Platinum catalysed hydrosilylation of propargylic alcohols

Article abstract of DOI:10.1039/c3ob40496j

A facile and user-friendly protocol has been developed for the selective synthesis of E-vinyl silanes derived from propargylic alcohols using a PtCl ₂/XPhos catalyst system. The reaction is generally high yielding and provides a single regioiso

Full text of DOI:10.1039/c3ob40496j

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Platinum catalysed hydrosilylation of propargylic
alcohols†
Cite this: DOI: 10.1039/c3ob40496j
Catherine A. McAdam,a Mark G. McLaughlin,a Adam J. S. Johnston,a Jun Chen,a
Magnus W. Walterb and Matthew J. Cook*a
A facile and user-friendly protocol has been developed for the selective synthesis of E-vinyl silanes
derived from propargylic alcohols using a PtCl2/XPhos catalyst system. The reaction is generally high
yielding and provides a single regioisomer at the β-position with E-alkene geometry. The reaction is extre-
mely tolerant of functionality and has a wide scope of reactivity both in terms of alkynes and silanes
used. The catalyst loading has been investigated and it is found that good reactivity is observed at extre-
mely low catalyst loadings. This methodology has also been extended to a one-pot hydrosilylation
Denmark–Hiyama coupling.
Received 11th March 2013,
Accepted 10th May 2013
DOI: 10.1039/c3ob40496j
www.rsc.org/obc
altering the nature of the Cu(I) species involved.10–13 Organo-
chromium species have proven to be of great use in the for-
Introduction
Vinyl silanes are useful intermediates which can undergo a mation of vinyl silanes from aldehydes, which react selectively
wide range of chemical transformations.1 The use of silanes as over ketones.14–17 Further molecular complexity of these sub-
a protecting group for oxygen functionalities is, of course, well strates can be achieved through Mizoroki–Heck type cross-
documented, and much interest has focused on their use in coupling reactions18 and Peterson olefinations.19
low cost, non-toxic routes to the formation of carbon–carbon
The hydrosilylation of alkynes is a powerful method of
bonds. These include Sakurai allylations,2 fluoride mediated forming vinyl silanes in a stereocontrolled manner.9,20 There
Hiyama cross-coupling,3 and the fluorine-free Denmark– are many catalysts that promote this reaction and late tran-
Hiyama cross-coupling variation4 and a number of copper sition metal catalysts have been shown to be especially
mediated oxygen–carbon silicon migrations have been efficient.21,22 There are two regioisomeric products alongside
reported in the last decade.5 They have also found use in the E/Z isomers available in this reaction. In the case of pro-
formation of carbon–oxygen bonds through Tamao–Fleming pargylic alcohols the two regioisomers are referred to as the α
oxidation6 and the development of an epoxidation–oxidation and the β-isomers where the silyl group is located α and β to
reaction sequence.7,8
the alcohol and affords 1,1 or 1,2-substituted vinyl silanes,
There are many methods for the preparation of vinyl respectively (eqn (1)).
silanes.9 The most widely used of these methods centre
around the use of either hydrosilylation or other silylmetalla-
tion reactions. The majority of existing methods do not toler-
ate the incorporation of further functionality in either the
substrate or the silane used, thus severely limiting their utility
in synthesis. Such methods include the use of silylcuprates,
ð1Þ
developed by Fleming and later modified by Lipshutz, with
each isomer of the vinyl silane being formed selectively by
Ruthenium complexes are especially efficient at producing
the internal α-isomer with high selectivity. Trost and co-
workers have investigated this reaction extensively, firstly using
a cyclopentadienyl ruthenium complex to perform the desired
hydrosilylation with moderate stereoselectivity.22 Further inves-
tigation led to the development of a highly active and selective
cationic catalyst, [Cp*Ru(MeCN)3]PF6, which gives the α-vinyl-
silane in a >20 : 1 ratio.23 The Lewis acid catalysed hydrosilyl-
ation of a range of alkynes with diverse functionality, as
developed by Yamamoto,24–27 also affords the α-isomer as a
single product, although this method is still in its infancy.
aSchool of Chemistry and Chemical Engineering, Queen’s University Belfast, Belfast,
BT9 5AG Northern Ireland, UK. E-mail: m.cook@qub.ac.uk;
Fax: +44 (0) 28 90976524; Tel: +44 (0) 28 90974682
bEli Lilly and Company Limited, Erl Wood Manor, Windlesham, Surrey GU20 6PH,
UK
†Electronic supplementary information (ESI) available: Details of starting
material synthesis and spectra of the compounds reported (1H and 13C NMR) are
included. See DOI: 10.1039/c3ob40496j
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The majority of transition metal catalysed hydrosilylation chloride for the secondary and tertiary propargylic alcohols,
reactions give the β-isomer as the major product.28,29 Metals respectively.
such as rhodium,30–35 ruthenium36–38 and titanium39 have
Herein we report a full investigation into the scope and
proven useful. Platinum complexes are by far the most well limits of these hydrosilylation reactions including the use of
developed catalysts for the hydrosilylation of alkynes, affording highly functionalised substrates.
the β-isomer, in the E-geometry as the major product.21,40
Complexes such as Speier’s catalyst [H2PtCl6] and Karstedt’s
catalyst [Pt2(dvs)3] (dvs = 1,3-divinyl-1,1,3,3-tetramethyldisil-
Results and discussion
Optimisation of Pt catalysed hydrosilylation
oxane) can produce high catalyst turnovers; however, both the
regio and E/Z selectivity can be poor.41–43
We began investigating the hydrosilylation of commercially
available but-3-yn-2-ol (Table 1). Using 5 mol% PtCl2 and
10 mol% XPhos the reaction afforded the vinyl silane as a
single regio- and geometric isomer in excellent yield (entry 1).
When the reaction was carried out in the absence of ligand,
the regioselectivity fell to 9 : 1 (entry 2). Further optimisation
of the transformation led to a reduction of the amount of cata-
lyst needed, and at 1 mol% PtCl2 excellent yields were still
being obtained (entry 4). If the catalyst loading is dropped
further, the reaction becomes sluggish and lower yields are
A solution to this problem was found through the use of bulky
obtained (entry 5). The amount of silane can also be reduced,
trialkylphosphine ligands44–47 and more recently the use of
but once again a noticeable slowing of the reaction is observed
platinum N-heterocyclic carbene complexes.48–52 These steri-
cally encumbered catalysts can impart high levels of selectivity
(entry 6).
on the reactions. Of note was the development of the (dvs)Pt-
Hydrosilylation of secondary propargylic alcohols
Pt-Bu3 catalyst which exhibits excellent catalytic activity and a
With the optimised reaction conditions in hand, we began by
high level of selectivity. The drawbacks to these methods are
examining the scope of the reaction using secondary propargyl
the cost of the Pt(0) precatalysts and the pyrophoric nature of
alcohols (Table 2). We soon discovered that propargyl alcohol
the phosphines required.
itself was a very poor substrate for this reaction with only 47%
yield of the vinyl silane 2a being produced. Contrary to this, a
wide range of alkyl substituents were well tolerated, including
linear 2b–c and branched groups 2d–e all providing good
yields of the corresponding hydrosilylated product. Our atten-
tion then turned to vinyl and aryl substituents. A styrenyl
derivative 2f was well tolerated as were many aromatic groups
2g–l even including aryl groups bearing ortho-substituents 2m
that are tolerated albeit in a reduced yield. We also examined
Alami reported that a combination of Pt(II) salts and bulky di-
heterocycles 2n–q, especially those containing basic nitrogen
alkylarylphosphines,53 such as XPhos, catalysed the hydrosilyl-
atoms to test whether these would inhibit the catalyst. Gratify-
ation of alkynes, with one example of propargyl alcohol itself
ingly, these were all good substrates providing the requisite
reported.54 The reaction proceeded in good yields and excel-
lent selectivities; however, a large catalyst loading is required,
Table 1 Optimisation studies
typically 5 mol% Pt and 10 mol% phosphine.
We required a rapid and reliable method for the synthesis
of β-silyl alyllic alcohols that was tolerant of significant steric
encumbrance.55 Panek previously disclosed the use of the
highly reactive (dvs)Pt-Pt-Bu3 catalyst for the regioselective
hydrosilylation of propargylic alcohols;56,57 however, no
examples of sterically congested or tertiary propargylic alco-
hols were reported. We speculated that we could modify the
reaction reported by Alami to combine the catalytic activity of
the bulky Pt(0) catalyst with the selectivity and operational
ease of the air stable Pt(II) system. We discovered that the
PtCl2/XPhos catalyst system was very efficient for propargylic
alcohols vida infra.58 Under these conditions the catalyst
Entry
mol% PtCl2/XPhos
Equiv. R3SiH
β : α ratioa
Yieldb (%)
1
2
3
4
5
6
5/10
5/10
2/4
1/2
0.5/1
1.6
1.6
1.5
1.5
1.5
1.1
>99.1
>91.9
>99.1
>99.1
>99.1
>99.1
93
72
93
91
74
83
1/2
a Determined by 1H NMR of the crude. b Isolated yield of the pure
loading could be lowered to 1 mol% and 0.5 mol% platinum(II) isomer.
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vinyl silane in moderate to high yields in all cases. In general
these heterocyclic substrates afforded slightly lower yields and
required prolonged reaction times compared to their less func-
tionalised counterparts. When the hydrosilylation was
attempted using the ortho-chloroaryl derivative 1r, no reaction
was observed. Both increasing the reaction time and the cata-
lyst loading did not afford any product, with starting material
recovered in each case. This class of substrate is the only one
we have found so far to be ineffective for this reaction.
Table 2 Secondary propargylic alcohols
Hydrosilylation of tertiary propargylic alcohols
We next turned our attention to tertiary propargylic alcohols as
prior to our original communication the hydrosilylation of hin-
dered propargylic alcohols was not widely reported except in
the presence of non-commercial specialist ligands.59 We found
that the PtCl2/XPhos system was especially efficient for the
hydrosilylation of tertiary propargylic alcohols and that
0.5 mol% of PtCl2 could be used to give excellent yields. We
have further expanded the scope of the reaction and found
that it is tolerant of a wide range of functional groups
(Table 3).
