Pyridine-catalyzed desulfonative borylation of benzyl sulfones

Article abstract of DOI:10.1039/c9ob01099h

Herein, we report the transition-metal free, pyridine-catalyzed desulfonative borylation of benzyl sulfones with bis(pinacolato)diboron (B₂pin₂). A variety of benzhydryl- and benzyl boronic esters could be synthesized from readily prepared sulfone derivatives. The borylation of cyclic sulfones accompanied by ring opening also proceeded to afford the corresponding sulfonate, which could be converted into functionalized sulfones and sulfonamides.

Full text of DOI:10.1039/c9ob01099h

View Article Online
View Journal
Organic &
Biomolecular
Chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: Y. Maekawa, Z.
Ariki, M. Nambo and C. Crudden, Org. Biomol. Chem., 2019, DOI: 10.1039/C9OB01099H.
Volume 15
Number 47
21 December 2017
Pages 9945-10124
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Organic &
Biomolecular
Chemistry
Accepted Manuscripts are published online shortly after acceptance,
rsc.li/obc
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
ISSN 1477-0520
PAPER
I . J. Dmochowski et al.
Oligonucleotide modifi cations enhance probe stability for
shall the Royal Society of Chemistry be held responsible for any errors
single cell transcriptome in vivo analysis (TIVA)
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
rsc.li/obc

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 1 of 5
View Article Online
DOI: 10.1039/C9OB01099H
Journal Name
COMMUNICATION
Pyridine-catalyzed Desulfonative Borylation of Benzyl Sulfones
Yuuki Maekawaa,b, Zachary T. Arikia, Masakazu Nambo*b, and Cathleen M. Crudden*a,b
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
borylated to afford a versatile sulfinate intermediate, which can be
trapped with electrophiles to afford functionalized sulfones and
sulfonamides. The use of pyridine-based catalysts was inspired by the
recent reports by Zhang and Jiao on dehalogenative borylation16.
Herein, we report the transition-metal free, pyridine-catalyzed
desulfonative borylation of benzyl sulfones with
bis(pinacolato)diboron (B2pin2). A variety of benzhydryl- and
benzyl boronic esters could be synthesized from readily
prepared sulfone derivatives. The borylation of cyclic sulfones
accompanied by ring opening also proceeded to afford the
corresponding sulfonate, which could be converted into
functionalized sulfones and sulfonamides.
Our group has recently demonstrated the versatility of sulfones as
electrophiles in metal-catalyzed cross-coupling reactions, with the
significant advantage that sulfones can be used to increase the
functionality of a molecule prior to coupling, for example by
alkylation and arylation (Figure 1a)1,2. However, there are limited
examples of the direct transformation of a carbon–sulfonyl bond to a
carbon–heteroatom bond1d, 3, 4, 5 such as boron3, nitrogen1d or oxygen4.
Although the direct formation of carbon–carbon bonds through cross
coupling chemistry is an important transformation6, carbon-boron
bonds are important functional groups in their own right as they can
be used as key precursors for 1,2-metallate rearrangements7,
deborylative nucleophilic addition reactions8, and are precursors to
carbon–oxygen and –nitrogen bond via hydrolysis and aminolysis9.
To add to the chemical capacity of the borylation reaction10, we
decided to investigate the direct transformation of a sulfonyl group to
a boryl group via sulfone intermediates. Herein, we report the
transition metal-free desulfonative borylation of benzylic sulfones
catalyzed by simple pyridine derivatives (Figure 1b). The use of
diarylmethyl phenyl sulfones provides a variety of symmetric and
unsymmetric borylated products, which typically require strong bases,
such as organolithium reagents11 and alkali metals12, or transition
metals13 for their preparation14, and cannot be prepared by classical
hydroboration reactions of alkenes15. Cyclic sulfones were also
Fig. 1 Catalytic transformations of benzyl sulfone derivatives
We began our investigation into the desulfonative borylation
reaction with benzhydryl phenyl sulfone 1a as a model substrate, since
the borylated product is valuable in the production of
triarylmethanes17 and is challenging to prepare by other routes. In
early experiments, the sulfonyl group in 1a was successfully
converted into the pinacolboryl (Bpin) group with 4-phenylpyridine
(4-PhPy) as a precatalyst, affording the desired dibenzylic boronic
ester 2a along with diphenylmethane 3a as a byproduct in 45% and
24% yields, respectively (Table 1, entry 1). The use of trifluorotoluene
as a solvent in place of ethereal solvents was preferred, giving 2a in
70% yield (Table 1, entries 2-4). The counterion of the base proved
a. Department of Chemistry, Queen’s University, Chernoff Hall, Kingston Ontario,
Canada.
b. Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University,
Chikusa, Nagoya, Japan.
