LiHMDS-Promoted Palladium or Iron-Catalyzed ipso-Defluoroborylation of Aryl Fluorides

Article abstract of DOI:10.1021/acs.orglett.8b02228

A novel and efficient method for the synthesis of arylboronic acid pinacol esters via a palladium- or iron-catalyzed cross-coupling reaction of aryl fluorides with bis(pinacolato)diboron (B₂pin₂) in the presence of LiHMDS was developed. The Pd-catalyzed defluoroborylation of fluoroarenes is compatible with a variety of functional groups such as primary and secondary amine, ketone, trifluoromethyl, alkoxy, and boryl. Remarkably, no external ligand is required for enhanced conversion efficiency.

Full text of DOI:10.1021/acs.orglett.8b02228

Letter
pubs.acs.org/OrgLett
Cite This: Org. Lett. XXXX, XXX, XXX−XXX
LiHMDS-Promoted Palladium or Iron-Catalyzed ipso-
Defluoroborylation of Aryl Fluorides
Xianghu Zhao, Mingsheng Wu, Yisen Liu, and Song Cao*
Shanghai Key Laboratory of Chemical Biology, School of Pharmacy, East China University of Science and Technology (ECUST),
Shanghai 200237, China
S
* Supporting Information
ABSTRACT: A novel and efficient method for the synthesis
of arylboronic acid pinacol esters via a palladium- or iron-
catalyzed cross-coupling reaction of aryl fluorides with
bis(pinacolato)diboron (B2pin2) in the presence of LiHMDS
was developed. The Pd-catalyzed defluoroborylation of
fluoroarenes is compatible with a variety of functional groups
such as primary and secondary amine, ketone, trifluoromethyl,
alkoxy, and boryl. Remarkably, no external ligand is required
for enhanced conversion efficiency.
rylboronate esters are indispensable and versatile reagents
in organic synthesis due to their broad availability, high
Scheme 1. C−F Bond Borylation of Fluoroarenes
A
stability, and ease of handling.1 They have found wide
applications in carbon−carbon bond formations, especially in
palladium-catalyzed Suzuki−Miyaura cross-coupling reactions.2
Therefore, the efficient synthesis of arylboronate esters
continues to attract considerable attention from synthetic
chemists.3 To date, numerous methods have been developed
for the synthesis of arylboronate esters.4 Among the various
methodologies reported, the transition-metal-catalyzed boryla-
tion of aryl halides or triflates with bis(pinacolato)diboron
(B2pin2) is probably the most common and efficient synthetic
access to aryl boronic esters.5 Typically, aryl iodides, bromides,
and even aryl chlorides could serve as effective coupling partners
in transition-metal-catalyzed borylation reactions,6 whereas
unreactive aryl fluorides are seldom used as coupling partners
due to the inertness of the aryl−F bond toward oxidative
addition to transition-metal complexes.7
co-workers disclosed a Ni(IMes)2-catalyzed C−F bond
borylation of polyfluoroarenes using B2pin2 as the boron source
(Scheme 1e).14 Although these reported methods for the
defluoroborylation of fluoroarenes are efficient and versatile,
these methodologies still suffer from one or more limitations,
such as the use of additional ligand, limited substrate scope, and
high catalyst loadings. Therefore, there is plenty of room for the
exploration of a new catalytic system that can display broad
substrate scope and high functional group compatibility.