We began by examining simple alkyl substituents 4a–c and
found that these underwent the hydrosilylation reaction in
excellent yields. Similarly, aryl substituents, both with one and
two aryl groups 4d–f, were tolerated. Fluoroalkyl groups could
be included in 4g as could heterocycles, with thiophene 4h
substituents easily incorporated. Our attention then turned to
cyclic tertiary propargylic alcohols. A wide range of cyclic alkyl
substituents were addressed in this reaction, all of which pro-
ceeded in good to excellent yields 4i–n. Substituents on these
carbocycles were also tolerated with a difluoromethylene and
ketal groups 4o–p, alongside fused aromatics 4q–r being
installed with little effect on the yields of the reaction. Finally
we examined heterocyclic substrates, with nitrogen containing
heterocycles performing well in this reaction, including azeti-
dines 4s, piperidines 4t and even tropanes 4u to afford good
yields of vinyl silanes, albeit with a substantial increase in the
required reaction time. Chalcogen containing heterocycles 4v–w
were also examined, with the reaction proceeding in a similar
fashion to their carbocyclic analogues providing the corres-
ponding vinyl silanes in good to excellent yields.
Catalyst loading studies
As the reaction is highly efficient for tertiary propargylic alco-
hols, using just 0.5 mol% catalyst loading, we examined the
effect of further reducing the amount of catalyst and whether
this would have a negative effect on the reaction (Table 4).
Halving the catalyst loading to 0.25 mol% proved to have very
little effect on the reaction and further reductions showed that
this system still gave synthetically useful yields when dropped
to as low as 0.05 mol%. Further reductions, to 0.025 and
0.01 mol%, were possible; however, the reaction slows signifi-
cantly. A prolonged reaction time appears to counteract this to
some degree, leading to the conclusion that the catalyst is
stable for extended periods of time; hence, further reductions
in catalyst loading could be possible if required. A TON of 6900
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Table 3 Tertiary propargylic alcohols
was achieved which shows the catalyst’s stability and applica-
bility. It is difficult to directly compare to other catalysts as our
studies were performed using PhMe2SiH and most other
hydrosilylation catalysts are tested against Et3SiH as a stan-
dard. In general, Et3SiH is a more reactive silane with TONs of
around 70 000 being achieved in certain cases.59 Our catalyst
system does, however, benefit from excellent stability and func-
tional group tolerance, making it a very practical method.
Table 4 Catalyst loading studies
Entry
Pt loading
Time (h)
Yielda
1
2
3
4
5
6
0.5 mol%
0.25 mol%
0.1 mol%
0.05 mol%
0.025 mol%
0.01 mol%
16
16
16
16
40
90
94%
93%
83%
81%
73%
69%
Use of other silanes
As all of the examples shown in Tables 1–4 utilised phenyldi-
methylsilane, we then began examining the use of other com-
mercially available silanes. We found that the reaction is
tolerant of a wide range of silanes, with the triethylsilyl 5a,
a Isolated yield of a single isomer.
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tert-butyldimethylsilyl 5c, benzyldimethylsilyl 5d triphenylsilyl
5e and triethoxysilyl 5f derivatives formed in good yields.
When tri-iso-propylsilane was used no reaction was observed
with quantitative recovery of starting material. Presumably the
increased steric bulk of the silane prevents the reaction from
occurring. Interestingly when diphenyl silane and phenylsilane
were used, two or three sequential hydrosilylations could be
carried out on the same silicon atom, forming dimers and
trimers of the propargylic alcohols (Table 5).60
Table 5 Other silanes
Our attention next turned to the hydrosilylation using bis-
(dimethylsiloxane) to allow subsequent Hiyama couplings.
Unfortunately this afforded poor isolated yields, although
there was complete conversion to the vinylsilane from analysis
of the crude reaction mixture suggesting that the product 5h
was unstable for silica gel chromatography. To circumvent this
issue, a one-pot Denmark–Hiyama coupling was attempted.61
The hydrosilylation occurred in good conversion using the
standard conditions and then simply cooling the reaction,
adding TBAF followed by Pd2dba3 and iodobenzene afforded a
very facile cross-coupling which gave 72% yield after just
10 minutes (eqn (2)).
ð2Þ
a Using 0.5 equivalent of Ph2SiH2. b Using 0.3 equivalent of PhSiH3.
Alami observed this effect when applied to the palladium cata-
lyzed hydrostannylation of 13, with 4 : 1 regioselectivity for
β-substitution being observed.65 They also showed that the
regioselectivity in these systems directly correlated to the
Hammett σ-value for substituted benzene rings. When strong
electron withdrawing groups were present in the para-position
of the benzene ring a single β-regioisomer was obtained
whereas electron releasing groups produce selectivities of the
order of a 3 : 1 β : α ratio.
Similarly when a trimethylsilyl group is installed at the
β-position 17, the product ratio is contrary to the steric
environment (eqn (8)). The mild polarisation of the alkyne
group caused by the silane is enough to override the signifi-
cant steric bias to afford the β-regioisomer 18a as the major
product. If the steric environment at the β-position is
increased greatly by installing a tert-butyl group 19, the regio-
selectivity of the reaction can be switched to give solely the
α-isomer. No traces of the β-isomer 20a were observed with
only the α-isomer 20b being formed in good yield (eqn (9)). A
single regioisomer could again be obtained when the pro-
pargylic position was highly substituted compared to the
β-position 21. In this instance only the β-isomer 20a was
observed again in good yield (eqn (10)). The results in eqn (9)
and (10) demonstrate that the steric environment around the
alkyne plays a pivotal role in determining the selectivity of the
products. However, when the alkyne is polarised and an
Internal alkynes
We also examined internal alkynes to investigate whether the
Lewis basic oxygen atom was co-ordinating to the metal and
directing the addition62 or whether the regioselectivity was
based purely on steric factors. The first substrate attempted
was but-2-yn-1-ol 7, which gave a 1 : 1 mixture of regioisomers
(eqn (3)). This clearly suggests that the oxygen is not directing
the addition and that pure sterics govern the regioselectivity.
This also demonstrates that primary propargylic alcohols can
participate well in this reaction when extra substitution is
present at the β-position as an overall yield of 84% was
obtained. When steric bulk is increased in the propargylic
position the ratio increases to give moderate β selectivity. Alkyl
groups give around 3 : 1 selectivity with methyl 9 affording
2.7 : 1 β : α, butyl 11 3.2 : 1 and when a cyclohexyl group 13 is
introduced a β-selectivity of 3.2 : 1 was observed (eqn (4)–(6)).
This is in line with what one would expect based on the steric
environment of the alkyne.
When the terminal alkyne position of propargyl alcohol was
substituted with a phenyl group 15, modest selectivity was
observed with the β-isomer 16a prevailing in a 4.1 : 1 ratio (eqn (7)).
This is contrary to the steric environment around the alkyne
and is clearly showing preference for hydride attack at the
more electrophilic terminus of the alkyne.23,47,63,64 Indeed,
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electronic bias is present, such as eqn (7) and (8), the regio-
chemistry will be dictated by the attack of the hydridic hydro-
gen at the more electron deficient terminus.
ð3Þ
ð4Þ
ð5Þ
ð10Þ
Similarly, when a trimethylsilyl substituted alkyne was used
the hydrosilylation gave a 2.2 : 1 mixture of β : α isomers. The
reaction proceeds to give a differentially substituted 1,1-vinyl-
disilane. Again the polarising effect of the silane can rational-
ise the regiochemical outcome as the β position is more
electrophilic than the α.
Mechanistic insights
Fig. 1 highlights our model for regioselectivity. In the cases
where there is a steric bias, the large group orientates itself
away from the bulky XPhos ligand. The result of this is the
selective formation of a product with the hydrogen adjacent to
the large group and the silyl group next to the smaller group.
In the case of the electronically biased substrates, the phenyl
or silyl group creates a polarised alkyne and the hydridic
hydrogen on the platinum adds at the more electrophilic ter-
minus thus resulting in the hydrogen adjacent to the less elec-
tron withdrawing group and the silyl group next to the electron
withdrawing substituent. This polarisation appears to be sig-
nificant enough to override the inherent steric bias for one
product over the other.
ð6Þ
We conducted a competition experiment between propargyl
alcohol 1a, but-3-yn-2-ol 1b, and 2-methyl but-3-yn-2-ol 3a
where the reaction was conducted with one equivalent of each
of the substrates and one equivalent of PhMe2SiH to ascertain
the relative rate of reactions. As expected the tertiary alcohol
reacted faster than the secondary which in turn was faster
than the primary in a krel of 2.7 : 1.7 : 1. This proves that the
enhanced reactivity observed for tertiary propargylic alcohols
is due to an inherently faster reaction rate rather than factors
such as product inhibition or catalyst decomposition
(Scheme 1).
We next examined whether the incorporation of deuterium
at the terminal position of the alkyne led to an observable
kinetic isotope effect. Alkyne 23 was readily prepared and was
subjected to competition experiment with its non-deuterated
analogue. Following conversion to 49%, the product 4k/24 was
protioenriched alongside the recovered starting material being
deuteroenriched in the same ratio. Both recovered starting
material and product conversion gave a kH/kD value of 1.44.
This suggests a large secondary kinetic isotope effect consist-
ent with a change in geometry from sp to sp2 during the rate
limiting step (Scheme 2).66
ð7Þ
ð8Þ
ð9Þ
We observed significant evolution of gas, presumably
hydrogen, upon addition of the silane to the reaction mixture.
This led us to examine the origin of this gas. There are several
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Fig. 1 Origin of regioselectivity.
Scheme 2 Alkyne kinetic isotope effect.
Scheme 1 Primary/secondary/tertiary competition experiment.
ð11Þ
possible explanations including: the simple reduction of the Pt(II)
salt to Pt(0) producing H2 and a disilane or the OH bond
reacting directly with the catalyst producing a Pt(OR) type
complex. To probe the effect the O–H bond may have on the
reactivity of this reaction a series of experiments were con-
ducted. Firstly we performed a control experiment with benzyl
alcohol to determine whether any O-silylation was observed
during the reaction (eqn (11)). No reaction or O-silylation was
observed with quantitative recovery of the starting material
being achieved.
We next investigated the use of the methyl ether 27 and
found that the hydrosilylation occurred in a similar overall
yield to the hydroxyl analogue 28 (eqn (12)). This suggests
that the OH is not required for reactivity and to obtain high
yields.
