Iodine(III)-Mediated Oxidative Hydrolysis of Haloalkenes: Investigation of the Effect of Iodine(III) Reagents

Article abstract of DOI:10.1055/s-0036-1588439

The iodine(III)-mediated oxidative transposition of vinyl halides to the corresponding α-halo ketones has been recently reported. The method is high yielding and offers good substrate scope. The investigation of other iodine(III) reagents to promote this

Full text of DOI:10.1055/s-0036-1588439

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2017, 49, A–E
special topic
A
en
R. Dagenais et al.
Special Topic
Synthesis
Iodine(III)-Mediated Oxidative Hydrolysis of Haloalkenes:
Investigation of the Effect of Iodine(III) Reagents
Robin Dagenais
Structure–Reactivity
Relationship
Antoine Jobin-Des Lauriers
TsO
R
I
OH
Claude Y. Legault*
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7
3
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Université de Sherbrooke, Department of Chemistry, 2500
boul. de l’Université, Sherbrooke (Québec), J1K 2R1, CanadaFax+
claude.legault@usherbrooke.ca
X
X
O
O
1
8
(
1
9
8
)
2
1
8
0
1
7
R2
R4
R2
R4
R1
R3
R1
R3
MeCN, r.t.
X
X
Published as part of the Special Topic Modern Strategies with
Iodine in Synthesis
Chemoselectivity
Profiles
Received: 31.03.2017
Accepted after revision: 04.05.2017
Published online: 07.06.2017
have initially developed new chiral precatalysts for the en-
antioselective iodine(III)-promoted α-tosyloxylation of ke-
tones (Scheme 1A).8 Selectivity issues encountered in our
group and others9 for this transformation led us to investi-
gate enol surrogates,10 in particular enol esters,11 to access
these products (Scheme 1B). From the success of this recent
work, we then explored the use of haloalkenes as possible
substrates to access similar α-substituted ketones (Scheme
1C).
We have recently demonstrated that chloro- and bro-
moalkenes could be converted in usually very high yields
into their corresponding α-halo ketone products by the ac-
tion of [hydroxy(tosyloxy)iodo]benzene (HTIB, 1) (Equation
1).12 The method presents a good scope and is an attractive
strategy to access α-halo ketones from non-ketonic sub-
strates.
DOI: 10.1055/s-0036-1588439; Art ID: ss-2017-c0216-st
Abstract The iodine(III)-mediated oxidative transposition of vinyl ha-
lides to the corresponding α-halo ketones has been recently reported.
The method is high yielding and offers good substrate scope. The inves-
tigation of other iodine(III) reagents to promote this reaction is de-
scribed. The newly developed protocol reduces the number of waste
products formed in the synthetic transformation. A structure–reactivity
relationship study of numerous [hydroxy(tosyloxy)iodo]arenes toward
haloalkenes is reported. The results highlight the challenge of obtaining
a chemoselective reaction using these reagents.
Key words hypervalence, iodine, oxidation, vinyl halides, chemoselec-
tivity
The development of oxidative transformations mediated
by hypervalent iodine reagents has, without doubt, greatly
influenced the field of synthetic chemistry. These com-
pounds and their applications have been receiving in-
creased attention for many years.1 Due to their carbon-
based nature, they tend to have lower environmental im-
pact, compared with common heavy-metal-based oxi-
dants.2 Both iodine(III) and iodine(V) reagents give access to
a wide diversity of synthetic transformations, such as phe-
nolic dearomatizations3 and various other oxidative rear-
rangements.4 Of particular interest, there have been nu-
merous reports recently concerning the development of
stereoselective methods using these reagents.5
C
A
B
O
OAc
X
R
R'
R'
R'
X = Cl, Br
R
R
R
O
R
X
X = OTs, Cl, Br
Scheme 1 Iodine(III)-mediated strategies to access α-substituted ke-
tones
Our group has been involved in the development of io-
dine(III)-mediated methods to access functionalized ketone
derivatives.6 This has been an active area of research in hy-
pervalent iodine chemistry,7 because of the widespread
presence and usefulness of α-functionalized ketones. Our
approach has focused on the introduction of a leaving
group α to the carbonyl, because we considered these prod-
ucts to be versatile synthetic precursors. In this regard, we
1 (1.05 equiv)
TsOH·H2O (0.1 equiv)
H2O (0–10 equiv)
MeCN, r.t., 1–40 h
X
O
TsO
I
OH
R'
R''
R'
R
R
Ph
R''
X = Cl, Br
X
1, HTIB
15 examples
32–98%
Equation 1 Oxidative hydrolysis of haloalkenes
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E

