Development of Imino-λ3-iodanes with Improved Reactivity for Metal-Free [2+2+1] Cycloaddition-Type Reactions

Article abstract of DOI:10.1002/adsc.201700934

Aiming at the enhancement of electrophilicity of imino-λ³-iodanes, we have developed (tosylimino)pentafluorophenyl-λ³-iodane, which shows superior reactivity compared to the commonly used (tosylimino)phenyl-λ³-iodane in the [2+2+1]-type synthesis of imidazoles. (Figure presented.).

Full text of DOI:10.1002/adsc.201700934

Title: Development of Imino-λ³-iodanes with Improved
Reactivity for Metal-Free [2+2+1] Cycloaddition-Type Reactions
Authors: Takafumi Baba, Shunsuke Takahashi, Yui Kambara, Akira
Yoshimura, Victor Nemykin, Viktor Zhdankin, and Akio Saito
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To be cited as: Adv. Synth. Catal. 10.1002/adsc.201700934
Link to VoR: http://dx.doi.org/10.1002/adsc.201700934

10.1002/adsc.201700934
Advanced Synthesis & Catalysis
UPDATE
DOI: 10.1002/adsc.201((will be filled in by the editorial staff))
Development of Imino-3-iodanes with Improved Reactivity for
Metal-Free [2+2+1] Cycloaddition-Type Reactions
Takafumi Baba,a Shunsuke Takahashi,a Yui Kambara,a Akira Yoshimura,b,c Victor N.
Nemykin,b,d Viktor V. Zhdankinb and Akio Saitoa,*
a
Division of Applied Chemistry, Institute of Engineering Tokyo University of Agriculture and Technology, Koganei,
Tokyo 184-8588, Japan
E-mail address: akio-sai@cc.tuat.ac.jp
Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN 55812, United States
The Tomsk Polytechnic University, 634050 Tomsk, Russia
Department of Chemistry, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
b
c
d
Received: ((will be filled in by the editorial staff))
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201######.((Please
delete if not appropriate))
intermolecular
I···N
secondary
bonds.[2a,b,d,8]
Abstract. Directed toward Aiming at the enhancement of
electrophilicity of imino-3-iodanes, we have developed Therefore, the addition of BF3•nitrile complexes,
(tosylimino)pentafluorophenyl-λ3-iodane, which shows the
superior reactivity compared to the commonly used
(tosylimino)phenyl-λ3-iodane for our previously reported in
the [2+2+1]-type synthesis of imidazoles.
which would disassociate the I···N secondary bonds
leading to monomeric iodonium species, is effective
has strong effect on the [2+2+1] cycloaddition-type
reactions. However, PhINTs/ BF3•nitrile systems
cannot be applied to the bulky substrates and low
nucleophilic nitriles, and therefore there is still room
for improvement of the [2+2+1] cycloaddition-type
reactions. Herein, we report the preparation and the
improved reactivity of N-tosyliminoaryl-3-iodanes
(ArINTs) having electron-withdrawing group
substituents on their aromatic rings for the metal-free
[2+2+1] cycloaddition-type reactions (Scheme 1).
Although Protasiewicz’s, Zhdankin’s and other group
succeeded to in developing ArINTs as highly soluble
and reactive nitrene precursors by means of the
introduction of coordinating group such as alkoxy
and sulfonyl group to iodine at ortho-position,[9] to
the best of our knowledge, such a chemical
modification was not examined for the enhancement
of electrophilicity of ArINTs.
Keywords: alkynes; cycloaddition; iminoiodanes; metal-
free; imidazoles
In late recent years, hypervalent iodine reagents have
found a broad range of applications to in organic
syntheses because of their low toxicities toxicity,
oxidizing abilities ability similar to heavy metal
oxidants, transition metal-like reactivities reactivity
and so on other beneficial features.[1] Among them,
N-sulfonyl-iminophenyl-3-iodanes
reagents
(PhINSO2R) have been well recognized as a useful
nitrene precursors in the aziridination of alkenes and
the amidation reactions of various organic substrates
under metal-catalyzed[2,3] or metal-free conditions.[4]
Although the catalyst-free aziridination of alkenes
was has also been achieved by the modification of
substituents on nitrogen atoms of iminophenyl-3-
iodane reagents,[5] the investigation on the synthetic
methods utilizing the cationic property of iodonium
ion in the iminoiodanes makes little progress have not
been explored.[6]
On the other hand, we have developed the a metal-
free method for the synthesis of heterocycles through
the activation of alkynes by hypervalent iodine(III)
reagents,[7] and recently found the [2+2+1]
cycloaddition-type reactions of alkynes, nitriles and
nitrogen from PhINTs (Scheme 1).,[7f] Unfortunately,
Scheme 1. Iminoiodane-mediated [2+2+1] cycloaddition.