ð12Þ
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Fig. 2 Possible H-bond acceleration of hydrometallation.
reaction was performed using equimolar amounts of 3k and
d1-3a, which was formed in 86% isotopic purity,67 the order of
reactivity was reversed with the dimethyl compound reacting
at a faster rate. As the alcohol was only deuterated to 86% we
had to adjust this value to 100% isotopic purity assuming a
linear relationship and found a krel (3k : d1-3a) of 0.86. This
was then used to measure the kinetic isotope effect which
equated to 0.69 (Scheme 4).
An inverse kinetic isotope effect could be due to several
factors, including a pre-equilibrium; however, the absence of
deuterium in the vinyl silane and the rapid evolution of
hydrogen gas make this unlikely. A more likely scenario is
the OH moiety hydrogen bonding to the hydridic hydrogen
bound to the platinum centre and accelerating the hydrome-
tallation step through mild acid catalysis. Indeed, this is con-
sistent with the hydrometallation step being rate limiting.
This can be seen in Fig. 2 where the OD/OH group can
H-bond to the hydridic hydrogen, thus weakening the Pt–H
bond and accelerating the reaction. This interaction does
explain the rate acceleration; however, one would predict
some regioselectivity based on this, which is not seen in the
case of internal alkynes. Either this chelate is not possible
in the internal cases or this occurs in an intermolecular
fashion.
Scheme 3 Role of the OH bond.
A competition experiment was conducted between the OH
and OMe compounds to elucidate the relative rates of the reac-
tions. The OH compound 3k reacted much faster than the
OMe analogue 27 with a krel of 2.3 being observed, suggesting
that the OH does accelerate the reaction (Scheme 3).
To further probe this effect, we prepared the O-deuterated
analogue and subjected this to the reaction conditions. Again
the reaction proceeded with a similar overall yield and with no
deuterium incorporated into the resultant alkene (eqn (13)).
This suggests that the formation of Pt(OR) complexes is unli-
kely as deuterium would also be delivered to the platinum
catalyst which would in turn be observed in the vinyl silane
product.
ð13Þ
More sterically hindered substrates react much faster in
this reaction and we sought to rationalise this mechanistically.
In the standard Chalk–Harrod mechanism28 for hydrosilyl-
ation of alkynes, there are two events that can occur to lead to
product (Fig. 3): either oxidative addition of the silane followed
by alkyne coordination (Pathway 1) or alkyne coordination fol-
lowed by oxidative addition (Pathway 2). Pathway 1 would
favour relatively small alkynes as the coordination event occurs
on a sterically congested Pt(II) species C. These types of sub-
strates are excellent with Speier’s catalyst and Karstedt’s
catalyst.
Finally, we examined whether there was a OH/OD kinetic
isotope effect which would elucidate the true role of the
alcohol moiety. As this is an exchangeable deuterium measur-
ing the product or recovered starting material, deuterium
enrichment would be difficult. We therefore took two alkynes,
the dimethyl substrate 3a and the cyclohexyl derivative 3k. We
first of all performed a control experiment where we measured
the relative rate of reactions between the two compounds. The
cyclohexyl analogue was found to have a faster rate of reaction
with a krel (3k : 3a) of 1.24 and this was used as a correction
factor in the kinetic isotope effect calculations. When the
Scheme 4 OH kinetic isotope effects.
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Fig. 3 Proposed catalytic cycle.
Our results suggest that Pathway 2 is operating as the major
pathway as more hindered substrates are superior. A large alkyne
Conclusions
can bind to the coordinatively unsaturated Pt(0) species B thus We have shown the effectiveness and robustness of PtCl2/
stabilising this prior to oxidative addition. Alternatively, if a XPhos catalysed hydrosilylation. Both secondary and tertiary
small alkyne is bound to the coordinately unsaturated platinum– propargyl alcohols perform well as do internal alkynes. Fur-
ligand complex F, a second alkyne can then bind, thus removing thermore, the catalyst system is tolerant of various silanes
the coordination sites needed for the oxidative addition reaction. which improves the usefulness of this protocol. A one-pot
The result is that the catalyst is removed from the productive Hiyama–Denmark cross-coupling reaction was also performed
cycle I and the rate of reaction is based on the decomplexation using the catalyst system which allows access to a range of
of the second alkyne. When a bulky alkyne is used the complex- functionalities. We have examined the use of internal alkynes
ation of two substrates is disfavoured, thus leaving the catalytically and have found that this is governed by both steric and elec-
active species available for subsequent oxidative addition to tronic factors.
form G, migratory insertion H and reductive elimination. This
is very clearly demonstrated in the case of propargyl alcohol 1a.
Our experiments suggest that the migratory insertion event
Experimental section
is rate limiting with a large sp–sp2 secondary kinetic isotope
Compounds 2a–2g, 2o, 4a–4d, 4e, 4j–4k and 4v were fully
characterised and reported previously.58 For the synthesis of
the starting alkynes see the ESI.†
effect being observed. This could occur from G or an isomeri-
sation event to D could occur due to the large trans-effect of
both silanes and hydrides. Both complexes would give a
similar result in terms of kinetic isotope effects and therefore
cannot be distinguished.
General methods
It is also possible that the silane can react directly with F in
a concerted manner to proceed directly to H with the same
factors that would govern reactivity as in the two-step com-
plexation migratory insertion process.
All reactions were carried out under an atmosphere of argon in
oven-dried glassware with magnetic stirring. All reactions were
monitored by thin layer chromatography (TLC) using Merck
TLC silica gel 60 sheets, which were visualised with ultraviolet
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light and then developed with iodine and basic potassium per- (500 mg, 2.71 mmol) and dimethylphenylsilane (552 mg,
manganate solution. Flash chromatography was performed on 4.07 mmol) using PtCl2 (7.0 mg, 0.0263 mmol) and XPhos
Sigma-Aldrich silica gel 60 as the stationary phase and the sol- (25.6 mg, 0.0537 mmol) in THF (1 mL) which following the
1
vents employed were of analytical grade. H NMR spectra were conversion to the vinyl silane and column chromatography
recorded on a Bruker AVX400 (400 MHz) spectrometer at (9 : 1 hexane–EtOAc) afforded 2i (660.6 mg, 77%) as a colour-
ambient temperature. Data are reported as follows: chemical less solid.
shift in parts per million (δ, ppm) from deuterated chloroform
Rf (9 : 1 hexane–EtOAc) = 0.41; νmax (thin film)/cm−1; 3434,
(CDCl3) taken as 7.26 ppm, integration, multiplicity (s = 1634, 1247, 1114, 730.8, 699.4; 1H NMR: (400 MHz, CDCl3) δ
singlet; d = doublet; t = triplet; dd = double doublets; m = mul- 7.88–7.83 (4H, m), 7.58–7.47 (5H, m), 7.40–7.36 (3H, m), 6.39
tiplet), and coupling constant (Hz). 13C NMR spectra were (1H, dd, J = 18.6, 5.0 Hz), 6.22 (1H, dd, J = 18.8, 1.5 Hz), 5.41
recorded on a Bruker AVX400 (100 MHz) spectrometer. Chemi- (1H, t, J = 4.0 Hz), 2.18 (1H, s), 0.39 (3H, s), 0.39 (3H, s); 13C
cal shifts are reported in ppm from CDCl3 taken as 77.0 ppm. NMR (100 MHz, CDCl3) δ 148.9, 139.8, 138.4, 133.9, 133.4,
Infrared spectra were recorded on a Perkin Elmer RX I FT-IR 133.1, 129.1, 128.5, 128.1, 128.0, 127.9, 127.7, 126.2, 126.0,
spectrometer as liquid films or as dilute solutions between two 125.2, 124.5, 76.9, −2.6; HRMS (EI) calcd for C21H23OSi [M +
KBr discs. Mass spectra were recorded on either a Micromass H]+ 319.1518. Found 319.1513.
GCT Premier or a Waters Micromass LCT Premier spectro-
(E)-3-(Dimethyl(phenyl)silyl)-1-(4-methoxyphenyl)prop-2-en-
meter using electron ionisation (EI) at 70 eV or electrospray 1-ol (2j). The title compound was prepared according to
(ES) techniques, respectively. Unless stated otherwise, all com- general procedure A, from 1-(4-methoxyphenyl)prop-2-yn-1-ol68
mercially available reagents were used as received. When 1j (500 mg, 3.08 mmol) and dimethylphenylsilane (631 mg,
necessary, commonly used organic solvents were dried prior to 4.64 mmol) using PtCl2 (8.2 mg, 0.0308 mmol) and XPhos
use according to standard laboratory practices.
(29.4 mg, 0.0616 mmol) in THF (1 mL) which following the
conversion to the vinyl silane and column chromatography
(9 : 1 hexane–EtOAc) afforded 2j (643 mg, 70%) as a clear oil.
Rf (9 : 1 hexane–EtOAc) = 0.29; νmax (thin film)/cm−1; 3412,
General procedure A: hydrosilylation secondary propargyl
alcohols
To an oven dried 5 mL round bottom flask equipped with a 2955, 1612, 1512, 1247, 828; 1H NMR: (400 MHz, CDCl3) δ
reflux condenser and magnetic stirrer was added PtCl2 (1 mol%) 7.55–7.50 (2H, m), 7.38–7.35 (3H, m), 7.31–7.27 (2H, m)
and 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (2 mol%) 6.92–6.89 (2H, m), 6.30 (1H, dd, J = 18.6, 4.8 Hz), 6.14 (1H, dd,
(XPhos). The flask was then flushed quickly with argon J = 18.8, 1.5 Hz), 5.19 (1H, t, J = 3.52 Hz), 3.82, (3H, s), 1.95
and dry THF was added. The mixture was then stirred at 50 °C (1H, d, J = 4.0 Hz), 0.37 (3H, s) 0.37 (3H, s); 13C NMR
for 20 minutes until a yellow homogeneous mixture was (100 MHz, CDCl3) δ 159.2, 149.1, 138.4, 134.7, 133.8, 129.0,
obtained. The corresponding propargyl alcohol (1 eq.) was 127.9, 127.8, 114.0, 76.3, 55.3, −2.6; HRMS (EI) calcd for
added followed by the silane (1.1 equivalents) via syringe C18H21O2Si [M − H]+ 297.1311. Found 297.1321.
