consecutively over sodium and
NaH under N2. Commercially available dimethyl sulfate (DMS),
chlorotrimethylsilane (CTMS), dichlorodimethylsilane (DCDMS),
dichlorodimethylstannane (DCDMST) and sulfur dichloride (SDC)
were deoxygenated by a slow streem of N2 for 10–15 min before
use. Standard solutions of n-BuLi in hexane (1.6 M) and t-BuLi (1.6
M) in pentane were analysed before use by titration with anhyd
MeOH using 2,2 -bipyridyl as indicator.16 Mixture of EtOH and liq-
88
DCDMST 74c
SDC 84
a Yields of analytically pure products.
b Yields are determined by GC of the reaction mixture.
c Solution of an electrophile in Et2O was used.
d Reaction in THF.
uid N2 was used as a cooling bath (–100 to –105 °C). 1H, 2H and 13
C
NMR spectra were recorded on a Bruker ARX 400 instrument at
400.14, 61.42 and 100.62 MHz respectively, chemical shifts are
given in (ppm). EI mass spectra were determined at 70 eV by us-
ing a HP 5989B spectrometer. IR spectra were recorded on a PYE
UNICAM SP3-200 spectrometer. Analytical TLC was performed
on Kieselgel 60 F 254 and Al2O3 60 F 254 neutral (Type E) plates
(Merck). Al2O3 (Fluka) for chromatography (100–125 mesh, neu-
tral) and silica gel 60 (Merck) for chromatography (63-200 mesh,
neutral) were used as sorbents. Melting points are uncorrected.
tives 12–13 were isolated in a high yields (86%)
(Scheme 4, Table 2). Their structures were confirmed by
spectral evidence and by comparison with the data known
from the literature.
Ph
Ph
2-Bromo-1,1-diphenylethen (2) was synthesised by the reaction of
1,1-diphenylethene (1) with bromine in CCl4.2 The crude product
was dissolved in CH2Cl2, washed with 10% aq NaHCO3 and puri-
fied by two consecutive distillations under N2 in 80% yield as a sol-
id with spectroscopic data identical to those reported in the
literature (IR,17 1H NMR,18 13C NMR19). Bp 100–104 °C/0.1 mbar;
mp 40–41 °C (Lit.2 bp 124–140 °C/1.0 mbar; mp 40–41 °C).
a
X
or
9
X
X
15-17 (74-88%)
12 -13 (86%)
14 (0%)
X = D Me SiMe3 SiMe2 SnMe2
______________________________________
12 13 14 15 16 17
S
2-Lithio-1,1-diphenylethene (3)
A solution of n-BuLi in hexane (1.25 mL, 2 mmol) was added to a
solution of TMEDA (0.3 mL, 2 mmol) in pentane (10 mL) at
–100 °C (internal temp) during 1 min and the reaction mixture was
stirred at –100 °C for 10 min. A solution of the bromide 1 (259 mg,
1 mmol) in pentane (5 mL) was added dropwise at –100 °C over a
3 min period and the mixture was allowed to warm to 0 °C over a
30 min period resulting in the formation of orange-yellow solution
of 3. A solution was again cooled to –90 °C and thus generated sus-
pension of 3 was used for further reactions.
Scheme 4 Reaction conditions: a) electrophile, –100 °C.
The most significant spectral evidence for the ortho-sub-
stitution in the aromatic ring was provided by the 1H NMR
spectrum of diiodide 11 which showed 4 unequal multip-
lets from 4 protons in the ortho-substituted aromatic ring
(experimental part). In order to confirm the lithiation of
the Z-located phenyl ring in 3, compound 9 was treated
with sulfur dichloride and dichlorodimethylsilane. Prod-
ucts with the correct spectral characteristics for ben-
2-Iodo-1,1-diphenylethene (5); General Procedure
Excess of powdered I2 (493 mg, 2 mmol) was added at –90 °C (in-
ternal temp) during 4 min to a stirred suspension of 3 prepared as
above. The reaction was allowed to warm to 20 °C over a 1 h period
Synthesis 2002, No. 4, 491–496 ISSN 0039-7881 © Thieme Stuttgart · New York

494
S. M. Korneev, D. E. Kaufmann
PAPER
and was stirred at this temperature for the next 3 h. The mixture was
treated with 10% aq Na2S2O3 to destroy the excess of I2, the light
yellow organic layer was separated, and the aqueous phase was ex-
tracted with Et2O (3 5 mL). The combined organic phases were
washed with H2O, dried (Na2SO4), concentrated and the crude prod-
uct was purified by column chromatography over silica gel (10 g)
using hexane as eluent (200–500 mL); yield: 284 mg (93%); mp 39–
40 °C (Lit.2 mp 40–41 °C).
