Transition metal-catalyzed dehydrogenative germylation of olefins with tri-n-butylgermane

Article abstract of DOI:10.1021/om990336l

The catalyzed reaction of an excess of styrene with n-Bu₃GeH using several ruthenium and rhodium complexes gave the corresponding vinylgermanes (α-trin-butylgermylstyrene, (Z)-β-tri-n-butylgermylstyrene, and (E)-β-tri-n-butylgermylstyrene), whi

Full text of DOI:10.1021/om990336l

3764
Organometallics 1999, 18, 3764-3767
Tr a n sition Meta l-Ca ta lyzed Deh yd r ogen a tive
Ger m yla tion of Olefin s w ith Tr i-n -bu tylger m a n e
Naoyuki Furukawa, Noriko Kourogi, and Yoshio Seki*
Laboratory of Commodity Science, Faculty of Economics, Kagawa University,
Takamatsu, Kagawa 760-8523, J apan
Fumitoshi Kakiuchi and Shinji Murai*
Department of Applied Chemistry, Faculty of Engineering, Osaka University,
Suita, Osaka 565-0871, J apan
Received May 6, 1999
Summary: The catalyzed reaction of an excess of styrene
with n-Bu3GeH using several ruthenium and rhodium
complexes gave the corresponding vinylgermanes (R-tri-
n-butylgermylstyrene, (Z)-â-tri-n-butylgermylstyrene, and
(E)-â-tri-n-butylgermylstyrene), which are dehydrogena-
tive germylation products. The most effective catalyst
was Ru3(CO)12, whose use resulted in selective formation
of the vinylgermanes in high yields.
5), is less common than the hydrosilylation of olefins, it
has been extensively studied in the last two decades.3
On the other hand, no example of dehydrogenative
germylation, which would produce vinylgermanes di-
rectly from hydrogermanes and olefins, has been re-
ported (eq 6).
In tr od u ction
It is well-known that metal-catalyzed reactions of
hydrosilanes parallel those of hydrogermanes. For ex-
ample, the catalyzed reaction of alkynes with a hydrosi-
lane produces vinylsilanes as shown in eq 1.1 Similarly,
the reaction of alkynes with a hydrogermane gives
vinylgermanes (eq 2).2 Hydrosilylation of olefins with a
hydrosilane is well-known to give alkylsilanes (eq 3).1
Similarly, the reaction of olefins with a hydrogermane
usually produces alkylgermanes (eq 4).2
Vinylsilanes are versatile synthetic intermediates in
organic synthesis,4 and the dehydrogenative silylation
reaction provides a useful method for their preparation.
Similarly, a new synthesis of vinylgermanes by the
dehydrogenative germylation of olefins is expected to
be a useful development in vinylgermane chemistry.
Ru3(CO)12-catalyzed dehydrogenative silylation of ole-
fins has already been reported as the first example of
the exclusive formation of vinylsilanes from hydrosi-
lanes and olefins.3c,e We have now found that Ru3(CO)12
also is an active catalyst for the dehydrogenative
(3) (a) Kakiuchi, F.; Tanaka, Y.; Chatani, N.; Murai, S. J . Orga-
nomet. Chem. 1993, 456, 45. (b) Takeshita, K.; Seki, Y.; Kawamoto,
K.; Murai, S.; Sonoda, N. J . Org. Chem. 1987, 52, 4864. (c) Seki, Y.;
Takeshita, K.; Kawamoto, K.; Murai, S.; Sonoda, N. J . Org. Chem.
1986, 51, 3890. (d) Takeshita, K.; Seki, Y.; Kawamoto, K.; Murai, S.;
Sonoda, N. J . Chem. Soc., Chem. Commun. 1983, 1193. (e) Seki, Y.;
Takeshita, K.; Kawamoto, K.; Murai, S.; Sonoda, N. Angew. Chem.,
Int. Ed. Engl. 1980, 19, 928. (f) Kesti, M. R.; Waymouth, R. M.
Organometallics 1992, 11, 1095. (g) Corey, J . Y.; Zhu, X.-H. Organo-
metallics 1992, 11, 672. (h) Doyle, M. P.; Devora, G. A.; Nefedof, A.
O.; High, K. G. Organometallics 1992, 11, 549. (i) Marciniec, B.;
Maciejewski, H.; Mirecki, J . J . Organomet. Chem. 1991, 418, 61. (j)
Kesti, M. R.; Abdulrahman, M.; Waymouth, R. M. J . Organomet. Chem.
