A convenient catalytic oxidative 1,2-shift of arylalkenes for preparation of α-aryl ketones mediated by NaI

Article abstract of DOI:10.1016/j.cclet.2014.11.006

Using a catalytic amount of NaI and a stoichiometric oxidant Oxone^@, a convenient procedure has been developed for the catalytic oxidative 1,2-shift of arylalkenes in CH₃CN/H₂O at room temperature, which provides the corresponding α-aryl ketones in moderate to good yields. In this protocol, sodium iodide is first oxidized into hypoiodous acid, which reacts with arylalkene to afford iodohydrin. Then, the iodohydrin is transformed into the α-aryl ketone via an oxidative 1,2-shift rearrangement.

Full text of DOI:10.1016/j.cclet.2014.11.006

Chinese Chemical Letters 26 (2015) 248–250
Contents lists available at ScienceDirect
Chinese Chemical Letters
journal homepage: www.elsevier.com/locate/cclet
Original article
A convenient catalytic oxidative 1,2-shift of arylalkenes for
preparation of
a
-aryl ketones mediated by NaI
b
Min Zhu a, , Yang Zhao
*
a College of Biological and Environmental Sciences, Zhejiang Shuren University, Hangzhou 310015, China
b Foreign Language School, Zhejiang Shuren University, Hangzhou 310015, China
A R T I C L E I N F O
A B S T R A C T
Using a catalytic amount of NaI and a stoichiometric oxidant Oxone@, a convenient procedure has been
developed for the catalytic oxidative 1,2-shift of arylalkenes in CH3CN/H2O at room temperature, which
Article history:
Received 9 September 2014
Received in revised form 19 October 2014
Accepted 24 October 2014
Available online 8 November 2014
provides the corresponding
first oxidized into hypoiodous acid, which reacts with arylalkene to afford iodohydrin. Then, the
iodohydrin is transformed into the -aryl ketone via an oxidative 1,2-shift rearrangement.
a-aryl ketones in moderate to good yields. In this protocol, sodium iodide is
a
ß 2014 Min Zhu. Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of
Keywords:
Materia Medica, Chinese Academy of Medical Sciences. All rights reserved.
Oxidative 1,2-shift
a
-Aryl ketone
Sodium iodide
Catalysis
1. Introduction
unusual 2-iodo-5-methylbenzenesulfonic acid is used as catalyst
in the method. Therefore, the simple and convenient catalytic
Hypervalent iodine reagents have found broad application in
organic chemistry and nowadays frequently used in synthesis as
they are nonmetallic oxidation reagents and avoid the issues of
toxicity of many transition metals commonly involved in such
processes [1–10]. Using the hypervalent iodine reagent, [hydro-
xyl(tosyloxy)]iodobenzene (Koser’s reagent, HTIB), Koser and co-
workers have developed a convenient oxidative 1,2-shift proce-
oxidative 1,2-shift reactions are still desired.
Due to that iodobenzene (PhI) can be prepared by the reaction
of molecule iodine (I2) with benzene in the presence of oxidants,
Togo and co-workers have developed a new way for the
a-
tosyloxylation of ketones using I2 as catalyst in place of the
expensive PhI, which has been demonstrated via hypervalent
iodine intermediate [20]. At the same time, we have also
investigated the possibility of using inorganic iodides which are
more environmentally benign in place of PhI in the catalytic
reaction, and a convenient route for monobromination of electron-
rich aromatic compounds using I2 or NH4I as catalyst has been
developed [21]. Herein, we wish to report a novel and convenient
catalytic oxidative 1,2-shift rearrangement of arylalkenes using a
catalytic amount of NaI together with a stoichiometric Oxone@
(2KHSO5-KHSO4-K2SO4) as the terminal oxidant, and to the best of
our knowledge this method has not been reported before.
