Oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III)

Article abstract of DOI:10.1016/j.tetlet.2013.08.012

A novel protocol for the oxidative rearrangement of alkenes using in situ generated hypervalent iodine(III) was developed. This approach uses inexpensive, readily available, and stable chemicals (PhI, mCPBA, and TsOH) giving rearrangement products in yields comparable to those obtained using the more expensive commercially available [hydroxy(tosyloxy)iodo]benzene [HTIB or Koser's reagent]. Additionally, an alternative protocol for the synthesis of 1-methyl-2-tetralone through the one-step epoxidation/rearrangement of 4-methyl-1,2-dihydronaphthalene using mCPBA and TsOH was developed.

Full text of DOI:10.1016/j.tetlet.2013.08.012

Tetrahedron Letters 54 (2013) 5818–5820
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Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Oxidative rearrangement of alkenes using in situ generated
hypervalent iodine(III)
a
a
a,b
b
a,
⇑
Anees Ahmad , Paulo Scarassati , Nazli Jalalian , Berit Olofsson , Luiz F. Silva Jr.
a
Instituto de Química—Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, CP 26077, CEP 05513-970 São Paulo, SP, Brazil
Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden
b
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel protocol for the oxidative rearrangement of alkenes using in situ generated hypervalent
iodine(III) was developed. This approach uses inexpensive, readily available, and stable chemicals
Received 14 July 2013
Revised 29 July 2013
Accepted 3 August 2013
Available online 11 August 2013
(PhI, mCPBA, and TsOH) giving rearrangement products in yields comparable to those obtained using
the more expensive commercially available [hydroxy(tosyloxy)iodo]benzene [HTIB or Koser’s reagent].
Additionally, an alternative protocol for the synthesis of 1-methyl-2-tetralone through the
one-step epoxidation/rearrangement of 4-methyl-1,2-dihydronaphthalene using mCPBA and TsOH was
developed.
Keywords:
Rearrangement
Hypervalent iodine
Ring contraction
Oxidation
Ó 2013 Elsevier Ltd. All rights reserved.
Alkenes
Hypervalent iodine reagents are extensively used in chemical
cyclic alkene 1 as substrate, several alternatives to perform an oxi-
dative rearrangement were investigated using TFE and HFIP as sol-
vents. The reaction is performed in three steps. First step, HTIB was
generated in situ by treating iodobenzene with mCPBA and
1
2
synthesis for various carbon–carbon bond formations, rearrange-
ments, and functional group transformations.4 The inherent low
toxicity, high stability, and ready availability of the hypervalent
iodine reagents together with their fascinating reactivity make them
superior to the toxic heavy metal-based oxidants, such as lead(IV),
3
15
TsOHÁH
Second step involves the addition of the appropriate solvent for
the oxidative rearrangement of HFIP/CH Cl followed by addition
The presence of a small amount of water mini-
2 2 2
O at room temperature in a mixture of TFE and CH Cl .
1
mercury(II), and thallium(III). The development of reactions using
2
2
8
d,e
in situ generated hypervalent iodine species is one of the most nota-
of substrate 1.
mizes the formation of undesired acetal-like product.
4
hyde formed in this process was reduced in situ adding NaBH ,
3
e,5
8d,e
ble achievements in the area, especially for asymmetric reactions.
The alde-
Of the various hypervalent iodine(III) reagents, [hydroxy(tosyl-
oxy)iodo]benzene [HTIB or Koser’s reagent] is one of the most pop-
delivering the corresponding hydroxy ring contraction product 2
in 63% yield (Table 1, entry 1). Removal of the solvent after forma-
tion of the iodine(III), gave the desired product 2 in a similar yield
(entry 2). The effect of solvents on the model reaction was further
6
ular. HTIB is used for a variety of useful transformations, such as
7
8
rearrangement of alkenes (including ring contraction and expan-
9
10
sion ), electrophilic cyclization,
compounds, tosyloxylation of aromatic rings, and oxidative biar-
yl couplings. Herein we describe a flexible and general strategy for
in situ generation of HTIB and its use in the oxidative rearrangement
of alkenes. HTIB is formed from the inexpensive reagents iodoben-
zene, m-chloroperoxybenzoic acid (mCPBA), and p-toluene sulfonic
a-functionalization of carbonyl
1
1
12
2 2
examined. Using a 1:1 mixture of TFE/CH Cl and different
1
3
amounts of H O afforded the desired alcohol 2 in low to moderate
2
yield (entries 3–6). However, using a smaller amount of TFE gave
alcohol 2 in 56% yield (entry 7). The use of the highly polar and
1
4
low nucleophilic solvent HFIP in different mixtures with CH
and H
8–11). The best yield was obtained when 1:6 ratio of HFIP/CH
was used, in the presence of H
obtained using commercially available HTIB (entry 11). The desired
reaction failed to take place when CH Cl /H O was used (entry 12).
We also considered the use of other oxidants, like Oxone
2
Cl
2
2
acid (TsOHÁH O).
2
O gave the ring contraction product 2 in good yields (entries
Fluoroalcohols, like 2,2,2-trifluoroethanol (TFE) and 1,1,1,3,3,3-
hexafluoroisopropanol (HFIP), exhibit unique properties like high
polarity, low nucleophilicity, high ionizing power, and exceptional
hydrogen-bond donor ability. Moreover, TFE and HFIP have the
capability to stabilize reactive cationic intermediates which are
produced by the action of hypervalent iodine species.14 Using the
2
Cl
2
2
O. This yield is comparable to that
2
2
2
Ò
3a,16
5f
(KHSO
fate (K
TFE/ CH
5
),
S
hydrogen peroxide (H
2
O
2
), and potassium persul-
).1 Oxone was tested using different solvents (CH
CN,
Cl2, and CHCl ) without success (entries 13–15). The start-
7
2
2
O
8
3
⇑
Corresponding author. Tel.: +55 1130912388; fax: +55 1138155579.
E-mail address: luizfsjr@iq.usp.br (L.F. Silva).
2
3
0
040-4039/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2013.08.012