B
R. Dagenais et al.
Special Topic
Synthesis
Given the potential of this synthetic transformation, we
envisioned that it would benefit from an improvement of
its reaction conditions, and by having a better understand-
ing of the factors governing it. Herein, we present the re-
sults of an evaluation of the efficiency of other iodine(III)
reagents to promote the oxidative hydrolysis of
haloalkenes, as well as an investigation of the structure–
reactivity relationship of various [hydroxy(tosyloxy)io-
do]arenes for this transformation.
sequent tests were performed with bromoalkene 2d. Reac-
tion with DIB and water, without an additional acid, led to
low conversion and modest yield (entry 3), confirming the
requirement for a strong acid to access a Koser like reagent.
To achieve rapid conversion, we tested conditions involving
two equivalents of acid. Both TsOH·H2O and MsOH led to
complete conversions, albeit in lower yields than that ob-
tained using HTIB in our previous communication.12 The
next acid we considered in an effort to improve the reaction
was H2SO4. It has the particular advantage of being inex-
pensive, low-weight, and eco-friendly. To our delight, we
found that this acid led to rapid and clean conversion of 2d,
with or without additional water (entries 6 and 7). An ex-
tremely fast reaction (within 5 minutes) could be achieved
at 60 °C (entry 8). This protocol is particularly practical
because the only waste products are water-soluble acids
(H2SO4 and AcOH) and PhI. Following work-up, the final
product can thus be obtained in pure form by simple re-
moval of PhI under vacuum. Finally, we tested these condi-
tions with chloroalkene 2c. Lower yields were obtained
with this substrate, and addition of water to the reaction
did not improve the yield (entries 9 and 10).
Br
X
X
n
Ph
Ph
2a, X = Cl
2b, X = Br
2c, X = Cl
2d, X = Br
2e
TsO
I
OH
TsO
I
OH
TsO
I
OH
TsO
F
I
OH
F
F
F
X
F
4
5
6, X = Cl
8
7, X = NO2
Figure 1 Haloalkenes and [hydroxy(tosyloxy)iodo]arenes used in the
study
Table 1 Effect of Acid on the DIB-Mediated Oxidative Hydrolysis of
Haloalkenes
Our initial reported protocol for the direct conversion of
haloalkenes into their corresponding α-halo ketone prod-
ucts presented unprecedented reaction scope and excellent
yields with most substrates. However, in contrast to our
previous work involving the conversion of enol esters to α-
tosyloxy ketones, the toluenesulfonic acid (TsOH) released
in the reaction, coming from HTIB, is not consumed in the
process. Additionally, we have demonstrated that an excess
of TsOH·H2O is beneficial to achieve short reaction times,
increasing the mass of unused acid in the reaction. These
conditions thus lead to large amount of waste products. In
this context, and in an effort to reduce the environmental
impact of this reaction, we explored the replacement of
HTIB and TsOH·H2O to effect this transformation.
From a practical point of view, we considered (diacet-
oxyiodo)benzene (DIB) to be a good alternative iodine(III)
reagent. It is commercially available, well-defined, and sta-
ble. It is known that this compound can be readily convert-
ed into HTIB by addition of TsOH·H2O,13 hence we envi-
sioned that generation of a Koser like reagent in situ would
be sufficient to promote the reaction. We tested various
strong acids, and the results are reported in Table 1.
