Iridium-catalysed hydrosilylation of cyclopropanes: Via regioselective carbon-carbon bond cleavage

Article abstract of DOI:10.1039/c7cc04296e

While cyclopropanes have been explored as synthetically valuable building blocks, their transformation without conjugated substituents or directly substituted heteroatoms remains challenging. The current study describes the iridium-catalysed ring-opening hydrosilylation of cyclopropanes. A nitrogen-based directing group was found to control the reactivity of iridium active species as well as the regiochemistry of carbon-carbon bond cleavage and hydrosilylation.

Full text of DOI:10.1039/c7cc04296e

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Iridium-Catalysed Hydrosilylation of Cyclopropanes via
Regioselective CarbonCarbon Bond Cleavage
Masahito Murai,a,* Atsushi Nishiyama,a Naoki Nishinaka,a Haruka Morita,a and Kazuhiko Takaia,*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
proximal carboncarbon bonds (Scheme 1(c)).4d Because the
While cyclopropanes have been explored as synthetically valuable
building blocks, transformation of cyclopropanes without
conjugated substituents or directly substituted heteroatoms
remains challenging. The current study describes iridium-catalysed
ring-opening hydrosilylation of cyclopropanes. A nitrogen-based
directing group was found to control the reactivity of iridium
active species as well as the regiochemistry of carboncarbon
bond cleavage and hydrosilylation.
selectivity of addition was dependent on the stability of the
carbocation intermediates generated from cyclopropanes,
formation of regioisomer mixtures was observed in some cases, and
the functional group compatibility was low.
Catalytic hydrosilylation is an efficient and atom-economical
approach to organosilanes, and represents a useful transformation
due to the wide industrial utility of the resulting organosilanes.1 In
contrast to the well-studied hydrosilylation of carboncarbon or
carbonheteroatom unsaturated bonds, such as alkenes, allenes,
alkynes, carbonyl compounds, CO2, and nitriles, much less attention
has been paid to the corresponding hydrosilylation of
cyclopropanes. While the formal cleavage of carboncarbon bonds
with hydrosilylation of alkylidenecyclopropanes has been
investigated, insertion of a silylmetal species into carboncarbon
double bonds followed by cleavage of carboncarbon single bonds
is proposed in the reaction mechanism.2,3 Therefore, these methods
are unsuitable for hydrosilylation of other cyclopropanes with a
direct cleavage of carboncarbon bonds. Pioneering work was done
by Beletskaya, who reported silylative cleavage of
vinylcylopropanes and gem-divinylcyclopropane in the presence of
Wilkinson complex, RhCl(PPh3)3 (Scheme 1(a)).4a Slough and
Yorimitsu independently reported catalytic hydrosilylation of
cyclopropyl ketones leading to silyl enol ethers (Scheme 1(b)).4b,c
While these studies demonstrated the hydrosilylation of
cyclopropanes with direct cleavage of carboncarbon bonds, the
protocols were limited in substrate scope, and were effective only
for cyclopropanes with conjugated substituents, such as vinyl and
acyl groups, or heteroatoms.5 An exception was reported by
Yamamoto on the aluminum(III) chloride-catalysed hydrosilylation
of cyclopropanes with chlorohydrosilane via selective cleavage of
Scheme 1. Previous catalytic hydrosilylation of cyclopropanes with
direct cleavage of cyclopropyl carboncarbon bonds
Activation and cleavage of cyclopropanes is
a useful and
important organic transformation because even catalytic reduction
of cyclopropyl groups leading to isopropyl groups is often applied to
the total synthesis of natural biologically active compounds.6
However, catalytic transformations of electronically unactivated
cyclopropanes with the exceptions of hydrogenation and simple
isomerization remains challenging,5 and the need exists to develop
operationally simple and regioselective cleavage reactions of
carboncarbon bonds with functionalization. While developing a
method for the dehydrogenative silylation of carbonhydrogen
bonds,7 we found a catalytic cleavage of cyclopropane ring with
addition of hydrosilane under neutral and mild conditions.8
A
nitrogen-based directing group was found to control the reactivity
of hydrosilane as well as the regiochemistry of carboncarbon bond
cleavage and hydrosilylation.
