Rhodium-catalyzed C(sp2)-H addition of arylboronic acids to alkynes using a boron-based, convertible ortho-directing group

Article abstract of DOI:10.1246/cl.170404

Temporary modification of a boronyl group with pyrazoryl-aniline allowed insertion of arylpropiolates and diphenylacet-ylenes into the o-C-H bond of arylboronic acids in the presence of rhodium catalysts, giving 3,3-diarylacrylates and triarylethene conta

Full text of DOI:10.1246/cl.170404

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Rhodium-Catalyzed C(sp2)–H Addition of Arylboronic Acids to Alkynes Using a
Boron-Based, Convertible ortho-Directing Group
Takeshi Yamamoto, Aoi Ishibashi, and Michinori Suginome*
Advance Publication on the web May 20, 2017
doi:10.1246/cl.170404
© 2017 The Chemical Society of Japan
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1
Rhodium-Catalyzed C(sp2)–H Addition of Arylboronic Acids to Alkynes Using a Boron-
Based, Convertible ortho-Directing Group
Takeshi Yamamoto, Aoi Ishibashi, and Michinori Suginome*
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering,
Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
E-mail: suginome@sbchem.kyoto-u.ac.jp
cinnamate12 and the Cu-catalyzed conjugate addition of
Temporary modification of a boronyl group with
arylboronic acid to alkynoate,13 only a few examples of
pyrazorylaniline allowed insertion of arylpropiolates and
diphenylacetylenes into the o-C–H bond of arylboronic acids
in the presence of rhodium catalysts, giving 3,3-
diarylacrylates and triarylethene containing aryl groups
bearing an o-boryl group stereoselectively. The boronyl
group in the 3,3-diarylacrylates was converted into various
functional groups, including chlorine, hydrogen, hydroxy,
and aromatic groups.
regioselective
synthesis
of
o-functionalized
3,3-
diarylpropanoate have been reported. Herein, we report Rh-
catalyzed o-C–H alkenylation of PZA-modified arylboronic
acids with arylpropiolate and diarylacetylenes. The boronyl
group serving as a directing group in the alkenylation was
subsequently converted into various functional groups.
We initially utilized PZA as a modifier of the boronyl
group, which serves as an effective directing group for o-C–
H
silylation8a and borylation8c of arylboronic acids.
Directed or nondirected addition of an aromatic C–H
bond across carbon–carbon multiple bonds is recognized as
one of the most efficient synthetic methods for arylethene
and styrene derivatives.1 In particular, directed C–H
alkenylation has attracted much attention because it allows
the highly regioselective introduction of organic groups into
the o-position of the directing group. Since the establishment
of Murai’s Ru-catalyzed, carbonyl-directed alkenylation,2 a
variety of directing groups in combination with various
transition metals, including Ru,3 Rh,4 Ir,5 and Pd6 have been
developed for o-C–H alkenylation. However, this strategy
significantly limits the substrate scope, when the directing
group is not removable or convertible. To overcome this
limitation, much attention has been focused on the
development of convertible or traceless directing groups,7
such as triazene4f and carboxylic acid3o groups. However,
those convertible directing groups often lack high versatility
in the subsequent transformations. Therefore, it is highly
desirable to establish directing groups that can be converted
into a variety of functional groups.
Condensation of 3-methylphenylboronic acid with PZA
afforded PZA-modified m-tolylboronic acid 1A
quantitatively. In the presence of rhodium and iridium
complexes, 1A was subjected to reaction with 3 equiv of
methyl phenylpropiolate (2a) in N-methylpyrrolidone (NMP)
at 80 °C for 18 h (Table 1). The resultant reaction mixture
was treated with pinacol for detection and quantification of
the product in the form of pinacol ester 3. Although
[RhCl(cod)]2 failed to catalyze C–H alkenylation (entry 1),
[RhCl(coe)2]2 afforded alkenylated product 3Aa and
regioisomeric 3Aa in 29% yield with 84:16 ratio (entry 2).