temperature for the next 3 h. The reaction mixture was worked up
as described above for 5; yield: 778 mg (90%); oily liquid, which
solidified at –5 to –2 °C to a low-melting mass.
1H NMR (CDCl3): = 7.94 (dd, 1 H, J = 8.1, 1.0 Hz, H-3), 7.45 (m,
1 H, H-5), 7.30–7.22 (m, 5 H, C6H5), 7.20 (dd, 1 H, J = 7.6, 1.5 Hz,
H-6), 7.15 (s, 1 H, =CHI), 7.08 (m, 1 H, H-4).
13C NMR (CDCl3): = 154.3 (Ph2C=), 146.8 (C-1), 139.6 (C-3),
138.6 (C-1 ), 130.3 (C-6), 129.4 (C-4), 128.6 (C-3 ), 128.5 (C-5),
128.3 (C-4 ), 127.0 (C-2 ), 98.4 (C-2), 82.6 (=CI).
13C NMR (CDCl3): = 152.7 (Ph2C=), 141.8, 141.1, 129.4, 128.3,
128.2, 128.0, 127.9, 127.5, 79.0 (=CHI).
IR (0.3 mol/L, CH2Cl2): 3107, 3065, 3037, 3025, 2965, 2927, 1965,
1957, 1948, 1923, 1890, 1805, 1727, 1605, 1585, 1557, 1495, 1465,
1446, 1431, 1405, 1392, 1337, 1320, 1285, 1265, 1255, 1200, 1155,
1100 cm–1.
IR (0.2 mol/L, CCl4): 3107, 3085, 3075, 3029, 2965, 2928, 1966,
1950, 1806, 1600, 1584, 1554, 1494, 1445, 1322, 1201, 1182, 1149,
1074, 1029 cm–1.
NMR and MS data were in agreement with those partially report-
ed.20,21
MS: m/z (%) = 432 (8, M+), 306 (15), 305 (92), 179 (15), 178 (100),
177 (12), 176 (22), 152 (14), 151 (10), 150 (6).
Anal. Calcd for C14H10I2: C, 38.92; H, 2.33. Found: C, 39.08; H,
2.17.
2-Deuterio-1,1-diphenylethene (6)
Excess of CD3OD (0.16 mL, 4 mmol) was added dropwise to a sus-
pension of 3 at –90 °C followed by the standard warming proce-
dure, neutralised with 5% HCl and worked up as described above
for 5; yield: 174 mg (96%); colourless liquid.
1H NMR (CDCl3): = 7.31–7.20 (m, 10 H, 2 C6H5), 5.39 (s, 1
H, =CHD) (<5% of 1 was detected by the signal at 5.40 (s, 2
H, =CH2).
2H NMR (CH2Cl2):22 = 5.47 (s, 1 D, =CDH).
13C NMR (CDCl3): = 150.0 (Ph2C=), 141.5, 128.3, 128.2, 127.7,
114.0 (t, =CHD, JCD = 24.17 Hz).
(Z)-2-Deuterio-1-(2-deuteriophenyl)-1-phenylethene (12)
Excess of CD3OD (0.32 mL, 8 mmol) was added dropwise to a sus-
pension of 9 at –100 °C followed by the standard warming proce-
dure. The reaction mixture was worked up as described above for 6;
yield: 303 mg (86%); colourless liquid.
