(N-Phosphinoamidinate)cobalt-Catalyzed Hydroboration: Alkene Isomerization Affords Terminal Selectivity

Article abstract of DOI:10.1002/chem.201403945

Herein we establish the utility of a three-coordinate (N-phosphinoamidinate)cobalt(amido) pre-catalyst that is capable of effecting challenging alkene isomerization/hydroboration processes at room temperature, leading to the selective terminal addition of the boron group. Chain-walking hydroborations: A three-coordinate (N-phosphinoamidinate)cobalt(amido) pre-catalyst is capable of effecting challenging alkene isomerization/hydroboration processes at room temperature, leading to the selective terminal addition of the boron group.

Full text of DOI:10.1002/chem.201403945

DOI: 10.1002/chem.201403945
Communication
&
Hydroboration
(N-Phosphinoamidinate)cobalt-Catalyzed Hydroboration: Alkene
Isomerization Affords Terminal Selectivity
Adam J. Ruddy,[a] Orson L. Sydora,*[b] Brooke L. Small,[b] Mark Stradiotto,*[a] and
Laura Turculet*[a]
design in enabling such reactivity is established in these re-
Abstract: Herein we establish the utility of a three-coordi-
nate (N-phosphinoamidinate)cobalt(amido) pre-catalyst
ports, with appropriately substituted tridentate bis-
(imino)pyridine[9] and bipyridylphosphine[8] ligands, as well as
that is capable of effecting challenging alkene isomeriza-
[10]
photochemically activated (NHC)Fe(CO)4 pre-catalysts prov-
tion/hydroboration processes at room temperature, lead-
ing effective. However, a number of important substrate scope
ing to the selective terminal addition of the boron group.
limitations have been encountered to date in iron-catalyzed
hydroboration chemistry; efficient transformations involving
linear internal aliphatic alkenes have proven to be a considera-
Over the past thirty years, metal-catalyzed alkene hydrobora-
tion[1] has evolved into a versatile and atom-economical syn-
thetic methodology for the assembly of alkylboronic ester syn-
thons that in turn can be applied in a range of chemical trans-
formations, including now-ubiquitous Suzuki–Miyaura[2,3] cross-
couplings. Complexes based on the platinum-group metals, in
particular rhodium and iridium, are among the most widely ex-
plored and broadly effective classes of catalysts for such trans-
formations, offering high levels of selectivity and excellent sub-
strate scope.[4] Notwithstanding the utility of platinum-group
metals in this context, their expensive and toxic nature pro-
vides motivation for the pursuit of alternative classes of hydro-
boration catalysts that mimic the desirable behavior of plati-
num-group metals, and/or provide access to entirely new reac-
tivity manifolds. Catalysts based on comparatively abundant
first-row transition metals, including iron[5,6] and cobalt, repre-
sent attractive candidates in this regard.
ble challenge, with reports of such reactivity being limited to
a small number of examples, whereby high conversion but
poor regiochemistry is achieved.[9,10]
Despite recent progress in the development of iron-cata-
lyzed alkene hydroborations, and the well-established efficacy
of rhodium and iridium in such transformations,[1,4] reports of
cobalt-catalyzed alkene hydroboration are few. At the time we
initiated the studies disclosed herein, reports documenting
cobalt-catalyzed alkene hydroboration reactions were limited
to a pair of publications by Zaidlewicz and Meller,[12,13] in which
(bisphosphine)CoCl2 complexes were shown to catalyze the hy-
droboration of 1-octene as well as isoprene in combination
with catecholborane, albeit with poor conversion and/or regio-
selectivity. During the preparation of this manuscript, the re-
markable catalytic efficacy of (bis(imino)pyridine)CoMe[14] and
[15]
(bipyridylphosphine)CoCl2/NaBHEt3 in alkene hydroboration
was reported. The (bis(imino)pyridine)CoMe (1–5 mol%)
system disclosed by Obligacion and Chirik[14] proved capable of
catalyzing the addition of HBPin to terminal, geminal, disubsti-
tuted internal, tri- and tetrasubstituted alkenes with high activ-
ity and anti-Markovnikov selectivity, in neat substrate at room
temperature, and with selective terminal addition of the BPin
moiety. Use of the (bipyridylphosphine)CoCl2/NaBHEt3 catalyst
system by Huang and co-workers[15] enabled the room temper-
ature anti-Markovnikov hydroboration of vinylarenes and a-
olefins with HBPin, at catalyst loadings as low as 0.005 mol%.