Treatment of 2-(cyclopropylmethoxy)pyridine (1a) with
triethylsilane in the presence of a catalytic amount of [IrCl(cod)]2 in
toluene at 40 °C gave 2-[4-(triethylsilyl)butoxy]pyridine (2a) in 60%
yield (Table 1, entry 1). The proximal carboncarbon bond of the
cyclopropane ring was cleaved selectively, and corresponding
a. Division of Applied Chemistry, Graduate School of Natural Science and
Technology, and Research Institute for Interdisciplinary Science, Okayama
University, 3-1-1 Tsushimanaka, Kita-ku, Okayama 700-8530, Japan.
E-mail: masahito.murai@okayama-u.ac.jp ktakai@cc.okayama-u.ac.jp
†Electronic Supplementary Information (ESI) available: Experimental procedures,
spectroscopic data for all new compounds, and copies of 1H and 13C NMR spectra.
See DOI: 10.1039/x0xx00000x
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regioisomers were not obtained under the reaction conditions. In was a good substrate for the current ring-opening hydrosilylation to
contrast, the corresponding carbon analog, cyclopropylmethyl provide 2f in 70% yield. For the hydrosilylaDtiOoIn: 1o0f.1203-Va9ile/kCwy7lApCrtyCicr0lied4Oi2nn9lei6nsEe,
phenyl ether (3), was recovered and no similar cleavage of a better results were obtained in toluene than in diethyl ether.
Chloride functionality, which can be reduced by hydrosilanes, was
also applicable to yield 2g in 81% yield. Without elimination of a
benzyl group protecting a hydroxyl group, the expected adduct 2h
was obtained in 78% yield. Treatment of triethylsilane with a
substrate having two cyclopropane rings underwent smooth ring-
opening hydrosilylation twice to furnish 2i in moderate yield.
Proximal carboncarbon bonds were cleaved selectively in all
reactions, and the regioselectivity of hydrosilylation was well-
controlled without producing other ring-opening hydrosilylation
adducts.14
carboncarbon bond was observed under identical conditions even
upon heating to 135 °C.9 These results indicate that a nitrogen-
based auxiliary group is important to promote the carboncarbon
cleavage as well as hydrosilylation of cyclopropanes. Although
several iridium catalysts, including [Ir(OMe)(cod)]2, [IrCl(cod)]2
/
AgOTF, and [IrCl(cod)]2 / AgSbF6, exhibited marginal catalytic
activity (entries 2-5), the corresponding rhodium catalysts, such as
[RhCl(cod)]2 and [Rh(OMe)(cod)]2, as well as other transition metal
complexes, were completely ineffective (entry 6).10 In contrast to
Beletskaya’s report (Scheme 1(a)), Wilkinson complex, RhCl(PPh3)3,
also shut down the reaction (entry 7). Examination of solvents using
[IrCl(cod)]2 as a catalyst revealed that the best yield was obtained in
Table 2. Iridium-catalysed hydrosilylation of cyclopropanes with
diethyl ether (entry 8).11 Effect of reaction temperature was also an regioselective cleavage of proximal carboncarbon bonds
important factor, and the yield of 2a was highest when the reaction
was conducted at 50 °C, due to the competitive decomposition of
1a at high temperatures.12 Note that the reaction proceeded
efficiently in the absence of ligands or additives under mild
conditions. Addition of phosphine-, nitrogen-, or diene-based
ligands decreased the reaction efficiency.13 While the acidity of
cyclopropyl carbonhydrogen bonds is relatively high, competing
activation followed by the dehydrogenative silylation was not
observed in all cases.8
Table 1. Optimization of reaction conditions
The current catalyst system was also effective for silylative ring-
opening of arylcyclopropanes (Scheme 2). Reaction of 2-
cyclopropylquinoline 1j with triethylsilane took place efficiently to
afford 2-[3-(triethylsilyl)propyl]quinoline 2j in 70% yield.9,15
Cyclopropane 1k containing a benzimidazolyl group as a directing
group underwent hydrosilylation to afford 2k in 65% yield. Although
cyclopropane rings of arylcyclopropanes are generally reactive
compared to that of alkylcyclopropanes, a higher temperature was
required for the complete consumption of 1j and 1k, probably due
to the ring strain of the iridacycle intermediates generated (vide
infra).
