A new catalytic route to boryl- and borylsilyl-substituted buta-1,3-dienes

Article abstract of DOI:10.1002/chem.200800518

Vinyl-substituted boronates in the presence of complexes containing Ru-H bonds (preferably [Ru(CO)ClH(PCy₃)₂], Cy: cyclohexyl) react regioselectively with terminal ethynes (involving silylethynes), albeit with the exception of phenyl

Full text of DOI:10.1002/chem.200800518

FULL PAPER
DOI: 10.1002/chem.200800518
A New Catalytic Route to Boryl- andBorylsilyl-SubstitutedButa-1,3-dienes
Je¸drzej Walkowiak, Magdalena Jankowska-Wajda, and Bogdan Marciniec*[a]
Abstract: Vinyl-substituted boronates
in the presence of complexes contain-
new catalytic route for the preparation
of dienylboronates, and particularly di-
enylsilylboronates, that are functional-
ised building blocks in the synthesis of
organic and natural products. The
mechanism of this new reaction was
proved to involve an insertion of
À
À
ing
Ru H
bonds
(preferably
alkyne into Ru H bonds followed by
[Ru(CO)ClH
A
an insertion of coordinated vinyl boro-
À
react regioselectively with terminal
ethynes (involving silylethynes), albeit
nate into the Ru C= bond and b-hy-
C
drogen transfer to the metal to elimi-
nate boryldiene or borylsilyldiene.
with the exception of phenylacetylene,
to produce boryl- and borylsilyl-substi-
tuted buta-1,3-dienes with a preference
for E,E-diene. The reaction opens a
Keywords: alkynes
· butadiene ·
homogeneous catalysis · silylacety-
lene · vinylboronates
Introduction
The reactions are widely recognised as efficient catalytic ac-
À
ꢀ À
À
tivations of =C H, C H and =C E bonds of a vinylmetal-
loid with evolution of ethylene. The mechanisms of these re-
The well-known transition-metal (TM)-catalysed reactions
(developed by our group) of vinyl-substituted metalloid
(E=Si, Ge, B) compounds with olefins, called silylative cou-
pling (trans-silylation), trans-germylation and trans-boryla-
tion, respectively, are based on the activation of the =C E
bond and =C H bonds of olefins in the presence of M H
À
actions involve the insertion of vinyl–E into the TM H
bond and b-hydrogen transfer to the metal with elimination
À
of ethylene and generation of the TM E bond. This is fol-
À
À
lowed by the insertion of alkene or alkyne into the TM E
À
À
bond and b-hydrogen transfer to the metal to eliminate
silyl-, germyl- or borylethene, or the substituted silyl- or ger-
mylethyne, respectively. The latter step is directly responsi-
ble for metallative coupling of olefins and acetylenes.[1b]
In recent years, several applications of alkynyl, alkenyl
and dienyl boron derivatives have been developed as func-
tionalised building blocks in the synthesis of organic and
natural products.[6,7] This fact has made this topic a growing
and steadily more appealing field of research.
[1–3]
À
and M E catalysts [M=metal; see Eq. (1)].
This process was recently extended to the activation of sp-
Therefore, analogously to organosilicon and germanium
derivatives, we used vinylboronates in reaction with terminal
À
hybridised C H bonds in reaction with vinyl-silicon and
-germanium compounds [Eq. (2)].[4–5]
acetylenes catalysed by [Ru] H complexes, but, unexpected-
À
ly, instead of boryl-substituted ethynes, boryl-functionalised
buta-1,3-dienes were obtained in very good yields with high
regioselectivity.
Dienylboronates and particularly dienylsilylboronates
constitute a class of functionalised building blocks common-
ly used in the synthesis of organic and natural products, as
the boronate moiety (as well as the silyl group) can be
easily converted into other functional groups (see
Scheme 1).[8,9]
[a] J. Walkowiak, Dr. M. Jankowska-Wajda, Prof. B. Marciniec
Department of Organometallic Chemistry
Faculty of Chemistry
Adam Mickiewicz University
Grunwaldzka 6, 60-780 Poznan (Poland)
Fax : (+48)61-829-1508
Simultaneous unsymmetrical functionalisation of buta-1,3-
dienes with boryl and silyl groups opens the possibility for
E-mail: marcinb@amu.edu.pl
Chem. Eur. J. 2008, 14, 6679 – 6686
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
6679

À
plexes containing the Ru H
bond.
Results andDiscussion
The reaction, catalysed by
[Ru(CO)ClH
cyclohexyl),
ACHTREUNG
AHCTREUNG
A
ACHTREUNG
AHCTREUNG
method for selective synthesis
of 1-boryl- and 1-silyl-4-boryl-
substituted
buta-1,3-dienes
[(a)+(b)], sometimes accom-
panied by traces of ethyne di-
merisation (c) and/or vinylbor-
onate homocoupling (d) [see
Eq. (3) and Table 1].
Most of the reactions exam-
ined here proceed with high
conversion of acetylene (quan-
titatively under optimal condi-
tions) and in very good yields
Scheme 1. Potential applications of borylsilyl-substituted buta-1,3-dienes.
to give predominantly E,E-1,3-
selective replacement of one of these groups with retention
of the other and the use of the latter in the further function-
alisation in a different process.
diene (a) accompanied by one E,Z isomer (b). Although vi-
nylborane has to be used in excess, its homocoupling[3] has
been practically insignificant in this reaction. On the other
hand, dimerisation of acetylene has been observed, but in
the presence of most catalysts used, only as a side reaction
affording traces of byproducts (c). A threefold excess of vi-
nylborane over acetylene was tested as the optimum
amount for the co-dimerisation process to reduce acetylene
p–p conjugated C=C bonds occur often in natural polyen-
ic compounds, which exhibit significant biological activity.