We have demonstrated previously that our newly developed
N-phosphinoamidine/amidinate ligands are effective in sup-
porting first-row transition metal
Some progress has been made as of late with regard to the
development of iron catalysts for alkene hydroboration. Nota-
ble achievements include the addition of pinacolborane
(HBPin) to conjugated dienes,[7] terminal alkenes including un-
activated olefins and styrene,[8–11] as well as cyclic aliphatic al-
kenes,[9] where relevant with anti-Markovnikov selectivity and
including examples that proceed at room temperature in the
absence of added solvent. The key role of ancillary ligand
[a] A. J. Ruddy, Prof. Dr. M. Stradiotto, Prof. Dr. L. Turculet
Department of Chemistry
Dalhousie University
6274 Coburg Road, P.O. Box 15000
Halifax, Nova Scotia B3H 4R2 (Canada)
E-mail: mark.stradiotto@dal.ca
laura.turculet@dal.ca
catalysts with applications span-
ning the chromium-catalyzed se-
lective tri-/tetramerization of ethyl-
ene[16] to the iron-catalyzed hydro-
[b] Dr. O. L. Sydora, Dr. B. L. Small
Research and Technology, Chevron Phillips Chemical Company
1862 Kingwood Drive
silylation of aldehydes, ketones,
and esters to alcohols (using 1-Fe,
Kingwood, Texas 77339 (USA)
E-mail: sydorol@cpchem.com
Figure 1. Three-coordinate (N-
phosphinoamidinate)metal-
(amido) pre-catalysts, 1-Fe
Figure 1).[17]
Notably, whereas such hydrosily-
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201403945.
lations proceed under mild condi- and 1-Co.
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Communication
tions (0.01–1.0 mol% 1-Fe; room temperature), and with
broadest substrate scope known for such iron-catalyzed trans-
formations, the analogous cobalt complex 1-Co performed
poorly in this chemistry.[17] We have also successfully employed
this ligand class in the preparation of 16-electron Cp*Ru(N-
phosphinoamidinate) complexes.[18]
mized) of either catalyst. In moving to cis-4-octene (2b), near
quantitative formation of the terminal anti-Markovnikov hydro-
boration product (3) was again observed when using 1-Co
(1 mol%)—a transformation that corresponds to a net alkene
isomerization/hydroboration process. The use of modestly
higher loadings of 1-Co (1.5%) reproducibly enabled the quan-
titative formation of 3. Such transformations could also be ach-
ieved by use of 1-Fe, although consumption of 2b and clean
formation of the terminal addition product 3 was only ach-
ieved at the 2.5 mol% catalyst loading level. Significant differ-
ences in reactivity between 1-Fe and 1-Co were observed
when employing the more challenging substrate trans-4-
octene (2c); whereas quantitative formation of 3 was again
observed by use of 1-Co (2.5 mol%), no conversion was ach-
ieved when using 1-Fe as the pre-catalyst, even at the 5 mol%
loading level. Efforts to employ lower loadings of 1-Co in the
isomerization/hydroboration of trans-4-octene (2c) by conduct-
ing reactions at 658C were unsuccessful, resulting in apparent
catalyst decomposition with poor conversions. Notably, the
use of M{N(SiMe3)2}2 (M=Fe or Co)[24,25] as pre-catalysts result-
ed in negligible conversion of the starting materials for each of
the above-mentioned reactions under analogous conditions,
thereby underscoring the importance of the ancillary ligand in
supporting suitably reactive pre-catalysts in this system. In
keeping with these results, the hydroboration of an equimolar
mixture of 2a–c with HBPin in the presence of 1-Co
(2.5 mol%) afforded 3 cleanly over the course of one hour at
room temperature under neat reaction conditions. It is worthy
of mention that while synthetically useful, yet challenging, net
alkene isomerization/hydroboration processes of this type cata-
lyzed by rhodium or iridium complexes are known,[19–23] such
processes promoted by cobalt complexes are limited only to
a very recent publication by Obligacion and Chirik[14] that ap-
peared while this manuscript was in preparation, who em-
ployed tridentate (bis(imino)pyridine)CoMe catalysts.
