Hydrodebromination of allylic and benzylic bromides with water catalyzed by a rhodium porphyrin complex

Article abstract of DOI:10.1039/c8dt02168f

Hydrodebromination of allylic and benzylic bromides was successfully achieved by a rhodium porphyrin complex catalyst using water as the hydrogen source without a sacrificial reductant. Mechanistic investigations suggest that bromine atom abstraction via a rhodium porphyrin metalloradical operates to give the rhodium porphyrin alkyl species and the subsequent hydrolysis of the rhodium porphyrin alkyl species to a hydrocarbon product is a key step to harness the hydrogen from water.

Full text of DOI:10.1039/c8dt02168f

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Efficient extraction of sulfate from water using
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Hydrodebromination of Allylic and Benzylic Bromides with Water
Catalyzed by Rhodium Porphyrin Complex
Wu Yang,a Chen Chen,a and Kin Shing Chan*a
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
Hydrodebromination of allylic and benzylic bromides was converting HO–H to [Pd]–H (Scheme 1D).32, 33 To the best of
successfully achieved by rhodium porphyrin complex catalyst with our knowledge, catalytic hydrodebromination using water as
water without a sacrificial reductant. Mechanistic investigations the hydrogen source without a sacrificial reductant remains
suggest that the bromine atom abstraction via
a rhodium unknown.
porphyrin metalloradical operates to give the rhodium porphyrin
alkyl species and the subsequent hydrolysis of the rhodium
porphyrin alkyl species to hydrocarbon product is a key step to
harness the hydrogen from water.
86 kcal/mol (calcd)
Me
Me
Me
Me
Me
Me
H
(A)
R
B
OH
B
O
B
O
BMe3+ H2O
– RH
– Me
H
Me
H
Me
Hydrodebromination plays an indispensable role in synthetic
organic chemistry. For instance, the bromide group can be
removed by hydrodebromination with a hydrogen source.1, 2
The hydrodeoxygenation of alcohols has also been
accomplished via its bromide derivatives through
hydrodebromination.3 The common hydrogen sources in
hydrodebromination are H2 gas,4 alcohols and alcoholates,5, 6
formic acid and its salts,7 organosilanes,8, 9 metal hydrides,10-13
borohydrides,14-16 amines,17-19 etc.20
(B)
Cl
TiIV
OH
Cp
Cl
Cp
Cp
R
Ti
III
H
Cp2Ti Cl + H2O
– RH
O
Cp
H
49 kcal/mol (calcd)
(C)
<45 kcal/mol
H
SmII
I
R
I
SmIII
SmIII2 + H2O
O
OH
– RH
I
I
H
(D)
0.5B2(OH)4
– B(OH)3
[Pd]
+
HO–H
[Pd]–H
Water, as a green, economically more attractive reducing
agent, is generally believed unlikely to be the hydrogen source
due to the high bond dissociation energy (BDE) of HO–H bond
(118 kcal/mol).21 Weakening the H–OH bond by the
coordination of H2O to a Lewis acid makes water as the
hydrogen source possible. It has been recognized that
alkylborane (Scheme 1A)22, 23, Cp2TiIIICl (Scheme 1B),24-28 and
SmIII2 (Scheme 1C)29-31 are all effective Lewis acids to achieve
considerable H–OH bond weakening through the coordination
with H2O. The low valent Lewis acid also functions as a
stoichiometric reductant with Ti(III)/Sm(II) oxidized to a higher
valent one. Most recently, the Pd-catalyzed hydrogenations of
alkenes, alkynes and N-heteroaromatics using water as a
stoichiometric hydrogen source have been achieved by
(E)
(ttp)Rh–OH
– RH
(ttp)Rh–R + HO–H
R = alkyl
(ttp)Rh–OH
[Rh(ttp)]2
– H2O
– 0.5"O2"
PCP
This work
Rh(ttp)Mecatalyst
air, C6H6, heat
R
Br
+ H2O
R
H
– 0.5"O2"
– HBr
moderateto high yields
allylic and benzylic bromide
Water as the hydrogen source;
Without a sacrificial reductant
Me
Ar
N
employing B2(OH)4/B2pin2 as
a sacrificial reductant via
N
Ar
Rh
Rh(ttp)Me
Ar
N
N
Ar
Ar = 4-tolyl
Scheme 1 Common strategies to use water as the hydrogen source.