After optimized reaction conditions were established, substrate
scope was examined (Table 2). Reaction of cyclopropanes having 2-
quinolyl and 2-picolyl groups provided the corresponding
hydrosilylation products 2b and 2c, respectively, in yields lower
than those obtained from reaction of 1a, which indicated that the
basicity of nitrogen-containing directing group significantly affected
the efficiency of the reaction. Hydrosilylation, as well as
carboncarbon bond cleavage of substrates containing other
Scheme 2. Ring-opening hydrosilylation of arylcyclopropanes
directing groups, including a 2-pyrimidyl group, or cyclobutane
derivatives, did not occur (see Figure S1 in ESI). Using a pyridyl
Preliminary insights into the mechanism was obtained by
group as a directing group, 2e was obtained in 91% yield from a
reaction of 1a with a deuterium-incorporated triethylsilane (d-
substrate with a methyl group on the cyclopropane ring. Although a
content 97%) under standard conditions (Scheme 3). Introduction
higher temperature was required, 2-(1-cyclopropylethyl)pyridine
of deuterium into 2a was observed at the - and -positions of the
2 | J. Name., 2012, 00, 1-3
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oxygen atom as well as the 6-position of the pyridine ring. Partial
Reaction of 1a with HBpin or B2pin2 in place of trieVtihewylsAirltaicnleeOwnlianes
incorporation of deuterium into recovered 1a was also observed at conducted to investigate the ability DofOI:t1h0e.103c9o/rCr7eCsCp0o4n2d9in6Eg
the -position of the oxygen and nitrogen atoms (see Figure S1 in SI boryliridium species to mediate activation of carboncarbon bonds
for details). These results indicate that the competitive and in a similar manner (Scheme 5). However, none of the ring-opening
borylated products was observed, which confirms that the silyl
ligand on the iridium centre was important for cleavage of the
cyclopropyl rings.
reversible cleavage of carbonhydrogen bonds occurred during and
after ring-opening of cyclopropanes, and silylation occurred
selectively after carboncarbon bond cleavage of cyclopropane
rings.16 The recovery of cyclopropane 1a in the absence of
triethylsilane indicated that the presence of silane was required for
carboncarbon bond cleavage, and that direct activation of the
cyclopropane ring prior to hydrosilane with [IrCl(cod)]2 could be
ruled out.17
Scheme 5. Attempted borylation of cyclopropane
In conclusion, iridium-catalysed regioselective hydrosilylation of
electronically unactivated cyclopropanes was accomplished,
promoted by a nitrogen-based directing group. The combination of
an iridium complex with a hydrosilane was key for the cleavage and
functionalization of cyclopropyl carboncarbon bonds. Due to slight
differences in covalent radius and electronegativity between carbon
Scheme 3. Deuterium labelling experiment
Based on these results, a plausible mechanism is illustrated in and silicon, introduction of a silyl functionality could produce drug
Scheme 4, which exemplifies the hydrosilylation of 1a. The molecules with novel and unique physiological and biological
properties.21 The present silylation with cyclopropane ring-opening
siliconhydrogen bond is initially activated by a iridiumhydride
species18 coordinated to a nitrogen-based directing group, followed
provides new opportunities for the design of silicon-containing
functional molecules.
by reductive elimination of dihydrogen. The resulting silyliridium
species A, in which an iridium centre is in close proximity to the
proximal carboncarbon bond of the cyclopropane ring, induced
oxidative addition to produce the iridacyclobutane intermediate B.
Coordination of silyliridium species A with a pyridyl directing group
is inevitable because: (1) hydrosilylation did not occur when
phosphine and nitrogen-based ligands were added,12 and (2)
Notes and references
1
For recent reviews, see: (a) Hydrosilylation: A Comprehensive
Review on Recent Advances; B. Marciniec, Ed.; Springer:
Berlin, 2009; (b) Y. Nakajima and S. Shimada, RSC Adv., 2015,
(phenoxymethyl)cyclopropane
3
without
a
directing group
5, 20603; (c) J. Sun and L. Deng, ACS Catal., 2016, 6, 290.
remained intact under the present reaction conditions.9 Subsequent
reductive elimination of the carbonsilicon bond furnished the
alkyliridium species C.19 Regioselectivity of silylation in this step was
determined by the greater stability of the resulting six-membered
iridacycle intermediate C, compared with the possible eight-
membered iridacycle intermediate possessing a silyl group at the -
position of the oxygen atom.20 Intermediate C was then added
2
(a) A. G. Bessmertnykh, K. A. Blinov, Y. K. Grishin, N. A.