The preparation of the employed iminoiodanes 1a-
1f was is summarized in Scheme 2. Initially,
PhINTs has which have
a
three-dimensional
aAccording
to
Zhdankin’s
method,[9f]
o-
polymeric structure and thereby therefore is
characterized by a very low solubility due to
alkoxyphenyliminoiodane 1a was prepared in two
1
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10.1002/adsc.201700934
Advanced Synthesis & Catalysis
steps starting from 2a (Scheme 2a). Thus In the first
step, aryl iodide 2a was oxidized by peracetic acid to
form diacetate 3a, which was then converted to
iminoiodanes 1a by treatment with TsNH2 under
basic conditions in methanol.[10] On the other hand,
when we attempted a similar although the oxidation
of 2b by with peracetic acid was attempted for the
dimer-like structure formed by two I···N secondary
bonds (3.020 Å, Figure 1). Also, one of the oxygen
atoms in the nitro group (I···O: 2.689 Å) is located to
trans of relative to the intramolecular NTs ligand
around across the iodine center (C–I–N: 96.73º, C–
I···O: 68.46º), and thus the nitrogen atom in the
intermolecular NTs ligand is located to trans of to the
aryl ligand (C–I···N: 168.13º). However, unlike the
o-tert-butylsulfonyl analogue,[9b] intramolecular I···O
contacts (3.168 Å)[15] are formed between the iodine
center and one of the oxygen atoms in the NTs ligand.
preparation
of
o-(alkoxycarbonyl)-
phenyliminoiodane, 2-iodosylbenzoic acid (5) was
obtained as a main product instead of the expected o-
(alkoxycarbonyl)-phenyliminoiodane (Scheme 2b).
However Therefore, we prepared the iodane 1b from
5 was exposed to Ac2O and then the obtained via
initial conversion to acetate 6 followed by the
reaction reacted with TsNH2 in the presence of
TMSOTf to afford 1b,.[11a] Treatment of 1b which
would be treated with BF3 would be expected to
afford generate the iodonium species 1b•BF3, which
is similar to the complex of o-(alkoxycarbonyl)-
phenyliminoiodane[12] with BF3. Since the oxidation
of o-nitro-iodobenzene (2c) by with peracetic acid
also did not give diacetate 3c, the diacetate 3c was
On the other hand, 1d has
a
polymeric,
asymmetrically bridged structure (C–I–N: 98.15º, N–
I···N: 87.92º, Figure 2) like PhINTs[8b] and the o-
alkoxy analogue such as 1a.[9f] Surprisingly, the nitro
groups do not participate in the formation of the
polymeric structure of 1d, which depends on is
created by the I···N secondary bonds (2.951 Å) by
involving the nitrogen atom in NTs ligand and I···O
secondary bonds (2.943 Å) by the oxygen atom in the
other NTs ligand. However, in contrast to PhINTs[8b]
and the o-alkoxy analogue,[9f] the nitrogen atom in the
intermolecular NTs ligand is also located to in trans
of position to the aryl group (C–I···N: 162.52º).
Furthermore, the intermolecular I···N bond distance
of 1d (2.951 Å) is longer than those of PhINTs (2.482
Å)[8b] and the o-alkoxy analogue (2.735 Å).[9f] The A
similar elongation of intermolecular I···N bond[8c] of
1c (3.020 Å) is observed for structure of 1c (Figure 1).
This would be probably due to trans influences of
aryl ligand[1615] along with distortion of C–I···N bond
angles. Therefore, these weak intermolecular
interactions in 1c, d would be expected to lead to the
enhancement of their reactivities and solubilities,
albeit a slight lack of their stabilities.
synthesized in by a similar manner method to the
[11b]
Nikiforov’s method one
and then converted to
iminoiodane 1c (Scheme 2c). Other nitro-substituted
iminoiodanes 1d, 1e[13a] and pentafluorophenyl
derivative 1f[13b,c] were prepared from 4d-f, which
were formed by the oxidation of 2d-f with oxone in
the presence of trifluoroacetic acid (TFA, Scheme
2a).[11c] Novel The new iminoiodanes 1c-f were
identified by elemental analysis and NMR
spectroscopy, and the structures of 1c and 1d were
characterized by single crystal X-ray analysis
(Figures 1 and 2).[14]
Figure 1. X-ray crystal structures of 1c.