dure of arylalkenes, with which the corresponding a-aryl ketones
have been obtained in good yields [11–13]. In recent years, the
catalytic utilization of hypervalent iodine reagents is increasing in
importance, with the growing interest in the development of
environmentally benign synthetic transformations [14–18]. In
these reactions,
a catalytic amount of an iodine-containing
molecule together with a stoichiometric oxidant is used. The
oxidant generates the hypervalent iodine reagent in situ, and after
the oxidative transformation, the reduced iodine-containing
molecule is re-oxidized. Very recently, Purohit and co-workers
just reported the first catalytic oxidative 1,2-shift of arylalkenes by
the in situ generated hypervalent iodine species [19]. However, the
reaction conditions are somewhat complex and the yields are not
as high as those Koser’s group reported [13]; moreover, the
2. Experimental
A typical procedure for the catalytic oxidative 1,2-shift of
arylalkenes: To a mixture solvent MeCN-H2O (5:1) (2 mL),
a-
methylstyrene (0.5 mmol), Oxone@ (1.0 mmol) and NaI
(0.05 mmol) were added. The mixture was stirred at room
temperature for 15 h, then H2O (5 mL) was added. Extraction of
the mixture with CH2Cl2 (3 Â 5 mL) and the combined organic
*
Corresponding author.
E-mail address: hzzm60@163.com (M. Zhu).
http://dx.doi.org/10.1016/j.cclet.2014.11.006
1001-8417/ß 2014 Min Zhu. Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. All rights
reserved.

M. Zhu, Y. Zhao / Chinese Chemical Letters 26 (2015) 248–250
249
layer was dried over anhydrous Na2SO4, filtered, and concentrated
under reduced pressure. The residue was purified on silica gel plate
(5:1 hexane-ethyl acetate) to give 1-phenylpropan-2-one in 81% of
As shown from Table 2 that the reaction was compatible with
most of the studied arylalkenes and the corresponding -aryl
a
ketones were obtained in moderate to good yields (entries 1–11). It
was notable that the arylalkenes with electron-donating groups on
the benzene ring usually led to better yields than those having
electron-withdrawing groups on benzene ring (entries 2–5). Due to
that the hinder effect of groups, arylalkenes 1g, 1h and 1i resulted
yield. Colorless oil; 1H NMR (500 MHz, CDCl3):
d
7.39–7.36 (m, 2H),
7.31–7.28 (m, 1H), 7.22 (d, 2H, J = 8.4 Hz), 3.71(s, 2H), 2.17 (s, 3H);
13C NMR (125 MHz, CDCl3):
d
206.5, 134.3, 129.3, 128.8, 127.1,
51.1, 29.2; IR (film, cmÀ1):
n
1713; MS (EI, m/z, %): 134 (M+, 100).
in the corresponding
a-aryl ketones with the somewhat lower
yields compared with 1a (entries 1, 7–9). 1-Phenyl cyclohexene
(1k), a trisubstituded alkene, when it was treated under the same
conditions, the respect product 2k was afforded in 70% yield (entry
11).
According to the above results, a plausible reaction pathway is
shown in Scheme 2. Thus, NaI is first oxidized to HOI by Oxone@,
3. Results and discussion
We first examined the reaction of
a-methylstyrene with
1.5 equiv. of oxidant Oxone@ in the presence of 0.1 equiv. of
NH4I in water at room temperature, and found that the desired
product 1-phenylpropan-2-one was obtained in only 5% yield after
20 h (Table 1, entry 1). When several mixture solvents were used in
place of water, the reaction gave the product in great different
yields, in which the mixture solvent MeCN-H2O (5:1) was proved
to be the favorable solvent system for the reaction (entries 2–10).
Compared with NH4I, KI and NaI were more active in the reaction,
in which NaI was the most effective one, and 0.1 equiv. of it was the
best choice (entries 2, 11–14). However, if NaI was absent, no
desired product was observed (entry 15). The amount of Oxone@
was checked and 2.0 equiv. of it was suitable for the reaction
(entries 12, 16–18). The suitable reaction time should be 15 h
(entries 16, 19–21).
which reacts with
a-methylstyrene in the presence of water to
form an iodohydrin. The iodohydrin is then easily transformed into
the highly unstable hypervalent iodine iodosyl intermediate by the
continuing oxidation of Oxone@ [1,2], which rearranges via a 1,2-
shift procedure to afford the final product 1-phenylpropan-2-one.
To identify it, a-methylstyrene was first treated with HOI [22],
which provided iodohydrin in good yield. Then, the reaction of
iodohydrin with Oxone@ was examined. The result showed that in
the absence of Oxone@, the desired product 1-phenylpropan-2-one
was not observed after a long reaction time. However, when
Under the optimum reaction conditions, we investigated the
catalytic oxidative 1,2-shift reaction of 1.0 equiv. of arylalkenes (1),
2.0 equiv. Oxone@ and 0.1 equiv. of NaI in CH3CN-H2O (5:1) at
room temperature for 15 h (Scheme 1), the results are summarized
in Table 2.