The first tests were made using bromoalkene 2b. The re-
quirement for water in the reaction was explored by using
anhydrous MsOH. Treatment of the substrate with DIB and
an equimolar quantity of MsOH at 60 °C for three hours re-
sulted in only partial conversion into the desired product
(Table 1, entry 1). Under the same conditions, but with the
addition of an equimolar quantity of water, complete con-
version was observed within 20 minutes, affording the de-
sired product 3b in almost quantitative yield (entry 2). Sub-
PhI(OAc)2 (1.1 equiv)
acid
X
O
R
R
Ph
Ph
MeCN, r.t., time
X
2b–d
3b–d
Entry
Substrate
Acid (equiv)
Time (min)
Yield (%)a
1
2
2b
2b
2d
2d
2d
2d
2d
2d
2c
2c
MsOH (1.15)b
MsOH (1.15)b,d
–
180
20
75c
99
17
76
75
92
89
95
82
82
3e
4
120
120
120
120
120
5
TsOH·H2O (2.0)
MsOH (2.0)d
H2SO4 (2.0)
H2SO4 (2.0)d
H2SO4 (2.0)b
H2SO4 (2.0)
H2SO4 (2.0)d
5
6
7
8
9
120
120
10
a Isolated yield.
b Reaction performed at 60 °C.
c Conversion, based on 1H NMR spectroscopic analysis.
d One equivalent of water per acid equivalent was added.
e Two equivalents of water was added to the reaction.
Another aspect we wanted to explore was the relative
rates of reaction of haloalkenes toward HTIB, to determine
whether synthetically useful selectivities could be obtained
when multiple reactive sites were present in the reaction.
Additionally, since the oxidative hydrolysis reaction is high
yielding with no discernible side products, we decided to
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E

C
R. Dagenais et al.
Special Topic
Synthesis
exploit this to investigate the chemoselectivity aspect of
[hydroxy(tosyloxy)iodo]arene reagents. We considered that
the information obtained on this specific transformation
could be, at least in part, applicable to other methodologies
involving reagents such as HTIB. The selected haloalkenes
2a–e to be used for the chemoselectivity study, as well as
the selected iodine(III) reagents 4–8, are illustrated in Fig-
ure 1. The latter were selected to evaluate both the steric
and electronic parameters of these reagents.
The first chemoselectivity profile was determined for
the 2b/2d bromoalkene pair, using HTIB and its derivatives;
the results are reported in Table 2. TsOH·H2O was used as an
additive in all cases to insure clean and rapid conversion of
the haloalkenes. Under these conditions, the iodine(III) re-
agents were consumed within two hours. The results show
a very small preference for the less sterically hindered sub-
strate 2b. Surprisingly, neither steric nor electronic factors
of the iodine(III)-reagents had a noticeable effect on the
chemoselectivities. For this substrate pair, it is clear that
synthetically useful selectivities are not easily achievable.
To evaluate whether the nature of the halogen atom could
greatly influence the chemoselectivity, we performed simi-
lar competition experiments using the chloroalkene pair
2a/2c.
Table 3 Chemoselectivity Profile of the 2a/2c Pair
reagent: TsOH⋅H2O
(1:1, 0.25 equiv)
H2O (10 equiv)
O
O
2a/2c
(1:1)
Ph
Ph
6
CD3CN, r.t., 2 h
Cl
Cl
Entry
Reagent
Conv. 2a/2ca
1b
2
1
1
4
5
6
7
1.2
1.2
1.3
1.3
1.3
1.2
3
4
5
6
a The ratios were determined from the relative conversions, based on
1H NMR spectroscopic analysis.
b Reaction was performed without TsOH·H2O additive.
hindrance of the substrate alkyl chain has a marginal effect
on reaction rate.