For the hydrodehalogenation with rhodium porphyrin
catalysts, the Fu group has previously realized photocatalytic
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Table 1 Substrate scope of allylic bromides for the hydrodebrominationa,b
hydrodefluorination of perfluoroarene with silane as the
sacrificial reductant.34 Based on our earlier success of
employing water as the hydrogen source for hydrogenating
the carbon–carbon σ-bond of [2.2]paracyclophane (PCP)
through the hydrolysis of Rh(ttp)(alkyl) (ttp = 5,10,15,20-
tetratolylporphyrinato dianion) precatalyst and intermediates
(Scheme 1E),35, 36 herein, we disclose a rhodium porphyrin
complex catalyzed hydrodebromination of allylic and benzylic
bromides with water as the hydrogen source without a
sacrificial reductant.
Initially, we aimed to conduct the selective C–C bond
hydrogenation of the gem-dibromocyclopropane (1) with
water catalyzed by rhodium porphyrin complex. However, the
reaction of (2,2-dibromocyclopropyl)benzene (
catalyzed by Rh(ttp)Me at 180 °C for 48 h gave the unexpected
debromination product: (2-bromoprop-1-en-1-yl)benzene (2a
in 45% yield (eq 1). As was reported to undergo thermal ring
opening reaction with concomitant bromide migration to give
1) with water
)
1
aReaction conditions: allylic bromides (0.1 mmol), Rh(ttp)Me (4.0 mg, 5.1 × 10–3
mmol), H2O (90 μL, 5.0 mmol), 2,6-di-(tBu)pyridine (21 μL, 0.1 mmol), and
benzene (2.0 mL) at 200 °C under air in Teflon screw capped pressure tubes.
bNMR yield with 1,1,2,2-tetrachloroethane as the internal standard.
the allylic bromide: (2,3-dibromoprop-1-enyl)benzene (1a
)
quantitatively (eq 2),37, 38 we suspected that 2a stemmed from
1a through the hydrodebromination reaction with water.
-ile product of (2-bromoprop-1-en-1-yl)benzene (2a) for ease
of isolation. The optimal conditions were shown in eq 4 with
2a obtained in 50% yield and trace amount of 2-bromo-3-
phenylacrylaldehyde (2a’).
Under the optimal conditions, the substrate scope of allylic
bromides was examined (Table 1). The hydrodebromination of
Br Br
H2O (50 equiv)
Ph
Br
(2)
1a and (E)-1-(4-bromophenyl)-1-propen-3-yl bromide (1b
occurred chemo-selectively with the retention of C(sp2)–Br
bonds to give isomeric 2a and 4-bromo-β-methylstyrene (2b
)
C6D6, dark
Br
1a
quant
Ph
180 °C, 48 h
1
)
To validate the hypothesis, the allylic bromide (Z)-1a was
reacted with water in the presence of Rh(ttp)Me catalyst. The
hydrodebromination product 2a was obtained in 41% yield
under air at 200 °C for 12 h (eq 3). Without Rh(ttp)Me catalyst,
only trace amount of 2a was obtained with 94% recovery of 1a
(eq 3), and the catalytic role of Rh(ttp)Me was established.
respectively in moderate yields. With the β-unsubstituted
allylic bromide: (E)-2-(3-bromoprop-1-en-1-yl)naphthalene
(
1c), the reaction also underwent smoothly to give 1-(2-
naphthyl)propene 2c in 40% yield. With the non-
polymerizable alkene: (3-bromoprop-1-ene-1,1-diyl)dibenzene
(
)
(
(
1d), the hydrodebromination product of 1,1-diphenylpropene
2d was obtained in higher yield of 76%.