Scheme 2. Preparation of ArINTs.
Similar to the o-tert-butylsulfonyl analogue
reported by Protasiewicz,[9b] 1c has a centrosymmetric
2
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10.1002/adsc.201700934
Advanced Synthesis & Catalysis
entry ArINTs (Xn) Y (equiv) 8a (%)[a] 9 (%)[a]
1
2
3
4
5
6
7
PhINTs
1a (o-PrO)
1b
1c (o-NO2)
1d (m-NO2)
1e (p-NO2)
1f (F5)
1f (F5)
1f (F5)
1f (F5)
1f (F5)
2.0
2.0
2.0
2.0
2.0
2.0
2.0
2.4
0.3
0
60
20
17
27
68
72
83
85 (76)
2
6
14
13
3
8
21
11
3
5
0
8[b]
9[c]
10[c]
0
47
11[d]
2.0
21
[a]
1
Yields were determined by H NMR analysis. Value in
parenthesis is isolated yield.
[b] 1f: 1.8equiv.
[c] Reaction conditions: 80 ºC, 24 h.
[d]
CH2Cl2 in the presence of 40 equiv MeCN was
employed instead of MeCN (corresponds to ca. 210 equiv)
as a solvent at rt for 24h.
Figure 2. X-ray crystal structures of 1d. Hydrogen atoms
have been omitted for clarity.
Subsequently, the reaction scope of various
alkynes 7 and nitriles was investigated under the
optimal conditions (Method A, Table 2). Thus, in the
presence of BF3•MeCN (2.4 equiv), terminal and
internal alkynes 7a-e, to which our previous method
using PhINTs (Method B)[7f] can be applied, reacted
with C6F5INTs (1f, 1.8 equiv) in MeCN to give the
Next, we focused on the evaluation of have
evaluated iminoiodanes 1a-f (1.5 equiv) as reagents
for the [2+2+1] cycloaddition-type reactions of
alkyne 7a and acetonitrile as a solvent in the presence
of BF3•MeCN (2.0 equiv) at room temperature for 4 h
(Table 1). Compared with PhINTs (entry 1), o-
substituted iminoiodanes 1a, b, and even nitro-
substituted 1c drastically reduced the yields of 2a
(entries 2-4). Taking the results of X-ray structure
analysis (Figure 1)[9f,12] into consideration, the
electrophilicities of o-substituted 1a-c may be
decreased by the secondary bonding of o-substituents
such as alkoxy, carboxyl and nitro groups to positive
iodine center, even in the presence of BF3•MeCN.
These results suggest that the electrophilicities of o-
substituted 1a-c would be decreased by the secondary
bonding of o-substituents such as alkoxy, carboxyl
and nitro groups to positive iodine center. This is
supported by the results of X-ray structure analysis
(Figure 1).[9f,12] On the other hand, the use of m- or p-
nitro derivative 1d or 1e led to the improved yields of
2a up to ca. 70% (entry 5 or 6). Furthermore, the use
of pentafluorophenyl derivative 1f gave 2a in 83%
yield (entry 7). When the amounts of 1f and
BF3•MeCN were increased up to 1.8 and 2.4 equiv,
respectively, the formation of oxazole 9 as a
byproduct was suppressed and 8a was isolated in
76% yield (entry 8). Unfortunately, the diminution in
the amounts of BF3•MeCN and MeCN brought about
the reduced yields of 2a even in cases of prolongation
of reaction time and/or under the temperature-rising
conditions (entries 9-11).
corresponding
2,4-disubstitued
and
2,4,5-
trisubstituted imidazoles 8a-e in 60–76% yield with
complete regioselectivities (entries 1–5). To our
delight, the yields of 8c, d were improved as well as
that of 8a (entries 1, 3, 4). Furthermore, method A
promoted the reactions of bulky alkynes 7f, g with
MeCN, although method B hardly yielded the
corresponding products 8f, g (entries 6, 7). Also, in
cases of 7h–j having bulky and/or electron-
withdrawing halogens (entries 8-10) or in cases of
i
bulky and lower nucleophilic BuCN or PhCN
(entries 11-15), method A gave the desired products
in ca. 10–30% higher yields than method B. In
addition, method A was more effective on the
conversion of mono-imidazole 8k (Scheme 3).