1991, 417, C12. (k) Skoda-Foldes, R.; Kollar, L.; Heil, B. J . Organomet.
Chem. 1991, 408, 297. (l) Tanke, R. S.; Crabtree, R. H. Organometallics
1991, 10, 415. (m) Seitz, F.; Wrighton, M. S. Angew. Chem., Int. Ed.
Engl. 1988, 27, 3366. (n) Fernandez, M. J .; Esteruelas, M. A.; J imenez,
M. S.; Oro, L. A. Organometallics 1986, 5, 1519. (o) Oro, L. A.;
Fernandez, M. J .; Esteruelas, M. A.; J imenez, M. S. J . Mol. Catal. 1986,
37, 151. (p) Cornish, A. J .; Lappert, M. F. J . Organomet. Chem. 1984,
271, 153. (q) Fernandez, M.-J .; Bailey, P. M.; Bentz, P. O.; Ricci, J . S.;
Koetzle, T. F.; Maitlis, P. M. J . Am. Chem. Soc. 1984, 106, 5458. (r)
Cornish, A. J .; Lappert, M. F. J . Organomet. Chem. 1979, 172, 153.
(s) Schroeder, M. A.; Wrighton, M. S. J . Organomet. Chem. 1977, 128,
345.
Although dehydrogenative silylation, which produces
vinylsilanes directly from hydrosilanes and olefins (eq
(1) (a) Ojima, I. In The Chemistry of Organic Silicon Compounds;
Patai, S., Rapport, Z., Eds.; J ohn Wiley & Sons: Chichester, 1989;
Chapter 25. (b) Lukevics, E.; Belyakova, Z. V.; Pomerantseva, M. G.;
Voronkov, M. G. J . Organomet. Chem. Libr. 1977, 5, 1. (c) Hiyama,
T.; Kusumoto, T. In Comprehensive Organic Synthesis; Trost, B. M.,
Fleming, I., Eds.; Pergamon: Oxford, U.K., 1991; Vol. 8, pp 763-792.
(d) Speier. J . L. Adv. Organomet. Chem. 1979, 17, 407. (e) Corey, J . Y.
In Advances in Silicon Chemistry; Larson, G. L., Ed.; J AI: Greenwich,
1991; Col. 1, pp 355-382.
(2) (a) Piers, E.; Lemieux, R. J . Chem. Soc., Perkin Trans. 1995, 3.
(b) Wada, F.; Abe, S.; Yonemaru, N.; Kikukawa, K.; Matsuda, T. Bull.
Chem. Soc. J pn. 1991, 64, 1701. (c) Oda, H.; Morisawa, Y.; Oshima,
K.; Nozaki, H. Tetrahedron Lett. 1984, 25, 3221. (d) Lukevics, E.;
Barabanov, D. I.; Ignatovich, L. M. Appl. Organomet. Chem. 1991, 5,
379. (e) Corriu, R. J . P.; Moreau, J . J . E. J . Organomet. Chem. 1972,
40, 73. (f) Corriu, R. J . P.; Moreau, J . J . E. Chem. Commun. 1971,
812. (g) Nozaki, K.; Ichinose, Y.; Wakamatsu, K.; Oshima, K.; Utimoto,
K. Bull. Chem. Soc. J pn. 1990, 63, 2268. (h) Wolfsberger, W. J . Prakt.
Chem. 1992, 334, 453.
(4) (a) Chan, T. H.; Fleming, I. Synthesis 1979, 761. (b) Colvin, E.
W. Silicon in Organic Synthesis; Butterworth: London, 1981. (c)
Weber, W. P. Silicon Reagents for Organic Synthesis; Springer-
Verlag: Berlin, 1983. (d) Bassindale, A. R.; Taylor, P. G. In The
Chemistry of Organic Silicon Compounds; Patai, S., Rapport, Z., Eds.;
J ohn Wiley & Sons: Chichester, 1989; Chapter 14.