Indeed, a number of them have found clinical utility as
drugs and antibacterial and antifungal compounds.[6–7]
Boryl-substituted 1,3-dienes can be prepared by classic
stoichiometric routes using or-
ganometallic reagents[10,11] or
Table 1. Co-dimerisation of terminal acetylenes with 2-vinyl-1,3-dioxaborinane (A).
by more recently applied cata-
lytic methods, such as hydrobo-
ration of enynes,[12] cross-cou-
pling of 1,1-diborylated al-
kenes with alkenyl halides,[13]
Heck coupling of vinylboro-
nate with vinylarylic iodid-
es,[8e,14] as well as cross-meta-
thesis of vinylboronates with
1,3-dienes.[15] Additionally, si-
lylboryl-substituted dienes can
be synthesised by means of
nickel-catalysed silaborative di-
merisation of alkynes.[16]
Herein we report a new cat-
alytic transformation of vinyl-
substituted boronates with se-
lected terminal ethynes (also
silylethynes) occurring in the
presence of ruthenium com-
Cat.[d] Conversion [%][e] Selectivity a/b/c/d [%][f] Isolated yield Product no.[g]
of (a) [%]
ꢀÀ
Entry
R
1
I[a]
100
83/15/traces/2
74
1
2
3
4
5
6
I[b]
II
77
93
49
67
20
86/14/0/0
81/19/traces/traces
77/23/0/0
11/0/89/0
0/0/100/0
III[c]
IV
V[c]
7
8
I, IV
0
0/0/0/0
V[c]
46
0/0/100/0
9
I
85
84/16/0/0
66
70
2
10
11
I
I
97
99
81/19/0/0
60/40/0/0/
3
4
[a] Reaction conditions unless otherwise stated: [Ru]/[acetylene]/
(0.5m), t=18 h, T=808C. [b] [Ru]/[acetylene]/
[borane]=10À2:1:3. [c] Dichloroethane (0.5m) as a solvent.
[d] Catalyst: [Ru(CO)ClH(PCy3)2] (I), [Ru(CO)ClH(PiPr3)2] (II), [Ru(CO)H(MeCN2)(PCy3)2][BF4] (III),
[Ru(CO)ClH(PPh3)3] (IV), [RuCl(PCy3)
[borane]=2”10À2:1:3; open system, toluene
ACHTREUNG
AHCTREUNG
A
G
U
G
ACHTREUNG
A
A
ACHTRE(UNG p-cymene)]OTf (V). [e] Substituted acetylene conversion; deter-
mined by GC analysis. [f] Determined by GC analysis and 1H NMR spectroscopy. [g] See the Experimental
Section.
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Chem. Eur. J. 2008, 14, 6679 – 6686

Boryl- and Borylsilyl-Substituted Buta-1,3-dienes
FULL PAPER
dimerisation, as well as homocoupling of vinylboronate.
Similarly to the previously described trans-metalation re-
However, when six-coordinated [RuCO(Cl)H
A
actions of vinylmetalloid with olefins and acetylenes[2–5] (for
is used as the initial catalyst, then dimerisation of acetylene
is a major reaction.
a review see ref. [1]), [Ru(CO)ClHACHTRE(UNG PCy3)2] (IV) was the
most effective and selective catalyst for this process.
Application of 2-vinyl-1,3-dioxaborolane as a reagent in
the reactions with terminal silyl and organic acetylenes with
the optimal process parameters gives boryl- and borylsilyl-
substituted dienes also with good yields and selectivity com-
parable to the reactions with 2-vinyl-1,3-dioxaborinane (see
Table 3).
In our research we observed that the co-dimerisation re-
action with vinylboronates occurred not only for terminal
organic acetylenes, but also for alkynylsilanes (see Table 2).
Triethylgermylacetylene was also tested in the reaction with
2-vinyl-1,3-dioxaborinane, but its homocoupling played, in
this case, a significant role (see Table 2).
Optimisation of the synthesis parameters was carried out
for the reaction of triethylsilylacetylene with 2-vinyl-1,3-di-
oxaborinane. The best results (the highest yield and selectiv-
ity) were observed for the reaction carried out at 808C for
18 h and at a threefold excess of borane compound (see
Table 2). A fivefold excess of boronate over acetylene in-
creased the contribution of the side reaction of vinylboro-
nate homocoupling.
Our separate study of the reaction of equimolar amounts
of the ruthenium–boryl complex [Ru
ACHTRE(UGN BO2C6H4)(CO)Cl-
(PCy3)2] (VI) and silylacetylene monitored by 1H NMR
spectroscopy and GC–MS reveals that the insertion of acety-
À
lene into the Ru Bbond occurs to a very low degree (silyl-
boryl-substituted ethyne is not observed in the GC–MS
À
spectrum and only traces of regenerated Ru H bond (triplet
at d=À24.3 ppm) were detected by H NMR spectroscopy).
1
This is the reason why contrary
to vinylsilane[4] and vinylger-
mane,[5] the metalation of acet-
ylene with vinylboronate was
not observed during the cata-
lytic process. Instead, the co-
dimerisation of vinylboronate
with most terminal acetylenes
(except phenylacetylene) was
noted.
