Nickel-catalyzed dimerization and carbosilylation of 1,3-butadienes with chlorosilanes and Grignard reagents

Article abstract of DOI:10.1002/anie.200351579

In a multicomponent coupling reaction, 1,3-butadienes underwent Ni-catalyzed dimerization and carbosilylation in the presence of a chlorosilane and a Grignard reagent at -20°C (see scheme). The coupling product was obtained regio- and stereoselectively when unsubstituted 1,3-butadiene was used. (R = H, Me, or C₉H₁₉; R′, R″ = hydrocarbon substituent.).

Full text of DOI:10.1002/anie.200351579

Communications
telomerization) by using Ni catalysts resulted in the formation
of mixtures of products.[1b,4] We have recently developed new
methods for the regioselective addition of silicon and/or
carbon functionalities to alkenes or dienes in the presence of
early-transition-metal catalysts, such as zirconium com-
plexes[5] and titanium complexes.[6] During the course of
these studies, we found that Ni catalyzes the dimerization and
carbosilylation of butadienes in the presence of chlorosilanes
and Grignard reagents to give rise to 1,6-dienes with high
regio- and stereoselectivity [Eq. (1)].
When a catalytic amount of [Ni(acac)2] (0.05 mmol;
acac = acetylacetone) was added to a solution of isoprene
(2 mmol), chlorotriethylsilane (1 mmol), and nBuMgCl
(1.2 mmol) in THF (1.3 mL) at À208C, and the resulting
mixture was stirred for a further 18 hours at the same
temperature, compound 1, with Et3Si and nBu groups at
positions 3 and 8 of its dimerized isoprene skeleton, was
isolated in 87% yield (E/Z = 76:24) from the crude mixture
by HPLC, with CHCl3 as the eluent (Table 1, entry 1). No
regioisomers of 1 were formed in the reaction. When NiCl2
and [Ni(cod)2] (cod = 1,5-cyclooctadiene) were used as cata-
lysts, 1 was obtained in yields of 78 and 80%, respectively, but
no reaction took place in the presence of nickel catalysts with
phosphane ligands, such as [(PPh3)2NiCl2], [(dppe)NiCl2]
(dppe = ethane-1,2-diylbis(diphenylphosphane), or [(dppp)-
Carbosilylation-Dimerization
Nickel-Catalyzed Dimerization and
Carbosilylation of 1,3-Butadienes with
Chlorosilanes and Grignard Reagents**
NiCl2]
(dppp = propane-1,3-diylbis(diphenylphosphane),
under identical conditions. This reaction also proceeded
efficiently when a phenyl-substituted chlorosilane (Table 1,
entries 2, 6, and 7) and/or a secondary alkyl Grignard reagent
(Table 1, entries 2, 3, and 5) were used. The use of a
cyclohexyl Grignard reagent with isoprene led to the for-
mation of only the E isomer of the product (Table 1, entry 3).
The reaction of 2-nonyl-1,3-butadiene with Et3SiCl and
iBuMgCl gave a mixture of stereoisomers 8 in a 40:60 ratio
and 42% yield (Table 1, entry 8).
When unsubstituted 1,3-butadiene was used, the coupling
products were obtained not only regioselectively but also
stereoselectively in all cases examined (Table 1, entries 4–7).
A phenyl and a vinyl Grignard reagent could also be used to
prepare the allyl arene 6 and the triene 7, respectively, in good
yields (Table 1, entries 6 and 7). However, the reaction of a
primary alkyl Grignard reagent gave the desired product 9 in
only moderate yield (32%), along with the hydrosilylated
products 10a and 10b in 27 and 29% yields, respectively
[Eq. (2)]. The desired product was not obtained when
Jun Terao, Akihiro Oda, Aki Ikumi,
Akifumi Nakamura, Hitoshi Kuniyasu, and
Nobuaki Kambe*
Ni0 reacts with 1,3-butadienes to form octadienediyl–nickel
complexes, which play an important role as key intermediates
in the oligomerization of butadienes.[1,2] This reaction dem-
onstrates extreme synthetic utility as a straightforward
method for the formation of C8 building blocks in organic
synthesis. The cycloaddition of butadienes is one of the most
successful transformations of this type.[1d,3] However, many
attempts toward the synthesis of functionalized oligomers (i.e.