Table 2. Reaction scope.
product (%)[a]
entry
7
R1
R2
A
B
1
2
3
4
5
6
7
Ph
H
H
H
Me
Pr
H
76
62
75
60
63
33
16
61
71
70
52
72
7a
7b
7c
7d
7e
7f
8a
8b
8c
8d
8e
8f
Table 1. Optimization of the reaction conditions.
phenethyl
hexyl
Ph
Pr
tBu
trace
trace
mesityl
H
7g
8g
3
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10.1002/adsc.201700934
Advanced Synthesis & Catalysis
8
9
2-BrC6H4
4-ClC6H4
4-BrC6H4 pentyl
Ph
Ph
Ph
phenethyl
Ph
H
H
56
53
52
43
42
36
49
47
41
33
41
21
14
18
20
22
7h
7i
7j
7a
7d
7a
7b
7d
8h
8i
8j
10a
10d
11a
11b
11d
10
11
12
13
14
15
H
Me
H
H
Me
[a] Isolated yields.
Scheme 4. Proposed mechanism.
Scheme 3. Conversion of mono-imidazole 8k.
In summary, we have developed some new imino-
3-iodanes with the aim to improve the
electrophilicity of these reagents. Among these
reagents, C6F5INTs led to demonstrated the excellent
results for reactivity in the [2+2+1] cycloaddition-
type reaction of alkyne, nitriles and N-atom in the
presence of BF3•nitrile complexes. Thus, compared to
our previous method using PhINTs, the present
procedure could be applied to the even bulky and/or
low nucleophilic substrates and expand the scope of
substrates. Furthermore, the structures of o- and m-
NO2C6H4INTs were characterized by single crystal
X-ray analysis. Since the chemical modification was
not examined for the enhancement of electrophilicity
of iminoiodanes, our findings not only provide an
attractive procedure for the access to highly
substituted oxazoles but also open a new possibility
for the use of iminoiodanes in organic syntheses.
On the basis of these results and our previous
reports on the [2+2+1] cycloaddition-type reactions
using iodine (III) reagents,[7e-g] the proposed
formation mechanism for the formation of imidazoles
is shown in Scheme 4. That is, iodonium species A
(and/or A’), in situ generated from ArINTs and BF3,
would activate alkyne 7 to form the intermediate
trans-B via the the Ritter-type addition of R3CN. And
then, the trans-B is converted to trans-C by the
formal reductive elimination of ArI. Finally, after the
isomerization to cis-C through the enamine-imine
tautomerization, the cyclization of cis-C gives
imidazoles. Considering the presence of a large
excess amount of nitrile and the leaving ability of a
unilateral nitrile of bis-nitrilium intermediate, the
trans-B serve as the highly reactive Michael-
acceptor[1716] to form cis-B by the addition and
elimination of R3CN. Subsequently, the cyclization of
cis-B followed by the reductive elimination of PhI in
intermediate D yields the imidazoles. Therefore, the
regiochemistry of imidazoles depends on the outcome
of the Ritter-type addition step, in which the bulky
iodonium ion would bind to the less sterically
hindered R2 side of the alkyne carbon. Also, the
enhancement of electrophilicity of iodonium species
A by the strong electron-withdrawing property of
pentafluorophenyl group would lead to the more
powerful activation of alkynes, and thus the Ritter-
type processes of bulky and/or low nucleophilic
substrates proceeded more smoothly.
Experimental Section
Representative procedure for the formation of
imidazole 8a from alkyne 7a with MeCN and C6F5INTs
BF3•MeCN (0.43 mL, 0.96 mmol) was added to a
suspension of 7a (44 L, 0.40 mmol) and 1f (334 mg, 0.72
mmol) in MeCN (4.0 mL) at 0 ºC under an argon
atmosphere. After being stirred at ambient temperature for
4 h, the mixture was quenched with sat. NaHCO3 (0.5 mL),
diluted with ether and filtered through a short alumina
column. Concentration of the filtrate to dryness and the
subsequent purification of the residue by silica gel column
chromatography (hexane/AcOEt = 85/15) gave 8a (95.8
mg, 76%) as a white solid.
Acknowledgements
This work was partially supported by JSPS Grants-in-
Aid for Scientific Research (C) (Grant No 15K07852),
by the Asahi Glass Foundation and by the Takeda
Science Foundation. V.V.Z. is also thankful to the
National Science Foundation (CHE-1262479).