(CAUTION: Rapid evolution of hydrogen gas) and the solution
(E)-3-(Dimethyl(phenyl)silyl)-1-(4-fluorophenyl)prop-2-en-1-
was stirred at 50 °C overnight. The solvent was evaporated and ol (2k). The title compound was prepared according to general
the crude mixture was applied to the top of a column and chro- procedure A, from 1-(4-fluorophenyl)prop-2-yn-1-ol69 1k
matographed to afford the requisite (E)-vinyl silane.
(350 mg, 2.33 mmol) and dimethylphenylsilane (473 mg,
(E)-3-(Dimethyl(phenyl)silyl)-1-(p-tolyl)prop-2-en-1-ol (2h). The 3.50 mmol) using PtCl2 (6.2 mg, 0.0233 mmol) and
title compound was prepared according to general procedure A XPhos (22.2 mg, 0.0466 mmol) in THF (1 mL) which
from 1-(p-tolyl)prop-2-yn-1-ol68 1h (990 mg, 6.77 mmol) and following the conversion to the vinyl silane and column
dimethylphenylsilane (1.38 g, 10.2 mmol) using PtCl2 chromatography (9 : 1 hexane–EtOAc) afforded 2k (501 mg,
(18.0 mg, 0.0677 mmol) and XPhos (64.3 mg, 0.135 mmol) in 75%) as a clear oil.
THF (2 mL), which following the conversion to the vinyl silane
and column chromatography (9 : 1 hexane–EtOAc) afforded 2h 2956, 1604, 1508, 1223, 838; 1H NMR: (400 MHz, CDCl3) δ
Rf (9 : 1 hexane–EtOAc) = 0.30 νmax (thin film)/cm−1; 3350,
(1.38 g, 72%) as a colourless oil.
7.55–7.50 (2H, m), 7.40–7.30 (5H, m), 7.09–7.03 (2H, m), 6.28
Rf (9 : 1 hexane–EtOAc) = 0.29; νmax (thin film)/cm−1; 3001, (1H, dd, J = 18.6, 4.8 Hz), 6.14 (1H, dd, J = 18.6, 1.3 Hz), 5.22
3068, 2956, 1619, 1427, 248, 1114, 842, 822, 730, 699; 1H NMR: (1H, d, J = 4.5 Hz), 2.07 (1H, s), 0.39 (3H, s), 0.38 (3H, s) 13C
1
(400 MHz, CDCl3) δ 7.53–7.48 (2H, m), 7.37–7.32 (3H, m), NMR (100 MHz, CDCl3) δ 162.3 (d, JC–F = 244.3 Hz), 158.7,
7.25–7.21 (2H, m), 7.18–7.13 (2H, m), 6.28 (1H, m), 6.12 (1H, 138.2, 138.1 (d, JC–F = 3.3 Hz), 133.8, 129.1, 128.1 (d, JC–F
dt, J = 18.8, 1.28 Hz), 5.17 (1H, t, J = 4.3 Hz), 2.43 (3H, s), 1.96 8.3 Hz), 127.9, 127.8, 115.4 (d, JC–F = 21.1 Hz), 76.1, −2.7;
(1H, m), 0.35 (3H, d, J = 2.0 Hz), 0.34 (3H, d, J = 2.0 Hz); 13C HRMS (EI) calcd for C17H17SiF [M − H2O]+ 268.1084. Found
NMR (100 MHz, CDCl3) δ 149.0, 139.5, 138.4, 137.5, 133.7, 268.1103.
4
3
=
2
129.3, 129.0, 127.8, 127.2, 126.5, 76.5, 21.1, −2.65; HRMS (ES+)
(E)-3-(Dimethyl(phenyl)silyl)-1-(3-fluorophenyl)prop-2-en-1-
ol (2l). The title compound was prepared according to general
calcd for C18H22OSiNa [M + Na]+ 305.1330. Found 305.1338.
(E)-3-(Dimethyl(phenyl)silyl)-1-(naphthalen-2-yl)prop-2-en-1- procedure A, from 1-(3-fluorophenyl)prop-2-yn-1-ol 1l (930 mg,
ol (2i). The title compound was prepared according to general 6.18 mmol) and dimethylphenylsilane (1.22 g, 9.27 mmol)
procedure A, from 1-(naphthalen-2-yl)prop-2-yn-1-ol68 1i using PtCl2 (16.4 mg, 0.0618 mmol) and XPhos (63.3 mg,
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0.133 mmol) in THF (5 mL) which following the conversion to to the vinyl silane and column chromatography (9 : 1 hexane–
the vinyl silane and column chromatography (9 : 1 hexane– EtOAc) afforded 2r (297 mg, 61%) as a yellow oil.
EtOAc) afforded 2l (1.31 g, 79%) as a colourless oil.
Rf (9 : 1 hexane–EtOAc) = 0.49; νmax (thin film)/cm−1; 3466,
Rf (9 : 1 hexane–EtOAc) = 0.33; νmax (thin film)/cm−1; 3391, 3068, 2979, 2900, 1724, 1617, 1478, 1427, 1408, 1371, 1342,
3069, 2957, 1613, 1591, 1486, 1449, 1428, 1249, 1115, 844, 699; 1248, 1229, 1162, 1124, 1064, 998, 884, 821, 728, 700; 1H NMR:
1H NMR: (400 MHz, CDCl3) δ 7.55–7.49 (2H, m), 7.43–7.30 (4H, (400 MHz, CDCl3) δ 7.53 (2H, m), 7.47–7.44 (2H, m), 7.35–7.30
m), 7.16–7.08 (2H, m) 7.02–6.96 (1H, m), 6.26 (1H, dd, J = 18.8, (2H, m), 7.17 (1H, m), 6.40–6.34 (1H, dd, J = 18.6, 4.3 Hz), 6.13
5.0 Hz), 6.15 (1H, dd, J = 18.8, 1.2 Hz), 5.23 (1H, t, J = 5.08 Hz), (1H, d, J = 7.8 Hz), 6.10 (1H, d, J = 3 Hz), 6.03–5.99 (1H, m),
2.09 (1H, d, J = 4.0 Hz), 0.38 (3H, s), 0.38 (3H, s); 13C NMR 1.57 (9H, d, J = 11.5 Hz), 0.36 (6H, s); 13C NMR (100 MHz,
1
(100 MHz, CDCl3) δ 163.0 (d, JC–F = 245.6 Hz), 148.2, 145.0 (d, CDCl3) δ 146.9, 136.2, 134.1, 128.9, 127.9, 127.6, 122.3, 114.7,
3
3JC–F = 6.6 Hz), 138.1, 133.8, 133.0, 130.0, (d, JC–F = 8.4 Hz), 113.4, 110.3, 110.1, 84.8, 69.8, 69.0, 27.9, −2.3; HRMS (EI+)
2
129.1, 128.5, 127.8, 122.0, 121.9, 114.5 (d, JC–F = 21.1 Hz), calcd for C16H16Si 236.1021. Found 236.1025.
2
4
113.2 (d, JC–F = 21.9 Hz), 76.2 (d, JC–F = 1.8 Hz), −2.7; HRMS
(ES+) calcd for C17H19OFNaSi [M + Na]+ 309.1087. Found prop-2-en-1-ol (2q). The title compound was prepared accord-
309.1085. ing to general procedure A, from 1-(1,3-diphenyl-1H-pyrazol-4-
(E)-3-(Dimethyl(phenyl)silyl)-1-(1,3-diphenyl-1H-pyrazol-4-yl)
(E)-3-(Dimethyl(phenyl)silyl)-1-(o-tolyl)prop-2-en-1-ol (2m). The yl)prop-2-yn-1-ol 1q (275 mg, 1.01 mmol) and dimethylphenyl-
title compound was prepared according to general procedure silane (150 mg, 1.11 mmol) using PtCl2 (2.7 mg, 0.011 mmol)
A, from 1-(o-tolyl)prop-2-yn-1-ol68,70 1m (102 mg, 0.721 mmol) and XPhos (9.6 mg, 0.020 mmol) in THF (2 mL) which follow-
and dimethylphenylsilane (108 mg, 0.793 mmol) using PtCl2 ing conversion to the vinyl silane and column chromatography
(1.9 mg, 7.21 μmol) and XPhos (6.9 mg, 14.4 μmol) in THF (19 : 1 hexane–EtOAc) afforded 2q (290 mg, 71%) as a colour-
(0.75 mL) which following the conversion to the vinyl silane less oil.
and column chromatography (9 : 1 hexane–EtOAc) afforded 2m
(109 mg, 56%) as a colourless oil.
Rf (9 : 1 hexane–ethyl acetate) = 0.26; IR: νmax (thin film)/
cm−1; 3402, 2953, 1600, 1503, 1426, 1355, 1248, 1113, 1060,
Rf (9 : 1 hexane–EtOAc) = 0.32; νmax (thin film)/cm−1; 3069, 820, 773, 756, 698; H NMR: (400 MHz, CDCl3) δ 7.87 (2H, d,
3001, 2954, 1628, 1427, 1114, 842, 830, 738, 699; 1H NMR: J = 5.0 Hz), 7.83–7.80 (1H, m), 7.77–7.69 (2H, m), 7.61–7.57 (1H,
(400 MHz, CDCl3) δ 7.53–7.46 (2H, m), 7.41–7.32 (3H, m), m), 7.83–7.80 (1H, m), 7.50–7.27 (7H, m), 7.20 (2H, m), 6.37
7.23–7.18 (2H, m), 7.17–7.13 (2H, m), 6.27 (1H, dd, J = 18.6, 4.8 Hz), (1H, dd, J = 18.5, 4.8 Hz), 6.18 (1H, dd, J = 18.5, 1.25 Hz), 5.42
6.11 (1H, dd, J = 18.6, 4.8 Hz), 5.42 (1H, dt, J = 18.8, 1.28 Hz), (1H, s), 0.35 (6H, s); 13C NMR (100 MHz, CDCl3) δ 151.6, 148.1,
2.35 (3H, s), 0.35 (3H, s), 0.34 (3H, s); 13C NMR (100 MHz, 140.0, 139.9, 138.8, 133.8, 133.2, 133.0, 129.4, 129.2, 128.9,
CDCl3) δ 148.4, 134.7, 133.8, 133.0, 130.6, 130.3, 129.7, 128.9, 128.6, 128.3, 127.8, 126.4, 125.7, 124.6, 119.0, 68.6, −2.5, −2.7;
127.8, 126.6, 73.6, 72.9, 32.1, 19.2, 11.7, −2.6; HRMS (ES+) HRMS (ES) calcd for C26H27N2OSi [M + H]+ 256.1647. Found
1
calcd for C18H22OSi [M]+ 282.1493. Found 282.1440.