We next evaluated the effect of Z/E isomerism on the re-
activity, using the 2b/2e bromoalkene pair; the results are
described in Table 4. Alkene stereochemistry was found to
have a much more pronounced effect on oxidation rate,
with E alkenes being roughly four times more reactive than
their Z counterpart, yielding synthetically useful selectivi-
ties. Unfortunately, the steric and electronic properties of
the iodine(III) reagents have again only marginal effect on
the selectivities. At this point, we decided to explore the in-
fluence of the halogen atom on reaction rate, to probe the
electronic effect of the substrates, since only limited selec-
Table 2 Chemoselectivity Profile of the 2b/2d Pair
reagent: TsOH⋅H2O
(1:1, 0.25 equiv)
O
O
2b/2d
(1:1)
Ph
Ph
6
CD3CN, r.t., 2 h
Br
Br
Entry
Reagent
Conv. 2b/2da
1
2
3
4
5
1
4
5
6
7
1.3
1.3
1.2
1.3
1.3
Table 4 Chemoselectivity Profile of the 2b/2e Pair
reagent: TsOH⋅H2O
O
a The ratios were determined from the relative conversions, based on
1H NMR spectroscopic analysis.
O
(1:1, 0.25 equiv)
Br
2b/2e
(1:1)
Ph
CD3CN, r.t., 1 h
6
Br
As was shown in our previous communication,12 in this
process we added 10 equivalents of water to prevent forma-
tion of aryl migration side products. The results of the com-
petition experiments are presented in Table 3.
In analogy to the results measured for the 2b/2d pair,
the chloroalkene pair 2a/2c presents almost identical che-
moselectivity profiles. Again, the nature of the iodine(III)
reagent does not affect the selectivity obtained in any no-
ticeable manner. We also evaluated whether the absence of
additional TsOH·H2O would change the selectivity, but
found no effect (Table 3, entry 1 vs. entry 2). From these
first competition experiments, it seems clear that the steric
Entry
Reagent
Conv. 2b/2ea
1b
2
3
4
5
6
7
1
1
4
5
6
7
8
3.8
3.7
3.3
4.0
3.2
3.7
3.7
a The ratios were determined from the relative conversions, based on
1H NMR spectroscopic analysis.
b Reaction was performed without TsOH·H2O additive.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E

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R. Dagenais et al.
Special Topic
Synthesis
Table 5 Chemoselectivity Profile of the 2a/2d Pair
mediated processes. To account for the behavior reported,
one could raise the possibility that the iodine(III) reagent is
not involved in the selectivity-determining step. A theoreti-
cal investigation of this transformation is under way to bet-
ter understand the reaction mechanism and the require-
ments to achieve chemoselectivity.
reagent: TsOH⋅H2O
(1:1, 0.25 equiv)
H2O (10 equiv)
O
O
2a/2d
(1:1)
CD3CN, r.t., 2 h
Ph
Ph
6
Br/Cl
Br/Cl
Entry
Reagent
Conv. 2a/2da
1b
2
3
4
5
6
7
1
1
4
5
6
7
8
2.1
2.0
2.0
1.9
2.1
2.2
1.9
CDCl3 was dried over anhydrous K2CO3 but not thoroughly dried.
CD3CN was used as received. Analytical thin-layer chromatography
(TLC) was performed on precoated, glass-backed silica gel (Merck 60
F
254). NMR spectra (1H, 13C, DEPT) were recorded with either Avance
III HD 300 (Bruker, Billerica, MA, USA) or Mercury+ 400 (Agilent Tech-
nology, Santa Clara, CA, USA) spectrometers. Chemical shifts for 1H
NMR spectra are recorded in parts per million (ppm) from tetrameth-
ylsilane with the solvent resonance as the internal standard. High-
resolution mass spectra were recorded with a Maxis ESI-Q-Tof
(Bruker, Billerica, MA, USA) at the Université de Sherbrooke. All com-
mercial materials were used without further purification. The
a The ratios were determined from the relative conversions, based on
1H NMR spectroscopic analysis.
haloalkenes 2a–e12 and [hydroxy(tosyloxy)iodo]arenes 4 and 6,14
and 7,15 and 816 were prepared by using reported procedures.