10.1021/om990336l CCC: $18.00 © 1999 American Chemical Society
Publication on Web 08/12/1999

Notes
Organometallics, Vol. 18, No. 18, 1999 3765
Ta ble 1. Ca ta lytic Activities of Ru th en iu m Meta l
Com p lexesa
Ta ble 2. Effect of th e Rea ction Con d ition s to th e
Yield
yield, %
yield, %
styrene HGeBu3 temp time
expt (mmol) (mmol)
(°C)
(h) solvent 1a 2a 3a 4a
1a
2a
3a
4a
1
2
3
4
5
6
7
8
9
2.5
1
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25
reflux
reflux
reflux
reflux
reflux
100
3
3
3
3
3
3
3
3
toluene
toluene
toluene
toluene
toluene
toluene
toluene
hexane
2
2
1
0
0
0
0
1
1
0
0
0
4
0
1
1
1
0
0
1
2
0
0
0
91
66
53
31
43
34
2
31
70
39
0
0
0
0
0
1
0
0
1
1
0
0
0
Ru3(CO)12
2
0
0
0
0
0
0
4
1
1
0
0
0
0
91
62
20
10
7
0
6
1
2
0
1
0
RuHCl(CO)(PPh3)3
RuCl2(PPh3)4
RuCl2(PPh3)3
RuHCl(PPh3)3
[RuCl2(benzene)]2
RuH2(PPh3)4
0.5
0.25
0.1
2.5
2.5
2.5
2.5
2.5
2.5
2.5
6
3
80
110a
110a
100a
100a
60a
a
Reaction conditions: styrene (2.5 mmol), n-Bu3GeH (0.25
22 hexane
mmol), catalyst (0.01 mmol), toluene (5 mL), reflux, 3 h.
10
11
12
3
3
3
CH3CN
THF
CH2Cl2
0
germylation of olefins with hydrogermanes to give vin-
ylgermanes selectively.
a
Temperature of oil bath.
Resu lts a n d Discu ssion
catalyst for the dehydrogenative silylation of styrene.3
The fact that dehydrogenative germylation has taken
place implies that degermylation is involved in the
reaction course, and this represents the first example,
to the best of our knowledge, in the chemistry of
germanium. This result suggests that the dehydroge-
native silylation (eq 5) also parallels the dehydrogena-
tive germylation (eq 6).
The effect of reaction conditions on the yield and the
product distribution was examined in the Ru3(CO)12-
catalyzed reaction of styrene with tri-n-butylgermane.
No reaction occurred at 80 °C (expt 7 in Table 2). Using
more vigorous reaction conditions such as toluene reflux,
the correponding vinylgermane was obtained in high
yield. In comparison, the similar reaction of a hydrosi-
lane usually proceeds smoothly at 80 °C to give the
vinylsilane in high yield.
Deh yd r ogen a tive Ger m yla tion of Styr en e Ca ta -
lyzed by Ru th en iu m Com p lexes. Ruthenium carbo-
nyl-catalyzed reaction of styrene with tri-n-butylger-
mane afforded four types of products, R-tri-n-butyl-
germylstyrene (1a ), (Z)-â-tri-n-butylgermylstyrene (2a ),
(E)-â-tri-n-butylgermylstyrene (3a ), and a simple addi-
tion compound (4a ) as shown in eq 7.5 Products 1a , 2a ,
The hydrogenation of styrene was a side-reaction to
give ethylbenzene as a byproduct. A reaction using a
1:1 ratio of styrene to tri-n-butylgermane gave the
vinylgermane in only 32% yield. The yield of the
vinylgermane increased with an increase in the molar
ratio of styrene to the hydrogermane, and with a 10-
fold excess of styrene, the vinylgermane (3a ) was
obtained in high yield. Using hexane and acetonitrile
as a solvent also gave the vinylgermane (3a ) in 70% and
39% yields, respectively. On the other hand, no reaction
occurred in THF and CH2Cl2.
Scop e a n d Lim ita tion w ith Resp ect to Olefin s.
Styrene derivatives smoothly reacted with hydroger-
manes to give vinylgermanes (3), as shown in eq 8. The
reaction of p-methylstyrene, p-chlorostyrene, p-fluo-
rostyrene, and p-trifluoromethylstyrene also gave the
corresponding vinylgermanes (3c, 3d , 3e, and 3f) in
65%, 66%, 60%, and 56% yield, respectively. Trieth-
ylgermane also reacted smoothly to give 3b in 58% yield.
and 3a are dehydrogenative germylation products, and
4a is a hydrogermylation product. We have investigated
the catalytic activity of various commercially available
ruthenium complexes for the reaction of an excess of
styrene with tri-n-butylgermane at toluene reflux condi-
tion. Typically, a solution of styrene (2.5 mmol), n-Bu3-
GeH (0.25 mmol), and Ru3(CO)12 (0.01 mmol) in toluene
(5 mL) was stirred at reflux for 3 h. GLC analysis
showed that the reaction mixture contained 3a in 91%
yield, along with small amounts of 2a (4%) and 1a (2%).