Table 2
The result of the catalytic oxidative 1,2-shift of arylalkenes.
Entry
1
Substrate (1)
Product (2)
Yield (%)a
81
O
2a
1a
Table 1
Optimization of the catalytic oxidative 1,2-shift of
a-methylstyrene
2
3
4
5
6
7
83
85
O
Me
2b
Me
1b
O
MeO
Cl
2c
MeO
Cl
1c
–
Entry
Oxone
I
(equiv.)
Solvent
H2O
Time
Yield
(%)a
(equiv.)
(h)
67
O
2d
1
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
2.0
1.2
1.0
2.0
2.0
2.0
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
NH4I (0.1)
KI (0.1)
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
10
15
24
5
71
13
4
1d
2
MeCN-H2O (5:1)
CH2Cl2-H2O (5:1)
THF-H2O (5:1)
3
55b
76
O
4
2e
F
F
1e
5
CH3OH-H2O (5:1)
CF3CH2OH-H2O (5:1)
EtOAc-H2O (5:1)
MeCN-H2O (1:1)
MeCN-H2O (2:1)
MeCN-H2O (10:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
MeCN-H2O (5:1)
65
68
18
19
35
63
74
76
78
57
0
6
7
O
8
2f
1f
9
10
11
12
13
14
15
16
17
18
19
20
21
72
O
O
NaI (0.1)
NaI (0.2)
NaI (0.05)
–
2g
1g
1i
8
9
70
65
NaI (0.1)
NaI (0.1)
NaI (0.1)
NaI (0.1)
NaI (0.1)
NaI (0.1)
82
63
55
65
81
80
2h
1h
Ph
Ph
Ph
Ph
O
2i
a
Isolated yield.
10
62
70
O
2j
1j
Ph
Ph
11
1k
O
2k
a
Isolated yield.
b
Scheme 1. The catalytic oxidative 1,2-shift of arylalkenes.
Reaction time was 24 h.

250
M. Zhu, Y. Zhao / Chinese Chemical Letters 26 (2015) 248–250
References
H O
2
I
Ph
Ph
[1] P.J. Stang, V.V. Zhdankin, Organic polyvalent iodine compounds, Chem. Rev. 96
(1996) 1123–1178.
[2] V.V. Zhdankin, P.J. Stang, Recent developments in the chemistry of polyvalent
iodine compounds, Chem. Rev. 102 (2002) 2523–2584.
_
+
H
+
[3] K.C. Nicolaou, K. Sugita, P.S. Baran, et al., Iodine(V) reagents in organic synthesis.
Part 1. Synthesis of polycyclic heterocycles via DessÀMartin periodinane-medi-
ated cascade cyclization: generality, scope, and mechanism of the reaction, J. Am.
Chem. Soc. 124 (2002) 2212–2220.
I (HOI)
OH
I
Ph
Oxone
H
[4] M. Ochiai, Nucleophilic vinylic substitutions of l3-vinyliodanes, J. Organomet.
Chem. 611 (2000) 494–508.
O
I
Oxone
2
I
O
[5] T. Okuyama, Solvolysis of vinyl iodonium salts. New insights into vinyl cation
intermediates, Acc. Chem. Res. 35 (2002) 12–18.
[6] J. Barluenga, M. Maro-Arias, F. Gonza´lez-Bobes, et al., Reaction of alkenes with
hydrogen peroxide and sodium iodide: a nonenzymatic biogenic-like approach to
iodohydrins, Chem. Eur. J. 10 (2004) 1677–1682.
Ph
Oxone
NaI
Ph
O
[7] K.C. Nicolaou, Y.L. Zhong, P.S. Baran, New synthetic technology for the rapid
construction of novel heterocycles
periodinane with anilides and related compounds, Angew. Chem. Int. Ed. 39
(2000) 622–625.
– Part 1: The reaction of Dess–Martin
Scheme 2. Proposed mechanism for the catalytic oxidative 1,2-shift of arylalkenes.
[8] T. Dohi, M. Ito, N. Yamaoka, et al., Hypervalent iodine(III): selective and efficient
single-electron-transfer (SET) oxidizing agent, Tetrahedron 65 (2009) 10797–
10815.