Electronic Supplementary Information (ESI) available: [details of any supplementary
information available should be included here]. See DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 2 of 5
COMMUNICATION
Journal Name
critical to the reaction’s success with lithium and potassium
methoxide being less effective or completely ineffective (Table 1,
entries 5 and 6). Replacing 4-PhPy with 4-anthracenylpyridine (4-
AnthPy) as the precatalyst resulted in similar yields of 2a and 3a, and
gave better overall reproducibility (Table 1, entry 7). In the absence
of the pyridine precatalyst, only 22% of 2a was observed, suggesting
that although there is some uncatalyzed pathway, the presence of the
pyridine precatalyst is important to provide reasonable yields of
product (Table 1, entry 8). We also found that increasing the amount
of B2pin2 and pyridine precatalyst gave better yields for electron rich
substrates (Supporting Information and Table 2).
View Article Online
DOI: 10.1039/C9OB01099H
Table 2 Scope of benzyl sulfones 1.
4-AnthPy
NaOMe or NaOEt
Ar1
Bpin
Ar1
B2pin2
+
R
R
SO2Ph
C6H5CF3, 90 °C
2
2
1
(R = Ar , Me, H)
Ph
Ph
Ph
Bpin
Bpin
Bpin
Bpin
Bpin
Cl
MeO
2b
a
a
, 66%
, 61%b (49%)b,c
2a
2d
2c
, 52%
Ph
Ph
Ph
Table 1 Optimization of reaction conditions.a
Me
O
Bpin
Bpin
Catalyst (5 mol%)
B2pin2 (1.3 equiv)
Base (1.3 equiv)
O
b
a
, 64%a (57%)a,d
Ph
2e
2f
, 55%
, 54%
Ph
Ph
Ph
+
Bpin
2a
Ph
Ph
SO2Ph
1a
Me Ph
OMe Ph
Solvent, 90 °C, 48 h
Ph
H
3a
Bpin
Bpin
Conv.
(%)
Yield (%)b
2a/3a
a
b
b
2g
2h
2i
, 32%
Ph
, 37%
, 47%
Entry
Catalyst
Base
Solvent
CPME
Ar1
Ph
Ph
1
2
3
4
5
6
7
8
4-PhPy
4-PhPy
4-PhPy
4-PhPy
4-PhPy
4-PhPy
NaOMe
NaOMe
NaOMe
NaOMe
LiOMe
KOMe
69
61
60
93
77
56
90
56
45/24
42/18
3/37
Ar2
Bpin
Bpin
Bpin
Bpin
Me
H
MTBE
DMSO
(Ar1, Ar2 = 4-MeOC6H4)
S
b
a,e
b
b
2l
2j
, 72%
, 33%
2k
2m
, 96%
, 50%
C6H5CF3
C6H5CF3
C6H5CF3
C6H5CF3
C6H5CF3
70/22
56/14
0/29
Unsuccesful substrates
Ph
I
Ph
Ph
SO2Ph
SO2Ph
SO2Ph
4-AnthPy
-
NaOMe
NaOMe
69 (66)/19
22/8
R
(R = CF3, CO2Me, CN)
Desulfonation
No reaction
a Conditions: catalyst (5 mol %), B2pin2 (1.3 equiv), base (1.3 equiv), solvent
(1M), 48 h. bYields were determined by 1H NMR using 1,3,5-
trimethoxybenzene as an internal standard. Isolated yield is shown in
parentheses.