Various transition metal complexes which have been
known to be effective for dehydrogenative silylation and
are easily available have been examined for the catalytic
activities. The ruthenium complexes examined were
[RuCl2(benzene)]2, RuCl2(PPh3)4, RuCl2(PPh3)3, RuH2-
(PPh3)4, RuHCl(PPh3)3, RuHCl(CO)(PPh3)3, [RuCl2(p-
cymene)]2, Ru(acac)3, CpRuCl(PPh3)2, RuH2(CO)(PPh3)3,
RuCl2(CO)2(PPh3)2, [Cp*RuCl2]n, Cp*2Ru, Cp2Ru, [RuCl2-
(CO)3]2, RuCl3, and Ru3(CO)12. Several ruthenium com-
plexes that showed catalytic activity are listed in Table
1. The reaction using Ru3(CO)12 selectively gave the
corresponding vinylgermanes in quantitative yield. We
had already found that Ru3(CO)12 is the most effective
(5) The products 1a , 2a , and 4a were identified by agreement with
the retention times and mass spectra of authentic samples. The
authentic samples of 1a and 2a were prepared from phenylacetylene
and n-Bu3GeH. See ref 2c. That of 4a was prepared by the Ru(acac)-
(CO)2-catalyzed reaction of styrene with n-Bu3GeH. The structure of
4a was determined by NMR and IR spectra: 1H NMR (CDCl3) δ 0.60-
1.84 (c, 29H, CH2, Bu), 2.53-2.70 (m, 2H, CH2), 7.16-7.36 (m, 5H,
Ph); IR (neat) 2940 s, 2910 s, 2840 s, 1460 m, 1080 w, 700 m.
The dehydrogenative silylation of allylbenzene and
1-hexene using Ru3(CO)12 is known to give the corre-
sponding vinylsilane or allylsilane in high yield.3c The
vinylsilane is obtained under mild reaction conditions,
but the allylsilane requires vigorous conditions. On the
other hand, the same reaction in which tri-n-butylger-

3766 Organometallics, Vol. 18, No. 18, 1999
Notes
Ta ble 3. Ca ta lytic Activities of Rh od iu m Meta l
Com p lexesa
silane as internal standard. Data are reported as follows:
chemical shift in ppm (δ), multiplicity, coupling constant (Hz),
integration, and interpretation. Infrared spectra (IR) were
obtained on a Shimadzu 435 spectrometer; absorptions are
reported in cm-1. Mass spectra were obtained on a Shimadzu
GCMS-QP2000A with ionization voltage of 70 eV. Elemental
analyses were performed by Elemental Analysis Section of
Osaka University. Analytical GC was carried out on a Shi-
madzu GC-14A gas chromatograph, equipped with a flame
ionization detector. Preparative GC was carried out on a
Hitachi GC-164 gas chromatograph.
Ma ter ia ls. Toluene was distilled from CaH2. Ru3(CO)12,
n-Bu3GeH, Et3GeH, p-fluorostyrene, p-trifluoromethylstyrene
were purchased from Aldrich Chemical Co. and used without
further purification. p-Methylstyrene and p-chlorostyrene were
purchased from Tokyo Kasei Kogyo Co. and used without
further purification.
yield, %
1a
2a
3a
4a
Rh6(CO)16
RhH(CO)(PPh3)3
RhCl3
[RhCl(CO)2]2
[RhCl(1,5-hexadiene)]2
Rh4(CO)12
0
0
0
0
0
0
0
0
0
0
0
55
0
34
0
36
30
0
0
0
0
13
0
13
15
32
0
31
67
27
30
25
30
10
21
28
17
18
0
[Cp*RhCl2]2
47
34
27
30
8
RhCl(CO)(PPh3)2
[RhCl(COD)]2
Rh(acac)(CH2dCH2)2
Cp*Rh(CO)2
a
Reaction conditions: styrene (2.5 mmol), n-Bu3GeH (0.25
mmol), catalyst (0.01 mmol), toluene (5 mL), reflux.
Gen er a l P r oced u r es. In a 10 mL, two-necked, round-
bottomed flask were placed Ru3(CO)12 (0.01 mmol), n-Bu3GeH
(0.25 mmol), styrene (2.5 mmol), and toluene (5 mL). The
reaction mixture was heated in an oil bath at reflux under an
atmosphere of N2. The reactions were complete within 3 h.