[*] Prof. Dr. N. Kambe, Dr. J. Terao, A. Oda, A. Ikumi, A. Nakamura,
Dr. H. Kuniyasu
Department of Molecular Chemistry and Frontier Research Center
Graduate School of Engineering, Osaka University
Suita, Osaka 565-0871 (Japan)
Fax: (+81)6-6879-7390
E-mail: kambe@chem.eng.osaka-u.ac.jp
[**] This research was supported financially through a grant from the
Ministry of Education, Culture, Sports, Science, and Technology of
Japan and by the JSPS COE program. We thank the Instrumental
Analysis Center, Faculty of Engineering, Osaka University for MS
and HRMS measurements as well as elemental analyses.
Supporting information for this article is available on the WWW
under http://www.angewandte.org or from the author.
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DOI: 10.1002/anie.200351579
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Angewandte
Chemie
Table 1: Ni-catalyzed regioselective coupling of 1,3-dienes with Grignard reagents and chlorosilanes.[a]
These results suggest that
Yield [%][b] E/Z[c]
Grignard reagents do, in fact, pro-
Entry Diene
R’3SiCl
R’’MgX
Product
À
mote the C Si bond-forming step.
The fact that the hydrosilylated
products 10a and 10b did not con-
tain deuterium may suggest that a
hydrogen atom of the butyl group of
the Grignard reagent was transfer-
red to 10a and 10b. The formation
1
Et3SiCl
nBuMgCl
1
2
87
86
76:24
2
3
PhMe2SiCl iPrMgCl
92:8
Me3SiCl
c-C6H11MgCl
3
84
100:0
of the coupling product
9 and
hydrosilylated products 10a and
10b can be rationalized by assuming
a common intermediate 11, the
reaction of which leads to 9 through
reductive elimination of the allyl
and nBu groups or to 10a and 10b
through b-hydrogen elimination.
This b-hydrogen-elimination pro-
cess may be disfavored when iso-
prene (Table 1, entry 1) or iBuMgCl
(Table 1, entry 4) is used, because of
steric reasons, thus resulting in the
selective formation of coupling
products 1 and 4, respectively.
4
5
Et3SiCl
Et3SiCl
iBuMgCl
4
5
78
93
100:0
100:0
c-C6H11MgCl
6
7
PhMe2SiCl PhMgBr
PhMe2SiCl
6
7
78
76
100:0
100:0
8
Et3SiCl
iBuMgCl
8
42
40:60[d]
We then tested the reaction in
the presence of a primary alkyl
Grignard reagent with no b-hydro-
gen atom. The reaction of 1,3-buta-
[a] For experimental details, see Supporting Information. [b] Yields of isolated products. [c] Determined
by GC. [d] Ratio of the stereoisomers: their stereochemistry was not assigned.
diene
with
Et3SiCl
and
PhMe2CCH2MgCl afforded the
expected coupling product 13 in
MeMgCl[7] or tBuMgCl was used. Under identical conditions,
2,3-dimethyl-1,3-butadiene and 1,4-diphenyl-1,3-butadiene
did not react.
26% yield along with cyclized compound 14 (39%;
Scheme 2). The latter compound might be formed via 16,
generated by insertion of the terminal carbon–carbon double
bond into the allyl–nickel bond of 15, as reductive elimination
from 15 to give 13 is probably retarded because of steric
reasons.
A plausible reaction pathway, which takes into account
the above evidence, is shown in Scheme 3. The reaction of
[Ni(acac)2] with a Grignard reagent affords Ni0 (17), which
reacts with butadiene and a Grignard reagent to give h1,h3-
octadienediyl–nickelate complex 19[8] via h3,h3-octadienediyl–
We carried out several control experiments to prove the
reaction pathway and product selectivity. For example,
Et3SiCl, a stoichiometric amount of [Ni(cod)2], and excess
1,3-butadiene (10 equiv) were stirred as a solution in THF for
10 min at À208C. The reaction was quenched with HCl (1n,
1.5 mL), and analysis of the mixture by NMR spectroscopy
and GC–MS showed no evidence for the formation of
silylated products. However, when 1 equivalent of nBuMgCl
was added to the reaction mixture prior to quenching with
D2O, a mixture of the monosilylated compounds 9, 10a, and
10b (Scheme 1) was obtained in a similar total yield and ratio
to those shown in Equation 2.