Palladium-catalyzed cross-coupling reactions have emerged as
a tremendously valuable synthetic tool in organic synthesis and
pharmaceutical chemistry because a palladium catalyst exhibits
powerful catalytic ability.2 Particularly, various palladium-
catalyzed methods have emerged for the transformation of aryl
iodides, bromides, chlorides, and triflates to the corresponding
pinacol boronate esters.5b,c,6a,c However, no examples of
defluoroborylation of fluoroarenes to arylboronate esters using
The activation and functionalization of the strong carbon−
fluorine bond have gained growing interest during the past two
decades since they provide an alternative method for synthesis of
structurally diverse molecules from fluoroorganic compounds.8
The transition-metal-catalyzed borylation of the C−F bond in
polyfluorinated alkenes and arenes has become a hot topic in
organic chemistry.9 For example, the group of Zhang reported
an ortho-selective C−F bond borylation of polyfluoroarenes
using [Rh(cod)2]BF4 as catalyst (Scheme 1a).10 In 2015, Martin
et al. described the first Ni-catalyzed borylation of mono-
fluoroarenes with B2nep2 via C−F activation and C−B bond
formation (Scheme 1b).11 Almost at the same time, Niwa and
Hosoya developed a Ni-catalyzed defluoroborylation of
monofluoroarenes with B2pin2 with the assistance of CuI
(Scheme 1c).12 Two years later, the same group reported Cu-
catalyzed ipso-borylation of polyfluoroarenes which enabled the
synthesis of di- and triborylated arenes from di- and
trifluoroarenes (Scheme 1d).13 In 2016, Radius, Marder, and
Received: July 17, 2018
© XXXX American Chemical Society
A
DOI: 10.1021/acs.orglett.8b02228
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
palladium catalysts have been reported so far. Considering the
fact that palladium-catalyzed borylation of aryl halides methods
offer a higher degree of functional group tolerance, we envisaged
that defluoroborylation of unactivated fluoroarenes might be
feasible under palladium catalysis. In this letter, we reported a
novel and efficient method for the synthesis arylboronic acid
pinacol esters via Pd- or Fe-catalyzed borylation of fluoroarenes
with B2pin2 in the presence of LiHMDS (Scheme 1f).
effect on the reaction and the yield of 3a could be dramatically
increased to 85%. We were delighted to find that decreasing the
amount of Pd2dba3 from 5 mol % to 2 mol % would also furnish
3a in good yield (entry 18). Further decreasing the amount of
Pd2dba3 to 0.5 mol % led to a remarkable decrease in the yield
(entry 19). Finally, the effect of amount of LiHMDS on the
reaction was also studied (entries 5 and 20−21). The highest
yield (95%) of the borylation product 3a was achieved when 2.0
equiv of LiHMDS were used.
We began our studies using the borylation of 4-fluoro-1,1′-
biphenyl (1a) with B2pin2 as the model reaction to optimize the
reaction conditions (Table 1). Initially, different Pd catalysts
With the optimized conditions in hand (Table 1, entry 20), we
next examined the scope of the Pd-catalyzed borylation of
various fluoroarenes with B2pin2 (2) (Scheme 2). In most cases,
a
Table 1. Optimization of the Reaction Conditions
Scheme 2. Pd-Catalyzed Defluoroborylation of Various
a
Fluoroarenes
b
entry catalyst (x mol %)
base (x equiv)
solvent
yield (%)
1
2
3
4
5
6
7
8
none
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
CsF (2.5)
LiOtBu (2.5)
NaOPh (2.5)
NaHMDS (2.5)
KHMDS (2.5)
LDA (2.5)
THF
THF
THF
THF
THF
THF
THF
THF
THF
THF
THF
THF
CH3CN
DMF
MTBE
dioxane
toluene
toluene
toluene
toluene
toluene
0
Pd(PPh3)4 (5)
Pd(OAc)2 (5)
PdCl2 (5)
15
25
35
41
0
0
0
2
12
20
0
0
0
12
27
85
84
18
95
80
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (5)
Pd2dba3 (2)
Pd2dba3 (0.5)
Pd2dba3 (2)
Pd2dba3 (2)
9
10
11
12
13
14
15
16
17
18
19
20
21
tBuLi (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.5)
LiHMDS (2.0)
LiHMDS (1.5)
a
Reaction conditions: 1a (0.1 mmol), B2pin2 (0.15 mmol), solvent
b
(1.0 mL), 80 °C, 12 h, Ar. Yields determined by GC analysis and
based on 1a.