Donskaya, E. V. Tveritinova, N. M. Yur‘eva and I. P.
Beletskaya, J. Org. Chem., 1997, 62, 6069; (b) M. Itazaki, Y.
Nishihara and K. Osakada, J. Org. Chem., 2002, 67, 6889; (c) Y.
Nishihara, M. Itazaki and K. Osakada, Tetrahedron Lett., 2002,
43, 2059; (d) S. Simaan, A. F. G. Goldberg, S. Rosset and I.
Marek, Chem. Eur. J., 2010, 16, 774.
3
For reviews on the catalytic transformation of
alkylidenecyclopropanes. See: (a) A. Brandi, S. Cicchi, F. M.
Cordero and A. Goti, Chem. Rev., 2003, 103, 1213; (b) A.
Brandi, S. Cicchi, F. M. Cordero and A. Goti, Chem. Rev., 2014,
114, 7317; (c) H. Pellissier, Tetrahedron, 2014, 70, 4991; (d) L.
oxidatively to
a second hydrosilane, followed by reductive
elimination to provide 2a along with regeneration of catalytically
active silyliridium species A. The final reductive elimination to form
2a accounted for the deuterium introduction at the -position of
the oxygen atom observed in Scheme 3.
Yu, M. Liu, F. Chen and Q. Xu, Org. Biomol. Chem., 2015, 13
,
8379.
4
5
(a) A. G. Bessmertnykh, K. A. Blinov, Y. K. Girishin, N. A.
Donskaya and I. P. Beletskaya, Tetrahedron Lett., 1995, 36
,
7901; (b) C. Sun, A. Tu and G. A. Slough, J. Organomet. Chem.,
1999, 582, 235; (c) Y. Sumida, H. Yorimitsu and K. Oshima, J.
Org. Chem., 2009, 74, 7986; (d) S. Nagahara, T. Yamakawa
and H. Yamamoto, Tetrahedron Lett., 2001, 42, 5057.
For reviews of catalytic transformation of cyclopropanes via
CC bond cleavage, see: (a) M. Rubin, M. Rubina and V.
Gevorgyan, Chem. Rev., 2007, 107, 3117; (b) K. Ruhland, Eur.
J. Org. Chem., 2012, 2683; (c) L. Souillart and N. Cramer,
Chem. Rev., 2015, 115, 9410; (d) C. T. To and K. S. Chan,
Tetrahedron Lett., 2016, 57, 4664; (e) G. Fumagalli, S.
Stanton and J. F. Bower, Chem. Rev., 2017, 117, 9404. For
the synthetic application of activated cyclopropanes, such as
cyclopropanols and cyclopropylamines, see: (f) A. Nikolaev
and A. Orellana, Synthesis, 2016, 48, 1741; (g) V. A. Rassadin
Scheme 4. Proposed reaction mechanism (Si = SiR3)
and Y. Six, Tetrahedron, 2016, 72
,
4701. For
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(3+1+2)cycloaddition
reaction
with
unactivated
Yield of 2a was 18% for 1 h, 38% for 2 h, 50% foVrie3whA,rti5cl9e%Onflioner
cyclopropanes, see: (h) Y. Koga, K. Narasaka, Chem. Lett.
6 h, 69% for 15 h, 70% for 24 h.
1999, 705; (i) G.-W. Wang, N. G. McCreanor, M. H. Shaw, W. 13 When 1,10-phenanthroline (5 mol%)DwOaI:s10a.d10d3e9d/Cu7CnCd0e4r2t9h6eE
G. Whittingham, J. F. Bower, J. Am. Chem. Soc., 2016, 138
,
condition shown in Table 1, entry 8, 2a was obtained in 8%
yield. Formation of 2a was not observed with the following
additives: PPh3, PCy3, 1,2-bis(diphenylphosphino)ethane, (R)-
DTBM-SEGPHOS, 3,4,7,8-tetramethyl-1,10-phenanthroline,
4,4’-di-tert-butyl-2,2’-bipyridyl, and 1,5-cyclooctadiene.