Scheme 1. Significance of the Grignard reagent: Treatment of 1,3-buta-
diene with Et3SiCl and [Ni(cod)] in the presence and in the absence of
nBuMgCl.
Scheme 2. Reaction of a primary alkyl Grignard reagent that bears no
b-hydrogen atom.
Angew. Chem. Int. Ed. 2003, 42, 3412 – 3414
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Communications
Röper in Comprehensive Organometallic Chemistry, Vol. 8
(Eds.: E. W. Abel, F. G. A. Stone, G. Wilkinson), Pergamon,
Oxford, 1982, pp. 371–462; c) W. Keim, Angew. Chem. 1990, 102,
251–260; Angew. Chem. Int. Ed. Engl. 1990, 29, 235–244; d) M.
Lautens, W. Klute, W. Tam, Chem. Rev. 1996, 96, 49–92.
[2] We recently reported that octadienediyl–nickel complexes show
unique catalytic activity in C(sp3)–C(sp3) coupling reactions of
alkyl halides with RMgX: J. Terao, H. Watanabe, A. Ikumi, H.
Kuniyasu, N. Kambe, J. Am. Chem. Soc. 2002, 124, 4222–4223; J.
Terao, A. Ikumi, H. Kumiyasu, N. Kambe, J. Am. Chem. Soc.
2003, 125, 5646–5647.
[3] S. McN. Sieburth, N. T. Cunard, Tetrahedron 1996, 52, 6251–
6282.
[4] For a Ni-catalyzed reaction of 1,3-butadiene with Me2Zn and a
ketone, see: a) M. Kimura, S. Matsuo, K. Shibata, Y. Tamaru,
Angew. Chem. 1999, 111, 3586–3589; Angew. Chem. Int. Ed.
1999, 38, 3386–3388; for reviews of Pd-catalyzed reactions, see:
b) J. Tsuji, Palladium Reagents and Catalysts, Wiley, Chichester,
1995, pp. 422–449; c) F. Bouachir, P. Grenouillet, D. Neibecker,
J. Poirier, I. Tkatchenko, J. Organomet. Chem. 1998, 569, 203–
215.
[5] a) J. Terao, K. Torii, K. Saito, N. Kambe, A. Baba, N. Sonoda,
Angew. Chem. 1998, 110, 2798–2801; Angew. Chem. Int. Ed.
1998, 37, 2653–2656; b) J. Terao, T. Watanabe, K. Saito, N.
Kambe, N. Sonoda, Tetrahedron Lett. 1998, 39, 9201–9204.
[6] a) J. Terao, K. Saito, S. Nii, N. Kambe, N. Sonoda, J. Am. Chem.
Soc. 1998, 120, 11822–11823; b) S. Nii, J. Terao, N. Kambe, J.
Org. Chem. 2000, 65, 5291–5297.
Scheme 3. A plausible reaction pathway.
nickel complex 18 or its h1,h3 isomer.[9a] Complex 19 then
reacts with a chlorosilane at the g allylic carbon atom to form
an allyl complex 20.[9] The subsequent reductive elimination
of 20 affords the coupling product and regenerates 17 to
complete the catalytic cycle.
In conclusion, a new method for the highly regioselective
nickel-catalyzed four-component coupling[10] of two diene
molecules, a chlorosilane, and a Grignard reagent has been
developed. This reaction affords 1,6-dienes with an allyl silane
unit[11] under mild conditions and, when unsubstituted 1,3-
butadiene is used, proceeds stereoselectively to produce only
[7] Direct reaction with the chlorosilane predominated.
[8] For a similar h1,h3-octadienediyl–nickelate complex reported for
Li, see: S. Hole, P. W. Jolly, R. Mynott, R. Salz, Z. Naturforsch. B
1982, 37, 675–676.
À
trans olefins. This study provides the first example of a C Si
[9] a) An h1,h3-octadienediyl–nickel complex reacts with H+ at the
g allylic carbon: R. Benn, B. Bꢀssemeier, S. Holle, P. W. Jolly, R.