a
Reaction conditions: 1 (0.5 mmol), 2 (0.75 mmol), Pd2dba3 (0.01
mmol), LiHMDS (1.0 mmol), toluene (2.5 mL), 80 °C, 12 h, Ar.
b
Isolated yields. 1w = 4,4′-difluoro-1,1′-biphenyl, 1w′ = 4-chloro-4′-
were examined. Among the tested Pd catalysts, Pd2dba3 proved
to be more suitable for the reaction (entries 2−5). As
anticipated, no borylated product was observed in the absence
of a Pd catalyst (entry 1). Generally, the borylation reaction
could be achieved by using CsF, NaOPh and MOtBu (M = Na,
K, Li) as bases.4a,6c,7a However, alkaline metal hexamethyldisi-
lazide (MHMDS, M = Na, K, Li) is scarcely used as bases or
additives in borylation reactions.15 The only successful example
of a borylation reaction of this type involved the Pd-catalyzed
ipso-borylation of aryl sulfides with B2pin2 using lithium
hexamethyldisilazide (LiHMDS or LiN(SiMe3)2) as activator.16
Subsequently, the influence of the base on the reaction was
examined (entries 5−12). The results indicate that LiHMDS
was uniquely effective for the transformation, affording the
expected product 3a in 41% yield (entry 5), whereas the use of
other bases, such as NaHMDS, KHMDS, and LDA, resulted in
poor yields. Moreover, no reaction took place with CsF, NaOPh,
LiOtBu, and tBuLi, recovering the starting fluoroarene 1a.
Next, a brief screening of the solvents was carried out (entries
5 and 13−17), and it revealed that toluene had a pronounced
fluoro-1,1′-biphenyl, 1w″ = 4-bromo-4′-fluoro-1,1′-biphenyl, 3w =
3w′ = 3w″.
the defluoroborylation reaction proceeded smoothly to give the
corresponding borylation products 3 in moderate to good yields
under the optimal conditions. Generally, fluoroarenes bearing
electron-neutral (1b), weak (such as 1d, 1f, and 1h) or strong
electron-donating groups (1c) gave the desired products in
higher yields than substrates bearing electron-withdrawing
groups (1k). However, the fluoroarenes having strong
electron-withdrawing groups such as NO2 and CN (e.g., 1-
fluoro-4-nitrobenzene and 4-fluorobenzonitrile) were unfavor-
able for the reaction and gave complex mixtures. Notably,
fluoroacetophenones (1k and 1l) are suitable substrates for this
transformation, leaving the keto group intact. Unfortunately,
substrates containing ester and amide groups (e.g., ethyl 4-
fluorobenzoate and N-(4-fluorophenyl)acetamide) could not
work well and only small amounts of borylated products were
detected (GC-MS, ∼30%). Importantly, when ortho-, meta-, or
B
DOI: 10.1021/acs.orglett.8b02228
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
para-fluoroanilines were used as the substrates, the reactions
proceeded efficiently to furnish the borylation products in high
yields (GC-MS, above 80%). Although the reaction itself
proceeded well, borylated anilines are not very stable, only para-
and meta-borylated anilines (3m and 3n) could be isolated in
moderate yields. The ortho-borylated aniline was presumably
lost in the workup procedure. In addition, secondary anilines are
compatible with this new Pd-based catalytic system (3o). The
position of the substituent on the benzene ring of fluoroarenes
has an obvious influence on the yield of the desired product. For
example, fluoroarenes possessing a phenyl group in the para-
position afforded the expected product in excellent yield (3a),
whereas the shift of the phenyl group to the meta- or ortho-
positions gave reduced reaction yields (3f and 3g). However,
when difluorobenzene or 1,2,3,4,5-pentafluorobenzene were
used as substrates, only small or trace amounts of borylated
products were detected and no diborylated products were
observed.