Table 2. Co-dimerisation of terminal silylacetylenes and triethylgermylacetylene with 2-vinyl-1,3-dioxabori-
nane (A).[a]
Cat.[f]
T
[8C]
Conversion
[%][g]
Selectivity a/b/c/d
[%][h]
Isolated
yield
of (a) [%]
Product
no.[i]
ꢀÀ
R
Entry
1
2
3
4
5
6
7
8
I[b]
I
80
80
88
98
83
99
10
35
100
91
54
73
80/13/7/traces
84/16/traces/traces
82/18/traces/traces
78/14/0/8
89/11/traces/traces
88/12/traces/traces
70/15/15/0
80/20/0/traces
72/28/0/0
12/7/81/0
0/0/100/0
83/17/traces/traces
84/16/0/0
90/10/0/traces
40/5/55/0
44/14/21/23
78
5
I[c]
I[d]
I
80
40
60
100
80
80
I
I
It is well recognised that
ruthenium–hydride complexes
react with terminal acetylenes
very smoothly at room temper-
ature (with phenylacetylene
reaction occurred immediately
even at À208C) to form the vi-
II
III[e]
IV
V[e]
I
I
I
I
I
9
10
11
12
13
14
15
16
80
80
35
100
100
94
43
88
79
81
79
6
7
8
9
10
nylphenylruthenium
com-
plex[4,17,18] according to Equa-
tion (4).
[a] Reaction conditions unless otherwise stated: [Ru]/[acetylene]/
(0.5m), t=18 h. [b] [Ru]/[acetylene]/
[borane]=2”10À2:1:2. [c] [Ru]/[acetylene]/
[acetylene]/
[borane]=2”10À2:1:5. [e] Dichloroethane (0.5m) as a solvent. [f] Catalyst: [Ru(CO)ClH
(I), [Ru(CO)ClH(PiPr3)2] (II), [Ru(CO)H(MeCN2)(PCy3)2][BF4] (III), [Ru(CO)ClH(PPh3)3] (IV), [RuCl-
(PCy3)(p-cymene)]OTf (V). [g] Substituted acetylene conversion; determined by GC analysis. [h] Determined
by GC analysis and H NMR spectroscopy. [i] See the Experimental Section.
ACHTREUNG
R
ACHTREUNG
These complexes are there-
fore well known as catalysts of
acetylene dimerisation occur-
ring by means of insertion of
R
ACHTREUNG
A
N
G
N
ACHTREUNG
A
ACHTREUNG
1
Chem. Eur. J. 2008, 14, 6679 – 6686
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6681

B. Marciniec et al.
Table 3. Co-dimerisation of terminal acetylenes with 2-vinyl-1,3-dioxaborolane (B).
onate was added to the reac-
Entry
Conversion [%][b] Selectivity a/b/c/d [%][c] Isolated yield of (a) [%] Product no.
[d]
À
ꢀÀ
R
tion mixture. The [Ru] H
95[a]
92
83/14/3/0
86/14/0/0
71
11
12
13
14
complex was monitored after
24 h (by 1H NMR spectrosco-
py), whereas borylsilyl-substi-
tuted dienes (yield 47%) were
monitored by GC–MS analy-
ses. Reduction of the reso-
nance line characteristic of vi-
nylene–ruthenium complexes
and the appearance of new
lines typical of olefinic protons
also proved the co-dimerisa-
tion route (Figure 1b).
1
2
3
4
84
88
83/17/traces/0
75/25/0/0
74
63
5
78
70/30/traces/0
15
6
7
73
96
89/11/0/0
82/18/0/0
16
17
[borane]=2”10À2:1:3; open
[a] Reaction conditions unless otherwise stated: [Ru(CO)ClHACTHRE(NGU PCy3)2]/[acetylene]/ACHTREUGN
system, toluene (0.5m), t=18 h, T=808C. [b] Substituted acetylene conversion; determined by GC analysis.
1
[c] Determined by GC analysis and H NMR spectroscopy. [d] See the Experimental Section.
During stoichiometric pro-
cesses we also observed evolu-
tion of ethylene (singlet at d=5.25 ppm) in the 1H NMR
À
spectrum. We can explain this fact by formation of the Ru
Bcomplex followed by insertion of the vinylboronate used
in excess to the regenerated (after elimination of borylsilyl-
À
substituted buta-1,3-diene) Ru H complex [see Eq. (6)].
À
the second molecule of acetylene into the Ru vinyl complex
and were also observed in an experiment with [Ru(CO)ClH-
Bis
A
ACHTREUNG
of vinylboronates with termi-
nal acetylenes occurs different-
ly from those with vinylsilanes
and vinylgermanes, as well as
to identify the mechanism of
the co-dimerisation process,
we carried out stoichiometric
reactions of ruthenium hydride
complex [Ru(CO)ClHACHTRE(UNG PCy3)2]
(I) with silylacetylene and vi-
nylboronate.
The first step leads to the
synthesis of a vinylene rutheni-
um complex (two doublets at
d=5.62–5.66
and
8.80–
8.85 ppm) [see Eq. (5) and Fig-
ure 1a].
The reaction was carried out
for 24 h. After the total disap-
À
pearance of the Ru H bond
(triplet at d=À24.3 ppm), the
Figure 1. a) 1H NMR spectrum of silylvinylene ruthenium complex generated in situ; b) 1H NMR spectrum of
the stoichiometric reaction of silylvinylene ruthenium complex with 2-vinyl-1,3-dioxaborolane, monitored after
24 h.
equimolar amount of vinylbor-
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Chem. Eur. J. 2008, 14, 6679 – 6686

Boryl- and Borylsilyl-Substituted Buta-1,3-dienes
FULL PAPER
pling is also observed in the GC–MS spectrum (for detailed
experiments of vinylborane homocoupling see ref. [3]).