Me Me
Me Me
Me
SO2Ph
Ph
SO2Ph
Ph
SO2Ph
Decomposition
-Elimination
aConditions A: Anth-Py (5 mol%), B2pin2 (1.3 equiv), NaOMe (1.3 equiv),
C6H5CF3 (1M), 48 h bConditions B: Anth-Py (10 mol%), B2pin2 (2 equiv),
NaOEt (1.3 equiv), C6H5CF3 (0.5M), 24 h cReaction was conducted under air.
dReaction was conducted at 1.0 mmol scale. eReaction temperature: 80 ºC
With optimized conditions in hand, we then examined the scope
of the reaction in terms of benzylic sulfones with (Table 2).
Benzhydryl sulfones bearing electron-neutral and electron-rich aryl
groups (1a-c, 1k) afforded the corresponding diarylmethyl boronic
esters (2a-c, 2k) in good yields. We also found that the borylation of
1b proceed under air to give the product 2b in only slightly reduced
yield (Table 2, parenthesis). Meta-substituted aryl groups (1d-f) were
borylated to the corresponding boronic esters 2d-f in good yields.
Sterically hindered ortho-substituted aryl groups (1g-i) also provided
the desired products 2g-i, albeit in lower yields. A sulfone bearing the
2-thienyl group (1j) was also tolerated, affording the desired product
2j in moderate yield. Our reaction conditions could also be applied to
1-phenethyl sulfone (1l) to give the borylated product 2l in good yield.
Unfortunately, sulfones bearing electron-withdrawing substituents
such as trifluoromethyl, esters, cyano, allyl and iodide groups were
not tolerated in this transformation. Furthermore, tertiary alkyl and
methyl sulfones were also unreactive, even though secondary and
primary alkyl sulfones afforded desired boronic esters in moderate to
good yields (Table 2).
Cyclic sulfones 4 are an interesting substrate class since cleavage
of the benzylic C–SO2 bond results in a product that still contains the
sulfone. To test this approach, sulfones 4a-d were prepared and
subjected to the reaction conditions (Scheme 1). The resulting
intermediate sulfonates were isolated by treatment with iodomethane
to give the borylated benzyl sulfone products 5. Cyclic sulfones
bearing 4-methyl (4a), chloro (4b), and methoxy (4c) groups on the
arene were tolerated, and afforded the desired ring-opened borylated
products (5a-c) in moderate yields. As in the case of acyclic sulfones,
compound 4d bearing the electron withdrawing 4-trifluoromethyl
group was not a feasible substrate for this borylation.
Scheme 1 Reaction of cyclic sulfones 4a-d.
4-AnthPy
B2pin2
NaOMe
a
5a
78%
Ar = 4-MeC6H4
(60%)b
MeI
c
4-ClC6H4
Me 4-MeOC6H4
4-CF3C6H4
5b
5c
5d
31%
Ar
S
c
C6H5CF3
100 °C
DMSO
80 °C
SO2
Bpin
36%
O
O
Ar
0%
4a d
-
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 5
Organic & Biomolecular Chemistry
Please do not adjust margins
Journal Name
COMMUNICATION
aConditions A: Anth-Py (30 mol%), B2pin2 (1.3 equiv), NaOMe (1.3 equiv),
C6H5CF3 (0.5M), 7 h, then methyl iodide, DMSO, 80 ºC, 2 h bReaction was
conducted at 3.9 mmol (1.0 g) scale with 20 mol% of Anth-Py. cConditions B:
Anth-Py (10 mol%), B2pin2 (2 equiv), NaOEt (1.3 equiv), C6H5CF3 (0.5 M),
12 h, then methyl iodide, DMSO, 80 ºC, 3 h
Scheme 3 Mechanistic studies
View Article Online
DOI: 10.1039/C9OB01099H
4-AnthPy (10 mol%)
(a)
B2pin2 (2.0 equiv)
NaOEt (1.3 equiv)
Ar
Ar
Ar
Bpin
Bpin
SO2Ph
C6H5CF3, 90 °C, 24 h
1n
2n
10n
(Ar = 4-ClC6H4)
75%
Not observed
Next, we examined the scope of electrophiles that could be
employed to trap the sulfonate intermediate (Scheme 2). Primary alkyl
halides were effective, affording alkyl sulfones (6a and 7a) in
moderate yields. Diphenyl iodonium iodide could be employed and
afforded diaryl sulfone 8a in moderate yield. Additionally,
electrophilic chlorination using SO2Cl2 followed by amination gave
the sulfonamide 9a in 49% yield from 4a in three-step sequence.