3Aa was obtained as a mixture of E- and Z-isomers in 94:6
ratio. Although [RhCl(C2H4)2]2 exhibited comparable
catalytic activity (entry 3), [RhCl(PPh3)3], [Rh(cod)2]BF4,
and [Cp*RhCl2]2 showed no catalytic activity for o-C–H
alkenylation (entries 4–6). No product was formed in the
presence of [IrCl(coe)2]2, which is known to catalyze
hydroxy-directed C–H alkenylation (entry 7).14 The addition
of monodentate or bidentate phosphine ligand suppressed the
reaction (entries 8–10). Use of THF or toluene instead of
NMP decreased the yield with improved E/Z ratio (entries 11
and 12). Polar solvents such as DMA and DMF were not
suitable for this reaction (entries 13 and 14). Use of a 1:1
mixture of NMP and THF improved the yield to 48% (entry
15). We finally obtained a mixture of 3Aa and 3Aa (88:12)
in 68% isolated yield (E:Z = 94:6) using 5 mol% of
[RhCl(coe)2]2 in NMP/THF (entry 16). It is notable that
dialkenylated product was not observed under these reaction
conditions. Ethyl phenylpropiolate (2b) and isopropyl
phenylpropiolate (2c) gave almost the same results as 2a
(entries 17 and 18).
We have established pyrazorylaniline (PZA)8 and
anthranilamide (AAM)9 as easily attachable and detachable
directing groups for directed C–H functionalization reactions.
In these studies, the PZA-modified boronyl group (Bpza)
served as an o-directing group, which could be utilized for
further transformations by the versatile reactivity of the
boronyl group. However, the use of PZA has so far been
limited to Ru-catalyzed o-C–H silylation8a and Ir-catalyzed
o-C–H borylation.8c Our current focus is on the utilization of
temporary directing groups such as PZA and AAM in o-C–H
addition to carbon–carbon multiple bonds. In this work, we
demonstrate the addition of o-C–H bonds of arylboronic
acids to arylpropiolates, which provides 3,3-diarylacrylates
bearing two different aryl groups, one of which has an o-
boryl group. Unsymmetrical 3,3-diarylacrylates are utilized
as key starting materials for asymmetric reactions for the
synthesis of enantioenriched 3,3-diarylpropanoates.10
Although stereoselective synthesis of unsymmetrical 3,3-
diarylacrylates has been accomplished through several
reactions,11 such as Mizoroki–Heck-type reactions of
Table 1. Optimization of Reaction Conditionsa

2
3.0 equiv
CO2Et
Ph
2b
5 mol%
[RhCl(coe)2]
CO2Et
Ph
pinacol
PTSA•H2O
B
Bpin
Bpin
H
+
Ph
CO2Et
80 °C, 1 h
THF/NMP (0.2 M)
80 °C, 18 h
1B
3Bb
3Bb
B =
% yieldb
(3:3)c
E:Z of
3c
O
entry 2
Cat.
solvent additive
3
O
O
HN
NH
HN
N
HO
OH
HN
NH
O
N
N
N
B
B
B
B
B
B
1
2
3
4
5
6
7
8
9
2a [RhCl(cod)2]2
2a [RhCl(coe)2]2
NMP
NMP
–
–
–
–
–
–
–
3Aa
0
–
3Aa 29 (84:16) 94:6
3Aa 27 (85:16) 94:6
–Bpza
82%
3Bb:3Bb = 88:12
–B(OH)2
–Bpin
–Bdan
no reaction
–Baam
–Bpzp
2a [RhCl(C2H4)2]2 NMP
E-3Bb:Z-3Bb = 93:7
2a [RhCl(PPh3)3]
2a [Rh(cod)2]BF4
2a [Cp*RhCl2]2
2a [IrCl(coe)2]2
2a [RhCl(coe)2]2
2a [RhCl(coe)2]2
NMP
NMP
NMP
NMP
NMP
NMP
NMP
THF
3Aa
3Aa
3Aa
3Aa
0
0
–
–
–
–
–
–
–
–
–
–
–
The scope of the reaction was assessed by varying
alkynes under the optimized reaction conditions (Table 2).