The above-described experiment provides convincing evi-
dence for the mechanism of the new catalytic reaction oc-
acetylene dimerisation (see Tables 1 and 2). The mechanism
of the reaction was proposed to involve the ruthenium vinyl-
idene complex as an active intermediate responsible for this
catalytic process.[19]
curring in the presence of [Ru(CO)ClH
Scheme 2).
ACHTRE(UGN PCy3)2] (I) (see
Conclusion
We have developed a new catalytic route for the efficient
coupling of vinylboronates with terminal alkynes involving
silylacetylenes (except phenylacetylenes) catalysed by ruthe-
À
nium complexes containing a Ru H bond. This leads to
boryl- and borylsilyl-substituted buta-1,3-dienes in high
yield with a preference for the E,E-diene. It is worth noting
that we have established the optimal reaction parameters to
obtain the target compound without any byproducts.
Experimental Section
General methods: 1H (300 MHz), 13C (75 MHz), 29Si (79 MHz) and
11BNMR (96 MHz) spectra were recorded by using
a
Varian XL
300 MHz spectrometer with samples in
a solution of CDCl3 or
[D8]toluene (C6D5CD3). Chemical shifts are reported in ppm with refer-
1
ence to the residue portion solvent (CH3Cl) peak for H and 13C, to TMS
for 29Si and to BF3–Et2O for 11B. Analytical GC analyses were performed
by using a Varian Star 400CX with a DB-5 fused-silica capillary column
(30 m”0.15 mm) and thermal-conductivity detector (TCD). Mass spectra
of the substrates and products were obtained by GC–MS analysis (Var-
ianSaturn 2100T, equipped with a BD-5 capillary column (30 m) and an
ion-trap detector). Elemental analyses were carried out by using a Vario
EL III system and high-resolution (HR) MS analyses were performed by
using an AMD-402 instrument. Thin-layer chromatography (TLC) was
carried out by using plates coated with 250 mm-thick silica gel (Aldrich
and Merck), and the column chromatography was performed by using
silica gel 60 (70–230 mesh; Fluka). Toluene was dried by distillation using
sodium and hexane from sodium hydride. Liquid substrates were also
dried and degassed by using bulb-to-bulb distillation. All of the reactions
were carried out under a dry argon atmosphere. The chemicals were ob-
tained from the following sources: toluene, dodecane and hexane were
purchased from Fluka; ethyl acetate from POCH; CDCl3 and C6D5CD3
from Dr. Glaser, A.G. Basel. The substituted acetylene was bought from
Aldrich. 2-Vinyl-1,3-dioxaborolane and 2-vinyl-1,3-dioxaborinane were
synthesised according to the literature with some modifications.[20,21] The
ruthenium complexes I–VI were prepared according to the litera-
ture.[3,22–25]
Scheme 2. Mechanism of co-dimerisation of terminal acetylene (silyl
ylene) with vinylboronates.
ACHTREaUNG cet-
ACHTREUNG
The crucial point of this mechanism (contrary to that es-
tablished in vinylsilane and vinylgermane) is the fact that re-
À
action of Ru H with vinylboronate does not compete with
that with acetylene. The latter is preferred in this case to
À
À
yield the Ru vinylene complex (instead of Ru silyl and
À
Ru germyl complexes, which are preferred in the previous
systems[4,5]) directly responsible for the final step yielding
co-dimerisation products.
The co-dimerisation process of inactivated olefins with
terminal acetylenes, such as phenyl and cyclohexyl, was pre-
viously reported to be catalysed by the cationic ruthenium
Representative experimental procedure for synthesis of boryl- and boryl-
silyl-substitutedbuta-1,3-diene : In a typical test, the ruthenium catalyst I
(2 mol%) was dissolved in toluene and placed in a glass ampoule under
an argon atmosphere. The reagents and dodecane as internal standard
(all components 5% by volume), acetylene and vinylborane (usually
used in the molar ratio [Ru]/[acetylene]/[vinylborane] 2”10À2:1:3) were
added. Subsequently, the ampoule was heated to 80–908C and main-
tained at that temperature for 24 h. The progress of the reaction was
monitored by GC and GC–MS analyses. The conversion and chemoselec-
tivity of the reactions and yields were calculated by using the internal
complex [RuCpACHTREUNG(PPh3)2Py] (generated in situ; Cp: cyclopen-
tadienyl) to yield a mixture of E,E- and E,gem-dienes
(1008C, 10 h, NaPF6, pyridine), but neither boryl nor silyl
compounds were studied. Our experiments on the reaction
of vinylboronate with phenyl-, cyclohexyl- and triethylsilyl-
ACHTREUNG
A
N
ACHTREUNG
Chem. Eur. J. 2008, 14, 6679 – 6686
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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6683

B. Marciniec et al.
11BNMR (96 MHz, CDCl 3 258C, BF3 Et2O): d=27.5 ppm; MS (EI): m/z
(%): 308 (7) [M+], 293 (9), 279 (5), 265 (35), 251 (16), 238 (5), 209 (11),
193 (28), 167 (25), 159 (24), 134 (38), 119 (49), 105 (29), 91 (95), 73 (100),
59 (9); HRMS: m/z calcd for C15H21BO2Si [M+]: 272.14038; found:
272.13880.