1H NMR(CDCl3): = 7.35–7.31 (m, 9 H, Ar), 5.44 (s, 1 H, =CHD)
(1 (<3%) and 6 (<3%) were detected by signals at 5.39 and 5.40 re-
spectively).
2H NMR (CH2Cl2) : = 7.33 (s, 1 D, D-Ar), 5.46 (s, 1 D, =CHD).22
13C NMR (CDCl3): = 150.0 (Ph2C=), 141.5, 141.4, 128.3, 128.2,
128.0, 127.7 (C6H5), 114.0 (t, =CHD, JCD = 24.17 Hz).
13C NMR and MS were in agreement to those partially reported.23
1,1-Diphenylpropene (7)
MS: m/z (%) = 182 (100, M+), 181 (62), 180 (44), 179 (21), 167
(24), 166 (44), 165 (20).
Excess of DMS (0.38 mL, 4 mmol) was added dropwise to a sus-
pension of 3 at –90 °C followed by the standard warming proce-
dure. The reaction mixture was treated with 25% aq ammonia to
destroy the excess of DMS and worked up as described above for 5
to give the title compound as oily liquid, which solidified up on
standing; yield 180 mg (93%); mp 49–50 °C (Lit.24 mp 49–50 °C).
Anal. Calcd for C14H10D2: C, 92.26; H/D, 7.74. Found: C, 92.48; H,
7.52.
(Z)-1-(2-Methylphenyl)-1-phenylprop-1-ene (13)
13C NMR (CDCl3): = 142.9, 142.5, 140.3 (Ph2C=), 130.0, 128.1,
128.0, 127.2, 126.8, 126.7, 124.0 ( =CH), 15.7 (CH3).
Excess of DMS (0.86 mL, 9 mmol) was added dropwise to a sus-
pension of 9 at –100 °C followed by the standard warming proce-
dure. The reaction mixture was worked up as described above for 7;
yield: 357 mg (86%); colourless oil.
13C NMR (CDCl3): = 141.5, 141.4, 139.3, 136.6, 130.1, 130.0,
128.2, 127.1, 126.6, 126.1, 125.7, 123.8 (=CH), 19.5 (ArCH3), 15.4
(CH3C=).
IR, MS and 1H NMR data were in a good agreement to those report-
ed.25,26
(2,2-Diphenylethenyl)trimethylsilane (8)
Excess of CTMS (0.3 mL, 2.4 mmol) was added dropwise to a sus-
pension of 3 at –90 °C followed by the standard warming proce-
dure. The reaction mixture was carefully treated with 10% aq
NaHCO3 and worked up as described above for 5; yield: 237 mg
(94%); oil (Lit.27 bp 115 °C/0.3 mbar).
1H NMR and MS were in a good agreement to those partially report-
ed.25,29
(Z)-2-(2-(Trimethylsilyl)phenyl)-2-phenylethenyl)trimethylsi-
lane (14)
MS: m/z (%) = 252 (47, M+), 238 (22), 237 (100), 221 (7), 178 (6),
Excess of CTMS (0.38 mL, 3 mmol) was added dropwise to a sus-
pension of 9 at –100 °C followed by the standard warming proce-
dure. The reaction mixture was worked up as described above for 8.
The following compounds were isolated: 8: 45 mg (9%), 15: 387
mg (82%) and 1: 10 mg (3%). No traces of 14 were detected in the
reaction mixture by 1H and 13C NMR and GC-MS analysis.
159 (5), 136 (13), 135 (98), 107 (5), 105 (5).
1H and 13C NMR and IR data were in a good agreement to those re-
ported.27,28
(Z)-2-Lithio-1-(2-lithiophenyl)-1-phenylethene (9)
A solution of 3 prepared according to a standard protocol using n-
BuLi (384 mg, 6 mmol), TMEDA (696 mg, 6 mmol) and bromide
2 (518 mg, 2 mmol) in pentane (20 mL) was allowed to warm to
20 °C and stirred for further 4 h resulting in the formation of dark-
red suspension of 9.