)
a
Hydrodebromination also took place with the β-ester
substituted allylic bromide: (Z)-ethyl 2-(bromomethyl)-3-
phenylacrylate (1e) to give ethyl 2-methyl-3-phenylacrylate
(
2e) in 66% yield without the ester hydrolysis.
Hydrodebromination also worked well with less reactive
benzylic bromides (Table 2). The hydrodebromination occurred
smoothly both with 2-(bromomethyl)naphthalene (3a) and 4-
tert-butylbenzyl bromide (3b) to afford 2-methylnaphthalene
(
4a) and 4-tert-butyltoluene (4b) in 60% and 66% yields,
With this initial success, the reaction conditions of
temperature (180 °C, 200 °C) (Table S1 in the SI), atmosphere
(air, N2) (Table S1 in the SI), catalyst loading (0, 2.5, 5, 10 mol
%) (Table S2 in the SI), solvent (C6H6, PhCH3, PhCF3, DME,
EtOAc, tetrachloroethylene) (Table S3 in the SI), and additive
(pH = 4.0/5.0/6.0/7.0/8.0/9.0 buffer, K2CO3, CaCO3, pyridine,
DIPEA, 2,6-di-(tBu)pyridine, phenylacetylene) (Table S4 in the
SI) were then optimized using the model compound: (Z)-(2,3-
dibromoprop-1-enyl)benzene ((Z)-1a), which gave the non-
volat
respectively. 9-Bromofluorene (3c) underwent the smooth
hydrodebromination to give fluorene (4c) in 43% yield
together with a minor amount of the homo-coupling co-
product: 9,9’-bifluorene (4c’) in 9% yield. It suggests the
existence of the 9-fluorenyl radical intermediate, which might
be generated from the thermal homolytic cleavage of the
relatively weak Rh–C bond of Rh(ttp)(9-fluorenyl)21, 39 (BDE of
(tmp)Rh–CH2Ph (tmp = 5,10,15,20-tetra(2,4,6-trimethylphenyl)
porphyrinato dianion): ~33 kcal/mol) or from the bromine
atom abstraction of 9-bromofluorene via RhII(ttp)
2 | J. Name., 2012, 00, 1-3
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metalloradical.40-43 The hydrodebromination worked smoothly
with 4-phenyl-benzyl br
Table 2 Substrate Scope of Benzylic Bromides for the Hydrodebrominationa,b
R
R
Rh(ttp)Me (5 mol %)
H2O (50 equiv)
Br
H
Ar
Ar
4a–f
2,6-di-(tBu)pyridine (1 equiv)
The benzylic bromide of 2-(bromomethyl)naphthalene (3a
)
3a–f
C6H6, air, dark, 200 °C, 12–48 h
was also reacted with D2O to afford 4a-d in 56% yield with 73%
deuterium at the naphthalene C-1 position and 95% deuterium
at the benzylic position (eq 6), which is close to the theoretical
100% benzylic mono-deuterium incorporation. 80% deuterium
at the benzylic position were also determined by quantitative
13C NMR (eq S1 and Table S5 in the SI). There are mainly four
isotopomers: d0-isotopologue in 5% composition, d1-
isotopologue (with deuterium at the benzylic position in 26%
or C-1 position in 14%), d2 isotopologue (with deuterium at
both the benzylic and C-1 positions in 55% composition).