5
b Reaction was performed without TsOH·H2O additive.
Oxidative Hydrolysis using DIB and H2SO4; Typical Procedure for α-
Bromoisovalerophenone (3d)
tivity could be obtained from the steric properties of the
haloalkenes. The substrate pair 2a/2d was selected, and the
results are reported in Table 5.
To a reaction flask were added haloalkene 2d (56.3 mg, 0.250 mmol),
MeCN (1.33 mL, 0.2 M), concentrated (98%) H2SO4 (27 μL, 0.50 mmol,
2.0 equiv) and (diacetoxyiodo)benzene (88.6 mg, 0.275 mmol, 1.1
equiv). The suspension was stirred at r.t. for 2 h, then the solution was
diluted with water (1:1) and extracted with three portions of Et2O.
The combined organic layers were washed with brine, dried over
magnesium sulfate, filtered and concentrated by rotatory evapora-
tion. The crude material was purified by flash chromatography (1%
Et2O/pentane) to obtain the pure α-halo ketone 3d (57.3 mg, 95%). Al-
ternatively, pure 3d can be obtained by removal of PhI under vacuum.
The analytical and spectral data for this compound were consistent
with reported data.12
Halogen scrambling on the final products was observed,
as expected from a control experiment of our previous
communication.12 Chloroalkene 2a was found to be roughly
twice as reactive as bromoalkene 2d. Considering the slight
steric bias toward the less hindered substrate 2a, the chlo-
roalkene/bromoalkene preference factor is thus approxi-
mately 1.6. This preference is in line with the Hammett–
Brown σ+ values (0.150[Br], 0.114[Cl]), in support of the
p
presence of a strong positive charge on the carbon bearing
the halogen atom at the selectivity-determining step.17 Sur-
prisingly, almost no influence on selectivity was observed
from the different iodine(III) reagents, even for the strongly
electron attracting perfluorophenyl variant 8.
Chemoselectivity Experiments; Typical Procedure
Reagent 1 (6.2 mg, 0.0157 mmol, 0.25 equiv) was added to a small vi-
al. To the solid was added a stock solution containing TsOH·H2O (2.7
mg, 0.0157 mmol, 0.25 equiv) in CD3CN (100 μL). To this suspension
was then added a stock solution containing bromoalkene 2b (16.8
mg, 0.0629 mmol) and bromoalkene 2d (14.2 mg, 0.0629 mmol) in
CD3CN (500 μL). The resulting suspension was stirred at r.t. for 2 h, at
which point the reaction mixture was now a clear solution. The
whole reaction mixture was filtered over a small quantity of solid
NaHCO3 directly into an NMR tube. 1H NMR spectroscopic analysis
(8 s relaxation time) was performed and conversions were deter-
mined by integration of the vinylic protons of the remaining starting
materials and protons α to the carbonyl of the products. Reference 1H
NMR spectra for all substrates and final products were obtained from
the literature.12
In summary, we have demonstrated that it is possible to
reduce the amount of waste products of the oxidative hy-
drolysis of haloalkenes to their corresponding α-halo ke-
tones by using DIB and sulfuric acid. By removing the pres-
ence of an organic sulfonic acid, this new protocol has the
added advantage of simplifying access to the pure final
product. On the other hand, our investigation of the chemo-
selectivity profiles of haloalkenes and structure–reactivity
relationship investigation of numerous iodine(III) reagents
has exposed a limitation of the current methodology. Ex-
cept for the more important preference for E vs. Z alkenes,
the selectivities measured are not synthetically useful.