Among a series of aryl propiolates having a monosubstituted
aromatic ring (entries 1–5), 4-methyl-substituted 2d afforded
3Bd and 3Bd in 75% yield with 91:9 E/Z ratio. 4-Methoxy-
substituted 2e afforded 3Be with higher stereoselectivity for
the Z-isomer (entry 2). In contrast, 2f bearing an electron-
withdrawing 4-trifluoromethyl group afforded E-3Bf with
high selectivity (entry 3). A 2-methyl group on the aromatic
ring gave 3Bh with lower regioselectivity but with higher
E/Z ratio (entry 5). 2-Naphthyl- and 1-naphthyl-substituted
propiolates (2i and 2j) also gave the corresponding products
(entries 6 and 7). While acetylenedicarboxylate 2k resulted
in no reaction (entry 8), diphenylacetylene (2l) underwent C–
H insertion at 135 °C with moderate yield with high
stereoselectivity (entry 9). Although diphenylacetylene 2m
bearing an electron-donating 4-methoxyphenyl group
showed no reactivity even at 135 °C (entry 10), the reaction
of 2n bearing 4-trifluoromethylphenyl groups proceeded at
110 °C, giving the hydroalkenylation product in 72% yield
(entry 11).
0
0
BINAP 3Aa
DPPE 3Aa
PCy3 3Aa
0
11
0
10 2a [RhCl(coe)2]2
11 2a [RhCl(coe)2]2
–
–
–
–
–
–
–
–
3Aa 13 (97:3)
3Aa 11 (91:9)
12 2a [RhCl(coe)2]2 toluene
13 2a [RhCl(coe)2]2
14 2a [RhCl(coe)2]2
15 2a [RhCl(coe)2]2
16d 2a [RhCl(coe)2]2
17d 2b [RhCl(coe)2]2
18d 2c [RhCl(coe)2]2
DMA
3Aa
3Aa
3
0
DMF
NMP/THF
NMP/THF
NMP/THF
NMP/THF
3Aa 48 (88:12) 94:6
3Aa 68e (88:12) 94:6
3Ab 74e (86:14) f 93:7
3Ac 69e (85:15) f 95:5
a1A (0.2 mmol), 2 (0.6 mmol), and [RhCl(coe)2]2 (5 mol) were stirred
in solvent (1.0 mL) at 80 °C for 18 h. GC yield. Determined by GC
analysis. d10 mol% Rh. fIsolated yield. eDetermined by NMR analysis.
b
c
Table 2. Scope of Alkyne
Other modifiers on the boronyl group were also tested
under the optimized reaction conditions for 1A (Scheme 1).
PZA-modified phenylboronic acid 1B afforded a mixture of
3Bb and 3Bb in 82% yield in 88:12 ratio. On the other hand,
the reaction of phenylboronic acid and its pinacol ester did
not give any desired products. Phenylboronic acid modified
with 1,8-diaminonaphthalene (Bdan), which serves as a
protecting group in Suzuki–Miyaura cross-coupling,15
showed
no
reactivity.
Anthranilamide-modified
entry 2
R1
R2
product % yieldb (3:3)c E:Z of 3c
phenylboronic acid (Baam), which serves as an efficient
directing group in Ru-catalyzed o-C–H silylation gave no
product either. The pyrazorylphenol-modified boronyl group
(Bpzp), which forms a dimeric structure even in solution (11B
NMR signal at 3.3 ppm in benzene-d6), also exhibited no
directing ability.8b These results indicate that PZA is an
essential directing group to promote the C–H alkenylation.
1
2
3
4
5
6
2d 4-MeC6H4
2e 4-MeOC6H4
2f 4-CF3C6H4
2g 3-MeC6H4
2h 2-MeC6H4
2i 2-naphthyl
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
CO2Et
Ph
3Bd
3Be
3Bf
3Bg
3Bh
3Bi
75 (89:11)
67 (93:7)
52 (91:9)
69 (87:13)
59 (74:26)
84 (89:11)
51 (80:20)
0
91:9
71:29
99:1
94:6
99:1
92:8
89:11
–
Scheme 1. Scope of Substrate
7d 2j 1-naphthyl
3Bj
3Bk
3Bl
8
9
2k
2l
CO2Et
Ph
47
>99:1

3
To gain insights into the reaction mechanism,
deuterium-labeling experiments were carried out. The
reaction of deuterium-labeled substrate 1Bb-d5 and 2b
proceeded under the optimized conditions, giving 3Bb-d5
and 3Bb-d5 in 66% combined yield (88:12) (eq. 2).