13501.
6
For selected examples, see: (a) M. Harmata and P.
Rashatasakhon, Org. Lett., 2000,
2, 2913; (b) D. C. Harrowven,
M. C. Lucas and P. D. Howes, Tetrahedron, 2001, 57, 9157;
(c) G. Mehta, A. S. K. Murthy and J. D. Umarye, Tetrahedron 14 Reaction of 1a or 1f with other hydrosilanes, such as
n
Lett., 2002, 43, 8301; (d) S. Karimi and P. Tavares, J. Nat.
Prod., 2003, 66, 520; (e) D. F. Taber and K. J. Frankowski, J.
Org. Chem., 2005, 70, 6417; (f) D. F. Taber and W. Tian, J. Org.
(EtO)3SiH, ClSiMe2H, BnMe2SiH, docMe2SiH, PhMe2SiH, and
Et2SiH2, gave the expected hydrosilylation products in low
yields (less than 10% yield).
Chem., 2008, 73, 7560; (h) S. Hendrata, F. Bennett, Y. Huang, 15 2-nPropylquinoline was obtained in 10% yield as a byproduct.
M. Sannigrahi, P. A. Pinto, T.-M. Chan, C. A. Evans, R. 16 Pyridyl group directed the incorporation of deuterium atom
Osterman, A. Buevich and A. T. McPhail, Tetrahedron Lett.,
2006, 47, 6469; (i) Z.-Y. Zhang, Z.-Y. Liu, R.-T. Guo, Y.-Q. Zhao,
X. Li, X.-C. Wang Angew. Chem. Int. Ed., 2017, 56, 4028.
(a) T. Ureshino, T. Yoshida, Y. Kuninobu, and K. Takai, J. Am.
Chem. Soc., 2010, 132, 14324; (b) Y. Kuninobu, K. Yamauchi,
N. Tamura, T. Seiki and K. Takai, Angew. Chem. Int. Ed., 2013,
52, 1520; (c) Y. Kuninobu, T. Nakahara, H. Takeshima and K.
Takai, Org. Lett. 2013, 15, 426; (d) M. Murai, H. Takeshima, H.
at the specific locations based on the site-selective cleavage
of carbon hydrogen bonds.

17 Chirik et al. reported a catalytic hydrosilylation of a terminal
olefin, which was generated in situ from subsequent ring-
7
opening and double-bond migration reaction of
cyclopropylcarbinol derivative with a Wilkinson complex.
See: S. C. Bart and P. J. Chirik, J. Am. Chem. Soc., 2003, 125
a
,
886. Because olefins were not detected in the current study
with or without hydrosilanes, direct addition of silyliridium
Morita, Y. Kuninobu and K. Takai, J. Org. Chem., 2015, 80
,
5407; (e) M. Murai, K. Takami and K. Takai, Chem.-Eur. J.,
2015, 21, 4566; (f) M. Murai, K. Takami, H. Takeshima and K.
Takai, Org. Lett., 2015, 17, 1798; (g) M. Murai, K. Matsumoto, 18 The HIr(PR3)n species, generated via oxidative addition of
species
A with cyclopropane derivatives appears to be more
plausible for the reaction mechanism.
Y. Takeuchi and K. Takai, Org. Lett., 2015, 17, 3102; (h) M.
Murai, Y. Takeuchi, K. Yamauchi, Y. Kuninobu and K. Takai,
Chem.-A Eur. J., 2016, 22, 6048; (i) M. Murai, R. Okada, A.
Nishiyama and K. Takai, Org. Lett., 2016, 18, 4380; (j) M.
ClIr(PR3)n to R’3SiH followed by reductive elimination of
R’3SiCl, is proposed as an active catalytic species in the
hydrosilylation of alkynes. See: M. A. Esteruelas, M. Olivꢀn
and A. Vꢁlez, Inorg. Chem., 2013, 52, 12108.