Moreover, it is surprising to find that modification of either
the steric or electronic properties of the involved iodine(III)
reagents does not lead to a noticeable enhancement of
these selectivities. While this might be specific to the oxi-
dative hydrolysis of haloalkenes, it does raise the concern
that it could also be an issue for other similar iodine(III)-
Acknowledgment
This work was supported by the National Science and Engineering Re-
search Council (NSERC) of Canada, the Canada Foundation for Innova-
tion (CFI), the FRQNT Centre in Green Chemistry and Catalysis
(CGCC), and the Université de Sherbrooke.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2017, 49, A–E

E
R. Dagenais et al.
Special Topic
Synthesis
References
(7) Reviews on hypervalent iodine-mediated functionalization of
carbonyl compounds: (a) Dong, D.-Q.; Hao, S.-H.; Wang, Z.-L.;
Chen, C. Org. Biomol. Chem. 2014, 12, 4278. (b) Merritt, E. A.;
Olofsson, B. Synthesis 2011, 517.
(1) (a) Zhdankin, V. V. Hypervalent Iodine Chemistry: Preparation,
Structure, and Synthetic Applications of Polyvalent Iodine Com-
pounds; Chichester, UK, Wiley 2013. (b) Tohma, H.; Kita, Y. In
Hypervalent Iodine Chemistry; Wirth, T., Ed.; Berlin, Springer
2003, 209. (c) Zhdankin, V. V.; Stang, P. J. Chem. Rev. 2002, 102,
2523. (d) Moriarty, R. M.; Prakash, O. Org. React. 2001, 57, 327.
(e) Varvoglis, A. Hypervalent Iodine in Organic Synthesis; Aca-
demic Press: San Diego, 1997.
(2) (a) Khanna, M. S.; Garg, C. P.; Kapoor, R. P. Tetrahedron Lett.
1992, 33, 1495. (b) For an Iodine(III) variant, see: Koser, G. F.;
Relenyi, A. G.; Kalos, A. N.; Rebrovic, L.; Wettach, R. H. J. Org.
Chem. 1982, 47, 2487.
(3) (a) Bosset, C.; Coffinier, R.; Peixoto, P. A.; El Assal, M.; Miqueu,
K.; Sotiropoulos, J.-M.; Pouységu, L.; Quideau, S. Angew. Chem.
Int. Ed. 2014, 53, 9860. (b) Volp, K.; Harned, A. M. Chem.
Commun. 2013, 3001. (c) Uyanik, M.; Yasui, T.; Ishihara, K.
Angew. Chem. Int. Ed. 2013, 52, 9215. (d) Uyanik, M.; Yasui, T.;
Ishihara, K. Angew. Chem. Int. Ed. 2010, 49, 2175. (e) Uyanik, M.;
Yasui, T.; Ishihara, K. Tetrahedron 2010, 66, 5841. (f) Quideau, S.;
Lyvinec, G.; Marguerit, M.; Bathany, K.; Ozanne-Beaudenon, A.;
Buffeteau, T.; Cavagnat, D.; Chénedé, A. Angew. Chem. Int. Ed.
2009, 48, 4605. (g) Boppisetti, J. K.; Birman, V. B. Org. Lett. 2009,
11, 1221. (h) Dohi, T.; Maruyama, A.; Takenaga, N.; Senami, K.;
Minamitsuji, Y.; Fujioka, H.; Caemmerer, S. B.; Kita, Y. Angew.
Chem. Int. Ed. 2008, 47, 3787.
(4) (a) Singh, F. V.; Wirth, T. Chem. Asian J. 2014, 9, 950. (b) Dohi, T.;
Kita, Y. Chem. Commun. 2009, 2073. (c) Uyanik, M.; Ishihara, K.
Chem. Commun. 2009, 2086. (d) Zhdankin, V. V. ARKIVOC 2009,
1. (e) Richardson, R. D.; Wirth, T. Angew. Chem. Int. Ed. 2006, 45,
4402. (f) Wirth, T. Angew. Chem. Int. Ed. 2005, 44, 3656.