1,1-Dimethyl-3-phenyl-1-silaindene (15)
Excess of DCDMS (0.36 mL, 3 mmol) was added dropwise to a sus-
pension of 9 at –100 °C followed by the standard warming proce-
dure. The reaction mixture was treated with H2O, the organic layer
was separated and filtered through a layer of silica gel (5 cm) using
hexane as an eluent and 15 was obtained on concentration of the
first fraction (100 mL) to give the title compound as a colourless liq-
uid; yield: 416 mg (88%).
(Z)-2-Iodo-1-(2-iodophenyl)-1-phenylethene (11)
Excess of powdered I2 (2.02 g, 8 mmol) was added to a suspension
of 9 at –100 °C (internal temp) during 4 min, the reaction was al-
lowed to warm up to 20 °C over a 1.5 h period and was stirred at this
Synthesis 2002, No. 4, 491–496 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Efficient Mono- and Dilithiation of 2-Bromo-1,1,diphenylethene
495
1H NMR (CDCl3): = 7.59 (ddd, 1 H, H-7, J = 6.6, 1.3, 1 Hz),
7.45–7.21 (m, 8 H, Ar), 6.16 (s, 1 H, =CHSi), 0.37 [s, 6 H,
Si(CH3)2].
An attempt was made to use column chromatography on alumina
for the purification of 10, but only ethene 1 in nearly quantitative
yield was eluted with Et2O.
13C NMR, IR and MS were in a good agreement to those partially
reported.30
References
1,1-Dimethyl-3-phenyl-1-stannaindene (16)
(1) Current address: Institute of Organic Chemistry, Georg-
August-Universität Göttingen, Tammannstr.2, 37077
Göttingen, Germany. Fax: +49(551)399475; E-mail:
sergei.korneev@gmx.de.
(2) Curtin, D. Y.; Flynn, E. W. J. Am. Chem. Soc. 1959, 81,
4714.
(3) (a) Braun, M. In Houben-Weyl, 4 th ed., Vol. E19d; Hanack,
M., Ed.; Thieme: Stuttgart, 1993, 171. (b) Braun, M.
Angew. Chem. Int. Ed. 1998, 37, 43; Angew. Chem. 1998,
110, 444.
(4) Köbrich, G.; Trapp, H.; Akhtar, A. Chem. Ber. 1968, 101,
2644.
(5) Köbrich, G.; Trapp, H. Chem. Ber. 1966, 99, 670.
(6) (a) Köbrich, G.; Trapp, H. Chem. Ber. 1966, 99, 680.
(b) Modena, G.; Scorrano, G. In The Chemistry of the
Carbon–Halogen Bond, Part 1; Patai, S., Ed.; Wiley: New
York, 1973, 301.
A solution of DCDMST (439 mg, 2 mmol) in Et2O (5 mL) was add-
ed dropwise to a suspension of 9 at –100 °C during 5 min followed
by the standard warming procedure. The solvent was removed at re-
duced pressure (50 mbar) and the residue was extracted with pen-
tane (5 5 mL). The combined extracts were concentrated and
yellow-orange oil was distilled in a Kugelrohr apparatus at 190–
210 °C/0.1 mbar; yield: 483 mg (74%); colourless oil.
1H NMR (CDCl3): = 7.64 (dd, 1 H, H-8, J = 6.1, 1.5 Hz), 7.41
7.16 (m, 8 H, Ar), 6.57 (s, 1 H, =CHSn), 0.50 (s, 6 H, Sn(CH3)2,
JSn,H = 60.5, 57.4 Hz).
13C NMR (CDCl3): = 161.1 (Ph2C=, JSn,C = 38.9 Hz), 149.2 (C-1,
JSn,C = 85.3 Hz), 142.8 (C-1 , JSn,C = 66.8 Hz), 141.3 (C-8), 135.5
(JSn,C = 45.5 Hz), 132.5 (=CSn, JSn,C = 433.9, 414.9 Hz), 128.5,
128.4, 128.1, 127.2, 127.0, 125.9 (JSn,C = 39.8 Hz), –8.9 [Sn(CH3)2,
JSn,C = 359.2, 344.1 Hz].