À
standard method. The final products were separated from the residues of
the catalyst and reactants by purification using a silica gel column with
hexane/ethyl acetate (1:1) as eluent. All products of catalytic transforma-
tion of terminal alkynes with vinylboronates were pale yellow oily liq-
uids.
Experimental procedure for stoichiometric reaction: Complex I (0.01 g,
0.012 mmol), triethylsilylacetylene (0.01 g, 0.018 mmol) and [D8]toluene
(0.6 mL) were placed in an NMR tube under an argon atmosphere. The
2-[(1E,3E)-Nona-1,3-dienyl]-1,3-dioxaborinane (4): MS (EI): m/z (%):
208 (43) [M+], 193 (11), 179 (23), 165 (47), 151 (27), 138 (27), 123 (13),
110 (30), 93 (57), 79 (100), 67 (54), 53 (13).
À
reaction was carried out at 1008C and after disappearance of Ru H and
A
(5):
appearance of Ru CH=CH SiEt3 bonds (monitored by 1H NMR spec-
À
À
Compound 5 was prepared from the appropriate starting materials ac-
cording to the above procedure for 1. The reaction afforded 5 as a pale
yellow liquid (0.196 g, 0.77 mmol, 78% isolated yield). 1H NMR
À
tra), 2-vinyl-[1,3,2]dioxaborinane (0.019 mmol) was added and the course
1
of the reaction was monitored by using H NMR spectroscopy.
Syntheses
(300 MHz, CDCl3, 258C): d=0.59 (quartet, JACHTRE(UNG H,H)=7.9 Hz, 6H; Si
CH2 CH3), 0.92 (t, J
(H,H)=5.5 Hz, 2H; BOCH2CH2CH2O), 4.04 (t, JACHTREUNG
ACHTREUNG(1E,3E)-1-(1’,3’-Dioxaborinan-2’-yl)-4-cyclohexylbuta-1,3-diene (1): Com-
G
plex I (0.015 g, 0.02 mmol), toluene (1 mL), 1-ethynylcyclohexane (0.11 g,
1 mmol) and 2-vinyl-1,3-dioxaborinane (0.34 g, 3 mmol) were placed in a
glass ampoule and heated under an argon atmosphere at 808C for 18 h.
Then the excess of borane and solvent were removed under vacuum and
the crude product was separated from the residues of the catalyst and re-
actants using a column of silica gel (hexane/ethyl acetate 1:1) to afford 1
BOCH2), 5.44 (d, J
18.4 Hz, 1H; CH=CH Si), 6.58 (dd, J
ACHTREUNG
À
À
CH Si), 6.89 ppm (dd,
13C NMR (75 MHz, CDCl3, 258C): d=3.35 (Si CH2CH3), 7.32 (Si
À
À
CH2CH3), 27.39 (BOCH2CH2), 61.76 (BOCH2CH2), 134.47 (Si CH=CH ),
147.07 (B CH=CH ), 149.75 (Si CH=CH ); Ca to boron atom is not
as
a pale yellow liquid (0.163 g, 0.740 mmol, 74% isolated yield).
observed in 13C NMR spectrum; 11BNMR (96 MHz, CDCl 3 258C, BF3
1H NMR (300 MHz, CDCl3, 258C): d=0.85 (t, 4H; C6H11), 1.25 (br, 2H;
C6H11), 1.69 (br, 4H; C6H11), 0.83–1.65 (brm, 10H; C6H11), 1.30 (s, 3H;
À
Et2O): d=27.6 ppm; 29Si NMR (79 MHz, CDCl3, 258C, TMS): d=
À0.83 ppm; MS (EI): m/z (%): 237 (1) [M+À15], 223 (76), 209 (2), 195
(100), 181 (4), 167 (45), 153 (6), 139 (32), 109 (58), 81 (25), 59 (16); ele-
mental analysis calcd (%) for C13H25BO2Si: C 61.90, H 9.99; found: C
61.99, H 10.12.
CCH3), 1.96 (quintet, J
E
ACHTREUNG(H,H)=5.5 Hz, 2H; BOCH2CH2CH2O), 4.03 (t, J-
À
À
À
CH), 5.78 (d, J
9.9, 15.4 Hz, 1H; CH=CH C), 6.89 ppm (dd, J
G
U
1H; B CH=CH ); 13C NMR (75 MHz, CDCl3, 258C): d=25.91 (3,5-
C6H5), 26.1 (4-C6H5), 27.4 (BOCH2CH2), 32.5 (2,6-C6H5), 40.7 (1-C6H5),
AHCTRE(UGN 1E,3E)-1-Tri(isopropylsilyl)-4-(1’,3’-dioxaborinan-2’-yl)buta-1,3-diene
À
(6): Compound 6 was prepared from the appropriate starting materials
according to the above procedure for 1. The reaction afforded 6 as a pale
yellow liquid (0.232 g, 0.788 mmol, 79% isolated yield). 1H NMR
À
62.7 (BOCH2CH2), 129.8 (CH=CH C), 144.2 (CH=CHC), 148.1 ppm
(B CH=CH); Ca to boron atom is not observed; 11BNMR (96 MHz,
À
+
À
CDCl3 258C, BF3 Et2O): d=27.6 ppm; MS (EI): m/z: 220 (49) [M ], 205
(300 MHz, CDCl3, 258C): d=0.97–1.14 (m, 21H; Si CH (CH3)2), 1.97
(quintet, (H,H)=5.5 Hz, 2H; BOCH2CH2CH2O), 4.04 (t, (H,H)=
(H,H)=17.6 Hz, 1H; B CH=CH), 5.94
(11), 177 (32), 164 (61), 151 (7), 138 (17), 121 (69), 110 (28), 105 (43), 91
(54), 79 (100), 67 (54); HRMS: m/z calcd for C13H21BO2 [M+]: 220.16347;
found: 220.16193.