A. Ahmad et al. / Tetrahedron Letters 54 (2013) 5818–5820
5819
Table 1
Rearrangement reactions of cyclic alkene 1 using in situ generated HTIB
Step i:
Step ii:
Step iii:
Oxidant
TsOH.H
solvent
OH
CHO
2
O
1
solvent
NaBH4
PhI
PhI(OH)OTs
2
Entry
Oxidant
Solvent step i
Solvent step ii
Yield of 2 (%)a
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
mCPBA
Oxone
Oxone
Oxone
TFE/CH
TFE/CH
TFE/CH
TFE/CH
TFE/CH
TFE/CH
TFE/CH
HFIP/CH
HFIP/CH
HFIP/CH
HFIP/CH
2
2
2
2
2
2
2
Cl
Cl
Cl
Cl
Cl
Cl
Cl
2
2
2
2
2
2
(1:1)
HFIP/CH
HFIP/CH
22 equiv H
—
2
Cl
Cl
2
(1:4), 22 equiv H
(1:4), 22 equiv H
O
2
O
O
63
64
48
23
57
31
56
47
(1:1) (solvent evaporated)
(1:1)
2
2
2
2
/H
2
O (1:1:1)
(1:1)
(1:1)
(1:6)
H
H
2
O (1 mL)
O (2 mL)
2
2
22 equiv H
—
22 equiv H
2
2
2
O
O
O
2
2
2
2
Cl
2
2
2
2
/H
(1:1)
2
O (1:3:3)
Cl
Cl
Cl
61
54
1
1
1
1
1
1
1
1
/H
2
O (1:6:6)
b
(1:6)
22 equiv H
—
71(65)
b
CH
CH
2
Cl
2
/H
2
O (1:1)
—
—
b
3
CN
HFIP/CH
HFIP/CH
HFIP/CH
2
2
2
Cl
2
(1:4), 22 equiv H
(1:4), 22 equiv H
(1:4), 22 equiv H
2
2
2
O
O
O
TFE/CH
CHCl
TFE/CH
2
Cl
2
(1:1)
Cl
Cl
2
27
c
3
2
11
b
K
2 2
S O
8
2
Cl
2
(1:6)
22 equiv H
22 equiv H
2
O
O
—
—
b
H
2
O
2
H
2
O
2
, TFE/CH
2
Cl
2
(1:1),
2
a
b
c
Isolated yields.
Reaction carried out with commercially available Koser’s reagent.
Starting material recovered.
Table 2
Rearrangement reactions of 1,2-dihydro-4-methylnaphthalene (3)
HO
i) 0.55 equiv p-C
6
H
4
I
2
, mCPBA, TsOH.H
2
O,
HFIP/CH Cl (1:6); ii) H
2
2
2
O, 1; iii) NaBH4.
O
i) PhI, mCPBA
TsOH.H
ii) 3
2
O
63%
1
2
Scheme 1. Koser’s reagent derivative from 1,4-diiodobenzene.
4
5
3
, mCPBA
TsOH.H O
O
3
2
ing material was recovered when K
oxidants (entries 16 and 17).
2 2 8 2 2
S O and H O were used as
Entry
Reagents and conditions
Product
The use of 1,4-diiodobenzene instead of iodobenzene was also
investigated. When the oxidative rearrangement of 1 was carried
out with this new Koser’s reagent derivative, the rearrangement
product 2 was obtained in 63% yield (Scheme 1).
Based on the previous work, we know that alkyl substituted
double bonds can have a different reactivity in rearrangements.
1
2
3
4
5
(i) PhI, mCPBA, TsOHÁH O, HFIP/CH Cl (1:6); (ii) 3
2
2
2
4 (41%)
4 (73%)
5 (73%)
5 (75%)
5 (81%)
(i) PhI, mCPBA, TsOHÁH
3, PhI, mCPBA, TsOHÁH
3, PhI (30 mol %), mCPBA, TsOHÁH
3, mCPBA, TsOHÁH O, TFE/CH Cl (1:4)
2
O TFE/CH
2
Cl
2
(1:1); (ii) 3
2
O TFE/CH
2
Cl
2
(1:4)
2
2 2
O, TFE/CH Cl (1:4)
2
2
2
8
f,18
Thus, a second screening was performed with alkene 3. Under the
optimized reaction conditions for 3, the desired ring contraction
product 4 was obtained in only 41% yield (Table 2, entry 1). Using
a mixture of TFE/CH