It was reported that fluoroarenes with an extended π-
conjugated system exhibited high reactivity in Ni or Cu-
catalyzed defluoroborylation reaction.11 Thus, Niwa, Hosoya,
and Martin have extensively investigated borylation of
fluorobiaryls.11−13 For comparison purposes, we also applied
this Pd-catalyzed borylation to a variety of substituted 4-
fluorobiaryls. The results indicate that both electron-rich and
-poor biaryl fluorides could be efficiently transformed to the
desired products in moderate to high yields. Functional groups
such as amino, methoxy, dioxole, tert-butyl, trifluoromethyl,
boryl, and fluoro groups were compatible with the borylation
process. The tolerance of amino and existing boryl groups was
particularly useful, which offers an opportunity for further
synthetic transformation. Compared to fluoroarenes, fluoro-
biaryls had no obvious impact on the reaction efficiency. Finally,
when 4-chloro- or 4-bromo-4′-fluoro-1,1′-biphenyl were used as
coupling partners, the borylation reaction took place selectively
at the C−Cl or C−Br bond in preference to the C−F bond and
the C−F bond remained intact (3w = 3w′ = 3w″). The results
suggest that aryl bromides and aryl chlorides are also suitable for
this Pd-catalyzed borylation reaction system.
Scheme 4. Proposed Reaction Mechanism
reductive elimination from the Pd complex IV furnishes the
desired arylboronic esters along with the regeneration of the
active catalytic species Pd(0) to close the catalytic cycle. In
addition, the resulting intermediate II may readily dissociate
into fluoroborane (FBpin) and LiN(TMS)2 which seem to be
unstable under the reaction conditions and convert into
pinBN(TMS)2 and LiF because of the strong Li−F
interaction.18 Furthermore, a considerable amount of byproduct
pinBN(TMS)2 could be detected by GC-MS. It should be
mentioned that when replacing LiHMDS with NaHMDS or
performing the reaction at room temperature, only small or trace
amounts of pinBN(TMS)2 could be observed.
Iron is one of the most abundant metals in nature.
Consequently, iron has attracted considerable attention in the
field of cross-coupling reactions. Compared to the expensive
palladium and relatively toxic nickel catalysts, iron catalysts are
inexpensive, readily available, and environmentally friendly.19
Although various iron-catalyzed borylations of alkyl, allyl, and
aryl halides have been realized,20 the borylation of fluoroarenes
with Fe catalysts remains unexplored. Encouraged by the above
results obtained from the borylation of fluoroarenes with Pd
catalyst, we turned our attention to the iron-catalyzed cross-
coupling reaction of fluoroarenes with B2pin2. After careful
screening of iron catalysts, solvents, and reaction temperatures,
we found that the borylation of fluoroarenes could proceed
smoothly in the presence of 20 mol % FeCl2 and 3.2 equiv of
LiHMDS using toluene and HMPA as the solvent (2:1 in
volume) at 110 °C for 12 h. Subsequently, we applied the
optimized conditions to a variety of fluoroarenes and biaryl
fluorides (Scheme 5). It was found that only biaryl fluorides
proceeded well, affording the borylation products in moderate to
good yields, whereas fluoroarenes without a π-conjugated
system such as 1b−1e gave the expected products in poor
yields (∼20%, GC). The scope of this Fe-catalyzed borylation
reaction was still limited, and the reaction efficiency was
relatively low. However, considering ready availability, low cost,
high earth abundance, and nontoxicity of the iron catalyst, this
new Fe-catalyzed borylation might be an alternative method for
the synthesis of arylboronate esters from biaryl fluorides.
In summary, we have developed a novel and efficient method
for the synthesis of arylboronate esters via Pd- or Fe-catalyzed
cross-coupling reaction of aryl fluorides with bis(pinacolato)-
diboron (B2pin2) in the presence of LiHMDS without any
additional ligand. In comparison with the earlier Ni- and Cu-
catalyzed defluoroborylation, the newly developed Pd-catalyzed
reaction systems can tolerate primary and secondary amine and
ketone groups. Notably, the Pd-catalyzed reaction could be
performed on a gram scale with lower catalyst loading.