(Table S6 and Figure S2 in the SI). As a control, little product-
H/D exchange of 2-methylnaphthalene (4a) with D2O was
observed (eq 7). Thus, the hydrogen from water is established
in the hydrodebromination of benzylic bromides. The 73%
deuterium incorporation at the naphthalene C-1 position is
likely resulted from the Rh(ttp)-catalyzed H/D exchange with
(0.1 mmol, 50 mM)
H
H
18 h, 60% (4a)
28 h, 66% (4b)c
H
Ph
+
H
12 h, 43% (4c)
48 h, 70% (4d)
9% (Co-product 4c')
H
+ HOOC
EtOOC
48 h, 38% (4e)
H
25% (Co-product 4e')
14 h, 57% (4f)d
D2O via the intermediate of Rh(ttp)(2-naphthylmethyl) (5),
which might undergo η1–η3 isomerization44-48 for the
aReaction conditions: benzylic bromides (0.1 mmol), Rh(ttp)Me (4.0 mg, 5.1 × 10–3
mmol), H2O (90 μL, 5.0 mmol), 2,6-di-(tBu)pyridine (21 μL, 0.1 mmol), and
benzene (2.0 mL) at 200 °C under air in Teflon screw capped pressure tubes. deuterium incorporation at the naphthalene C-1 position
bNMR yield with 1,1,2,2-tetrachloroethane as the internal standard. cGC yield.
d7% yield of 2-vinylnaphthalene (4f’).
(Scheme S5 in the SI).35, 40, 49-51
-omide (3d) to give 4-methyl-1,1’-biphenyl (4d) in 70% yield.
For ethyl (4-bromomethyl)benzoate (3e) containing an ester
group, the reaction gave the hydrodebromination product of
ethyl 4-methylbenzoate (4e) in 38% yield. The ester hydrolysis
product (4e’) was obtained in 25% yield, which might due to
the catalytic effect of in situ formed HBr. For the benzylic
bromide of 2-(1-bromoethyl)naphthalene (3f) bearing β-
hydrogens, the hydrodebromination product of 2-
ethylnaphthalene (4f) was obtained in 57% yield together with
the elimination product of 2-vinylnaphthalene (4f’) in 7% yield.
To ascertain that water is the hydrogen source, the
deuterium labeling experiment using D2O was carried out. 2a-d
was obtained in 42% yield with 84% deuterium incorporation
at the allylic position (eq 5), which is close to the theoretical
100% allylic mono-deuterium incorporation. Furthermore, the
deuterium incorporations determined by MS analysis did not
change with reaction time within the catalysis time scale
(Figure S1 in the SI). This indicates the hydrodebromination
product 2a did not undergo product-H/D exchange with D2O
under the optimal reaction conditions. In addition, the proton
signals of the allylic hydrogens of the trace amount of
recovered 1a appear at δ 4.45 (s, 2H, Z isomer), 4.41 (s, 2H, E
isomer) as singlets (Figure S22 in the SI), which indicates that
1a did not undergo starting material-H/D exchange with D2O.
Therefore, these results strongly support water as the
hydrogen source.
On the basis of the above findings, together with our
previous mechanistic understandings of the C–Br bond
activation40-43 and Rh(ttp)-catalyzed hydrogenation of PCP with
water,35, 36, 52 a plausible mechanism is proposed (Scheme 2).
Initially, Rh(ttp)Me undergoes hydrolysis to give Rh(ttp)OH and
53
methane.35,
At 200 °C, Rh(ttp)OH is unstable and
decomposes to give the RhII(ttp) metalloradical and H2O2.54
The indirect detection of H2O2 has been reported by the
formation of Ph3PO through the reaction of Rh(ttp)I with KOH
with Ph3P as a H2O2 trap.54 H2O2 further disproportionates
rapidly to give H2O and O2.35, 55-57 The detection of O2 is not
possible as the reaction was conducted under air and in a small
scale. The RhII(ttp) metalloradical is in an equilibrium with the
RhII (ttp)2 dimer,58-60 which undergoes the disproportionation
2
with H2O to generate Rh(ttp)OH and Rh(ttp)H.36,
Air-
61-64
promoted dehydrogenative dimerization of Rh(ttp)H gives
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back to the RhII (ttp)2 dimer.65, 66 Abstraction of the bromine
2
Conflicts of interest
atom from 2-(bromomethyl)naphthalene (3a) via the RhII(ttp)
There are no conflicts to declare.