411.1873.
(E)-3-(Dimethyl(phenyl)silyl)-1-(pyridin-3-yl)prop-2-en-1-ol
(2n). The title compound was prepared according to general
procedure A, from 1-(pyridin-3-yl)prop-2-yn-1-ol 1n71 (257 mg,
General procedure B: hydrosilylation of disubstituted
propargyl alcohols
1.9 mmol) and dimethylphenylsilane (284 mg, 2.09 mmol) To an oven dried 5 mL round bottom flask equipped with a
using PtCl2 (5.1 mg, 19.2 μmol) and XPhos (18.4 mg, reflux condenser and a magnetic stirrer was added PtCl2
38.7 μmol) in THF (0.75 mL) which following the conversion to (0.5 mol%) and 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbi-
the vinyl silane and column chromatography (3 : 2 hexane– phenyl (1 mol%) (XPhos). The flask was then flushed quickly
EtOAc) afforded 2n (271 mg, 53%) as a yellow oil.
with argon and dry THF was added. The mixture was then
Rf (9 : 1 hexane–EtOAc) = 0.35; νmax (thin film)/cm−1; 3290, stirred at 50 °C for 20 minutes until a yellow homogeneous
2853, 2114, 1581, 1427, 1248, 1041, 1028, 947, 823, 710, 634; mixture was obtained. The corresponding propargyl alcohol
1H NMR: (400 MHz, CDCl3) δ 7.94–7.90 (2H, m), 7.72–7.69 (1H, (1 eq.) was added followed by the silane (1.1 eq.) via syringe
m), 7.51–7.47 (2H, m), 7.37–7.30 (4H, m), 6.25 (1H, dd, J = (CAUTION: Rapid evolution of hydrogen gas) and the solution
18.6, 4.8 Hz), 6.17 (1H, dd, J = 18.6, 1.1 Hz), 5.27 (1H, d, J = 4.8 Hz), was stirred at 50 °C overnight. The solvent was evaporated and
1.43 (1H, s), 0.35 (3H, s), 0.35 (3H, s) 13C NMR (100 MHz, the crude mixture was applied to the top of a column and chro-
CDCl3) δ 149.4, 149.2, 148.1, 134.7, 133.8, 129.2, 127.9, 123.6, matographed to afford the requisite (E)-vinyl silane.
75.3, 75.4, 62.1, 61.9, −2.7, −2.7; HRMS (ES+) calcd for
C16H19NOSi 269.1236. Found 269.1293.
(E)-1-(Dimethyl(phenyl)silyl)-4-methyl-3-phenylpent-1-en-3-
ol (4e). The title compound was prepared according to general
(E)-tert-Butyl 2-(3-(dimethyl(phenyl)silyl)-1-hydroxyallyl)-1H- procedure B, from 4-methyl-3-phenylpent-1-yn-3-ol73 3e
pyrrole-1-carboxylate (2p). The title compound was prepared (104 mg, 0.601 mmol) and dimethylphenylsilane (89.9 mg,
according to general procedure A, from tert-butyl 2-(1-hydroxy- 0.661 mmol) using PtCl2 (1.8 mg, 6.61 μmol) and XPhos
prop-2-yn-1-yl)-1H-pyrrole-1-carboxylate72
1p
(302
mg, (5.8 mg, 12.2 μmol) in THF (2 mL) which following the conver-
1.34 mmol) and dimethylphenylsilane (200 mg, 1.47 mmol) sion to the vinyl silane and column chromatography
using PtCl2 (3.6 mg, 13.4 μmol) and XPhos (18.4 mg, (19 : 1 hexane–EtOAc) afforded 4e (154 mg, 83%) as a colour-
0.027 mmol) in THF (1.5 mL) which following the conversion less oil.
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Rf (9 : 1 hexane–EtOAc) = 0.39; νmax (thin film)/cm−1; 3479, 7.40–7.31 (3H, m), 6.38 (1H, d, J = 18.2 Hz), 5.98 (1H, d, J =
3068, 3023, 2960, 1685, 1446, 1427, 1254, 1118, 1048, 998, 832, 18.2 Hz), 1.72 (2H, s), 2.24–2.10 (1H, m), 2.00–1.92 (1H, m),
1
795, 729, 699, 469; H NMR: (400 MHz, CDCl3) δ 7.98 (1H, d, 1.83–1.76 (1H, m), 1.65–1.52 (2H, m), 0.37 (6H, s) 13C NMR
J = 7.0), 7.55–7.51 (2H, m), 7.50–7.46 (1H, m), 7.44 (2H, d, J = (100 MHz, CDCl3) δ 151.6, 138.7, 133.8, 133.0, 129.0, 127.9,
7.8), 7.39–7.29 (4H, m), 6.53 (1H, dd, J = 18.6 Hz), 6.10 (1H, d, 122.7, 36.1, −2.4, −3.2; HRMS (ES+) calcd for C14H20NaOSi
J = 18.8 Hz), 2.24–2.17 (1H, dq, J = 13, 6.8 Hz), 0.90 (6H, d, J = [M + Na+]+ 255.3833. Found 255.3819.
6.8 Hz), 0.35 (3H, s) 13C NMR (100 MHz, CDCl3) δ 151.5, 144.7,
(E)-1-(2-(Dimethyl(phenyl)silyl)vinyl)cycloheptanol (4j). The
133.0, 132.7, 132.2, 128.4, 128.2, 127.2, 126.7, 125.2, 124.6, title compound was prepared according to general procedure B,
79.2, 78.9, 16.3, 15.9, −3.2; HRMS (ES+) calcd for C20H26ONaSi from 1-ethynylcycloheptan-1-ol 3l75 (360 mg, 2.62 mmol) and
[M + Na]+ 333.1651. Found 333.1573.
dimethylphenylsilane (389 mg, 2.86 mmol) using PtCl2
(E)-4-(Dimethyl(phenyl)silyl)-1,1,1-trifluoro-2-phenylbut-3- (3.5 mg, 0.013 mmol) and XPhos (12.4 mg, 0.026 mmol) in
en-2-ol (4g). The title compound was prepared according to THF (2 mL) which following conversion to the vinyl silane and
general procedure B, from 1,1,1-trifluoro-2-phenylbut-3-yn-2-ol column chromatography (19 : 1 hexane–EtOAc) afforded 4l
3g (273 mg, 1.37 mmol) and dimethylphenylsilane (562 mg, 79%) as a colourless oil.
(205 mg, 1.51 mmol) using PtCl2 (3.6 mg, 13.7 μmol) and
Rf (9 : 1 hexane–ethyl acetate) = 0.48; IR: νmax (thin film)/
XPhos (13.3 mg, 0.028 mmol) in THF (2 mL) which cm−1; 3372, 3068, 2925, 1616, 1459, 1427, 1246, 1113, 1027,
following the conversion to the vinyl silane and column 993, 822, 731, 698; 1H NMR: (400 MHz, CDCl3) δ 7.53–7.50
chromatography (9 : 1 hexane–EtOAc) afforded 4g (369 mg, (2H, m), 7.38–7.34 (3H, m), 6.28 (1H, d, J = 20 Hz), 5.96 (1H, d,
80%) as a yellow oil.
J = 20 Hz), 1.79–1.40 (12H, m), 0.36 (6H, s); 13C NMR
Rf (9 : 1 hexane–EtOAc) = 0.41; νmax (thin film)/cm−1; 3546, (100 MHz, CDCl3) δ 158.3, 136.3, 131.4, 130.2, 123.9, 43.5,
3070, 2958, 1958, 18883, 1602, 1497, 1450, 1428, 1214, 11163, 33.4, 32.3, 31.9, 24.9, 24.7, −2.5; HRMS (ES) calcd for
1115, 997, 938, 844, 825, 761, 734, 699, 647; 1H NMR: C17H26OSiNa [M + Na]+ 297.1651. Found 297.1620.
(400 MHz, CDCl3) δ 7.56 (2H, d, J = 8.0 Hz), 7.50–7.46 (2H, m),
(E)-1-(2-(Dimethyl(phenyl)silyl)vinyl)cyclooctanol (4m). The
7.42–7.33 (6H, m), 6.63 (1H, d, J = 18.8 Hz), 6.42 (1H, d, J = title compound was prepared according to general procedure B,
18.8 Hz), 0.38 (6H, s) 13C NMR (100 MHz, CDCl3) δ 143.3, from 1-ethynylcyclooctan-1-ol 3m75 (201 mg, 1.32 mmol) and
137.1, 133.8, 133.5, 131.6, 129.4, 128.7, 128.3, 128.0, 127.9, dimethylphenylsilane (0.22 mL, 1.45 mmol) using PtCl2
2
126.7 (t, JC–F = 223 Hz), 7.4, −2.8, −2.8; HRMS (ES+) calcd for (1.8 mg, 6.60 μmol) and XPhos (6.2 mg, 0.0130 mmol) in THF
C18H18OF3Si [M − H+]+ 335.1079. Found 335.1081.
(2 mL) which following conversion to the vinyl silane and
(E)-4-(Dimethyl(phenyl)silyl)-2-(thiophen-3-yl)but-3-en-2-ol column chromatography (9 : 1 hexane–EtOAc) afforded 4m
(4h). The title compound was prepared according to general (303 mg, 80%) as a colourless oil.
procedure B, from 2-(thiophen-3-yl)but-3-yn-2-ol 3h (176 mg,
Rf (9 : 1 hexane–ethyl acetate) = 0.41; IR: νmax (thin film)/
0.761 mmol) and dimethylphenylsilane (89.9 mg, 0.662 mmol) cm−1; 3362, 3068, 2922, 2854, 1613, 1470, 1446, 1427, 1264,
using PtCl2 (2.0 mg, 7.61 μmol) and XPhos (7.2 mg, 1246, 1113, 1064, 994, 843, 828, 733, 698, 642; 1H NMR:
0.0152 mmol) in THF (2 mL) which following the conversion (400 MHz, CDCl3) δ 7.52–7.49 (2H, m), 7.36–7.33 (3H, m), 6.27
to the vinyl silane and column chromatography (19 : 1 hexane– (1H, d, J = 18.8 Hz), 5.97 (1H, d, J = 18.8 Hz), 1.80–1.60 (9H,
EtOAc) afforded 4h (202 mg, 92%) as a yellow oil.
m), 1.57–1.41 (5H, m), 0.34 (6H, s); 13C NMR (100 MHz, CDCl3)
Rf (9 : 1 hexane–EtOAc) = 0.39; νmax (thin film)/cm−1; 3399, δ 157.6, 141.4, 136.2, 135.4, 131.3, 130.2, 125.4, 78.5, 38.7,
3068, 2956, 1617, 1427, 1248, 1114, 991, 844, 827, 730. 698, 30.7, 27.1, 24.5, 2.4, −0.27, −0.71; HRMS (ES) calcd for
644; 1H NMR: (400 MHz, CDCl3) δ 7.52 (2H, dd, J = 5.5, 2.0 C8H28OSiNa [M + Na]+ 311.1807. Found 311.1787.