Deuterium incorporation at the vinyl position of 3Bb-d5 was
96%. We also measured the kinetic isotope effect (KIE) by
carrying out separate reactions of 1B and 1B-d5. In the
presence of 10 equiv of 2b, the KIE value in the initial stage
of the reaction was determined to be 1.1 (eq. 3, see SI). This
result suggests that C–H cleavage is not the rate-determining
step.
10 2m 4-MeOC6H4 4-MeOC6H4 3Bm
11 2n 4-CF3C6H4 4-CF3C6H4 3Bn
0
–
73
>99:1
a1B (0.2 mmol), 2 (0.6 mmol), and [RhCl(coe)2]2 (0.01 mmol) were
stirred in solvent (1.0 mL) at 80 °C for 18 h. bIsolated yield. cDetermined
by NMR analysis. d110 °C.
A variety of PZA-modified arylboronic acids were then
reacted with ethyl propiolate (2b) (Table 3). 1C and 1D
bearing 4-methyl and 4-methoxyphenyl groups gave the
corresponding products in 62% and 48% yields, respectively
(entries 1 and 2). Although the reaction of 1E bearing an
electron-withdrawing 4-trifluoromethyl group was found to
be inefficient, products were obtained in 30% yield in the
presence of 8 mol% [RhCl(coe)2]2 (entry 3). In the screening
of substituents at the 3-position, the reaction proceeded at the
less hindered o-positions selectively, giving methyl-,
methoxy-, trifluoromethyl-, and bromo-substituted 3 in 48–
74% yields (entries 4–7). The reaction was also applicable to
1I bearing the 2-methoxy group, giving 3Ib selectively,
albeit in low yield (entry 8). In these substrates,
dialkenylated products were not observed.
(2)
Table 3. Scope of PZA-Modified Arylboronic Acids
(3)
According to our experimental results, along with
16
previous studies by other groups,4j, a plausible reaction
mechanism is shown in Scheme 2. Coordination of the sp2-
nitrogen atom of the pyrazoryl group of Bpza to the Rh(I)
complex followed by oxidative addition of the o-C–H bond
to Rh provides six-membered rhodacycle A. Subsequent
coordination of alkyne 2 to A gives intermediate B, from
which insertion of the alkyne to the Rh–H bond forms
rhodacycle C. Subsequent reductive elimination provides
alkenylation product E. The possibility of alkyne insertion to
the C–Rh bond of B, which forms eight-membered
rhodacycle D, cannot be excluded.
% yieldb
(3:3)c
E/Z of
3c
entry
1
R1
R2
R3
3
1
2
3
4
5
6
7
8
1C
Me
H
H
H
H
3Cb
3Db
3Eb
3Ab
3Fb
3Gb
3Hb
3Ib
62 (87:13)
48 (90:10)
30 (87:13)
74 (86:14)
48 (87:13)
64 (87:13)
60 (88:12)
28 (nd)
93:7
94:6
91:9
93:7
97:3
94:6
94:6
nd
1D MeO
1E
1A
1F
1G
1H
1I
CF3
H
H
H
Me
MeO
CF3
Br
H
H
H
H
H
H
H
H
H
MeO
a1 (0.2 mmol), 2b (0.6 mmol), and [RhCl(coe)2]2 (0.01 mmol) were
stirred in solvent (1.0 mL) at 80 °C for 18 h. bIsolated yield, cDetermined
by NMR analysis.
2-Thienylboronic acid derivative 1J underwent C–H
alkenylation at the 3-position selectively, giving 3Jb in 56%
yield with an E/Z ratio of 88:12 (eq. 1).
3.0 equiv
Ph
CO2Et
Bpza
Bpin
CO2Et
Ph
2b
pinacol
PTSA•H2O
5 mol% [RhCl(coe)]2
S
S
80 °C, 1 h
THF/NMP (0.2 M)
110 °C, 18 h
Scheme 2. Proposed Reaction Mechanism
1J
3Jb
56% (E:Z = 88:12)
(1)

4
Org. Lett. 2012, 14, 2058. (h) M. C. Reddy, M. Jeganmohan,
Chem. Commun. 2013, 49, 481. (i) M. C. Reddy, M.