metalloradical affords Rh(ttp)Br and the Rh(ttp)(2-
naphthylmethyl) intermediate
transforms into Rh(ttp)H in the presence of H2O.67
hydrolysis with H2O to give the final hydrodebromination
(5
).40-43 Rh(ttp)Br further
5
undergoes
Acknowledgements
We thank the Research Grants Council of Hong Kong SAR
(14300214) and the Hong Kong PhD Fellowship (W. Y.) for
financial support.
product of 2-methylnaphthalene
Rh(ttp)OH to complete
(
4a)
and regenerate
Notes and references
1
2
3
4
5
6
A. N. French, S. Bissmire and T. Wirth, Chem. Soc. Rev., 2004,
33, 354–362.
X. Zhang, Y. Zhou, J. Zuo and B. Yu, Nat. Commun., 2015,
5879–5889.
J. M. Herrmann and B. König, Eur. J. Org. Chem., 2013, 2013
7017–7027.
P. R. Fleming and K. B. Sharpless, J. Org. Chem., 1991, 56
2869–2875.
6
,
,
,
J. Chen, Y. Zhang, L. Yang, X. Zhang, J. Liu, L. Li and H. Zhang,
Tetrahedron, 2007, 63, 4266–4270.
A. Dewanji, C. Muck-Lichtenfeld and A. Studer, Angew.
Chem. Int. Ed., 2016, 55, 6749–6752.
7
8
9
M. Radovan, Croat. Chem. Acta, 1990, 63, 203–206.
C. Chatgilialoglu, Acc. Chem. Res., 1992, 25, 188–194.
O. Yamazaki, H. Togo, S. Matsubayashi and M. Yokoyama,
Tetrahedron, 1999, 55, 3735–3747.
Scheme 2 Proposed mechanism for the hydrodebromination reaction with water.
10 W. E. Parham and C. D. Wright, J. Org. Chem., 1957, 22
1473–1477.
11 W. P. Neumann, Synthesis, 1987, 1987, 665–683.
12 E. C. Ashby, T. N. Pham and A. Amrollah-Madjdabadi, J. Org.
Chem., 1991, 56, 1596–1603.
13 E. C. Ashby and C. O. Welder, J. Org. Chem., 1998, 63, 7707–
7714.
14 R. O. Hutchins, D. Hoke, J. Keogh and D. Koharski,
Tetrahedron Lett., 1969, 10, 3495–3498.
15 S. Kim, Y. J. Kim and K. H. Ahn, Tetrahedron Lett., 1983, 24
3369–3372.
16 T. Kawamoto and I. Ryu, Org. Biomol. Chem., 2014, 12, 9733–
9742.
17 J. M. R. Narayanam, J. W. Tucker and C. R. J. Stephenson, J.
Am. Chem. Soc., 2009, 131, 8756–8757.
18 J. J. Devery, J. D. Nguyen, C. Dai and C. R. J. Stephenson, ACS
,
the catalytic cycle.35, 36, 68
To examine whether allylic Rh(ttp) species undergo the
hydrolysis process, Rh(ttp)(trans-cinnamyl) (
chosen as a model compound and subject to the hydrolysis
investigations. Indeed, Rh(ttp)(trans-cinnamyl) ( ) underwent
smooth hydrolysis at 180 °C for 4 h to give trans-β-
methylstyrene in 22% yield with 62% recovery of (eq 8).
6) was then
6
6
,
Hence, the hydrolysis of the allylic Rh(ttp) species is strongly
supported to harness the hydrogen from water. In a previous
reported model study, Rh(ttp)Bn has been shown to undergo
hydrolysis to afford toluene, which is a key step for the
incorporation of the hydrogen from water.35, 64
Catal., 2016, 6, 5962–5967.
19 D. Staveness, I. Bosque and C. R. J. Stephenson, Acc. Chem.
Res., 2016, 49, 2295–2306.
20 F. Alonso, I. P. Beletskaya and M. Yus, Chem. Rev., 2002, 102
4009–4092.