[9] M. Traore´, S. Ahmed-Ali, M. Peuchmaur, et al., Hypervalent iodine(III)-mediated
tandem oxidative reactions: application for the synthesis of bioactive polyspir-
ocyclohexa-2,5-dienones, Tetrahedron 66 (2010) 5863–5872.
[10] M. Arisawa, N.G. Ramesh, M. Nakaima, et al., Hypervalent iodine(III)-induced
intramolecular cyclization of a-(aryl) alkyl-b-dicarbonyl compounds: a conve-
nient synthesis of benzannulated and spirobenzannulated compounds, J. Org.
Chem. 66 (2001) 59–65.
[11] G.F. Koser, L. Rebrovic, R.H. Wettach, Functionalization of alkenes and alkynes
with [hydroxy(tosyloxy)iodo]benzene. Bis(tosyloxy)alkanes, vinylaryliodonium
tosylates, and alkynylaryliodonium tosylates, J. Org. Chem. 46 (1981) 4324–4326.
[12] L. Rebrovic, G.F. Koser, Reactions of alkenes with [hydroxy(tosyloxy)iodo]ben-
zene: stereospecific syn-1,2-ditosyloxylation of the carbon–carbon double bond
and other processes, J. Org. Chem. 49 (1984) 2462–2472.
[13] M.W. Justik, G.F. Koser, Oxidative rearrangements of arylalkenes with [hydro-
xy(tosyloxy)iodo]benzene in 95% methanol: a general, regiospecific synthesis of
a-aryl ketones, Tetrahedron Lett. 45 (2004) 6159–6163.
Scheme 3. Identification of the above mechanism.
Oxone@ was added to the reaction mixture, the desired product
was obtained in good yield. Therefore, the in situ generated
hypervalent iodine intermediate was responsible for the reaction
(Scheme 3).
[14] T. Dohi, Y. Kita, Hypervalent iodine reagents as a new entrance to organocatalysts,
Chem. Commun. (2009) 2073–2085.
[15] M. Ochiai, Y. Takeuchi, T. Katayama, et al., Iodobenzene-catalyzed a-acetoxyla-
tion of ketones. In situ generation of hypervalent (diacyloxyiodo)benzenes using
m-chloroperbenzoic acid, J. Am. Chem. Soc. 127 (2005) 12244–12245.
[16] M. Uyanik, K. Ishihara, Hypervalent iodine-mediated oxidation of alcohols, Chem.
Commun. (2009) 2086–2099.
[17] R.D. Richardson, T. Wirth, Hypervalent iodine goes catalytic, Angew. Chem. Int.
Ed. 45 (2006) 4402–4404.
[18] T. Dohi, A. Maruyama, M. Yoshimura, Versatile hypervalent-iodine(III)-catalyzed
oxidations with m-chloroperbenzoic acid as a cooxidant, Angew. Chem. Int. Ed. 44
(2005) 6193–6196.
[19] V.C. Purohit, S.P. Allwein, R.P. Bakale, Catalytic oxidative 1,2-shift in 1,10-disub-
stituted olefins using arene(iodo)sulfonic acid as the precatalyst and oxone as the
oxidant, Org. Lett. 15 (2013) 1650–1653.
[20] A. Tanaka, K. Moriyama, H. Togo, Iodoarene-mediated a-tosyloxylation of ketones
with MCPBA and p-toluenesulfonic acid, Synlett (2011) 1853–1858.
[21] M. Zhu, L. Li, H. Zhang, C.Q. Liu, Monobromination of aromatic compounds
catalyzed by iodine or ammonium iodide, Chem. J. Chin. Univ. 33 (2012)
1995–1999.
4. Conclusion
We have developed a new and convenient strategy for the
catalytic oxidative 1,2-shift reaction of arylalkenes mediated by
NaI together with Oxone@ in MeCN-H2O (5:1) at room tempera-
ture. The method using a catalytic amount of inorganic iodide
replacement of expensive aryl iodides has some advantages such
as mild reaction conditions, simple procedure and more environ-
mentally benign. Moreover, it extends the scope of hypervalent
iodine reagents in organic synthesis.
Acknowledgment
[22] G. Asensio, C. Andreu, C. Boix-Bernardini, R. Mello, M.E. Gonzalez-Nunez, Iodo-
methane oxidation by dimethyldioxirane: a new route to hypoiodous acid and
iodohydrines, Org. Lett. 1 (1999) 2125–2128.
Financial support from the National Natural Science Foundation
of China (No. 21072176) is greatly appreciated.