Encouraged by the utility of N-phosphinoamidines/amidi-
nates in these diverse applications, we turned our attention to
the identification of first-row transition metal derivatives that
could be used to address challenges in alkene hydroboration
chemistry. In particular we sought to identify catalysts of this
type that are useful in promoting alkene isomerization/hydro-
boration processes that transform linear internal aliphatic al-
kenes and related substrates selectively into 1-alkylboronate
products—a challenging yet useful reaction class that at the
time had only proved feasible with either rhodium or iridium
catalysts.[19–23] Herein we report on the successful application
of the three-coordinate (N-phosphinoamidinate)cobalt(amido)
pre-catalyst (1-Co) in the room-temperature addition of HBPin
to linear and branched mono-substituted terminal alkenes,
gem-disubstituted terminal alkenes, linear internal octenes,
and cyclic alkenes with or without added solvent and with ex-
cellent anti-Markovnikov selectivity (where relevant); the hy-
droboration of selected ketones using 1-Co is also presented.
The remarkable ability of 1-Co to promote alkene isomeriza-
tion/hydroboration processes involving linear internal alkenes,
leading to the selective terminal addition of the BPin group, is
demonstrated.
Our initial investigations focused on the application of 1-Fe
and 1-Co as pre-catalysts for the addition of HBPin to octene
isomers over the course of one hour at room temperature in
the absence of additional solvent (Figure 2). In the case of 1-
octene (2a), quantitative formation of the anticipated 1-octyl-
boronic ester (3) was achieved by use of 1 mol% (unopti-
In an effort to learn more about the progress of these
alkene isomerization/hydroboration processes involving 1-Co,
we sought to monitor the fate of trans-4-octene (2c) under
catalytically relevant conditions (neat, room temperature,
2.5 mol% 1-Co). In probing the reaction by use of 1H NMR
methods, the clean consumption of 2c and HBPin along with
the formation of 3 was observed within 20 min, in the absence
of detectable intermediates or alternative octene isomers. In
reducing the catalyst loading to 1 mol% 1-Co, again only 2c,
1
HBPin and 3 were observed by use of H NMR methods; the
reaction did not go to completion under these conditions. Sim-
ilarly, reactions conducted using 2.5 mol% 1-Co in the pres-
ence of a 2:1 mixture of 2c and HBPin afforded cleanly a 1:1
mixture of unreacted 2c and 3, in the absence of detectable
quantities of alternative octene isomers. Collectively, these pre-
liminary observations suggest that 1-Co catalyzed alkene iso-
merization/hydroboration chemistry employing trans-4-octene
(2c; and presumably other linear aliphatic internal alkenes by
analogy) proceeds via internal LnCo(octyl) isomeric intermedi-
ates that are resistant to reactivity with HBpin until the LnCo(n-
octyl) isomer is accessed. Moreover, presumptive b-hydride
elimination/1,2-insertion sequences that are likely to transform
Figure 2. Octene isomerization/hydroboration reactions catalyzed by 1-Fe
and 1-Co and employing HBPin (conversions given on the basis of NMR
spectroscopic data).
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internal LnCo(octyl) isomers into the terminal LnCo(n-octyl)
form that is apparently intercepted by HBPin must proceed in
a manner that does not involve facile loss of alkene from puta-
tive intermediates of the type LnCo(octene)(H), given the ab-
sence of alternative octene isomers observed during the
course of 1-Co catalyzed transformations involving 2c.