Hz), 7.40–7.32 (4H, m), 6.96–6.93 (2H, m), 6.42 (1H, d, J = 18.2
(E)-1-(2-(Dimethyl(phenyl)silyl)vinyl)cyclododecanol (4n). The
Hz), 6.13 (1H, d, J = 18.2 Hz), 1.72 (3H, s), 0.35 (6H, s) 13C title compound was prepared according to general procedure
NMR (100 MHz, CDCl3) δ 152.4, 138.3, 133.8, 133.6, 128.9, B, from 1-ethynylcyclododecan-1-ol 3n76 (188 mg, 0.901 mmol)
127.8, 126.7, 124.7, 124.4, 123.3, 74.2, 30.1, 9.7, −2.6; HRMS and dimethylphenylsilane (135 mg, 0.099 mmol) using PtCl2
(ES+) calcd for C16H21OSSi [M + H+]+ 289.1082. Found (1.2 mg, 4.52 μmol) and XPhos (4.3 mg, 9.04 μmol) in THF
289.1112.
(2 mL) which following conversion to the vinyl silane and
(E)-1-(2-(Dimethyl(phenyl)silyl)vinyl)cyclobutanol (4i). The column chromatography (9 : 1 hexane–EtOAc) afforded 4n
title compound was prepared according to general procedure (285 mg, 91%) as a yellow oil.
B, from 1-ethynylcyclobutan-1-ol 3i74 (133 mg, 1.38 mmol) and
Rf (9 : 1 hexane–ethyl acetate) = 0.46; IR: νmax (thin film)/
dimethylphenylsilane (207 mg, 1.52 mmol) using PtCl2 cm−1; 3364, 3070, 2940, 2848, 1615, 1469, 1427, 1246, 1114,
(1.9 mg, 6.95 μmol) and XPhos (6.7 mg, 0.014 mmol) in THF 994, 844, 823, 730, 698; 1H NMR: (400 MHz, CDCl3) δ
(1.5 mL) which following conversion to the vinyl silane and 7.53–7.49 (2H, m), 7.36–7.34 (3H, m), 6.24 (1H, d, J = 18.8 Hz),
column chromatography (19 : 1 hexane–EtOAc) afforded 4i 5.97 (1H, d, J = 18.8 Hz), 1.66–1.58 (2H, m), 1.53–1.42 (5H, m),
(287 mg, 88%) as a colourless oil.
1.40–1.32 (18H, m), 0.34 (6H, s); 13C NMR (100 MHz, CDCl3) δ
Rf (9 : 1 hexane–EtOAc) = 0.40; νmax (thin film)/cm−1; 3329, 157.0, 141.3, 136.3, 131.3, 130.1, 125.4, 78.7, 37.1, 28.9, 28.4,
3068, 3049, 2984, 2956, 1616, 1427, 1248, 1169, 1114, 991, 844, 25.0, 24.6, 22.1, 2.5, 0.3, −0.3; HRMS (ES) calcd for C22H35OSi
826, 729, 698; 1H NMR: (400 MHz, CDCl3) δ 7.54–7.47 (2H, m), [M − H+]+ 343.2457. Found 343.2454.
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(E)-1-(2-(Dimethyl(phenyl)silyl)vinyl)-4,4-difluorocyclohexa- and XPhos (2.0 mg, 4.16 μmol) in THF (1 mL) which following
nol (4o). The title compound was prepared according to the conversion to the vinyl silane and column chromatography
general procedure B, from 1-ethynyl-4,4,-difluorocyclohexan-1- (4 : 1 hexane–EtOAc) afforded 4r (55 mg, 76%) as a colourless
ol 3o (98 mg, 0.605 mmol) and dimethylphenylsilane solid.
(90.4 mg, 0.665 mmol) using PtCl2 (0.9 mg, 3.2 μmol) and
Rf (4 : 1 hexane–ethyl acetate) = 0.35; IR: νmax (thin film)/
XPhos (3.1 mg, 6.4 μmol) in THF (1 mL) which following con- cm−1; 3402, 3284, 2340, 2275, 1704, 1667, 1604, 1468, 1329,
1
version to the vinyl silane and column chromatography 1052, 962, 748, 667; H NMR: (400 MHz, CDCl3) δ 7.76 (1H, s),
(9 : 1 hexane–EtOAc) afforded 4o (136 mg, 76%) as a colourless 7.55–7.49 (2H, d, J = 6.0, 3.6 Hz), 7.44–7.33 (3H, m), 7.25 (1H,
oil.
m), 7.15–7.14 (2Hm), 6.37 (1H, d, J = 18.7 Hz), 6.17 (1H, d, J =
Rf (9 : 1 hexane–ethyl acetate) = 0.43; IR: νmax (thin film)/ 18.7 Hz), 2.95 (2H, d, J = 15.6 Hz), 2.88–2.70 (2H, dd, J = 14.4,
cm−1; 3419, 3069, 2953, 1700, 1618, 1443, 1427, 1377, 1358, 3.9 Hz), 2.04–1.87 (2H, m), 0.34 (6H, s); 13C NMR (100 MHz,
1250, 1117, 1113, 991, 844, 825, 721, 700, 667; 1H NMR: CDCl3) δ153.0, 138.3, 136.0, 133.4, 132.2, 128.6, 127.5, 127.5,
(400 MHz, CDCl3) δ 7.51–7.48 (2H, m), 7.40–7.33 (3H, m), 6.28 124.3, 121.1, 118.9, 117.4, 110.0, 106.9, 76.9, 72.2, 34.1, 33.7,
(1H, d, J = 18.8 Hz), 5.96 (1H, d, J = 18.8 Hz), 2.16–2.07 (4H, 19.7, −3.0; HRMS (ES) calcd for C22H26NOSi [M + H]+
m), 1.86–1.76 (2H, m), 1.70–1.61 (2H, m) 0.35 (6H, s); 13C NMR 348.1784. Found 348.1778.
(100 MHz, CDCl3) δ 153.4, 133.9, 133.5, 129.1, 129.0, 127.9 (t,
1JC–F = 241.6 Hz), 127.8, 33.8, 33.7, −2.4, −3.6; HRMS (ES) tidine-1-carboxylate (4s). The title compound was prepared
calcd for C16H21F2OSi [M − H+]+ 295.1337. Found 295.1330.
according to general procedure B, from tert-butyl 3-ethynyl-3-
(E)-tert-Butyl-3-(2-(dimethyl(phenyl)silyl)vinyl)-3-hydroxyaze-
(E)-8-(2-(Dimethyl(phenyl)silyl)vinyl)-1,4-dioxaspiro[4.5]- hydroxyazetidine-1-carboxylate 3s79 (135 mg, 0.685 mmol) and
decan-8-ol (4p). The title compound was prepared according dimethylphenylsilane (102 mg, 0.753 mmol) using PtCl2
to general procedure B, from 8-ethynyl-1,4-dioxaspiro[4.5] (0.9 mg, 3.43 μmol) and XPhos (3.3 mg, 6.85 μmol) in THF
decan-8-ol 3p77 (195 mg, 1.07 mmol) and dimethylphenylsi- (1.5 mL) which following the conversion to the vinyl silane and
lane (160 mg, 1.18 mmol) using PtCl2 (1.2 mg, 5.4 μmol) and column chromatography (9 : 1 hexane–EtOAc) afforded 4s
XPhos (5.2 mg, 0.011 mmol) in THF (1.5 mL) which following (163 mg, 72%) as a yellow oil.
the conversion to the vinyl silane and column chromatography
(9 : 1 hexane–EtOAc) afforded 4p (240 mg, 64%) as a yellow oil.
Rf (4 : 1 hexane–ethyl acetate) = 0.21; IR: νmax (thin film)/
cm−1; 2977, 2881, 1679, 1427, 1367, 1248, 1158, 1114, 825, 764,
Rf (4 : 1 hexane–ethyl acetate) = 0.41; IR: νmax (thin film)/ 699, 667; 1H NMR: (400 MHz, CDCl3) δ 7.53–7.47 (2H, m),
cm−1; 3444, 2922, 2854, 1640, 1397, 1268, 1248, 1102, 845, 749; 7.40–7.35 (3H, m), 6.36 (1H, dd, J = 18.8 Hz), 6.12 (1H, d, J =
1H NMR: (400 MHz, CDCl3) δ 7.51–7.48 (2H, m), 7.36–7.32 (3H, 18.8 Hz), 3.98 (1H, d, J = 9.3 Hz), 3.92 (1H, d, J = 9.3 Hz), 1.44
m), 6.21 (1H, dd, J = 18.8, 5.8 Hz), 6.03 (1H, d, J = 18.8 Hz), (9H, s), 0.38 (6H, s); 13C NMR (100 MHz, CDCl3) δ 156.5, 148.5,
4.03, (1H, s), 3.95 (4H, ddd, J = 5.5, 3.5, 1.7 Hz), 2.03–1.79 (4H, 137.7, 128.9, 127.9, 127.8, 126.5, 79.8, 70.6, 62.3, 28.4, −2.8;
m), 1.65–1.57 (4H, m), 0.34 (6H, s); 13C NMR (100 MHz, CDCl3) HRMS (ES) calcd for C18H27NO3SiNa [M + NH4]+ 356.1658.
δ 154.5, 138.5, 133.8, 129.1, 127.8, 123.7, 108.5, 71.9, 64.3, Found 356.1661.