The yields were determined by GLC, with n-heptadecane as
internal standerd. The toluene was removed under reduced
pressure, and the residue was passed through a short chro-
matography column of Wakogel C-200. Preparative GC af-
forded the analytical samples. The physical properties of new
compounds are give below.
(E)-1-P h en yl-2-(tr i-n -bu tylger m yl)eth ylen e (3a ): Color-
less oil; 1H NMR (CDCl3) δ 0.82-0.92 (c, 15H, Bu), 1.30-1.43
(c, 12H, Bu), 6.62 (d, J ) 18.9 Hz, 1H, CHd), 6.80 (d, J ) 18.9
Hz, 1H, CHd), 7.22 (dd, J ) 7.3, 7.3 Hz, 1H, Ph), 7.32 (dd, J
) 7.3, 7.3 Hz, 1H, Ph), 7.42 (d, J ) 7.3 Hz, 1H, Ph); IR (neat)
2910 s, 1599 m, 1572 w, 1495 m, 1460 m, 1418 w, 1377 m,
1341 w, 1292 w, 1192 w, 1078 w, 1022 w, 983 m, 878 w, 728
s, 687 m, 648 w; MS, m/z (rel intensity) 292 (54), 290 (41), 235
(74), 180 (88), 179 (100), 151 (51). Anal. Calcd for C20H34Ge:
C, 69.21; H, 9.87. Found: C, 68.89; H,9.81.
(E )-1-(p -Me t h ylp h e n yl)-2-(t r i-n -b u t ylge r m yl)e t h yl-
en e (3c): Colorless oil; 1H NMR (CDCl3) δ 0.83-0.91 (c, 15H,
Bu), 1.29-1.48 (c, 12H, Bu), 2.33 (s, 3H, CH3), 6.55 (d, J )
19.0 Hz, 1H, CHd), 6.77 (d, J ) 19.0 Hz, 1H, CHd), 7.13 (d,
J ) 8.0 Hz, 2H, Ph), 7.32 (d, J ) 8.0 Hz, 2H, Ph); IR (neat)
2900 s, 1615 m, 1562 m, 1507 s, 1461 s, 1416 m, 1377 s, 1338
m, 1284 m, 1218 m, 1190 m, 1176 m, 1079 s, 1017 m, 980 s,
962 m, 905 m, 880 s, 834 m, 772 s, 733 s, 702 s, 648 m, 660 w;
MS, m/z (rel intensity) 306 (52), 304 (37), 250 (61), 193 (100),
165 (48). Anal. Calcd for C21H36Ge: C, 69.85; H, 10.05.
Found: C, 69.91; H, 10.05.
(E )-1-(p -Ch lor op h e n yl)-2-(t r i-n -b u t ylge r m yl)e t h yl-
en e (3d ): Colorless oil; 1H NMR (CDCl3) δ 0.84-0.91 (c, 15H,
Bu), 1.31-1.40 (c, 12H, Bu), 6.60 (d, J ) 18.7 Hz, 1H, CHd),
6.74 (d, J ) 18.7 Hz, 1H, CHd), 7.26-7.29 (m, 2H, Ph), 7.33-
7.35 (m, 2H, Ph); IR (neat) 2943 s, 1599 m, 1487 s, 1459 m,
1401 m, 1376 m, 1338 w, 1269 w, 1094 m, 1011 m, 982 m, 879
w, 842 m, 778 s, 722 m, 698 m, 649 m; MS, m/z (rel intensity)
326 (39), 270 (67), 213 (100), 185 (33), 109 (29). Anal. Calcd
for C20H33Ge: C, 62.96; H, 8.72 Found: C, 62.74; H, 8.72.