(7) (a) Coleman, G. H.; Maxwell, R. D. J. Am. Chem. Soc. 1934,
56, 132. (b) Jacobs, T. L. Org. React. 1962, 5, 1.
(c) Zimmerman, H. E. In Molecular Rearrangements, Part 1;
de Mayo, P., Ed.; Wiley: New York, 1963, 345.
(d) Köbrich, G.; Buck, P. In Chemistry of Acetylenes; Viehe,
H. G., Ed.; Dekker: New York, 1969, 117.
MS: m/z (%) = 332 (4), 330 (3), 329 (5), 328 (23), 327 (9), 326 (18),
325 (7), 324 (10), 313 (100), 298 (11), 221 (5), 193 (10), 192 (11),
191 (9), 178 (19), 176 (7), 165 (5), 152 (5).
Anal. Calcd for C16H16Sn: C, 58.77; H, 4.93. Found: C, 58.49; H,
4.55.
(8) Bothner-By, A. A. J. Am. Chem. Soc. 1955, 77, 3293.
(9) Curtin, D. Y.; Richardson, W. H. J. Am. Chem. Soc. 1959,
81, 4719.
(10) (a) Fritsch, P. Liebigs Ann. Chem. 1894, 279, 319.
(b) Buttenberg, W. P. Liebigs Ann. Chem. 1894, 279, 324.
(c) Wiechell, H. Liebigs Ann. Chem. 1894, 279, 337.
(11) Köbrich, G.; Stöber, I. Chem. Ber. 1970, 103, 2744.
(12) Curtin, D. Y.; Quirk, R. P. Tetrahedron 1968, 24, 5791.
(13) Curtin, D. Y.; Flynn, E. W.; Nystrom, R. F. J. Am. Chem.
Soc. 1958, 80, 4599.
3-Phenyl-1-benzothiophene (17)
Excess of SDC (0.19 mL, 3 mmol) was added dropwise to a suspen-
sion of 9 at –100 °C followed by the standard warming procedure.
The filtered reaction mixture was concentrated and the crude prod-
uct was purified by column chromatography on silica gel using hex-
ane as an eluent (200 mL); yield: 353 mg (84%); colourless liquid;
nD20 1.6797 (Lit.31 nD25 1.6789).
1H NMR (CDCl3): = 7.94–7.89 (m, 2 H), 7.60–7.57 (m, 2 H),
7.50–7.46 (m, 2 H), 7.42–7.32 (m, 4 H).
1H, 13C NMR, MS and IR spectrum were in agreement to those par-
(14) One equivalent of n-BuLi is required for the metalation of 2
to 3. The second equivalent reacts with butyl bromide
formed to turn the metalation equilibrium to the side of
products: 2 + BuLi D 3 + BuBr, BuLi + BuBr Bu–Bu +
LiBr.
(15) Neugebauer, W.; Kos, A. J.; Schleyer, P. v. R. J. Organomet.
Chem. 1982, 228, 107.
(16) Vogel, A. Vogel’s Textbook of Practical Organic Chemistry,
4 th ed.; Longman: New York, 1981, 326.
(17) Pouchert, C. J. The Aldrich Library of Infrared Spectra;
Aldrich Chemical Co.: Wisconsin, Milwaukee, 1970.
(18) Cochran, J. C.; Phillips, H. K.; Tom, S.; Hurd, A. R.; Bronk,
B. S. Organometallics 1994, 13, 947.
(19) Bremser, W.; Ernst, L.; Franke, B. Carbon-13 NMR Spectral
Data, 4 th ed.; VCH: Weinheim, 1987.
(20) Barluenga, J.; Campos, P. J.; Gonzalez, J. M.; Suarez, J. L.;
Asensio, G. J. Org. Chem. 1991, 56, 2234.
(21) Sokolov, V. I.; Bashilov, V. V.; Reutov, O. A. J. Organomet.