64.2, 34.9, 30.4, −2.5; HRMS (ES) calcd for C18H30NO3Si
(E)-3-(2-(Dimethyl(phenyl)silyl)vinyl)-8-methyl-8-azabicyclo-
[3.2.1]octan-3-ol (4u). The title compound was prepared
[M + NH4]+ 336.1995. Found 336.1996.
(E)-2-(2-(Dimethyl(phenyl)silyl)vinyl)-1,2,3,4-tetrahydronaphtha- according to general procedure B, from 3-ethynyl-8-methyl-8-
len-2-ol (4q). The title compound was prepared according to azabicyclo[3.2.1]octan-3-ol 3u (78 mg, 0.472 mmol) and
general procedure B, from 2-ethynyl-1,2,3,4-tetrahydronaphtha- dimethylphenylsilane (70.2 mg, 0.520 mmol) using PtCl2
len-2-ol 3q (35.2 mg, 0.204 mmol) and dimethylphenylsilane (0.6 mg, 2.36 μmol) and XPhos (2.2 mg, 4.7 μmol) in THF
(30.6 mg, 0.225 mmol) using PtCl2 (0.3 mg, 1.02 μmol) and (1.5 mL) which following conversion to the vinyl silane and
XPhos (1.0 mg, 2.02 μmol) in THF (1 mL) which following the column chromatography (SCX-2 ion exchange resin) afforded
conversion to the vinyl silane and column chromatography 4u (82.7 mg, 59%) as a yellow oil.
(19 : 1 hexane–EtOAc) afforded 4q (47 mg, 77%) as a yellow oil.
Rf (9 : 1 hexane–ethyl acetate) = 0.35; IR: νmax (thin film)/
Rf (9 : 1 hexane–ethyl acetate) = 0.26; 1H NMR: (400 MHz, cm−1; 3435, 3069, 2957, 1656, 1639, 1427, 1253, 1119, 1054,
1
CDCl3) δ 7.53–7.47 (2H, m), 7.40–7.35 (3H, m), 7.17 (3H, m), 1027, 998, 830, 789, 725, 698, 649; H NMR: (400 MHz, CDCl3)
7.10 (1H, m), 6.31 (1H, dd, J = 18.8 Hz), 6.12 (1H, d, J = 18.8 δ 7.54–7.44 (2H, m), 7.38–7.31 (3H, m), 6.06 (1H, d, J = 18.8 Hz),
Hz), 2.84–2.78 (2H, m), 2.21 (2H, m), 2.07–1.88 (2H, ddddd, J = 5.90 (1H, d, J = 18.8 Hz), 2.51 (1H, s), 2.30–2.27 (3H, d, J =
18.1, 12.3, 7.8, 6.0, 5.8 Hz), 0.35 (6H, s); 13C NMR (100 MHz, 7.4 Hz), 2.20–2.11 (3H, m), 2.07–1.90 (6 H, m), 0.33 (6H, s); 13
C
CDCl3) δ 156.2, 136.3, 131.5, 131.4, 130.6, 130.2, 130.0, 128.8, NMR (100 MHz, CDCl3) δ 157.0, 141.2, 136.3, 132.1, 130.1,
127.1, 76.7, 40.1, 32.4, 32.2, 21.7, 12.2, 0.1, −0.6, −0.9; HRMS 125.3, 37.2, 28.9, 25.0, 24.4, 22.0, −0.69; HRMS (ES) calcd for
(ES) calcd for C20H25OSi [M + H]+ 309.1675. Found 309.1678.
C16H24NOSi [M − CH3]+ 286.1627. Found 286.1661.
(E)-3-(2-(Dimethyl(phenyl)silyl)vinyl)-2,3,4,9-tetrahydro-1H-
(E)-4-(2-(Dimethyl(phenyl)silyl)vinyl)tetrahydro-2H-thiopyran-
carbazol-3-ol (4r). The title compound was prepared according 4-ol (4w). The title compound was prepared according to
to general procedure B, from 3-ethynyl-2,3,4,9-tetrahydro-1H- general procedure B, from 4-ethynyl-tetrahydro-2H-thiopyran-4-
carbazol-3-ol 3r78 (43.7 mg, 0.208 mmol) and dimethylphenyl- ol 3w (107 mg, 0.760 mmol) and dimethylphenylsilane
silane (31.1 mg, 0.228 mmol) using PtCl2 (0.6 mg, 2.08 μmol) (113 mg, 0.836 mmol) using PtCl2 (1.0 mg, 3.80 μmol) and
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XPhos (3.6 mg, 7.60 μmol) in THF (2 mL) which following con-
version to the vinyl silane and column chromatography
Acknowledgements
(9 : 1 hexane–EtOAc) afforded 4w (173 mg, 82%) as a yellow oil. We thank Queen’s University Belfast and EPSRC (Grant
Rf (9 : 1 hexane–ethyl acetate) = 0.43; IR: νmax (thin film)/ Number: EP/I006605/1) for support. We are also grateful to Eli
cm−1; 3426, 2922, 2854, 1640, 1397, 1268, 1247, 1113, 849, 825, Lilly for a CASE award (CAM) and the Department of Employ-
748, 699; 1H NMR: (400 MHz, CDCl3) δ 7.49 (2H, m), 7.41–7.33 ment and Learning, Northern Ireland for a studentship
(3H, m), 6.15 (1H, d, J = 18.8 Hz), 6.00 (1H, d, J = 18.8 Hz), (MGM). GlaxoSmithKline and AstraZeneca are also thanked for
3.06–2.97 (4H, ddd, J = 10.3, 4.0, 3.8 Hz), 1.86–1.80 (4H, ddd, their generous donation of laboratory equipment. We also
J = 13.5, 3.5, 1.8 Hz), 0.39 (6H, s); 13C NMR (100 MHz, CDCl3) δ gratefully acknowledge the reviewers for insightful comments.
154.4, 138.4, 133.8, 132.9. 129.7, 129.1, 127.8, 115.3, 71.3, 38.0,
24.0, −2.6; HRMS (ES) calcd for C15H2721OSSi [M − H]+
277.1082. Found 277.1062.
(E)-4-(tert-Butyldimethylsilyl)-2-methylbut-3-en-2-ol (5c). The
title compound was prepared according to general procedure
Notes and references
B, from 2-methyl-3-butyn-2-ol 3a (97.0 μL, 1.00 mmol) and tert-
butyldimethyl silane (0.18 mL, 1.1 mmol) using PtCl2 (1.3 mg,
5.00 μmol) and XPhos (4.8 mg, 10.00 μmol) in THF (1 mL)
which following conversion to the vinyl silane and column
chromatography (19 : 1 hexane–EtOAc) afforded 5c (173 mg,
84%) as a yellow oil.
1 I. Fleming, A. Barbero and D. Walter, Chem. Rev., 1997, 97,
2063–2192.
2 A. Hosomi, M. Endo and H. Sakurai, Chem. Lett., 1976, 941.
3 R. R. Teizeira, L. C. A. Barbosa and D. Pilo-Veloso, Quim.
Nova, 2007, 30, 1704–1720.
4 S. E. Denmark and C. S. Regens, Acc. Chem. Res., 2008, 41,
1486–1499.
5 J. P. Pezacki, P. G. Loncke, J. P. Ross, J. Warkentin and
T. A. Gadosy, Org. Lett., 2000, 2, 2733–2736.
6 S. S. Magar and P. L. Fuchs, Tetrahedron Lett., 1991, 32,
7513–7516.
Rf (9 : 1 hexane–ethyl acetate) = 0.76; IR: νmax (thin film)/
cm−1; 3362, 2953, 2928, 2856, 1616, 1470, 1361, 1390, 1247,
1
1147, 963, 908, 830; H NMR: (400 MHz, CDCl3) δ 6.18 (1H, d,
J = 18.8 Hz), 5.84 (1H, d, J = 18.8 Hz), 1.31 (6H, s), 0.88 (9H, s),
0.04 (6H, s); 13C NMR (100 MHz, CDCl3) δ 154.6, 121.8, 72.1,
29.5, 26.4, 16.6, −6.14; HRMS (ES) calcd for C11H24NaOSi [M +
Na]+ 223.1494. Found 223.1397.
7 K. Suzuki, K. Inomata and Y. Endo, Org. Lett., 2004, 6, 409–
411.
(E)-4-(Benzyldimethylsilyl)-2-methylbut-3-en-2-ol (5f). The
title compound was prepared according to general procedure
B, from 2-methyl-3-butyn-2-ol 3a (300 mg, 3.57 mmol) and
dimethylbenzylsilane (803 mg, 3.93 mmol) using PtCl2
(4.8 mg, 0.018 mmol) and XPhos (17.1 mg, 0.036 mmol) in
8 G. B. Dudley, D. A. Engel, I. Ghiviriga, H. Lam,
K. W. C. Poon and J. A. Singletary, Org. Lett., 2007, 9, 2839–
2842.
9 D. S. W. Lim and E. A. Anderson, Synthesis, 2012, 983–
1010.
THF (1.5 mL) which following conversion to the vinyl silane 10 I. Fleming, T. W. Newton and F. Roessler, J. Chem. Soc.,
and column chromatography (9 : 1 hexane–EtOAc) afforded 5f
(808 mg, 97%) as a colourless oil.
Perkin Trans. 1, 1981, 2527.
11 I. Fleming and N. J. Lawrence, J. Chem. Soc., Perkin Trans.
1, 1998, 2679.
Rf (9 : 1 hexane–EtOAc) = 0.45; IR: νmax (thin film)/cm−1; 3496,
2900, 2655, 1644, 1066, 978; 1H NMR: (400 MHz, CDCl3) δ 12 B. H. Lipshutz, J. A. Sclafini and T. Takanami, J. Am. Chem.
7.24–7.17 (2H, m), 7.10–7.04 (1H, m), 7.01–6.97 (2H, m), 6.09 (1H,
d, J = 19.1 Hz), 5.77 (1H, d, J = 19.1 Hz), 2.15 (2H, s), 1.42 (1H, s), 13 G. Reginato, A. Mordini, M. Valacchi and E. Grandini,
1.29 (6H, s), 0.06 (6H, s); 13C NMR (100 MHz, CDCl3) δ 154.5,
J. Org. Chem., 1999, 64, 9211–9216.
Soc., 1998, 120, 4021–4022.