Encouraged by the remarkable catalytic behavior exhibited
by 1-Co, we sought to develop a more streamlined synthetic
route to this pre-catalyst (Figure 3). Our previously reported
synthesis of 1-Co involves addition of the amidine 4 to Co{N-
(SiMe3)2}2, followed by recrystallization to give 1-Co in 68% iso-
Figure 4. Alkene hydroboration employing 1-Co as a pre-catalyst. Isolated
yields (mol% 1-Co stated in parentheses) of the anti-Markovnikov hydrobo-
ration product derived from the corresponding terminal or cyclic alkene,
with the exception of hydroborations involving the internal 4-octene iso-
mers 2b and 2c. [a] 1.2 equivalents of the alkene employed.
Figure 3. Streamlined synthesis of 1-Co.
lated yield. While apparently simple, the published preparation
and subsequent isolation of Co{N(SiMe3)2}2 from CoCl2 and
NaN(SiMe3)2 is somewhat tedious, involving recrystallization of
crude Co{N(SiMe3)2}2 (reported 53% yield), followed by subli-
mation;[24] using this protocol we routinely obtain pure Co{N-
(SiMe3)2}2 in approximately 40% isolated yield, giving an effec-
tive yield of 1-Co of approximately 27% starting from CoCl2.
We have subsequently demonstrated that 1-Co can be pre-
pared in a more expedient fashion by sequentially treating
CoCl2 with LiN(SiMe3)2 and 4, thereby enabling the isolation of
pure 1-Co in 52% isolated yield following recrystallization.
We then turned our attention to exploring briefly the hydro-
boration reactivity of 1-Co with other olefinic or carbonyl-con-
taining substrates. The spectroscopically determined conver-
sions of the octenes 2a–c and HBPin to 3 in the presence of 1-
Co (Figure 2) were authenticated on the basis of the high iso-
lated yields obtained (Figure 4). A selection of other mono-sub-
stituted terminal alkenes with varying steric profile also under-
went successful hydroboration with HBPin in the presence of
1-Co, affording the anti-Markovnikov addition products 5–8 in
high isolated yield. Similarly excellent results were obtained in
the hydroboration of the gem-disubstituted terminal alkene 2-
methyl-1-pentene, leading to 9. The ability of 1-Co to catalyze
the hydroboration of cyclic alkenes was confirmed by the
clean transformation of cyclooctene and cyclohexene into the
cycloalkylboronate products 10 and 11 (Figure 4). While the
aforementioned transformations were conducted under neat
conditions, we also demonstrated that analogous reactions
leading to 3 (from 2a) and 5–7 could be conducted in the
presence of diethyl ether at the 0.5 mol% level, affording the
terminal HBPin addition products (92–97%). Further prelimina-
ry experimentation with 1-Co in alkene hydroborations using
HBPin under similar conditions revealed some important sub-
strate scope limitations, with styrenes, heteroatom-functional-
ized alkenes, dienes and enones affording low conversions
and/or complex product mixtures. The inability of 1-Co to cata-
lyze the hydroboration of enones cannot be attributed to the
presence of the ketone functionality alone; acetophenone, cy-
clohexanone, and 2-heptanone were each successfully hydro-
borated, affording the corresponding secondary alcohols 12–
14 cleanly upon workup (Figure 5).
Figure 5. Ketone hydroboration employing 1-Co as a pre-catalyst. The low
isolated yields in the case of 13 and 14 can be attributed to losses incurred
upon distillative workup.
In conclusion, the results presented herein establish the utili-
ty
of
the
easily
prepared,
three-coordinate
(N-
phosphinoamidinate)cobalt(amido) pre-catalyst (1-Co) in chal-
lenging room-temperature alkene hydroboration reactions that
can be conducted in the presence or absence of added sol-
vent. The efficient anti-Markovnikov addition of HBPin to linear
and branched mono-substituted terminal alkenes, gem-disub-
stituted terminal alkenes, and linear internal octenes is report-
ed, as is the hydroboration of cyclic alkenes and ketones. Par-
ticularly significant is the observation that 1-Co promotes
alkene isomerization/hydroboration processes involving both
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with pinacolborane (145 mL, 1 mmol) and the alkene substrate (1
or 1.2 mmol). Either 1-Co or 1-Fe (1–5 mol%) was then added as
a solid and the vial was sealed with a cap containing a PTFE
septum and stirred in the glovebox for 1 h. After 1 h the vial was
removed from the glovebox and the catalyst mixture was deacti-
vated by exposure to air. The contents were extracted with Et2O
(3ꢂ2 mL) and the ether extracts were subsequently filtered
through silica. The eluent was collected and concentrated under
reduced pressure to furnish the hydroboration product. The 1H
and 13C NMR spectra of the isolated material were analyzed to de-
termine the purity of the sample.