Notably, all of these transformations proceeded without loss of the
(b)
(c)
4-AnthPy (10 mol%)
B2pin2 (2.0 equiv)
NaOEt (1.3 equiv)
Ph
Ph
Ph
Bpin
Not observed
SO2Ph
3
3
C6H5CF3, 90 °C, 24 h
Bpin
1o
4-AnthPy (10 mol%)
B2pin2 (2.0 equiv)
NaOEt (1.3 equiv)
TEMPO (1.0 equiv)
Ph
Ph
Bpin
boryl
group.
SO2Ph
C6H5CF3, 90 °C, 24 h
1a
Not observed
Scheme 2 Scope of trapping agents for the ring-opening borylation
of cyclic sulfone 4aa
Although these results do not allow a conclusive statement of
mechanism, single electron transfer mechanism for this
a
transformation can be proposed based on work from Tuttle18 and
Zhang and Jiao16b as shown in Scheme 4. According to this proposal,
a combination of arylpyridine (A), B2Pin2, and sodium methoxide
Ph
O2S
Bpin
Ar
b
6a
44%
(a)
would afford species B (E1/2 = -1.1 V vs. Fc+/0 16b
) , which can reduce
O2S
Bpin
(b)
(c)
4-AnthPy
B2pin2
1a to radical anion I. Fragmentation of I affords benzylic radical II,
which can be rapidly reduced by D to benzylic anion III. The
generated anion III would then react with the borate ester to give the
desired boronic ester 2a. The byproduct, diarylmethane 3a, could be
produced by protonation of anion III by the starting sulfone 1a, which
is acidic, or during work-up.19
Ar
c
7a
33%
NaOMe
or NaOEt
Ar
S
C6H5CF3
100 °C
SO2Na
Bpin
O
O
Ar
4a
(Ar = 4-MeC6H4)
(d), (e)
Ph
SO2
Bpin
Ar
Scheme 4 Possible single electron transfer and boryl anion
routes
c
8a
45%
NEt2
SO2
Bpin
Ar
9a
49%
aConditions: Anth-Py (30 mol%), B2pin2 (1.3 equiv), NaOMe (1.3 equiv),
C6H5CF3 (0.5 M), 7 h bNaOEt (1.3 equiv) was used as base. cAnth-Py
(15mol%) was used as catalyst. (a) benzyl bromide, potassium iodide, DMF,
r.t., 12 h (b) allyl boromide, DMSO, 50 ºC, 16 h (c) diphenyl iodoniumiodide,
DMF, 90 ºC, 12 h (d) SO2Cl2, THF, –40 ºC to r.t. (e) HNEt2, r.t., 3 h
To gain insight into the mechanism of the borylation reaction, we
prepared sulfones 1n bearing a cyclopropyl group, to test the
propensity for ring-opening reactions. (Scheme 3a). Under standard
conditions, boronic ester 2n was obtained in good yield, without any
evidence for ring-opened product. Although this result suggests that a
radical pathway is unlikely, this cannot be completely excluded since
the benzyl radical generated from 1n should be more stable than
primary alkyl radical generated by ring opening, which might lead to
observation of the borylated product before ring opening.
Unfortunately, it is clear that alkenes inhibit the borylation reaction
(see Table 2), and thus sulfone 1o bearing a terminal olefin did not
afford any products (Scheme 3 b). However, TEMPO was found to
completely inhibit the borylation of 1a (Scheme 3 c).
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Organic & Biomolecular Chemistry
Page 4 of 5
COMMUNICATION
Journal Name
O
O
O
Am. Chem. Soc. 2018, 140, 78-81; (e) M. Nambo, Y.
View Article Online
B
B
Tahara, J. C. H. Yim, C. M. Crudden, Chem. Eur. J. 2019, 25,
DOI: 10.1039/C9OB01099H
Ar
N
O
A
MeONa
1923-1926.