Chem. 1978, 162, 271.
tially reported.31,32
Bis-(2,2-diphenylethenyl)dimethylstannane (10)
A solution of 3 was prepared according to a standard protocol in
THF (15 mL) as an alternative to pentane starting from 3 mmol of
n-BuLi (192 mg, 3 mmol), TMEDA (348 mg, 3 mmol) and bromide
2 (259 mg, 1 mmol). A solution of DCDMST (110 mg, 0.5 mmol)
in THF (5 mL) was added dropvise at –100 °C during 5 min fol-
lowed by the standard warming procedure. The solvent was re-
moved at reduced pressure (50 mbar), the rest was extracted with
pentane (5 5 mL) and the combined extracts were concentrated.
Unreacted bromide 2, ethene 1 and byproducts were distilled off in
vacuum (75–150 °C/0.7 mbar); yield: 132 mg (52%); light-yellow
oil.
1H NMR(CDCl3): = 7.36–7.15 (m, 10 H, 2 C6H5), 6.46 (s, 2
H, =CHSn, JSnH = 69.2, 66.1 Hz), –0.34 (s, 6 H, 2 CH3, JSnH = 57.4,
55.6 Hz).
13C NMR(CDCl3): = 158.1 (Ph2C=), 144.1, 142.9, 132.1 (=CSn),
129.5, 128.2, 128.0, 127.5, 127.4, –7.7 [Sn(CH3)2].
(22) Acetone-d6 was used as internal standard, = 2.05.
(23) Ludvig, M. M.; Lagow, R. J. J. Org. Chem. 1990, 55, 4880.
(24) Greenwald, R.; Chaykovsky, M.; Corey, E. J. J. Org. Chem.
1963, 28, 1128.
(25) van der Linde, R.; Korver, O.; Korver, P. K.; van der Haak,
P. J.; Veenland, J. U.; de Boer, Th. J. Spectrochimica Acta
1965, 21, 1893.
IR (0.3 mol/L, CCl4): 3107, 3085, 3055, 3027, 2967, 2927, 2877,
2863, 1965, 1950, 1900, 1885, 1810, 1765, 1735, 1665, 1655, 1600,
1585, 1550, 1493, 1446, 1385, 1370, 1353, 1327, 1312, 1280, 1245,
1194, 1158, 1145, 1125 cm–1.
Anal. Calcd for C30H28Sn: C, 71.04; H, 5.56. Found: C, 70.61; H,
5.19.
(26) Ni, Z.-J.; Mei, N.-W.; Shi, X.; Tzeng, Y.-L.; Wang, M. C.;
Luh, T.-Y. J. Org. Chem. 1991, 56, 4035.
Synthesis 2002, No. 4, 491–496 ISSN 0039-7881 © Thieme Stuttgart · New York

496
S. M. Korneev, D. E. Kaufmann
PAPER
(27) Gröbel, B.-T.; Seebach, D. Chem. Ber. 1977, 110, 852.
(28) Koerwitz, F. L.; Hammond, G. B.; Wiemer, D. F. J. Org.
Chem. 1989, 54, 743.
(29) Maercker, A.; Bös, B.; Hajgholipour, M. T. J. Organomet.
Chem. 1998, 566, 143.
(31) (a) Geneste, P.; Olive, J.-L.; Ung, S. N.; Faghi, M. E. A. E.;
Easton, J. W.; Beierbeck, H.; Saunders, J. K. J. Org. Chem.
1979, 44, 2887. (b) Seyferth, D.; Tronich, W.; Marmor, R.
S.; Smith, W. E. J. Org. Chem. 1972, 37, 1537.
(32) Kersey, I. D.; Fishwick, C. W. G.; Findlay, J. B. C.; Ward,
P. Tetrahedron 1995, 51, 6819.
(30) Kunai, A.; Matsuo, Y.; Ishikawa, M. Organometallics 1993,
12, 2536.
Synthesis 2002, No. 4, 491–496 ISSN 0039-7881 © Thieme Stuttgart · New York