cis- and trans-4-octene, leading to the selective terminal addi-
tion of the BPin group. Such alkene isomerization/hydrobora-
tion chemistry underscores how appropriately ligated cobalt
complexes can provide access to challenging and synthetically
useful reactivity manifolds that are normally reserved for the
platinum-group metals.
Experimental Section
General considerations: Unless otherwise noted, all experiments
were conducted under nitrogen in an MBraun glovebox or using
standard Schlenk techniques. Dry, deoxygenated solvents were
used unless otherwise indicated. Pentane was deoxygenated and
dried by sparging with nitrogen and subsequent passage through
General procedure for isolation of alkene hydroboration prod-
ucts (with solvent) (GP4): In a nitrogen atmosphere glovebox, an
oven-dried screw-capped vial containing a stirbar was charged
with pinacolborane (145 mL, 1 mmol) and the alkene substrate
(1 mmol). Either 1-Co or 1-Fe (0.5 mol%) was then added as
a stock solution (2 mm) in Et2O (250 mL) and the vial was sealed
with a cap containing a PTFE septum and stirred in the glovebox
for 1 h. After 1 h the vial was removed from the glovebox and the
catalyst mixture was deactivated by exposure to air. The contents
were extracted with Et2O (3ꢂ2 mL) and filtered through silica. The
eluent was collected and concentrated under reduced pressure to
furnish the hydroboration product. The 1H and 13C NMR spectra
were analyzed to determine product purity.
a
double-column solvent purification system purchased from
MBraun Inc. with one column packed with activated alumina and
one column packed with activated Q5. Diethyl ether and tetrahy-
drofuran were dried over Na/benzophenone and distilled under ni-
trogen. CDCl3 (Cambridge Isotopes) was used as received. All al-
kenes were degassed via three repeated freeze–pump–thaw cycles
and were stored over activated 4 ꢁ molecular sieves for a minimum
of 12 h prior to use. Pinacolborane (HBPin, Alfa) was used as re-
1
ceived and stored under nitrogen. H and 13C NMR characterization
data were collected at 300 K on a Bruker AV-300 spectrometer op-
erating at 300.1 and 75.5 MHz (respectively) with chemical shifts re-
ported in parts per million downfield of SiMe4. 11B NMR characteri-
zation data were collected at 300 K on a Bruker AV-300 spectrome-
ter operating at 96.3 MHz with chemical shifts reported in parts
per million downfield of BF3·OEt2. The N-phosphinoamidine 4[17]
was prepared according to literature procedures.
General procedure for isolation of alcohols (ketone hydrobora-
tion products) (GP5): In a nitrogen atmosphere glovebox, an
oven-dried screw-capped vial containing a stirbar was charged
with pinacolborane (290 mL, 2 mmol) and the ketone substrate
(2 mmol). 1-Co (0.013 g, 1 mol%) was then added as a solid and
the vial was sealed with a cap containing a PTFE septum and
stirred in the glovebox for 1 h. After 1 h, the vial was removed
from the glovebox and the contents were diluted with approxi-
mately 10 mL THF. The contents were then hydrolyzed by the addi-
tion NaOH (1.0m in H2O, 2.0 mL, 2 mmol) and H2O2 (30% in H2O,
1.13 mL, 10 mmol).[7] The organic layer was extracted with Et2O (3ꢂ
5 mL), washed with NaHCO3 and brine, dried over MgSO4, and con-
centrated under reduced pressure. The residues obtained were pu-
rified by short path distillation under reduced pressure to furnish
General procedure for determination of conversion in catalytic
hydroboration (GP1): In a nitrogen atmosphere glovebox, an
oven-dried screw-capped vial containing a stirbar was charged
with pinacolborane (145 mL, 1 mmol) and the alkene (1 or
1.2 mmol) or carbonyl compound (1 mmol). Either 1-Co or 1-Fe (1–
5 mol%) was then added as a solid and the vial was sealed with
a cap containing a PTFE septum and stirred in the glovebox for
1 h. After 1 h the vial was removed from the glovebox and the cat-
alyst mixture was deactivated by exposure to air. The contents of
the vial were extracted with CDCl3 and filtered through silica into
a NMR tube. The 1H and/or 11B NMR spectra were analyzed to mon-
itor the progress of the reaction. If no pinacolborane or alkene/car-
bonyl compound was found to be present in the sample, the reac-
tion was determined to have achieved full conversion. For 4-
octene isomers, the 13C DEPT-Q NMR spectrum was also analyzed
to aid in determining if an isomerization process involving the
starting alkene had occurred.