4
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10.1002/adsc.201700934
Advanced Synthesis & Catalysis
References
P. Power, Inorg. Chem. 1995, 34, 3210; c) M. Boucher,
D. Macikenas, T. Ren, J. D. Protasiewicz, J. Am. Chem.
Soc. 1997, 119, 9366.
[1] Recent reviews: a) Wirth, T. Angew. Chem. 2005, 117,
3722; Angew. Chem. Int. Ed. 2005, 44, 3656; b) V. V.
Zhdankin, P. J. Stang, Chem. Rev. 2008, 108, 5299; c)
T. Dohi, Y. Kita, Chem. Commun. 2009, 45, 2073; d)
V.V. Zhdankin in Hypervalent Iodine Chemistry:
Preparation, Structure and Synthetic Application of
Polyvalent Iodine Compounds, Wiley, Chichester,
2013; e) A. Yoshimura, V. V. Zhdankin, Chem. Rev.
2016, 116, 3328.
[9] a) Review: V. V. Zhdankin, J. D. Protasiewicz, Coord.
Chem. Rev. 2014, 275, 54; b) D. Macikenas, E.
Skrzypczak-Jankun, J. D. Protasiewicz, J. Am. Chem.
Soc. 1999, 121, 7164; c) B. V. Meprathu, J. D.
Protasiewicz, ARKIVOC 2003, 83; d) B. V. Meprathu, J.
D. Protasiewicz, Tetrahedron 2010, 66, 5768; e) A. J.
Blake, A. Novak, M. Davies, R. I. Robinson, S.
Woodward, Synth. Commun. 2009, 39, 1065; f) A.
Yoshimura, V. N. Nemykin, V. V. Zhdankin, Chem.
Eur. J. 2011, 17, 10538.
[2] Reviews: a) P. Dauban, R. H. Dodd, Synlett 2003,
1571; b) D. Karila, R. H. Dodd, Cur. Org. Chem. 2011,
15, 1507; c) J. W. W. Chang, T. M. U, Ton, P. W. H.
Chan, Chem. Rec. 2011, 11, 331; d) J. D. Protasiewicz,
Top. Curr. Chem. 2016, 373, 263.
[10] Y. Yamada, T. Yamamoto, M. Okawara, Chem. Lett.
1975, 361.
[11] a) V. V. Zhdankin, M. McSherry, B. Mismash, J. T.
Bolz, J. K. Woodward, R. M. Arbit, S. Erickson,
Tetrahedron Lett. 1997, 38, 21; b) V. A. Nikiforov, V.
S. Karavan, S. A. Miltsov, S. I. Selivanov, K.
Kolehmainen, E. Wegelius, M. Nissinen, Arkivoc 2003,
191; c) A. A. Zagulyaeva, M. S. Yusubov, V. V.
Zhdankin, J. Org. Chem. 2010, 75, 2119.
[3] Recent examples: a) D. Karila, L. Leman, R. H. Dodd,
Org. Lett. 2011, 13, 5830; b) J. Barlunga, L. Riesgo, G.
Lonzi, M. Tomás, L. A. López, Chem. Eur. J. 2012, 18,
9221; c) T. M. U. Ton, F. Himawan, J. W. W. Chang, P.
W. H. Chan, Chem. Eur. J. 2012, 18, 12020; d) L.
Maestre, M. R. Fructos, M. D. Requejo, P. J. Perez,
Organometallics 2012, 31, 7839; e) M. Yu, Q. Zhang,
G. Li, J. Yuan, N. Zhang, R. Zhang, Y. Liang, D. Dong,
Adv. Synth. Catal. 2016, 358, 410; f) K. Tokumasu, R.
Yazaki, T. Oshima, J. Am. Chem. Soc. 2016, 138, 2664.
[12] M. Ochiai, A. Nakano, A. Yoshimura, K. Miyamoto,
S. Hayashi, W. Nakanishi, Chem. Commun. 2009, 959.
[13] Although
the
example
using
p-
[4] Representative examples: a) A. A. Lamar, K. M.
Nicholas, J. Org. Chem. 2010, 75, 7644; b) K.
Kiyokawa, T. Kosaka, S. Minakata, Org. Lett. 2013, 15,
4853; c) C-B. Miao, X-W. Lu, P. Wu, J. Li, W-L. Ren,
M-L. Xing, X-Q. Sun, H.-T. Yang, J. Org. Chem. 2013,
78, 12257.
nitrophenyliminoiodanes 1e as nitrene precursors and
the preparation of pentafluorophenyl derivative 1f have
been reported, the physical data of 1e and 1f have been
unknown. See, a) R. R. Conry, A. A. Tipton, W. S.