JACHTREUNG
5.5 Hz, 4H; BOCH2), 5.45 (d, JACHTREUNG
(d,
À
18.4 Hz, 1H; CH=CH Si), 6.90 ppm (dd, J
CH=CH ); C NMR (75 MHz, CDCl3, 258C): d=10.85 (Si CH
18.58 (Si CH
ACHTREUNG(1E,3E)-1-(1’,3’-Dioxaborinan-2’-yl)-5-methyl-5-trimethylsiloxyhepta-1,3-
(CH3)2),
diene (2): Compound 2 was prepared from the appropriate starting mate-
rials according to the above procedure for 1. The reaction afforded 2 as a
colourless liquid (0.186 g, 0.659 mmol, 66% isolated yield). 1H NMR
À
À
(Si CH=CH ), 147.84 (B CH=CH ), 150.02 ppm (Si CH=CH ); Ca to
boron atom is not observed in 13C NMR spectrum; 11BNMR (96 MHz,
(300 MHz, CDCl3, 258C): d=0.09 (s, 9H; OSi ACHTREU(NG CH3)3), 0.81 (t, 3H;
CDCl3 258C, BF3 Et2O): d=27.8 ppm; 29Si NMR (79 MHz, CDCl3,
CCH2CH3), 1.30 (s, 3H; CCH3), 1.51 (quartet, 2H; CCH3), 1.97 (quintet,
258C, TMS): d=À0.45 ppm; MS (EI): m/z (%): 251 (78) [M+À43], 223
(26), 209 (100), 193 (3), 181 (88), 165 (35), 153 (54), 139 (40), 123 (56),
111 (38), 95 (47), 81 (18), 59 (26); elemental analysis calcd (%) for
C16H31BO2Si: C 65.29, H 10.62; found: C 65.35, H 10.69.
J
ACHTREUNG(H,H)=5.5 Hz, 2H; BOCH2CH2CH2O), 4.04 (t, JACHTRENUG
À
BOCH2), 5.43 (d, J
G
ACHTREUNG
À
À
À
15.4 Hz, 1H; CH=CH C), 6.17 (dd, J
(H,H)=10.4, 15.4 Hz, 1H; CH=
À
À
À
CH C), 6.90 ppm (dd,
JACHTRE(GNU H,H)=10.4, 17.6 Hz, 1H; B CH=CH );
13C NMR (75 MHz, CDCl3, 258C): d=2.48 (OSi
(CH3)3), 8.39
ACHTRE(UGN 1E,3E)-1-(Dimethyl(tert-butyl)silyl)-4-(1’,3’-dioxaborinan-2’-yl)buta-1,3-
À
U
(CCH2CH3), 26.84 (CCH3), 27.39 (BOCH2CH2), 36.35 (CCH2CH3), 61.75
diene (7): Compound 7 was prepared from the appropriate starting mate-
rials according to the above procedure for 1. The reaction afforded 7 as a
pale yellow liquid (0.204 g, 0.809 mmol, 81% isolated yield). 1H NMR
(300 MHz, CDCl3, 258C): d=0.04 (s, 6H; Si
E
À
À
À
(BOCH2CH2), 75.82 (CCH2CH3), 129.59 (C CH=CH ), 144.22 (B CH=
À
À
À
CH ), 147.20 ppm (C CH=CH ); Ca to boron atom is not observed in
13C NMR spectrum; BNMR (96 MHz, CDCl 3, 258C, BF3 Et2O): d=
11
À
27.7 ppm; MS (EI): m/z (%): 282 (11) [M+], 267 (11), 253 (97), 193 (16),
183 (19), 159 (58), 145 (6), 131 (26), 117 (29), 105 (16), 93 (35), 73 (100),
59 (7); HRMS: m/z calcd for C15H27BO3Si [M+]: 282.18225; found:
282.18308.
À
J
CH), 6.01 (d, J
10.2, 18.4 Hz, 1H; CH=CH Si), 6.76 ppm (dd, J
A
À
1H; B CH=CH ); C NMR (75 MHz, CDCl3, 258C): d=À6.25 (Si
ACHTREUNG(1E,3E)-1-(1’,3’-Dioxaborinan-2’-yl)-4-(1’’-trimethylsiloxycyclohex-1’’-
A
yl)buta-1,3-diene (3): Compound 3 was prepared from the appropriate
starting materials according to the above procedure for 1. The reaction
afforded 3 as a colourless liquid (0.216 g, 0.700 mmol, 70% isolated
À
61.77 (BOCH2CH2), 135.24 (Si CH=CH ), 147.02 (B CH=CH ),
149.60 ppm (Si CH=CH ); Ca to boron atom is not observed in
13C NMR spectrum; 11BNMR (96 MHz, CDCl 3 258C, BF3 Et2O): d=
1
À
yield). H NMR (300 MHz, CDCl3, 258C): d=0.07 (s, 9H; OSi
0.83–1.65 (brm, 10H; C6H10), 1.30 (s, 3H; CCH3), 1.97 (quintet, J
(CH3)3),
(H,H)=
27.7 ppm; 29Si NMR (79 MHz, CDCl3, 258C, TMS): d=0.34 ppm; MS
(EI): m/z (%): 237 (2) [M+À15], 195 (100), 137 (81), 125 (19), 109 (7), 95
(34), 73 (11), 59 (11); elemental analysis calcd (%) for C13H25BO2Si: C
61.90, H 9.99; found: C 61.95, H 10.05.