Importantly, LiHMDS plays a particularly key role in the
transformation, which might be attributed to the strong Li−F
Gratifyingly, the procedure could be scaled up to a gram scale
(1j, 7.0 mmol). Without further optimization, the borylation of
1j could produce the desired arylboronate product 3j in
moderate yield with 1.0 mol % of catalyst loading (Scheme 3).
Scheme 3. Borylation of 1-Fluoronaphthalene on a 7.0 mmol
Scale
According to our experimental results and the reported
literature studies,2b,16 a plausible reaction mechanism for Pd-
catalyzed defluoroborylation of fluoroarenes is proposed in
Scheme 4. Initially, one of the boron atoms of the B2pin2 is
coordinated to strong base LiN(SiMe3)2 to give the Lewis
adduct of sp2−sp3 diborane compound I.17 The B−B bond of
diborane compound could be activated and then cleaved
heterolytically. The oxidative addition of the C−F bond in
fluoroarenes at Pd(0) complex gives LArPd(II)F adduct III.
Subsequently, transmetalation of III with intermediate I results
the formation of LArPd(II)Bpin IV and intermediate II. Finally,
C
DOI: 10.1021/acs.orglett.8b02228
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
(2) (a) Suzuki, A. Angew. Chem., Int. Ed. 2011, 50, 6722. (b) Miyaura,
N.; Suzuki, A. Chem. Rev. 1995, 95, 2457. (c) Lennox, A. J.; Lloyd-
Jones, G. C. Chem. Soc. Rev. 2014, 43, 412.
Scheme 5. Fe-Catalyzed Defluoroborylation of Biaryl
Fluorides
a
(3) (a) Furukawa, T.; Tobisu, M.; Chatani, N. J. Am. Chem. Soc. 2015,
137, 12211. (b) Chen, K.; Wang, L.; Meng, G.; Li, P. Synthesis 2017, 49,
4719. (c) Xu, Y.; Fang, H. Youji Huaxue 2018, 38, 738. (d) Yan, G.;
Huang, D.; Wu, X. Adv. Synth. Catal. 2018, 360, 1040. (e) Xu, L.; Wang,
G.; Zhang, S.; Wang, H.; Wang, L.; Liu, L.; Jiao, J.; Li, P. Tetrahedron
2017, 73, 7123.
(4) (a) Neeve, E. C.; Geier, S. J.; Mkhalid, I. A.; Westcott, S. A.;
Marder, T. B. Chem. Rev. 2016, 116, 9091. (b) Zhang, L.; Jiao, L. J. Am.
Chem. Soc. 2017, 139, 607. (c) Hu, J.; Zhao, Y.; Liu, J.; Zhang, Y.; Shi, Z.
Angew. Chem., Int. Ed. 2016, 55, 8718. (d) Uetake, Y.; Niwa, T.;
Hosoya, T. Org. Lett. 2016, 18, 2758. (e) Li, H.-L.; Kuninobu, Y.; Kanai,
M. Angew. Chem., Int. Ed. 2017, 56, 1495.
(5) (a) Kleeberg, C.; Dang, L.; Lin, Z.; Marder, T. B. Angew. Chem.,
Int. Ed. 2009, 48, 5350. (b) Ratniyom, J.; Dechnarong, N.; Yotphan, S.;
Kiatisevi, S. Eur. J. Org. Chem. 2014, 2014, 1381. (c) Bej, A.; Srimani,
D.; Sarkar, A. Green Chem. 2012, 14, 661. (d) Kubota, K.; Iwamoto, H.;
Ito, H. Org. Biomol. Chem. 2017, 15, 285.
(6) (a) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 2002, 41, 4176.
(b) Murata, M. Heterocycles 2012, 85, 1795. (c) Chow, W. K.; Yuen, O.