Jeganmohan, Eur. J. Org. Chem. 2013, 1150. (j) C. Suzuki, K.
Hirano, T. Satoh, M. Miura, Org. Lett. 2013, 15, 3990. (k) R.
Manikandan, M. Jeganmohan, Org. Lett. 2014, 16, 912. (l) X. G.
Li, K. Liu, G. Zou, P. N. Liu, Eur. J. Org. Chem. 2014, 7878.
(m) K. Padala, M. Jeganmohan, Chem. Commun. 2014, 50,
14573. (n) M. C. Reddy, M. Jeganmohan, Chem. Commun. 2015,
51, 10738. (o) L. B. Huang, A. Biafora, G. D. Zhang, V. Bragoni,
L. J. Goossen, Angew. Chem. Int. Ed. 2016, 55, 6933.
(a) N. Umeda, K. Hirano, T. Satoh, M. Miura, J. Org. Chem.
2009, 74, 7094. (b) F. W. Patureau, T. Besset, F. Glorius, Angew.
Chem. Int. Ed. 2011, 50, 1064. (c) S. H. Park, J. Y. Kim, S.
Chang, Org. Lett. 2011, 13, 2372. (d) C. Feng, T. P. Loh, Chem.
Commun. 2011, 47, 10458. (e) N. Schroder, T. Besset, F.
Glorius, Adv. Synth. Catal. 2012, 354, 579. (f) C. M. Wang, H.
Chen, Z. F. Wang, J. A. Chen, Y. Huang, Angew. Chem. Int. Ed.
2012, 51, 7242. (g) Y. Y. Shen, G. X. Liu, Z. Zhou, X. Y. Lu,
Org. Lett. 2013, 15, 3366. (h) G. Liu, Y. Shen, Z. Zhou, X. Lu,
Angew. Chem. Int. Ed. 2013, 52, 6033. (i) X. Huang, J. Huang,
C. Du, X. Zhang, F. Song, J. You, Angew. Chem. Int. Ed. 2013,
52, 12970. (j) A. M. Martinez, J. Echavarren, I. Alonso, N.
Rodriguez, R. G. Arrayas, J. C. Carretero, Chem. Sci. 2015, 6,
5802. (k) R. Morioka, T. Satoh, M. Miura, Chem. Lett. 2016, 45,
682. (l) C. Q. Wang, C. Feng, T. P. Loh, Asian J. Org. Chem.
2016, 5, 1002.
The obtained ethyl 3,3-diarylacrylate 3Bb bearing an o-
boryl group serves as a versatile synthetic intermediate for
the synthesis of 3,3-diarylacrylates (Scheme 3). Suzuki–
Miyaura cross-coupling of E-3Bb with phenyl bromide
afforded biaryl compound 4 in 97% yield. Chlorination of E-
3Bb using CuCl2 afforded the corresponding product 5 in
78% yield. The Bpin group was also converted to a hydroxyl
group by oxidation, giving a phenol derivative 6 in 97%
yield. In these reactions, E/Z isomerization of alkene was not
observed. In addition, the Bpza group was removed by
4.
silver-catalyzed
diphenylacrylate 7 in 81% yield.
protodeborylation,17
giving
2,2-
5.
K. Tsuchikama, M. Kasagawa, Y.-K. Hashimoto, K. Endo, T.
Shibata, J. Organomet. Chem. 2008, 693, 3939.
6. (a) M. D. K. Boele, G. P. F. van Strijdonck, A. H. M. de Vries, P.
C. J. Kamer, J. G. de Vries, P. van Leeuwen, J. Am. Chem. Soc.
2002, 124, 1586. (b) G. Cai, Y. Fu, Y. Li, X. Wan, Z. Shi, J. Am.
Chem. Soc. 2007, 129, 7666. (c) K. M. Engle, D. H. Wang, J. Q.