N
5.5 Hz, 2H; BOCH2CH2CH2O), 4.04 (t, JACHTREUNG
À
5.44 (d, J
A
G
À
À
À
1H; CH=CH C), 6.18 (dd, J
(H,H)=10.2, 15.7 Hz, 1H; CH=CH C),
À
6.89 ppm (dd,
(H,H)=10.2, 17.6 Hz, 1H; B CH=CH ); 13C NMR
ACHTRE(UGN 1E,3E)-1-(Dimethylphenylsilyl)-4-(1’,3’-dioxaborinan-2’-yl)buta-1,3-
(75 MHz, CDCl3, 258C): d=2.57 (OSi
(CH3)3), 22.28 (3,5-C6H10), 25.72
(4-C6H10), 27.39 (BOCH2CH2), 38.35 (2,6-C6H10), 61.76 (BOCH2CH2),
diene (8): Compound 8 was prepared from the appropriate starting mate-
rials according to the above procedure for 1. The reaction afforded 8 as a
pale yellow liquid (0.215 g, 0.789 mmol, 79% isolated yield). 1H NMR
À
À
À
À
74.07 (1-C6H10), 130 (C CH=CH), 144.18 (B CH=CH ), 147.32 ppm
(C CH=CH ); Ca to boron atom is not observed in 13C NMR spectrum;
(300 MHz, CDCl3, 258C): d=0.034 (s, 6H; Si ACHTRE(UNG CH3)2), 1.97 (quintet, J-
À
À
6684
www.chemeurj.org
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2008, 14, 6679 – 6686

Boryl- and Borylsilyl-Substituted Buta-1,3-dienes
FULL PAPER
A
G
(BO2C2H4), 127.8 (C6H5), 129.1 (C6H5), 133.8 (C6H5), 137.0 (CH=CHSi),
À
À
BOCH2), 5.49 (d, J
N
C
146.9 (B CH=CH), 152.3 ppm (HC=CHSi); Ca to boron atom is not ob-
18.1 Hz, 1H; CH=CH Si), 6.63 (dd, J
U
served; 11BNMR (96 MHz, CDCl 3 258C, BF3 Et2O): d=7.7 ppm; MS
À
À
À
À
(EI): m/z (%): 257 (3) [M+À1], 243 (35), 228 (3), 215 (58), 187 (100), 171
(64), 157 (87), 135 (30), 129 (93), 87 (56), 77 (46); elemental analysis
calcd (%) for C13H21BO2Si: C 65.12, H 7.42; found: C 65.00, H 7.51.
À
À
À
CH Si), 6.91 (dd, J
(H,H)=10.1, 17.6 Hz, 1H; B CH=CH ), 7.36 (m,
3H; m,p-C6H5), 7.46 ppm (m, 2H; o-C6H5); 13C NMR (75 MHz, CDCl3,
À
258C): d=À2.68 (Si
(CH3)2), 27.37 (BOCH2CH2), 61.77 (BOCH2CH2),
127.76 (C6H5), 128.99 (C6H5), 133.84 (C6H5), 135.09 (Si CH=CH ),
À
À
AHCTRE(UGN 1E,3E)-1-(1’,3’-Dioxaborolan-2’-yl)-5-methyl-5-trimethylsiloxyhepta-1,3-
diene (15): MS (EI): m/z (%): 268 (9) [M+], 253 (7), 239 (90), 145 (18),
À
À
À
147.37 (B CH=CH ), 149.26 ppm (Si CH=CH ); Ca to boron atom in
13C NMR spectrum; 11BNMR (96 MHz, CDCl 3 258C, BF3-Et2O): d=
27.7 ppm; 29Si NMR (79 MHz, CDCl3, 258C, TMS): d=À22 ppm; MS
(EI): m/z (%): 271 (6) [M+À1], 257 (36), 215 (19), 199 (33), 187 (26), 171
(41), 157 (65), 143 (65), 121 (36), 101 (100), 91 (38) 77 (50), 59 (15);
HRMS: m/z calcd for C15H21BO2Si [M+]: 272.14038; found: 272.13880.
119 (12), 105 (8), 73 (100), 67 (5).
AHCTRE(UGN 1E,3E)-1-(1’,3’-Dioxaborolan-2’-yl)-4-(1’’-trimethylsiloxycyclohex-1’’-
yl)buta-1,3-diene (16): MS (EI): m/z (%): 294 (3) [M+], 279 (7), 265 (1),
251 (29), 237 (11), 183 (7), 167 (13), 145 (10), 134 (15), 119 (29), 105 (16),
91 (58), 73 (100), 67 (7).
(1E,3E)-1-Trimethylsilyl-4-(1’,3’-dioxaborinan-2’-yl)buta-1,3-diene
(9):
AHCTRE(UGN 1E,3E)-1-(1’,3’-Dioxaborolan-2’-yl)-4-cyclohexylbuta-1,3-diene (17): MS
MS (EI): m/z (%): 210 (3) [M+], 195 (35) 167 (10), 153 (10), 137 (100),
(EI): m/z (%): 206 (37) [M+], 191 (6), 177 (7), 163 (24), 150 (41), 121
125 (25), 109 (23), 95 (65), 59 (12).
(50), 105 (35), 93 (55), 79 (100), 67 (78), 53 (19).