21 Y. R. Luo, Comprehensive Handbook of Chemical Bond
Energies, CRC Press, Boca Raton, FL, 2007.
22 D. A. Spiegel, K. B. Wiberg, L. N. Schacherer, M. R. Medeiros
and J. L. Wood, J. Am. Chem. Soc., 2005, 127, 12513–12515.
23 M. R. Medeiros, L. N. Schacherer, D. A. Spiegel and J. L.
,
Furthermore, Rh(ttp)Br reacted with excess H2O (1000
equiv) to give Rh(ttp)H in 27% yield at 180 °C for 52 h (eq 9).
Therefore, Rh(ttp)Br can react with water to regenerate
RhII (ttp)2 for further catalysis.
2
Wood, Org. Lett., 2007, 9, 4427–4429.
24 A. F. Barrero, J. E. Oltra, J. M. Cuerva and A. Rosales, J. Org.
Chem., 2002, 67, 2566–2571.
25 J. M. Cuerva, A. G. Campaña, J. Justicia, A. Rosales, J. L. Oller-
López, R. Robles, D. J. Cárdenas, E. Buñuel and J. E. Oltra,
Angew. Chem. Int. Ed., 2006, 45, 5522–5526.
26 A. G. Campaña, R. E. Estévez, N. Fuentes, R. Robles, J. M.
Cuerva, E. Buñuel, D. Cárdenas and J. E. Oltra, Org. Lett.,
2007, 9, 2195–2198.
In summary, the catalytic hydrodebromination of allylic and
benzylic bromides was achieved to give the corresponding
hydrodebromination products in moderate to good yields
using H2O as the convenient hydrogen source without a
sacrificial reductant. The hydrolysis of Rh(ttp)(alkyl) species is
proposed to be the key step to transfer the hydrogen from
water to alkane.
27 T. Jiménez, A. G. Campaña, B. Bazdi, M. Paradas, D. Arráez-
Román, A. Segura-Carretero, A. Fernández-Gutiérrez, J. E.
4 | J. Name., 2012, 00, 1-3
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Oltra, R. Robles, J. Justicia and J. M. Cuerva, Eur. J. Org. 62 X. Fu and B. B. Wayland, J. Am. Chem. Soc., 2004, 126, 2623–
Chem., 2010, 2010, 4288–4295. 2631.
28 M. Paradas, A. G. Campaña, T. Jiménez, R. Robles, J. E. Oltra, 63 S. Y. Lee and K. S. Chan, Organometallics, 2013, 32, 5391–
E. Buñuel, J. Justicia, D. J. Cárdenas and J. M. Cuerva, J. Am.
Chem. Soc., 2010, 132, 12748–12756.
5401.
64 C. M. Tam, C. T. To and K. S. Chan, Dalton Trans, 2017, 46
,
29 T. V. Chciuk and R. A. Flowers, J. Am. Chem. Soc., 2015, 137
11526–11531.
30 M. Szostak, M. Spain and D. J. Procter, J. Org. Chem., 2014,
79, 2522–2537.
31 H. B. Kagan, Tetrahedron, 2003, 59, 10351–10372.
,
10057–10063.
65 J. Setsune, Z. Yoshida and H. Ogoshi, J. Chem. Soc., Perkin
Trans. 1, 1982, 983–987.
66 W. Cui and B. B. Wayland, J. Am. Chem. Soc., 2006, 128
10350–10351.
,
32 S. P. Cummings, T. N. Le, G. E. Fernandez, L. G. Quiambao 67 Please see the following supporting experimental data (eq
and B. J. Stokes, J. Am. Chem. Soc., 2016, 138, 6107–6110.
33 Q. Xuan and Q. Song, Org. Lett., 2016, 18, 4250–4253.
34 X. Liu, Z. Wang, X. Zhao and X. Fu, Inorg. Chem. Front., 2016,
9).
68 K. J. Del Rossi and B. B. Wayland, J. Am. Chem. Soc., 1985,
107, 7941–7944.