1
the alcohol product. The H and 13C NMR spectra were then ana-
lyzed to determine product purity.
Alternative synthesis of 1-Co: A solution of LiN(SiMe3)2 (0.788 g,
4.71 mmol) in Et2O (10 mL) was added via pipette over 2 min to
a magnetically stirred slurry of CoCl2 (0.306 g, 2.36 mmol) in Et2O
(5 mL). A color change from pale blue to deep blue green was ob-
served over the course of 5 min. The reaction mixture was magnet-
ically stirred for a total of 3 h, over which time the formation of
General procedure for determination of NMR yield in carbonyl
hydroboration (GP2): In a nitrogen atmosphere glovebox, an
oven-dried screw-capped vial containing a stirbar was charged
with pinacolborane (145 mL, 1 mmol) and the carbonyl substrate
(1 mmol). 1-Co (1 mol%) was then added as a solid, followed by
the addition of a stock solution of Cp2Fe (internal standard) in C6D6
(250 mL of 0.4m solution, 0.1 mmol) and the vial was sealed with
a cap containing a PTFE septum and stirred in the glovebox for
1 h. After 1 h an aliquot of the reaction mixture was analyzed by
use of 1H NMR spectroscopy. Comparison of the integrals of the
methine peaks of the hydroboration products and the Cp2Fe signal
was used to obtain the NMR yield.
a
white precipitate was observed. Subsequently, 4 (1.00 g,
2.36 mmol) was added to the reaction mixture as a solid and
a color change from deep blue green to deep red was observed
over the course of 2 min. After stirring for an additional 2 h the re-
action mixture was filtered through Celite, the eluent was collect-
ed, and the Et2O was removed under reduced pressure. The deep
red residue was then extracted with pentane (10 mL) and filtered
through Celite. The filtrate was then concentrated under reduced
pressure to a volume of about 3 mL, and the solution was placed
in the freezer at À358C for 18 h. After 18 h the brown supernatant
solution was decanted and the red solid crystalline precipitate was
washed with cold (À358C) pentane (2ꢂ0.5 mL). The remaining red
solid crystalline material (1-Co) was dried under reduced pressure
(0.786 g, 52%). Spectral data for 1-Co were in close agreement to
previously reported values.[17]
General procedure for isolation of alkene hydroboration prod-
ucts (solvent free) (GP3): In a nitrogen atmosphere glovebox, an
oven-dried screw-capped vial containing a stirbar was charged
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[14] J. V. Obligacion, P. J. Chirik, J. Am. Chem. Soc. 2013, 135, 19107–19110.
[15] L. Zhang, Z. Zuo, X. Leng, Z. Huang, Angew. Chem. 2014, 126, 2734–
2738; Angew. Chem. Int. Ed. 2014, 53, 2696–2700.
[16] O. L. Sydora, T. C. Jones, B. L. Small, A. J. Nett, A. A. Fischer, M. J. Carney,
ACS Catal. 2012, 2, 2452–2455.
[17] A. J. Ruddy, C. M. Kelly, S. M. Crawford, C. A. Wheaton, O. L. Sydora, B. L.
Small, M. Stradiotto, L. Turculet, Organometallics 2013, 32, 5581–5588.