Striejewske, E. Erkizia, M. A. Malwitz, A. Caffaratti, J.
A. Natkin, Organometallics 2004, 23, 5210; b) I. I.
Maletina, A. A. Mironova, V. V. Orda, L. M.
Yagupolskii, Synthesis 1983, 456; c) R. M. Moriarty, R.
Penmasta, I. Prakash, Tetrahedron Lett. 1987, 28, 877.
[5] W. B. Ma, S. N. Li, Z. H. Zhou, H. S. Shen, X. Li, Q.
Sun, L. He, Y. Xue, Eur. J. Org. Chem. 2012, 1554.
[6] Acids are known to promote the -amination of
dicarbonyl compounds with iminoiodanes, although the
enhancement of cationic property of iodonium ion is
not stated. See, a) J. Yu, S. Liu, J. Cui, X. Hou, C.
Zhang, Org. Lett. 2012, 14, 832; b) C. Tejo, H. Q. Yeo,
P. W. H. Chen, Synlett 2014, 25, 201.
[14] CCDC-1561899 (1c) and 1561900 (1d) contain the
supplementary crystallographic data for this paper.
These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[15] In comparison with the corresponding sum of the van
der Waal radii (I: 1.96, O: 1.50 Å), a weak interaction
exists between I and O (sulfonyl) atoms in 1c (I···O
distance: 3.168 Å) and 1d (I···O distance: 3.286 Å). A
similar behavior is observed in other imino-3-iodanes
(I···O distance: 3.139–3.278 Å) See, ref. 8c.
[7] a) A. Saito, A. Matsumoto, Y. Hanzawa, Tetrahedron
Lett. 2010, 51, 2247; b) A. Saito, T. Anzai, A.
Matsumoto, Y. Hanzawa, Tetrahedron Lett. 2011, 52,
4658; c) N. Asari, Y. Takemoto, Y. Shinomoto, T.
Yagyu, A. Yoshimura, V. V. Zhdankin, A. Saito, Asian
J. Org. Chem. 2016, 5, 1314; d) Y. Okamura, D. Sato,
A. Yoshimura, V. V. Zhdankin, A. Saito, Adv. Synth.
[1615]
Aryl ligands in hypervalent iodine are known to
Catal.
Accepted
Article
(DOI:
make their trans bonds between iodine and hetero atom
weakened. See, a) M. Ochiai, T. Sueda, K. Miyamoto,
P. Kiprof, V. V. Zhdankin, Angew. Chem. 2006, 118,
8383; Angew. Chem. Int. Ed. 2006, 45, 8203; b) P. K.
Sajith, C. H. Suresh, Inorg. Chem. 2012, 51, 967; c) P.
K. Sajith, C. H. Suresh, Inorg. Chem., 2013, 52, 6046.
d) E. M. Shustorovich, Y. A. Buslaev, Inorg. Chem.
1976, 15, 1142.
10.1002/adsc.201700587); e) A. Saito, A. Taniguchi, Y.
Kambara, Y. Hanzawa, Org. Lett. 2013, 15, 2672; fc) A.
Saito, Y. Kambara, T. Yagyu, K. Noguchi, A.
Yoshimura, V. V. Zhdankin, Adv. Synth. Catal. 2015,
357, 667; gd) T. Yagyu, Y. Takemoto, A. Yoshimura,
V. V. Zhdankin, A. Saito, Org. Lett. 2017, 19, 2506.
[8] a) C. J. Carmalt, J. G. Crossley, J. G. Knight, P.
Lightfoot, A. Martin, M. P. Muldowney, N. C. Norman,
A. G. Orpen, J. Chem. Soc. Chem. Commun. 1994,
2367; b) A. K. Mishra, M. M. Olmstead, J. J. Ellison, P.
[1716]
M. Ochiai, Y. Kitagawa, M. Toyonari, K.
Uemura, K. Oshima, M. Shiro, J. Org. Chem. 1997, 62,
8001.
5
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10.1002/adsc.201700934
Advanced Synthesis & Catalysis
UPDATE
Development of Imino-3-iodanes with Improved
Reactivity for Metal-Free [2+2+1] Cycloaddition-
Type Reactions
Adv. Synth. Catal. Year, Volume, Page – Page
Takafumi Baba, Shunsuke Takahashi, Yui
Kambara, Akira Yoshimura, Victor N. Nemykin,
Viktor V. Zhdankin and Akio Saito*
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