Y.; Choy, P. Y.; So, C. M.; Lau, C. P.; Wong, W. T.; Kwong, F. Y. RSC
Adv. 2013, 3, 12518.
(7) (a) Chen, W.; Bakewell, C.; Crimmin, M. Synthesis 2017, 49, 810.
(b) Teltewskoi, M.; Panetier, J. A.; Macgregor, S. A.; Braun, T. Angew.
Chem., Int. Ed. 2010, 49, 3947. (c) Lindup, R. J.; Marder, T. B.; Perutz,
R. N.; Whitwood, A. C. Chem. Commun. 2007, 3664. (d) Segawa, Y.;
Suzuki, Y.; Yamashita, M.; Nozaki, K. J. Am. Chem. Soc. 2008, 130,
16069. (e) Bosque, R.; Clot, E.; Fantacci, S.; Maseras, F.; Eisenstein, O.;
Perutz, R. N.; Renkema, K. B.; Caulton, K. G. J. Am. Chem. Soc. 1998,
120, 12634.
(8) (a) Ahrens, T.; Kohlmann, J.; Ahrens, M.; Braun, T. Chem. Rev.
2015, 115, 931. (b) Zhang, X.; Cao, S. Tetrahedron Lett. 2017, 58, 375.
(c) Shen, Q.; Huang, Y.-G.; Liu, C.; Xiao, J.-C.; Chen, Q.-Y.; Guo, Y. J.
Fluorine Chem. 2015, 179, 14. (d) Weaver, J.; Senaweera, S. Tetrahedron
2014, 70, 7413.
(9) (a) Zhang, J.; Dai, W.; Liu, Q.; Cao, S. Org. Lett. 2017, 19, 3283.
(b) Sakaguchi, H.; Uetake, Y.; Ohashi, M.; Niwa, T.; Ogoshi, S.;
Hosoya, T. J. Am. Chem. Soc. 2017, 139, 12855. (c) Kojima, R.; Kubota,
K.; Ito, H. Chem. Commun. 2017, 53, 10688. (d) Tan, D.-H.; Lin, E.; Ji,
W.-W.; Zeng, Y.-F.; Fan, W.-X.; Li, Q.; Gao, H.; Wang, H. Adv. Synth.
Catal. 2018, 360, 1032. (e) Chen, K.; Cheung, M. S.; Lin, Z.; Li, P. Org.
Chem. Front. 2016, 3, 875. (f) Mfuh, A. M.; Doyle, J. D.; Chhetri, B.;
Arman, H. D.; Larionov, O. V. J. Am. Chem. Soc. 2016, 138, 2985.
a
Reaction conditions: 1 (0.2 mmol), 2 (0.56 mmol), FeCl2 (0.04
mmol), LiHMDS (0.64 mmol), toluene/HMPA = 0.8 mL/0.4 mL,
b
110 °C, 12 h, Ar. Isolated yields. 20 mol % TMEDA (N,N,N′,N′-
tetramethylethylene diamine) was added, 0.5 h.
interaction. Despite the low catalytic activity of the Fe catalyst
for borylation, it is much cheaper and more easily available than
Ni- and Pd-based catalysts. Therefore, we anticipate that the
current protocol may provide a scalable, cost-effective, and
complementary method of accessing valuable arylboronate
esters from various fluoroarenes and biaryl fluorides.
ASSOCIATED CONTENT
■
S
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.orglett.8b02228.
Experimental details and spectral data for all products
(PDF)
AUTHOR INFORMATION
■
̈
(g) Kallane, S. I.; Teltewskoi, M.; Braun, T.; Braun, B. Organometallics
Corresponding Author
*E-mail: scao@ecust.edu.cn
ORCID
2015, 34, 1156.
(10) Guo, W.-H.; Min, Q.-Q.; Gu, J.-W.; Zhang, X. Angew. Chem., Int.
Ed. 2015, 54, 9075.
(11) Liu, X.-W.; Echavarren, J.; Zarate, C.; Martin, R. J. Am. Chem. Soc.