2.
For selected recent examples, see: (a) A. L. Moure, R. G.
Gomez Arrayaś, D. J. Caŕdenas, I. Alonso, J. C. Carretero, J.
Am. Chem. Soc. 2012, 134, 7219−7222; (b) S. E. Denmark,
A. J. Cresswell, J. Org. Chem. 2013, 78, 12593-12628; (c) B.
Gao, W. Zhang, J. Hu, J. Am. Chem. Soc. 2018, 140, 880-
883; (d) R. R. Merchant, J. T. Edwards, T. Qin, M. M.
Kruszyk, C. Bi, G. Che, D. H. Bao, W. Qiao, L. Sun, M. R.
Collins, O. O. Fadeyi, G. M. Gallego, J. J. Mousseau, P.
Nuhant, P. S. Baran, Science 2018, 360, 75-80; (e) F.
Takahashi, K. Nogi, H. Yorimitsu, Org. Lett. 2018, 20, 6601-
6605.
MeOBPin
SET
Ph
Ph
III
Na
MeOBPin
+
1a
Ar
Ar
(or H )
H
Ar
Ph
Ph
N
N
H
3a
BPin
Ph
B
Ph
Na
B
N
B
2a
D
O
O
Me
Na
II
O
O
O
NaSO2Ph
Ph
Ph
3.
C. B. Schwamb, K. P. Fitzpatrick, A. C. Brueckner, H. C.
Richardson, P. H. Y. Cheong and K. A. Scheidt, J. Am.
Chem. Soc. 2018, 140, 13985-13985.
Ph
SO2Ph
1a
Ph
SO2Ph
I
4.
5.
L. Liu, J. A. Henderson, A. Yamamoto, P. Brémond, Y. Kishi,
Org. Lett. 2012, 14, 2262-2265.
For examples of C–Si, C–P, and C–Ge bond formations,
see:(a) S. F. Wnuk, P. I. Garcia and Z. Wang, Org. Lett.
2004, 6, 2047-2049; (b) H.-M. Guo, Q.-Q. Zhou, X. Jiang,
D.-Q. Shi and W.-J. Xiao, Adv. Synth. Catal. 2017, 359,
4141-4146.
SET
Ar
Ar
N
B
C
MeONa
N
O
O
A
6.
7.
(a) N. Miyaura, T. Yanagi, A. Suzuki, Synth. Commun.
1981, 11, 513-519; (b) S. Kotha, K. Lahiri and D.
Kashinath, Tetrahedron, 2002, 58, 9633-9695.
(a) A. B. Levy, J. Org. Chem. 1978, 43, 4684-4685; (b) A.
Bonet, M. Odachowski, D. Leonori, S. Essafi, V. K.
Aggarwal, Nat. Chem. 2014, 6, 584; (c) C. M. Crudden, C.
Ziebenhaus, J. P. G. Rygus, K. Ghozati, P. J. Unsworth, M.
Nambo, S. Voth, M. Hutchinson, V. S. Laberge, Y.
Maekawa, D. Imao, Nat. Commun. 2016, 7 11065.
(a) R. Larouche-Gauthier, T. G. Elford and V. K. Aggarwal,
J. Am. Chem. Soc., 2011, 133, 16794-16797; (b) C.
Sandford, V. K. Aggarwal, Chem. Commun. 2017, 53, 5481-
5494.
In conclusion, we have developed the desulfonylative borylation
of alkyl sulfones via 4-arylpyridine catalysis. When cyclic sulfones
were employed, the transformation results in new C–B bonds in
complex sulfones and sulfonamides by functionalization of the
sulfonate intermediates. Importantly, our method can provide
synthetically useful benzylic boron compounds without the need for
transition-metal catalysts or reactive organometallic reagents. Further
investigations to elucidate the mechanism of this unique borylation
and the development of new transformations of organosulfones are
currently underway in our laboratories.
8.
9.
H. C. Brown, G. Zweifel, J. Am. Chem. Soc. 1961, 83, 2544-
2551.
10.