3, 861–865.
35 C. T. To, K. S. Choi and K. S. Chan, J. Am. Chem. Soc., 2012,
134, 11388–11391.
36 C. T. To, C. M. Tam and K. S. Chan, ACS Catal., 2015,
4336.
5, 4333–
37 S. R. Sandler, Chem. Ind. (London), 1968, 1481–1482.
38 M. Fedoryński, Chem. Rev., 2003, 103, 1099–1132.
39 W. Cui and B. B. Wayland, J. Am. Chem. Soc., 2004, 126
,
8266–8274.
40 R. S. Paonessa, N. C. Thomas and J. Halpern, J. Am. Chem.
Soc., 1985, 107, 4333–4335.
41 H. Ogoshi, J. Setsune and Z. Yoshida, J. Am. Chem. Soc., 1977,
99, 3869–3870.
42 W. Yang, H. Zuo, W. Y. Lai, S. Feng, Y. S. Pang, K. E. Hung, C.
Y. Yu, Y. F. Lau, H. Y. Tsoi and K. S. Chan, Organometallics,
2015, 34, 4051–4057.
43 Y. Y. Qian and K. S. Chan, Organometallics, 2012, 31, 5452–
5462.
44 N. Solin and K. J. Szabó, Organometallics, 2001, 20, 5464–
5471.
45 M. Bao, H. Nakamura and Y. Yamamoto, J. Am. Chem. Soc.,
2001, 123, 759–760.
46 A. Ariafard and Z. Lin, J. Am. Chem. Soc., 2006, 128, 13010–
13016.
47 B. M. Trost and L. C. Czabaniuk, Angew. Chem. Int. Ed., 2014,
53, 2826–2851.
48 A. Najib, K. Hirano and M. Miura, Org. Lett., 2017, 19, 2438–
2441.
49 B. B. Wayland, G. Poszmik and M. Fryd, Organometallics,
1992, 11, 3534–3542.
50 K. L. Wong, C. Chen and K. S. Chan, Organometallics, 2016,
35, 1847–1853.
51 W. Yang, H. J. Zhang, L. X. Li, C. M. Tam, S. Y. Feng, K. L.
Wong, W. Y. Lai, S. H. Ng, C. Chen and K. S. Chan,
Organometallics, 2016, 35, 3295–3300.
52 C. M. Tam, C. T. To and K. S. Chan, Organometallics, 2016,
35, 2174–2177.
53 H. S. Fung, B. Z. Li and K. S. Chan, Organometallics, 2010, 29
4421–4423.
,
54 K. S. Choi, T. H. Lai, S. Y. Lee and K. S. Chan, Organometallics,
2011, 30, 2633–2635.
55 H. S. Harned, J. Am. Chem. Soc., 1918, 40, 1461–1481.
56 C. Walling, Acc. Chem. Res., 1975, 8, 125–131.
57 S. Kato, T. Ueno, S. Fukuzumi and Y. Watanabe, J. Biol.
Chem., 2004, 279, 52376–52381.
58 Y. W. Chan and K. S. Chan, J. Am. Chem. Soc., 2010, 132
6920–6922.
,
59 B. B. Wayland, S. L. Van Voorhees and C. Wilker, Inorg.
Chem., 1986, 25, 4039–4042.
60 W. Cui, S. Li and B. B. Wayland, J. Organomet. Chem., 2007,
692, 3198–3206.
61 X. Fu, S. Li and B. B. Wayland, Inorg. Chem., 2006, 45, 9884–
9889.
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Dalton Transactions
Page 6 of 6
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DOI: 10.1039/C8DT02168F
Rh(ttp)Me catalyst
air, C6H6, heat
R
Br
+ H2O
R
H
– 0.5"O2"
moderate to high yields
allylic and benzylic bromide
– HBr
Water as the hydrogen source;
Without a sacrificial reductant
Rhodium porphyrin catalyzed Hydrodebormination of activated organic bromides
with water