ACHTREUNG(1E,3E)-1-Triethylgermyl-3-(1’,3’-dioxaborinan-2’-yl)buta-1,3-diene (10):
MS (EI): m/z (%): 269 (100), 268 (78) [M+ÀCH2CH3], 239 (39), 213
(22), 183 (25), 155 (15), 133 (4), 101 (26), 75 (8).
A
(11):
Acknowledgements
Complex I (0.015 g, 0.02 mmol), toluene (1 mL), triethylsilylacetylene
(0.14 g, 1 mmol) and 2-vinyl-1,3-dioxaborolane (0.29 g, 3 mmol) were
placed in a glass ampoule and heated under an argon atmosphere at
808C for 18 h. Then the excess of borane and solvent were removed
under vacuum and the crude product was separated from the residues of
the catalyst and reactants using a column of silica gel (hexane/ethyl ace-
tate 1:1) to afford 11 as a pale yellow liquid (0.169 g, 0.709 mmol, 71%
This work was supported by the project of The Ministry of Science and
High Education (PZB-KBN 118/T09/17).
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isolated yield). 1H NMR (300 MHz, CDCl3, 258C): d=0.61 (q, J
8.0 Hz, 6H; SiCH2CH3), 0.93 (t, J(H,H)=8.0 Hz, 9H; SiCH2CH3), 4.24
(s, 4H; BO2A(CH2)) 5.57 (d, J(H,H)=17.6 Hz, 1H; B CH=CH ), 6.04 (d,
(H,H)=18.5 Hz, 1H; Si CH=CH), 6.60 (dd, J(H,H)=9.9, 18.5 Hz, 1H;
À À
J
À
13C NMR (75 MHz, CDCl3, 258C): d=3.3 (Si
ACHTRE(UGN CH2CH3)3), 7.31 (Si-
A
146.7 (B CH=CH), 152.8 ppm (HC=CHSi); Ca to boron atom is not ob-
served; 11BNMR (96 MHz, CDCl 3 258C, BF3 Et2O): d=6.6 ppm; MS
(EI): m/z (%): 209 (42) [M+À29], 181 (100), 165 (6) 153 (38), 137 (18),
109 (31), 81 (20), 67 (2); elemental analysis calcd (%) for C12H23BO2Si: C
60.51, H 9.73; found: C 60.59, H 9.81.
ACHTREUNG(1E,3E)-1-Tri(isopropylsilyl)-4-(1’,3’-dioxaborolan-2’-yl)buta-1,3-diene
(12): MS (EI): m/z (%): 252 (14) [M+À28], 237 (100), 209 (33), 195 (84),
181 (8) 167 (42), 151 (47), 137 (23), 123 (69), 109 (24), 95 (52), 81 (19), 67
(7), 59 (27).
ACHTREUNG(1E,3E)-1-(Dimethyl(tert-butyl)silyl)-4-(1’,3’-dioxaborolan-2’-yl)buta-1,3-
diene (13): Compound 13 was prepared from the appropriate starting
materials according to the above procedure for 11. The reaction afforded
13 (0.176 g, 0.738 mmol, 74% isolated yield) as a pale yellow liquid.
1H NMR (300 MHz, CDCl3, 258C): d=0.05 (s, 6H; Si
0.87 (s, 9H; Si
(H,H)=17.6 Hz, 1H; B CH=CH), 6.09 (d, J
CH=CH), 6.60 (dd, J(H,H)=10.7, 18.1 Hz, 1H; CH=CH Si), 7.00 ppm
(dd,
(H,H)=10.0, 17.6 Hz, 1H; B CH=CH ); 13C NMR (75 MHz,
CDCl3, 258C): d=16.65 (Si(CH3)2(C(CH3)3)), 26.4 (Si(CH3)2(C(CH3)3)),
À À
A
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65.6 (BO2C2H4), 137.1 (CH=CHSi), 146.7 (B CH=CH), 152.7 ppm (HC=
CHSi); Ca to boron atom is not observed; 11BNMR (96 MHz, CDCl 3
+
258C, BF3 Et2O): d=7.6 ppm; MS (EI): m/z (%): 181 (100) [M À57],
137 (100), 95 (87), 73 (12), 57 (6); elemental analysis calcd (%) for
C12H23BO2Si: C 60.51, H 9.73; found: C 60.63, H 9.85.
´
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ACHTREUNG(1E,3E)-1-(Dimethylphenylsilyl)-4-(1’,3’-dioxaborolan-2’-yl)butadi-1,3-
ene (14): Compound 14 was prepared from the appropriate starting ma-
terials according to the above procedure for 11. The reaction afforded 14
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pp. 941–1024.
(0.163 g, 0.631 mmol, 63% isolated yield) as
a pale yellow liquid.
1H NMR (300 MHz, CDCl3, 258C): d=0.37 (s, 6H; Si
ACHTRE(UGN CH3)2), 4.25 (s,
À
À
4H; BO
A
G
U
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2002, 67, 4316–4324.
À
CH=CH Si), 7.03 (dd, J
(H,H)=9.9, 17.9 Hz, 1H; B CH=CH ), 7.38
(t, 1H; p-C6H5), 7.51 (t, 2H; m-C6H5), 7.60 ppm (d, 2H; o-C6H5);
13C NMR (75 MHz, CDCl3, 258C): d=À2.76 (Si
ACHRTUNEG(CH3)2CAHTREU(NG C6H5)), 65.6
Chem. Eur. J. 2008, 14, 6679 – 6686
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
6685

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Received: March 20, 2008
Published online: June 13, 2008
6686
www.chemeurj.org
ꢀ 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2008, 14, 6679 – 6686