For reviews, see:(a) J. F. Hartwig, Chem. Soc. Rev. 2011,
40, 1992-2002; (b) M. Norio, Bull. Chem. Soc. Jpn. 2008,
81, 1535-1553; (c) J. W. B. Fyfe, A. J. B. Watson, Chem,
2017, 3, 31-55.
Conflicts of interest
There are no conflicts to declare.
11.
12.
13.
14.
S. Roesner, C. A. Brown, M. Mohiti, A. P. Pulis, R.
Rasappan, D. J. Blair, S. Essafi, D. Leonori, V. K. Aggarwal,
Chem. Commun. 2014, 50, 4053-4055.
J. W. Clary, T. J. Rettenmaier, R. Snelling, W. Bryks, J.
Banwell, W. T. Wipke, B. Singaram, J. Org. Chem. 2011,
76, 9602-9610.
(a) S. H. Cho, J. F. Hartwig, Chem. Sci. 2014, 5, 694-698;
(b) D. F. Shi, L. Wang, C. G. Xia, C. Liu, Angew. Chem. Int.
Ed. 2018, 57, 10318-10322.
For other methods to prepare diaryl methyl boronic
esters, see:(a) C. Pintaric, C. Laza, S. Olivero, E. Duñach,
Tetrahedron Lett. 2004, 45, 8031-8033; (b) H. Li, L. Wang,
Y. Zhang, J. B. Wang, Angew. Chem. Int. Ed., 2012, 51,
2943-2946; (c) Y. Lou, P. Cao, T. Jia, Y. Zhang, M. Wang, J.
Liao, Angew. Chem. Int. Ed. 2015, 54, 12134-12138; (d) C.
Battilocchio, F. Feist, A. Hafner, M. Simon, D. N. Tran, D.
M. Allwood, D. C. Blakemore, S. V. Ley, Nat. Chem. 2016,
8, 360-367.
Acknowledgements
We acknowledge the Natural Sciences and Engineering Research
Council of Canada (NSERC) and the Canada Foundation for
Innovation (CFI) for funding of the work from her lab described in
this article. Y. M. thanks JSPS for a postdoctoral fellowship. JSPS and
NU are acknowledged for funding of this research through the World
Premier International Research Center Initiative (WPI) program.
Notes and references
1.
(a) M. Nambo, C. M. Crudden, Angew. Chem. Int. Ed.19
2014, 53, 742-746; (b) M. Nambo, Z. T. Ariki, D. Canseco-
Gonzalez, D. D. Beattie, C. M. Crudden, Org. Lett. 2016,
18, 2339-2342; (c) M. Nambo, E. C. Keske, J. P. G. Rygus, J.
C. H. Yim, C. M. Crudden, ACS. Catal. 2017, 7, 1108-1112;
(d) Z. T. Ariki, Y. Maekawa, M. Nambo, C. M. Crudden, J.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 5
Organic & Biomolecular Chemistry
Please do not adjust margins
Journal Name
COMMUNICATION
15.
(a) I. A. P. Beletskaya, A, Tetrahedron, 1997, 53, 4957; (b)
View Article Online
DOI: 10.1039/C9OB01099H
K. Burgess, M. J. Ohlmeyer, Chem. Rev. 1991, 91, 1179-
1191; (c) C. M. Crudden, D. Edwards, Eur. J. Org. Chem.
2003, 4695-4712.
16.
17.
18.
(a) L. Zhang, L. Jiao, J. Am. Chem. Soc. 2017, 139, 607-610;
(b) L. Zhang, L. Jiao, Chem. Sci. 2018, 9, 2711-2722.
S. C. Matthew, B. W. Glasspoole, P. Eisenberger and C. M.
Crudden, J. Am. Chem. Soc. 2014, 136, 5828-5831.
F. Schoenebeck, J. A. Murphy, S.-Z. Zhou, Y. Uenoyama, Y.
Miclo, T. Tuttle, J. Am. Chem. Soc. 2007, 129, 13368-
13369.
19.
Note that if conducted in the presence of solvents that
readily donate hydrogen atoms, the reduced
diarylmethane may originate from hydrogen atom
transfer. However, as reactions reported herein are
performed in trifluorotoluene, this is less likely.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins