Nickel-catalyzed allylation of lithium 1-alkynyl(trialkoxy)borates with 1,3-disubstituted allyl carbonates

Article abstract of DOI:10.1016/S0022-328X(00)00164-9

The first Suzuki-type cross-coupling of alkynylborates with 1,3-disubstitued allyl carbonates was studies. It was found that nickel complexes readily catalyzed the reaction giving normal coupling products in good to excellent yields. The nickel complexes of dppe or dppen revealed a higher catalytic activity than that of NiCl₂(PPh₃)₂ or NiCl₂(dppf). This is a substrate-controlled reaction with high regioselectivity. The asymmetric cross-coupling reaction of alkynylborates with allyl carbonate enantioselectively produced an allyl substituted alkyne with 13%ee.

Full text of DOI:10.1016/S0022-328X(00)00164-9

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 603 (2000) 189–193
Nickel-catalyzed allylation of lithium 1-alkynyl(trialkoxy)borates
with 1,3-disubstituted allyl carbonates
Han Chen, Min-Zhi Deng *
Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Academia Sinica, 354 Fenglin Lu,
Shanghai 200032, PR China
Received 2 December 1999; received in revised form 31 January 2000; accepted 9 March 2000
Abstract
The first Suzuki-type cross-coupling of alkynylborates with 1,3-disubstitued allyl carbonates was studies. It was found that
nickel complexes readily catalyzed the reaction giving normal coupling products in good to excellent yields. The nickel complexes
of dppe or dppen revealed a higher catalytic activity than that of NiCl2(PPh3)2 or NiCl2(dppf). This is a substrate-controlled
reaction with high regioselectivity. The asymmetric cross-coupling reaction of alkynylborates with allyl carbonate enantioselec-
tively produced an allyl substituted alkyne with 13%ee. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Nickel catalysts; Alkynylborates; Allyl carbonate; Cross-coupling
1. Introduction
Although this type of reaction tolerates functional
groups and the procedure is quite convenient, it has
been applied limitedly for unsubstituted allyl halides [4].
Moreover, the relatively unreactive allylic alcohol
derivatives hardly couple to terminal alkynes under
these conditions. The palladium-catalyzed allylation re-
action is a prolific area of research, but the reaction of
allyl carbonates with the terminal alkynes does not
provide normal allylation products [5] (Scheme 2).
It was also reported that alkynes coupled to allyl
acetates in the presence of Ni(COD)2, but the results
were unsatisfactory [6]. To the best of our knowledge,
very few methods are now available for the synthesis of
normal allylation products of terminal alkynes from the
substituted allylic alcohol derivatives.
The transition metal-catalyzed allylation of nucle-
ophiles is well-recognized as one of the most powerful
synthetic tools for the selective construction of car-
bonꢀcarbon bonds [1].
The allylation of the terminal alkynes with allyl
halides can be accomplished by a direct substitution of
allyl halides with 1-alkynylmetal compounds, such as
Cu(I), Mg, and Li reagents [2]. Among them the cop-
per-catalyzed allylation of terminal alkynes by allylic
halides is the most reliable method [3] (Scheme 1).
Metal 1-alkynylborates are useful synthetic interme-
diates, and have been used in many carbonꢀcarbon
bond forming reactions, such as 1,2-asymmetric addi-
tion to aldehydes [7]; Diels–Alder cycloaddition [8];
and the Suzuki–Miyaura coupling reaction with aryl or
alkenyl halides [9]. However, the allylation of alkynylb-
orates with allylic alcohol derivatives have not been
reported previously.
Scheme 1.
* Corresponding author. Tel.: +86-21-64163300; fax: +86-21-
64166128.
E-mail address: dengmz@pub.sioc.ac.cn (M.-Z. Deng)
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00164-9

190
H. Chen, M.-Z. Deng / Journal of Organometallic Chemistry 603 (2000) 189–193
Scheme 2.
Scheme 3.
2. Results and discussion
chemically nonrigid 18-electron h3-allyl complex, which
could undergo reductive elimination leading to the de-
sired allylation product quite readily [12].
2.1. The palladium(0)-catalyzed cross-coupling of
alkynylborates with (E)-3-(ethoxycarbonyloxy)-
1-phenyl-1-pentene
In the presence of a NiCl2(dppe) catalyst, the cou-
pling reaction of various alkynylborates with 1,3-disub-
stituted allyl carbonates in the different solvents was
accomplished successfully. The results are shown in
Table 2.
Table 2 illustrates that the addition of MeCN showed
minor influence on the reaction, although Kabayashi
reported that using the mixture of MeCN and THF in
a ratio of 1:1 as the solvent provided somewhat better
results in the coupling of 1,3-disubstitued secondary
allylic carbonates and lithium aryl- and alkenylborates
[11]. This is a substrate-controlled reaction with high
regioselectivity to give the normal allylation products of
alkynes in good to excellent yields. Considering that the
reaction conditions are mild, and alkynylborates can be
Various palladium complexes catalyzed the cross-
coupling of alkynylborates with (E)-3-(ethoxycarbony-
loxy)-1-phenyl-1-pentene; however, the palladium
complexes such as PdCl2(PPh3)2, Pd(PPh3)4 were inef-
fective for the coupling reaction due to the formation of
the diene instead of desired allylation products 3h
(Scheme 3). The allyl palladium intermediate formed by
oxidative–addition of allyl carbonate to palladium, un-
derwent the b-H elimination more quickly than the
transmetalation with alkynylborate.
2.2. The nickel-catalyzed cross-coupling of
alkynylborates with (E)-3-(ethoxycarbonyloxy)-1-
phenyl-1-pentene
Table 1
The effect of ligands in nickel-catalyzed coupling reaction of pheny-
lacetylenylborate with (E)-3-(ethoxycarbonyloxy)-1-phenyl-1-pen-
tene a
Nickel complexes were found to be excellent catalysts
for activating allyl derivatives [10], such as the
NiCl2(PPh3)2 or NiCl2(dppf)-catalyzed coupling reac-
tion of aryl- or alkenyl-borates with 1,3-disubstituted
allyl carbonates [11]. Therefore we investigated the
coupling reaction of alkynylborates with allyl carbon-
ates in the presence of a nickel complex as the catalyst.
However, the reaction did not provide any coupling
products when using NiCl2(PPh3)2 or NiCl2(dppf) (En-
tries 1,2). Thus, the effect of the ligands used in nickel
catalysts was reinvestigated in details. The results are
showed in Table 1.
Table 1 demonstrates that the coupling reaction is
readily accomplished by a NiCl2(dppe) or NiCl2(dppen)
catalyst (Entries 4, 5). The catalytic activity of nickel
complexes of dppe or dppen was higher than that of
PPh3, dppf or dppp ligands. The nickel catalyst having
a chelating diphosphine dppe or dppen forms a stereo-
Entry
Catalyst
Yield (%) b
1
2
3
4
5
6
NiCl2(PPh3)2
NiCl2(dppf)
Trace
Trace
Trace
68
NiCl2(dppp) c
NiCl2(dppe) d
NiCl2(dppe) d
NiCl2(dppen) e
64 f
70
a Phenylacetylenylborate (1.0 mmol), (E)-3-(ethoxycarbonyloxy)-1-
phenyl-1-pentene (1.2 mmol), 3 mol% nickel catalyst, THF 4 ml
(except entry 5) were stirred for 12 h at 60°C under nitrogen
atmosphere.
b Isolated yields.
c Dppp, 1,2-bis(diphenylphosphino)propane.
d Dppe, 1,2-bis(diphenylphosphino)ethane.
e Dppen, cis-1,2-bis(diphenylphosphino)ethylene.
f The mixture of THF and MeCN (2:2 ml) was used as the solvent.

H. Chen, M.-Z. Deng / Journal of Organometallic Chemistry 603 (2000) 189–193
191
Table 2
The coupling of 1,3-disubstituted allyl carbonates with alkynylboratesa
(Scheme 4) (determined by chiral HPLC analysis with
OD columns). This fact suggests that the use of nickel
catalysts with appropriate chiral ligands could induce
the enantioselective cross-coupling reaction of alkynyl-
borates with allyl carbonates. It is the first example of
the asymmetric cross-coupling of alkynylborate with
allylic carbonate.
easily prepared from corresponding alkynyllithiums and
B(OR)3, the reaction might be a facile method for the
allylation of various terminal alkynes with allyl
carbonates.
2.3. The asymmetric coupling of phenylacetylenyl-
bortate with (E)-3-(ethoxycarbonyloxy)-1-phenyl-
1-pentene
2.4. Conclusion
Preliminary study for the asymmetric reaction of
phenylacetylenylbortate with (E)-3-(ethoxycarbonyl-
oxy)-1-phenyl-1-pentene in the presence of a nickel
catalyst having a chiral ligand (S,S)-(chiraphos), gave a
product with some enantiomeric excess (13%ee)
In conclusion, we have demonstrated the first cross-
coupling of alkynylborates with 1,3-disubstituted allyl
carbonates to give normal allylation products of alky-
nes. It was found that the nickel complexes are better

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H. Chen, M.-Z. Deng / Journal of Organometallic Chemistry 603 (2000) 189–193
Scheme 4.
than palladium complexes as the catalysts, and the
nickel catalyst with dppe (or dppen) ligand has higher
activity than that of dppp and dppf complexes. The
substrate-controlled reaction affords the normal 1,3-dis-
ubstituted allylic products of alkynes. We are continuing
the study for the asymmetric reaction of alkynylbortates
with allyl carbonates by using the chiral nickel catalyst
and will report the further results accordingly.
in hexane,1.2 mmol) was added dropwise at −78°C.
Having stirred for 30 min, B(OMe)3 (0.134 ml, 1.2
mmol) was added, and the mixture was stirred for 2 h.
A second mixture of NiCl2(dppe) (15.85 mg, 0.03 mmol)
and (E)-3-(ethoxycarbonyloxy)-1-phenyl-1-pentene (2f)
(234 mg, 1 mmol) in THF (2 ml) was added. The
reaction mixture was stirred at 60°C for 12 h (monitored
by TLC), allowed to cool to room temperature (r.t.) and
pentane (30 ml) was then added. The organic phase was
washed with water (4×10 ml) and dried over MgSO4.
After removing the solvent in vacuo, (E)-3-pheny-
lacetynyl-1-phenyl-1-pentene (3h) (167 mg, 68%) was
isolated by silica gel chromatography, eluting with pure
pentane.
3. Experimental
1H-NMR spectra were recorded on VXL-300 instru-
ments using TMS as an internal standard in CDCl3
solution. 13C NMR spectral measurements were per-
formed at 75.4 MHz on a Bruker AMX-300 using
CDCl3 as internal standards. Infrared spectra were
recorded on Perkin–Elmer 983 FI-IR spectrometer as
liquid films on potassium bromide plates. Mass spectral
measurements were performed on Finnigan 4021. Ele-
mental analyses were carried out on a MOD-1606
elemental analyzer. High-resolution mass spectra were
recorded on an HP5989A mass spectrometer.
3.3. Characterization of the products
3.3.1. (E)-3-Phenylacetynyl-1-phenyl-1-pentene (3h)
1
Colorless liquid; H-NMR (300 MHz, CCl3D–TMS)
l ppm: 7.21–7.46 (m, 10H), 6.74 (d, J=16.0 Hz, 1H),
6.22 (dd, J=6.5, 15.7 Hz, 1H), 3.5 (q, J=6.4 Hz, 1H),
1.78–1.82 (m, 2H), 1.14 (t, J=7.4 Hz, 3H); 13C-NMR
l 131.74, 130.62, 129.88, 128.70, 127.80, 127.37, 126.43,
125.97, 90.61, 83.84, 37.04, 29.07, 15.35; IR (neat) 2232
cm−1; MS m/e (rel. intensity, %) 246 [M+, 33.87], 217
(100), 202 (68.77), 215 (57.57); Anal. Calc. for C19H18:
C, 92.64; H, 7.36. Found: C, 92.52; H, 7.50%.
3.1. Chemicals
THF, MeCN were purified and dried by standard
techniques just before use. All reactions were monitored
by thin layer chromatography (TLC) using GF254. All
the alkynyles were purchased from Aldrich Chemical
Co. and used after distillation except (trimethylsi-
lyl)acetylene. n-BuLi was purchased from Aldrich, and
allyl carbonates were prepared according to literature
procedures [13], and dried before used. The following
nicked catalysts were prepared as reported methods:
NiCl2(PPh3)2 [14], NiCl2(dppf) [15], NiCl2(dppe),
NiCl2(dppen), NiCl2(dppp) [16], and (S,S)-(chi-
raphos)NiCl2 [17].
3.3.2. (E)-4-Phenylacetynyl-2-hexene (3f)
1
Colorless liquid, H-NMR (300 MHz, CCl3D–TMS)
l ppm: 7.24–7.30 (m, 3H), 7.42–7.49 (m, 2H), 5.75 (dd,
J=16.3, 8.6 Hz, 1H), 5.50 (dq, J=16.4, 7.2 Hz, 1H),
3.41 (m, 1H), 1.70 (d, J=6.4 Hz, 3H), 1.22 (d, J=7.1
Hz, 3H); IR (film) 2232 cm−1; MS m/e (rel. intensity,
%) 170 [M+, 19.78], 169 (100), 141 (21.93), 115 (20.57);
Anal. Calc. for C13H14: C, 91.71; H, 8.29. Found: C,
91.48; H, 8.73%.
3.2. Representati6e procedure
3.3.3. (E)-3-Trimethylsilylacetynyl-1-phenyl-1-pentene
(3g)
Colorless liquid, H-NMR (300 MHz, CCl3D–TMS)
l ppm: 7.31–7.42 (m, 5H), 6.70 (d, J=15.8 Hz, 1H),
6.14 (dd, J=15.8, 6.5 Hz, 1H), 3.24 (q, J=6.4 Hz, 1H),
1.70 (m, 2H), 1.19 (t, J=6.4 Hz, 3H), 0.26 (s, 9H); IR
(film) 2169 cm−1; MS m/e (rel. intensity, %) 242 [M+,
10.44], 213 (25.45), 169 (21.87), 199 (14.63); HRMS for
C16H22Si, Anal. Calc: 242.1491. Found: 242.1500.
The coupling reactions of alkynylborates with 1,3-dis-
ubstituted allyl carbonates in the presence of
NiCl2(dppe).
1
3.2.1. Synthesis of (E)-3-phenylacetynyl-1-phenyl-
1-pentene
To a well-stirred solution of phenylacetylene (122.4
mg, 1.2 mmol) in THF (2 ml), n-BuLi (0.75 ml, 1.6 M