Mynott, I. Tkatchenko, G. Wilke, J. Organomet. Chem. 1985,
279, 63–86; b) an h1,h3-octadienediyl–palladium complex also
reacts with Me2HSiCl at the g position: P. W. Jolly, R. Mynott, B.
Raspel, K.-P. Schick, Organometallics 1986, 5, 473–481; c) an h1-
allyl–palladium complex reacts with electrophiles at the g posi-
tion: H. Kurosawa, A. Urabe, K. Miki, N. Kasai, Organometallics
1986, 5, 2002–2008.
bond-forming reaction that involves chlorosilanes and is
catalyzed by a late transition metal.[12]
Experimental Section
5: A solution of Et3SiCl (152 mg, 1.0 mmol) and a catalytic amount of
[Ni(acac)2] (12 mg, 0.05 mmol) in THF (1.2 mL) was cooled to
À788C, and 1,3-butadiene (45 mL at 208C under 1 atm, 2.0 mmol)
was added through a syringe. c-C6H11MgCl (2m in Et2O, 0.6 mL,
1.2 mmol) was then added at the same temperature and the mixture
was warmed to À208C and stirred for a further 18 h. The reaction was
quenched with HCl (1n), and the mixture was extracted with diethyl
ether to afford the yellow crude product, which was purified by HPLC
to give 5 (292 mg, 93%). IR (neat): n˜ = 2920, 2875, 2851, 1625, 968,
[10] For recent reviews of Ni-catalyzed multicomponent coupling
reactions, see: a) J. Montgomery, Acc. Chem. Res. 2000, 33, 467–
473; b) S. Ikeda, Acc. Chem. Res. 2000, 33, 511–519.
[11] Allyl silanes play an important role in organic synthesis as useful
intermediates in a number of synthetic transformations; see: T.-
Y. Luh, S.-T. Liu in The Chemistry of Organic Silicon Com-
pounds, Vol. 2 (Eds.: S. Patai, Z. Rappoport), Wiley, Chichester,
1998, pp. 1793–1868.
1
894, 730, 696 cmÀ1; H NMR (400 MHz, CDCl3, 258C): d = 5.62 (dt,
J = 17.1, 10.0 Hz, 1H), 5.41–5.26 (m, 2H), 4.86 (dd, J = 10.0, 1.7 Hz,
1H), 4.82 (d, J = 17.1 Hz, 1H), 2.17–2.08 (m, 1H), 1.92–1.82 (m, 3H),
1.75–1.62 (m, 6H), 1.47 (dt, J = 6.1, 7.8 Hz, 2H), 1.26–1.07 (m, 4H),
0.94 (t, J = 8.4 Hz, 9H), 0.92–0.82 (m, 2H), 0.54 ppm (q, J = 8.4 Hz,
6H); 13C NMR (100 MHz, CDCl3, 258C): d = 140.2, 130.9, 129.1,
111.8, 40.8, 38.3, 33.3, 33.2, 32.2, 31.4, 28.8, 26.8, 26.5, 7.8, 2.4 ppm;
MS (EI): m/z (%): 306 (0.1), 277 (7), 169 (18), 115 (100), 87 (58), 59
(47); HRMS (m/z): calcd for C20H38Si (M+): 306.2743, found
306.2745; elemental analysis: calcd for C20H38Si: C 78.35, H 12.49;
found: C 78.19, H 12.57.
[12] The oxidative addition of chlorosilanes to late transition metals
À
tends to be sluggish as a result of the strong Si Cl bond energy;
see: H. Yamashita, M. Tanaka, M. Goto, Organometallics 1997,
16, 4696–4704, and references therein; for the Zr-catalyzed
silylation of olefins with chlorosilanes, see reference [5a].
Received: April 4, 2003 [Z51579]
Keywords: dienes · Grignard reagents ·
.
multicomponent reactions · nickel · silanes
[1] a) P. W. Jolly, G. Wilke, The Organic Chemistry of Nickel,
Academic Press, New York, 1975; b) W. Keim, A. Behr, M.
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Angew. Chem. Int. Ed. 2003, 42, 3412 – 3414