139.9, 128.3, 128.0, 124.0, 122.6, 74.0, 30.9, 29.3, 26.1, −3.4; HRMS 14 G. Auer and M. Oestreich, Chem. Commun., 2006, 311–313.
(ES) calcd for C14H23OSi [M + H]+ 235.1518. Found 235.1528.
15 E. S. Schmidtmann and M. Oestreich, Chem. Commun.,
1-(2H)-Ethynyl-1-cyclohexanol (23). 1-Ethynyl-1-cyclohexanol
2006, 3643–3645.
(270 mg, 2.18 mmol) was added to an oven dried round 16 K. Takai, Y. Kataoka, T. Okazoe and K. Utimoto, Tetrahe-
bottom flask and placed under argon. Dry THF (4.5 mL) was dron Lett., 1987, 28, 1443–1446.
added to this and the temperature was lowered to −78 °C. 17 D. S. W. Lim and E. A. Anderson, Org. Lett., 2011, 13, 4806.
n-Butyl lithium (2.5 M) (1.04 mL, 2.61 mmol) was added slowly 18 Y. Kita, M. Tobisu and N. Chatani, Org. Lett., 2010, 12,
and the reaction mixture was allowed to stir at this temperature
for 1.5 hours. The reaction mixture was quenched with D2O, 19 K. Itami, T. Nokami and J.-i. Yoshida, Org. Lett., 2000, 2,
extracted with dry Et2O and dried over Na2SO4. The solvent 1299.
was removed under reduced pressure and the deuterated 20 A. L. Moure, R. Gómez Arrayás, D. J. Cárdenas, I. Alonso
1864.
product was used without any further purification. Product
was obtained (200 mg, 74%, 86% deuterium incorporation as
and J. C. Carretero, J. Am. Chem. Soc., 2012, 134, 7219–
7222.
determined by 1H NMR) as a colourless oil. 1H NMR: 21 B. M. Trost and Z. T. Ball, Synthesis, 2005, 887.
(400 MHz, CDCl3) δ 2.48 (0.15H, s), 1.99, (1H, s), 1.96–1.83 (2 H, 22 B. Marciniec, in Advances in Silicon Science, Springer
m), 1.77–1.48 (6H, m), 1.33–1.66 (1H, m).
Science, 2009.
Org. Biomol. Chem.
This journal is © The Royal Society of Chemistry 2013

View Article Online
Organic & Biomolecular Chemistry
Paper
23 B. M. Trost and Z. T. Ball, J. Am. Chem. Soc., 2005, 127, 51 P. D. Newman, K. J. Cavell and B. M. Kariuki, Dalton Trans.,
17644–17655. 2012, 41, 12395–12407.
24 N. Asao, T. Sudo and Y. Yamamoto, J. Org. Chem., 1996, 61, 52 A. S. K. Hashmi, C. Lothschuetz, K. Graf, T. Haeffner,
7654–7655.
A. Schuster and F. Rominger, Adv. Synth. Catal., 2011, 353,
1407–1412.
53 X. Huang, K. W. Anderson, D. Zim, L. Jiang, A. Klapars and
S. LBuchwald, J. Am. Chem. Soc., 2003, 125, 6653–6655.
54 A. Hamze, O. Provot, J.-D. Brion and M. Alami, J. Organo-
met. Chem., 2008, 693, 2789–2797.
25 E. Yoshikawa, V. Gevorgyan, N. Asao and Y. Yamamoto,
J. Am. Chem. Soc., 1997, 119, 6781–6786.
26 V. Gevorgyan, J.-X. Liu and Y. Yamamoto, J. Org. Chem.,
1997, 62, 2963–2967.
27 T. Sudo, N. Asao, V. Gevorgyan and Y. Yamamoto, J. Org.
Chem., 1999, 64, 2494–2499.
28 A. J. Chalk and J. F. Harrod, J. Am. Chem. Soc., 1965, 87, 16–21.
55 M. G. McLaughlin and M. J. Cook, J. Org. Chem., 2012, 77,
2058–2063.
29 S. B. Duckett and R. N. Perutz, Organometallics, 1992, 11, 56 C. E. Masse, L. A. Dakin, B. S. Knight and J. S. Panek,
90–98. J. Org. Chem., 1997, 62, 9335–9338.
30 A. K. Roy, in Adv. Organomet. Chem., ed. A. F. H. Robert West 57 R. T. Beresis, J. S. Solomon, M. G. Yang, N. F. Jain and
and J. F. Mark, Academic Press, 2007, vol. 55, pp. 1–59.
31 S. Clarson, Silicon, 2009, 1, 57–58.
32 M. V. Jiménez, J. J. Pérez-Torrente, M. I. Bartolomé,
J. S. Panek, Org. Synth., 2004, Coll. Vol. 10, 531.
58 M. G. McLaughlin and M. J. Cook, Chem. Commun., 2011,
47, 11104–11106.
V. Gierz, F. J. Lahoz and L. A. Oro, Organometallics, 2007, 59 W. Wu and C.-J. Li, Chem. Commun., 2003, 1668–1669.
27, 224–234.
60 H. Sasabe, N. Kihara, K. Mizuno, A. Ogawa and T. Takata,
Tetrahedron Lett., 2005, 46, 3851.
61 S. E. Denmark and J. H. C. Liu, Angew. Chem., Int. Ed.,
2010, 49, 2978–2986.
62 G. Berthon-Gelloz, J.-M. Schumers, G. De Bo and
I. E. Markó, J. Org. Chem., 2008, 73, 4190–4197.
63 A. Hamze, O. Provot, M. Alami and J.-D. Brion, Org. Lett.,
2005, 7, 5625–5628.
64 T. Konno, K.-I. Taku, S. Yamada, K. Moriyasu and
T. Ishihara, Org. Biomol. Chem., 2009, 7, 1167–1170.
65 F. Liron, P. Le Garrec and M. Alami, Synlett, 1999, 248.
66 A. Ishii and N. Nakata, Top. Organmet. Chem., 2013, 43,
21–50.
67 Y. Inoue, J. Ishikawa, M. Taniguchi and H. Hashimoto,
Bull. Chem. Soc. Jpn., 1987, 60, 1204–1206.
68 D. A. S. El, Z. M. A. Judeh, H. Basri, Z. Moussa, M. Messali
and G. Qi, Synth. Commun., 2011, 41, 533–540.
69 C.-F. Xu, M. Xu, L.-Q. Yang and C.-Y. Li, J. Org. Chem., 2012,
77, 3010–3016.
33 R. Takeuchi, S. Nitta and D. Watanabe, J. Org. Chem., 1995,
60, 3045–3051.
34 R. Takeuchi and N. Tanouchi, J. Chem. Soc., Chem.
Commun., 1993, 1319–1320.
35 R. Takeuchi and N. Tanouchi, J. Chem. Soc., Perkin Trans. 1,
1994, 2909–2913.
36 M. A. Esteruelas, J. Herrero and L. A. Oro, Organometallics,
1993, 12, 2377–2379.
37 M. Rivera-Claudio, J. Rozell, E. Ramirez-Oliva, J. Cervantes
and K. H. Pannell, J. Organomet. Chem., 1996, 521, 267–270.
38 Y. Na and S. Chang, Org. Lett., 2000, 2, 1887–1889.
39 T. Takahashi, F. Bao, G. Gao and M. Ogasawara, Org. Lett.,
2003, 5, 3479–3481.
40 R. Cano, M. Yus and D. J. Ramón, ACS Catal., 2012, 2,
1070–1078.
41 L. N. Lewis, K. G. Sy, G. L. Bryant and P. E. Donahue, Orga-
nometallics, 1991, 10, 3750–3759.
42 M. G. Voronkov, V. B. Pukhnarevich, I. I. Tsykhanskaya,
N. I. Ushakova, Y. L. Gaft and I. A. Zakharova, Inorg. Chim. 70 U. Galli, E. Ercolano, L. Carraro, C. R. B. Roman, G. Sorba,
Acta, 1983, 68, 103–105.
43 J. Stein, L. N. Lewis, Y. Gao and R. A. Scott, J. Am. Chem.
Soc., 1999, 121, 3693–3703.
44 G. Chandra, P. Y. Lo, P. B. Hitchcock and M. F. Lappert,
Organometallics, 1987, 6, 191–192.
45 P. J. Murphy, J. L. Spencer and G. Procter, Tetrahedron Lett.,
1990, 31, 1051–1054.
P. L. Canonico, A. A. Genazzani, G. C. Tron and
R. A. Billington, ChemMedChem, 2008, 3, 771–779.
71 V. Singh and V. Singh, Synth. Commun., 2010, 40, 1280–
1291.
72 J.-J. Liu, F. Konzelmann and K.-C. Luk, Tetrahedron Lett.,
2003, 44, 2545–2548.
73 E. A. Shapiro, A. V. Kalinin, B. I. Ugrak and O. M. Nefedov,
J. Chem. Soc., Perkin Trans. 2, 1994, 709–713.
74 L. R. M. De, WO, 2010135536A2, 2010.
46 D. A. Rooke and E. M. Ferreira, Angew. Chem., Int. Ed.,
2012, 51, 3225–3230.
47 D. A. Rooke and E. M. Ferreira, J. Am. Chem. Soc., 2010, 75 F. Iqbal, H. S. Ateeq, A. Malik, Z. Ali and Z. Ali, Z. Natur-
132, 11926–11928. forsch., B: Chem. Sci., 1998, 53, 1244–1245.
48 G. Berthon-Gelloz and I. E. Markò, N-Heterocyclic Carbenes 76 G. Frater and M. Nagel, EP, 1236707A1, 2002.
in Synthesis, Wiley-VCH Verlag GmbH & Co. KgaA, 2006. 77 C. Yoshida and K. Nakao, WO, 2011125836A1, 2011.
49 S. Dìez-Gonzàlez, N. Marion and S. P. Nolan, Chem. Rev., 78 J. A. Moore, J. W. Roche, P. Prince, R. D. Gandour and
2009, 109, 3612.
F. R. Fronczek, Org. Prep. Proced. Int., 1989, 21, 386–
50 A. S. K. Hashmi, C. Lothschütz, C. Böhling, T. Hengst,
388.
F. Hubbert and F. Rominger, Adv. Synth. Catal., 2010, 352, 79 J.A. Burkhard, C. Guerot, H. Knust and E. M. Carreira, Org.
3001.
Lett., 2012, 14, 66–69.
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