H. Chen, M.-Z. Deng / Journal of Organometallic Chemistry 603 (2000) 189–193
193
3.3.4. (E)-3-(Hexynyl)-1-phenyl-1-pentene (3k)
Colorless liquid, H-NMR (300 MHz, CCl3D–TMS)
ganic Chemistry, Chinese Academy of Sciences, for
financial support.
1
l ppm: 7.27–7.35 (m, 5H), 6.54 (dd, J=15.7, 1.0 Hz,
1H), 6.24 (dd, J=15.7, 6.5 Hz, 1H), 3.15 (m, 1H), 2.26
(t, J=6.4 Hz, 2H), 1.53–1.70 (m, 6H), 1.09 (t, J=7.3
References
Hz, 3H), 0.92 (t, J=7.2 Hz, 3H); IR (film) 2210 cm−1
;
MS m/e (rel. intensity, %) 226 [M+, 20.12], 197 (96.96),
155 (83.50), 153 (40.43); Anal. Calc. for C17H22: C,
90.20; H, 9.80. Found: C, 90.31; H, 9.60%.
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3.3.5. (E)-3-(Pentynyl)-1-phenyl-1-pentene (3l)
Colorless liquid, H-NMR (300 MHz, CCl3D–TMS)
1
l ppm: 7.26–7.35 (m, 5H), 6.53 (d, J=15.7 Hz, 1H,),
6.24 (dd, J=15.7, 6.4 Hz, 1H), 3.17 (m, 1H), 2.27 (t,
J=6.7 Hz, 2H), 1.53–1.70 (m, 4H), 1.09 (t, J=7.3 Hz,
3H), 0.91 (t, J=7.2 Hz, 3H); IR (film) 2212 cm−1; MS
m/e (rel. intensity, %) 212 [M+, 18.32], 183 (28.99), 155
(40.31), 91 (43.11); Anal. Calc. for C16H20: C, 90.56; H,
9.44. Found: C, 90.06; H, 9.45%.
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3.3.6. (E)-3-Phenylacetynyl-1-phenyl-1-butene (3i)
Colorless liquid, H-NMR (300 MHz, CCl3D–TMS)
1
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l ppm 7.21–7.46 (m, 10 H), 6.77 (d, J=16.1 Hz, 1H),
6.24 (dd, J=6.5, 16.0 Hz, 1 H), 3.5 (m, 1H), 1.45 (d,
J=7.4 Hz, 3 H); IR (film) 2230 cm−1; MS m/e (rel.
intensity, %) 232 [M+, 95.24], 217 (100), 215 (77.46),
202 (68.94); Anal. Calc. for C18H16: C, 93.10; H, 6.90.
Found: C, 92.97; H, 6.99%.
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3.3.7. 1-Phenylacetynyl-2-cyclohexene (3j)
Colorless liquid, H-NMR (300 MHz, CCl3D–TMS)
1
l ppm 7.22–7.40 (m, 5H), 5.74 (m, 2H), 3.29 (m, 1H),
1.97–2.10 (m, 2H), 1.56–1.88 (m, 4H); IR (film) 2227
cm−1; MS m/e (rel. intensity, %) 182 [M+, 100], 167
(86.97), 154 (69.93), 181 (52.20); Anal. Calc. for C14H14:
C, 92.30; H, 7.70. Found: C, 92.02; H, 7.90%.
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Acknowledgements
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We thank the NNSF of China and Laboratory of
Organometallic Chemistry, Shanghai Institute of Or-
.