2015, 137, 12470.
(12) Niwa, T.; Ochiai, H.; Watanabe, Y.; Hosoya, T. J. Am. Chem. Soc.
Song Cao: 0000-0002-3231-6136
Notes
2015, 137, 14313.
The authors declare no competing financial interest.
(13) Niwa, T.; Ochiai, H.; Hosoya, T. ACS Catal. 2017, 7, 4535.
(14) Zhou, J.; Kuntze-Fechner, M. W.; Berthel, J. H. J.; Friedrich, A.;
Du, Z.; Marder, T. B.; Radius, U. J. Am. Chem. Soc. 2016, 138, 5250.
(15) (a) Yang, C.-T.; Zhang, Z.-Q.; Tajuddin, H.; Wu, C.-C.; Liang, J.;
Liu, J.-H.; Fu, Y.; Czyzewska, M.; Steel, P.; Marder, T. B.; Liu, L. Angew.
Chem., Int. Ed. 2012, 51, 528. (b) Wu, H.; Garcia, J. M.; Haeffner, F.;
Radomkit, S.; Zhugralin, A. R.; Hoveyda, A. H. J. Am. Chem. Soc. 2015,
137, 10585.
ACKNOWLEDGMENTS
■
We are grateful for financial support from the National Natural
Science Foundation of China (Grant Nos. 21472043 and
21272070).
REFERENCES
■
(16) Bhanuchandra, M.; Baralle, A.; Otsuka, S.; Nogi, K.; Yorimitsu,
H.; Osuka, A. Org. Lett. 2016, 18, 2966.
(1) (a) Miyaura, N. In Metal-Catalyzed Cross-Coupling Reactions, 2nd
ed.; de Meijere, A., Diederich, F., Eds.; Wiley-VCH: Weinheim,
Germany, 2004. (b) Kotha, S.; Lahiri, K.; Kashinath, D. Tetrahedron
2002, 58, 9633. (c) Liu, Y.-Y.; Zhang, W.-B. Youji Huaxue 2016, 36,
2249. (d) Hu, J.; Gao, B.; Li, L.; Ni, C.; Hu, J. Org. Lett. 2015, 17, 3086.
(e) Gu, L.-J.; Jin, C.; Zhang, H.-T. Chem. - Eur. J. 2015, 21, 8741.
(f) Martin, R.; Buchwald, S. L. Acc. Chem. Res. 2008, 41, 1461.
(17) (a) Dewhurst, R. D.; Neeve, E. C.; Braunschweig, H.; Marder, T.
B. Chem. Commun. 2015, 51, 9594. (b) Pietsch, S.; Neeve, E. C.;
Apperley, D. C.; Bertermann, R.; Mo, F.; Qiu, D.; Cheung, M. S.; Dang,
L.; Wang, J.; Radius, U.; Lin, Z.; Kleeberg, C.; Marder, T. B. Chem. - Eur.
J. 2015, 21, 7082.
D
DOI: 10.1021/acs.orglett.8b02228
Org. Lett. XXXX, XXX, XXX−XXX

Organic Letters
Letter
(18) Iida, T.; Hashimoto, R.; Aikawa, K.; Ito, S.; Mikami, K. Angew.
Chem., Int. Ed. 2012, 51, 9535.
(19) (a) Bedford, R. B. Acc. Chem. Res. 2015, 48, 1485. (b) Sun, C.-L.;
Li, B.-J.; Shi, Z.-J. Chem. Rev. 2011, 111, 1293.
(20) (a) Bedford, R. B.; Brenner, P. B.; Carter, E.; Gallagher, T.;
Murphy, D. M.; Pye, D. R. Organometallics 2014, 33, 5940. (b) Yoshida,
T.; Ilies, L.; Nakamura, E. ACS Catal. 2017, 7, 3199.
E
DOI: 10.1021/acs.orglett.8b02228
Org. Lett. XXXX, XXX, XXX−XXX