Murai, Y. Takeuchi and K. Takai, Chem. Lett., 2017, 46, 1044; 19 Attempted intercept of alkyliridium species
C and the
(k) M. Murai, R. Okada, S. Asako and K. Takai, Chem. Eur. J.,
2017, doi:10.1002/chem.201701579. See also for our recent
work on the dehydrogenative borylation and germylation: (l)
corresponding benzyliridium species generated from 1j and
1k with alkynes, alkenes, and aldehydes failed due to the
rapid hydrosilylation of these additives.
Y. Kuninobu, T. Iwanaga, T. Omura, and K. Takai, Angew. 20 The trans effect may be another controlling factor involved
Chem. Int. Ed., 2013, 52, 4431; (m) M. Murai, K. Matsumoto,
R. Okada and K. Takai, Org. Lett., 2014, 16, 6492; (n) M.
Murai, T. Omura, Y. Kuninobu and K. Takai, Chem. Commun.,
2015, 51, 4583.
in the regioselective C
not have any structure and configuration information of the
intermediate and difficult to discuss exactly.
Si bond formation, although we do
B
21 (a) N. A. Meanwell, J. Med. Chem., 2011, 54, 2529; (b) S. Fujii,
Y. Miyajima, H. Masuno and H. Kagechika, J. Med. Chem.,
2013, 56, 160; (c) A. K. Franz and S. O. Wilson, J. Med. Chem.,
2013, 56, 388; (d) G. K. Min, D. Hernández and T. Skrydstrup,
Acc. Chem. Res., 2013, 46, 457.
8
9
Catalytic intramolecular dehydrogenative silylations of CH
bonds of cyclopropanes have been reported. See: (a) N.
Ghavtadze, F. S. Melkonyan, A. V. Gulevich, C. Huang, and V.
Gevorgyan, Nat. Chem., 2014, 6, 122; (b) T. Lee and J. F.
Hartwig, Angew. Chem. Int. Ed., 2016, 55, 8723.
Ring-opening reaction were not observed by the treatment
of triethylsilane with 3 in the presence of 2-methoxypyridine,
or 2-cyclopropylnahthalene in the presence of 2-
methylquinoline. These results confirm that pyridyl and
quinolyl groups act not only as ligands but also as directing
groups to cleave the cyclopropyl carboncarbon bonds.
10 The following metal complexes (5 mol%-M) did not convert
1a into 2a in toluene at 40 or 135 °C for 15 h: Re2(CO)10,
[ReBr(CO)3(thf)]2, Ru3(CO)12, [RuCl2(p-cymene)]2, CoCl(PPh3)3,
CoCl2, Co(OAc)2, [RhCl(cod)]2, [Cp*RhCl2]2, [RhCl(CO)2]2,
RhCl(PPh3)3, [RhCl(cod)]2 / AgOTf, IrCl3, NiCl2, Ni(OAc)2,
NiCl2(dppp), Pd(PPh3)4, Pd2(dba)3, Pd(OAc)2, and AgOTf.
11 Investigation of solvents with 5 mol% of [IrCl(cod)]2 at 40 °C
for 15 h: Yield of 2a was 61% in C6H5Cl, 68% in toluene, 62%
in octane, 59% in ClCH2CH2Cl, 80% in 1,4-dioxane, 78% in THF,
84% in Et2O, 8% in DMF. Ethereal solvents prevented the
side-reaction via the cleavage of CO bond leading to 2-
pyridone, and gave better results in the hydrosilylation of 2-
(cyclopropylalkoxy)pyridines.
12 Effect of temperature with 5 mol% of [IrCl(cod)]2 in toluene
for 15 h: Yield of 2a was 47% at 25 °C, 69% at 40 °C, 42% at
80 °C, 35% at 100 °C, and 26% at 135 °C. Investigation of
o
reaction time with 5 mol% of [IrCl(cod)]2 in toluene at 40 C:
4 | J. Name., 2012, 00, 1-3
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DOI: 10.1039/C7CC04296E
cat. Ir
N
X
N
X
R'3SiH
R'3Si
n
n
R
R
Catalytic and regioselective hydrosilylation of electronically unactivated cyclopropanes via the selective cleavage of proximal
carbon−carbon bonds was developed.