(5) Reviews on hypervalent iodine-mediated asymmetric transfor-
mations: (a) Kumar, R.; Wirth, T. Top. Curr. Chem. 2015, 373,
243. (b) Berthiol, F. Synthesis 2015, 47, 587. (c) Parra, A.;
Reboredo, S. Chem. Eur. J. 2013, 19, 17244. (d) Ngatimin, M.;
Lupton, D. W. Aust. J. Chem. 2010, 63, 653.
(8) (a) Thérien, M.-È.; Guilbault, A.-A.; Legault, C. Y. Tetrahedron:
Asymmetry 2013, 24, 1193. (b) Guilbault, A.-A.; Basdevant, B.;
Wanie, V.; Legault, C. Y. J. Org. Chem. 2012, 77, 11283.
(c) Guilbault, A.-A.; Legault, C. Y. ACS Catal. 2012, 2, 219.
(9) (a) Brenet, S.; Minozzi, C.; Clarens, B.; Amiri, L.; Berthiol, F. Syn-
thesis 2015, 47, 3859. (b) Brenet, S.; Berthiol, F.; Einhorn, J. Eur. J.
Org. Chem. 2013, 8094. (c) Rodriguez, A.; Moran, W. J. Synthesis
2012, 44, 1178. (d) Yu, J.; Cui, J.; Hou, X.-S.; Liu, S.-S.; Gao, W.-C.;
Jiang, S.; Tian, J.; Zhang, C. Tetrahedron: Asymmetry 2011, 22,
2039. (e) Farooq, U.; Schäfer, S.; Shah, A. A.; Freudendahl, D. M.;
Wirth, T. Synthesis 2010, 1023. (f) Altermann, S. M.; Richardson,
R. D.; Page, T. K.; Schmidt, R. K.; Holland, E.; Mohammed, U.;
Paradine, S. M.; French, A. N.; Richter, C.; Bahar, A. M.; Witulski,
B.; Wirth, T. Eur. J. Org. Chem. 2008, 5315. (g) Richardson, R. D.;
Page, T. K.; Altermann, S. M.; Paradine, S. M.; French, A. N.;
Wirth, T. Synlett 2007, 538. (h) Hirt, U. H.; Schuster, M. F. H.;
French, A. N.; Wiest, O. G.; Wirth, T. Eur. J. Org. Chem. 2001,
1569. (i) Hirt, U. H.; Spingler, B.; Wirth, T. J. Org. Chem. 1998, 63,
7674. (j) Wirth, T.; Hirt, U. H. Tetrahedron: Asymmetry 1997, 8,
23.
(10) Jobin-Des Lauriers, A.; Legault, C. Y. Asian J. Org. Chem. 2016, 5,
1078.
(11) (a) Basdevant, B.; Legault, C. Y. J. Org. Chem. 2015, 80, 6897.
(b) Basdevant, B.; Legault, C. Y. Org. Lett. 2015, 17, 4918.
(12) Jobin-Des Lauriers, A.; Legault, C. Y. Org. Lett. 2016, 18, 108.
(13) (a) Yusubov, M. S.; Wirth, T. Org. Lett. 2005, 7, 519. (b) Koser, G.
F.; Wettach, R. H.; Troup, J. M.; Frenz, B. A. J. Org. Chem. 1976, 41,
3609.
(14) Yamamoto, Y.; Togo, H. Synlett 2005, 2486.
(15) Merritt, E. A.; Carneiro, V. M. T.; Silva, L. F.; Olofsson, B. J. Org.
Chem. 2010, 75, 7416.
(16) Zagulyaeva, A. A.; Yusubov, M. S.; Zhdankin, V. V. J. Org. Chem.
2010, 75, 2119.
(6) Basdevant, B.; Guilbault, A.-A.; Beaulieu, S.; Jobin-Des Lauriers,
A.; Legault, C. Y. Pure Appl. Chem. 2017, DOI:10.1515/pac-2016-
1212.
(17) Brown, H. C.; Okamoto, Y. J. Am. Chem. Soc. 1958, 80, 4979.
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