Yu, Angew. Chem. Int. Ed. 2010, 49, 6169; (d) D.-H. Wang, K.
M. Engle, B.-F. Shi, J.-Q. Yu, Science 2010, 327, 315. (e) A.
Garcia-Rubia, M. A. Fernandez-Ibanez, R. G. Arrayas, J. C.
Carretero, Chem. Eur. J. 2011, 17, 3567. (f) A. Garcia-Rubia, B.
Urones, R. G. Arrayas, J. C. Carretero, Angew. Chem. Int. Ed.
2011, 50, 10927. (g) C. Huang, B. Chattopadhyay, V.
Gevorgyan, J. Am. Chem. Soc. 2011, 133, 12406. (h) M.
Mewald, J. A. Schiffner, M. Oestreich, Angew. Chem. Int. Ed.
2012, 51, 1763. (i) P. Gandeepan, C. H. Cheng, J. Am. Chem.
Soc. 2012, 134, 5738. (j) X. Cong, J. You, G. Gao, J. Lan, Chem.
Commun. 2013, 49, 662. (k) H. X. Dai, G. Li, X. G. Zhang, A. F.
Stepan, J. Q. Yu, J. Am. Chem. Soc. 2013, 135, 7567. (l) M.
Hasegawa, A. Nomoto, T. Suga, T. Soeta, Y. Ukaji, Chem. Lett.
2017, 46, 45.
Scheme 3. Synthetic Application
In summary, we demonstrated Rh-catalyzed o-C–H
alkenylation of arylboronic acids using PZA as a temporary
directing group on the boron atom. After replacement of the
PZA group with pinacol, the boron functionality was
converted to hydrogen, phenyl, chloro, and hydroxy groups.
The present protocol based on the o-C–H borylation of
arylboronic acids provides a new access to o-functionalized
3,3-diarylacrylates and triarylethenes.
This work was supported by JSPS KAKENHI Grant
JP15H05811 in Precisely Designed Catalysts with
Customized Scaffolding.
7.
8.
F. Zhang, D. R. Spring, Chem. Soc. Rev. 2014, 43, 6906.
(a) H. Ihara, M. Suginome, J. Am. Chem. Soc. 2009, 131, 7502.
(b) H. Ihara, A. Ueda, M. Suginome, Chem. Lett. 2011, 40, 916.
(c) T. Yamamoto, A. Ishibashi, M. Suginome, Org. Lett. 2017,
19, 886.
Supporting
Information
is
available
on
http://dx.doi.org/10.1246/cl.******.
References and Notes
9.
(a) H. Ihara, M. Koyanagi, M. Suginome, Org. Lett. 2011, 13,
2662. (b) M. Koyanagi, N. Eichenauer, H. Ihara, T. Yamamoto,
M. Suginome, Chem. Lett. 2013, 42, 541.
1. (a) V. Ritleng, C. Sirlin, M. Pfeffer, Chem. Rev. 2002, 102, 1731.
(b) F. Kakiuchi, T. Kochi, Synthesis 2008, 3013. (c) T. Kitamura,
Eur. J. Org. Chem. 2009, 1111. (d) D. A. Colby, R. G. Bergman,
J. A. Ellman, Chem. Rev. 2010, 110, 624. (e) F. Kakiuchi, T.
Kochi, S. Murai, Synlett 2014, 25, 2390. (f) Z. X. Huang, H. N.
Lim, F. Y. Mo, M. C. Young, G. B. Dong, Chem. Soc. Rev. 2015,
44, 7764.
10. (a) P. Tolstoy, M. Engman, A. Paptchikhine, J. Bergquist, T. L.
Church, A. W. M. Leung, P. G. Andersson, J. Am. Chem. Soc.
2009, 131, 8855. (b) K. Itoh, A. Tsuruta, J. Ito, Y. Yamamoto, H.
Nishiyama, J. Org. Chem. 2012, 77, 10914.
11. (a) C. G. Jia, W. J. Lu, J. Oyamada, T. Kitamura, K. Matsuda, M.
Irie, Y. Fujiwara, J. Am. Chem. Soc. 2000, 122, 7252. (b) C. G.
Jia, D. G. Piao, J. Z. Oyamada, W. J. Lu, T. Kitamura, Y.