[18] C. M. Kelly, A. J. Ruddy, C. A. Wheaton, O. L. Sydora, B. L. Small, M. Stra-
diotto, L. Turculet, Can. J. Chem. 2014, 92, 194–200.
[19] C. E. Tucker, J. Davidson, P. Knochel, J. Org. Chem. 1992, 57, 3482–3485.
[20] S. Pereira, M. Srebnik, J. Am. Chem. Soc. 1996, 118, 909–910.
[21] Y. Yamamoto, R. Fujikawa, T. Umemoto, N. Miyaura, Tetrahedron 2004,
60, 10695–10700.
[22] S. W. Hadebe, R. S. Robinson, Tetrahedron Lett. 2006, 47, 1299–1302.
[23] a) C. J. Lata, C. M. Crudden, J. Am. Chem. Soc. 2010, 132, 131–137;
b) D. R. Edwards, C. M. Crudden, K. Yam, Adv. Synth. Catal. 2005, 347,
50–54.
[24] H. Bꢃrger, U. Wannagat, Monatsh. Chem. 1963, 94, 1007–1012.
[25] R. A. Andersen, K. Faegri, J. C. Green, A. Haaland, M. F. Lappert, W. P.
Leung, K. Rypdal, Inorg. Chem. 1988, 27, 1782–1786.
[26] A. Caballero, S. Sabo-Etienne, Organometallics 2007, 26, 1191–1195.
[27] A. P. Dieskau, J. M. Begouin, B. Plietker, Eur. J. Org. Chem. 2011, 5291–
5296.
[28] G. B. Consiglio, P. Queval, A. Harrison-Marchand, A. Mordini, J. F. Lohier,
O. Delacroix, A. C. Gaumont, H. Gerard, J. Maddaluno, H. Oulyadi, J. Am.
Chem. Soc. 2011, 133, 6472–6480.
Acknowledgements
We thank Chevron Phillips Chemical Company for supporting
this research and for permission to publish. Profs. Mark Stra-
diotto and Laura Turculet are also grateful to NSERC of Canada
and Dalhousie University for their support of this work. Dr. Mi-
chael Lumsden (NMR-3, Dalhousie) is thanked for on-going
technical assistance in the acquisition of NMR data.
Keywords: alkene isomerization · cobalt · hydroboration ·
ketones · N-phosphinoamidinate
[1] C. M. Vogels, S. A. Westcott, Curr. Org. Chem. 2005, 9, 687–699.
[2] A. Suzuki, Angew. Chem. 2011, 123, 6854–6869; Angew. Chem. Int. Ed.
2011, 50, 6722–6737.
[3] R. Jana, T. P. Pathak, M. S. Sigman, Chem. Rev. 2011, 111, 1417–1492.
[4] C. M. Crudden, D. Edwards, Eur. J. Org. Chem. 2003, 4695–4712.
[5] B. D. Sherry, A. Fuerstner, Acc. Chem. Res. 2008, 41, 1500–1511.
[6] K. Junge, K. Schroeder, M. Beller, Chem. Commun. 2011, 47, 4849–4859.
[7] J. Y. Wu, B. Moreau, T. Ritter, J. Am. Chem. Soc. 2009, 131, 12915–12917.
[8] L. Zhang, D. Peng, X. Leng, Z. Huang, Angew. Chem. 2013, 125, 3764–
3768; Angew. Chem. Int. Ed. 2013, 52, 3676–3680.
[9] J. V. Obligacion, P. J. Chirik, Org. Lett. 2013, 15, 2680–2683.
[10] J. Zheng, J.-B. Sortais, C. Darcel, ChemCatChem 2014, 6, 763–766.
[11] M. D. Greenhalgh, S. P. Thomas, Chem. Commun. 2013, 49, 11230–
11232.
Received: June 12, 2014
[12] M. Zaidlewicz, J. Meller, Tetrahedron Lett. 1997, 38, 7279–7282.
[13] M. Zaidlewicz, J. Meller, Main Group Met. Chem. 2000, 23, 765–772.
Published online on September 3, 2014
Chem. Eur. J. 2014, 20, 13918 – 13922
www.chemeurj.org
13922
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