(E)-1-(p-F lu or op h en yl)-2-(tr i-n -bu tylger m yl)eth ylen e
(3e): Colorless oil; 1H NMR (CDCl3) δ 0.84-0.92 (c, 15H, Bu),
1.32-1.41 (c, 12H, Bu), 6.52 (d, J ) 18.8 Hz, 1H, CHd), 6.75
(d, J ) 18.8 Hz, 1H, CHd), 6.98-7.02 (m, 2H, Ph), 7.36-7.40
(m, 2H, Ph); IR (neat) 2944 s, 1599 m, 1487 s, 1459 m, 1400
m, 1376 m, 1093 m, 1011 m, 981 m, 841 m, 777 s, 693 m, 648
m; MS, m/z (rel intensity) 309 (39), 305 (22), 253 (57), 249 (32),
mane was used did not give the vinylgermane and the
allylgermane, respectively. To clarify the reason for this
difference, product formation in the reaction of allyl-
benzene was examined with time. Allylbenzene was
isomerized in the presence of Ru3(CO)12 to â-methyl-
styrene in the initial stages of the reaction. Internal
olefins are less reactive than terminal olefins in dehy-
drogenative silylation.3c The same appears to be true
for dehydrogenative germylation. The isomerization of
allylbenzene to unreactive â-methylstyrene in the initial
stage converted it to an unreactive internal olefin.
Deh yd r ogen a t ive Ger m yla t ion Ca t a lyzed b y
Rh od iu m Com p lexes. The catalytic activity of many
commercially available rhodium complexes was exam-
ined in the reaction of styrene with tri-n-butylgermane.
The products obtained were the same as those in the
Ru3(CO)12-catalyzed reaction. The rhodium complexes
were [RhCl(CO)2]2, RhCl(CO)(PPh3)2, RhH(CO)(PPh3)3,
Rh(acac)(CH2dCH2)2, Cp*Rh(CO)2, [Cp*RhCl2]2, RhCl3,
Rh6(CO)16, [RhCl(COD)]2, Rh4(CO)12, [RhCl(1,5-hexadi-
ene)]2, Rh(NO)(PPh3)3, Rh(acac)3, Rh(COD)2SO3CF3,
[Rh(OAc)2]2, [Rh(OOCCF3)2]2, [RhCl(norbornadiene)]2,
[RhCl(CH2dCH2)2]2, [RhCl(cyclooctene)2]2, Rh(acac)(nor-
bornadiene), [RhCl(2-phenylpyridine)2]2, RhCl(PPh3)3,
and Rh(acac)(COD). Several of these rhodium complexes
showed catalytic activity as shown in Table 3. In the
all of these reactions, the simple hydrogermylation
product (4a ) also was produced. Some rhodium com-
plexes gave the (Z)-isomer (2a ) as main product. Re-
cently, it was reported that rhodium complexes are
active catalysts for the dehydrogenative silylation of
olefins with a hydrosilane.6 However, no example of the
selective dehydrogenative silylation of olefins catalyzed
by a rhodium complex has been reported. The fact that
similar results were obtained with hydrosilanes and
hydrogermanes suggests that the mechanisms of dehy-
drogenative silylation and germylation of olefins are
very similar.
In conclution, this note reports the first example of
the dehydrogenative germylation of olefins with a
hydrogermane to give the vinylgermanes. This reaction
provids a useful method of a vinylgermane.
197 (100), 193 (67), 169 (41), 165 (24). Anal. Calcd for C20H33
Ge: C, 65.80; H, 9.11 Found: C, 65.81; H, 8.91.
(E)-1-(p-Tr iflu or om eth ylp h en yl)-2-(tr i-n -bu tylger m yl)-
eth ylen e (3f): Colorless oil; 1H NMR (CDCl3) δ 0.86-0.92 (c,
15H, Bu), 1.34-1.41 (c, 12H, Bu), 6.76 (d, J ) 19.0 Hz, 1H,
CHd), 6.83 (d, J ) 19.0 Hz, 1H, CHd), 7.50 (d, J ) 8.3 Hz,
-
Exp er im en ta l Section
1
Gen er a l In for m a tion . H NMR spectra were recorded on
a J EOL J MN-A400 spectrometer in CDCl3 with tetramethyl-
(6) Takeuchi, R.; Yasue, H. Organometallics 1996, 15, 2098.

Notes
Organometallics, Vol. 18, No. 18, 1999 3767
2H, Ph), 7.57 (d, J ) 8.3 Hz, 2H, Ph); IR (neat) 2944 m, 1612
m, 1461 m, 1410 w, 1376 w, 1325 s, 1161 s, 1122 s, 1076 s,
1015 m, 982 m, 852 m, 788 m, 757 w, 707 w, 612 w; MS, m/z
(rel intensity) 360 (24), 303 (72), 247 (100), 153 (85), 151 (68).
Anal. Calcd for C21H33F3Ge: C, 60.77; H, 8.01 Found: C, 60.82;
H, 7.79.
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research on Priority Areas
(No. 283, “Innovative Synthetic Reactions”) from Mon-
busho.
OM990336L