Fujiwara, Science 2000, 287, 1992. (c) M. Y. Yoon, J. H. Kim,
D. S. Choi, U. S. Shin, J. Y. Lee, C. E. Song, Adv. Synth. Catal.
2007, 349, 1725. (d) Y. Ashida, Y. Sato, T. Suzuki, K. Ueno, K.
Kai, H. Nakatsuji, Y. Tanabe, Chem. Eur. J. 2015, 21, 5934. (e)
A. Morinaga, K. Nagao, H. Ohmiya, M. Sawamura, Angew.
Chem. Int. Ed. 2015, 54, 15859.
2.
F. Kakiuchi, Y. Yamamoto, N. Chatani, S. Murai, Chem. Lett.
1995, 681.
3.
(a) Y. Hashimoto, T. Ueyama, T. Fukutani, K. Hirano, T. Satoh,
M. Miura, Chem. Lett. 2011, 40, 1165. (b) P. B. Arockiam, C.
Fischmeister, C. Bruneau, P. H. Dixneuf, Green Chem. 2011, 13,
3075. (c) K. Padala, M. Jeganmohan, Org. Lett. 2011, 13, 6144.
(d) Y. Hashimoto, T. Ortloff, K. Hirano, T. Satoh, C. Bolm, M.
Miura, Chem. Lett. 2012, 41, 151. (e) B. Li, J. F. Ma, N. C.
Wang, H. L. Feng, S. S. Xu, B. Q. Wang, Org. Lett. 2012, 14,
736. (f) K. Padala, M. Jeganmohan, Org. Lett. 2012, 14, 1134.
(g) Y. Hashimoto, K. Hirano, T. Satoh, F. Kakiuchi, M. Miura,
12. (a) M. MorenoManas, M. Perez, R. Pleixats, Tetrahedron Lett.
1996, 37, 7449. (b) C. Gurtler, S. L. Buchwald, Chem. Eur. J.
1999, 5, 3107. (c) G. Battistuzzi, S. Cacchi, G. Fabrizi, Synlett

5
2002, 439. (d) I. Kondolff, H. Doucet, M. Santelli, Tetrahedron
Lett. 2003, 44, 8487. (e) J. C. Pastre, C. R. D. Correia, Adv.
Synth. Catal. 2009, 351, 1217. (f) V. Calo, A. Nacci, A.
Monopoli, P. Cotugno, Angew. Chem. Int. Ed. 2009, 48, 6101.
(g) Z. He, S. Kirchberg, R. Froehlich, A. Studer, Angew. Chem.
Int. Ed. 2012, 51, 3699.
13. (a) Y. Yamamoto, N. Kirai, Y. Harada, Chem. Commun. 2008,
2010. (b) T. Murayama, M. Shibuya, Y. Yamamoto, Adv. Synth.
Catal. 2016, 358, 166.
14. T. Satoh, Y. Nishinaka, M. Miura, M. Nomura, Chem. Lett. 1999,
615.
15. (a) H. Noguchi, K. Hojo, M. Suginome, J. Am. Chem. Soc. 2007,
129, 758. (b) H. Noguchi, T. Shioda, C.-M. Chou, M. Suginome,
Org. Lett. 2008, 10, 377. (c) N. Iwadate, M. Suginome, Org. Lett.
2009, 11, 1899.
16. (a) D. A. Colby, R. G. Bergman, J. A. Ellman, J. Am. Chem. Soc.
2008, 130, 3645. (b) L. Li, Y. Z. Jiao, W. W. Brennessel, W. D.
Jones, Organometallics 2010, 29, 4593. (c) M. Valencia, M.
Martin-Ortiz, M. Gomez-Gallego, C. R. de Arellano, M. A.
Sierra, Chem. Eur. J. 2014, 20, 3831. (d) F. Y. Mo, G. B. Dong,
Science 2014, 345, 68. (e) F. Y. Mo, H. N. Lim, G. B. Dong, J.
Am. Chem. Soc. 2015, 137, 15518.
17. C. Liu, X. M. Li, Y. H. Wu, Rsc Adv. 2015, 5, 15354.