2
Cl
2
as a solvent enhanced the yield to 73% (en-
Dihydrobenzo[b]oxepine 6 afforded the corresponding chromane
7 in 83% yield (entry 1). A smooth oxidation took place with 1,2-
dihydronaphthalene (8) leading to the indane 9 (entry 2). The
methyl substituted olefins 10 and 12 were successfully trans-
formed into the corresponding rearrangement products 11 and
13, respectively (entries 3 and 4). The exocyclic alkene 14 gave
the corresponding ring expansion product 15 in nearly quantitative
yield (entry 5). The generality of methodology was further demon-
try 2). However, if the substrate is added together with mCPBA,
another rearrangement product, 1-methyl-2-tetralone (5), was ob-
tained presumably through epoxidation by mCPBA followed by
acid-catalyzed rearrangement (entry 3). This transformation also
took place in the presence of a catalytic amount of PhI (entry 4)
or even without it (entry 5). This one step transformation of 3 into
5
is fast, convenient, high yielding, and uses readily available
chemicals, constituting a useful method to obtain 2-tetralones.
Analogous two-step protocols were also reported.19 Additionally,
compounds like 5 can be obtained by the rearrangement of epox-
strated by the oxidative rearrangement of
a-methylstyrene into
thecorresponding -aryl ketone 17 in 81% yield (entry 6). It is
a
important to note that all yields are in the same range of that ob-
tained using commercially available HTIB.
19b,20
ides using lewis acids.
Another route to transform 3 into 5 is
through a hydroboration/oxidation sequence.21
In conclusion, a new method for the oxidative rearrangement of
alkenes using in situ generated iodine(III) was developed. The pro-
tocol uses inexpensive and stable chemicals, furnishing rearrange-
ment products in yields comparable to those obtained using
commercially available iodine(III).
Having established the optimal reaction conditions for the
in situ generation of HTIB, the scope and generality of the oxidative
rearrangement of alkenes were systematically examined. As shown
in Table 3, the reaction conditions were found to be very general.

5
820
A. Ahmad et al. / Tetrahedron Letters 54 (2013) 5818–5820
Table 3
Oxidative rearrangement of alkenes using in situ generated iodine(III)
some reviews about hypervalent iodine, see; (c) Zhdankin, V. V.; Stang, P. J.
Chem. Rev. 2008, 108, 5299; (d) Silva, L. F., Jr.; Olofsson, B. Nat. Prod. Rep. 2011,
2
8, 1722; (e) Merritt, E. A.; Olofsson, B. Angew. Chem., Int. Ed. 2009, 48, 9052.
Entry
Substrate
Product
Yield
2. For selected examples, see; (a) Moriarty, R.; Prakash, O.; Duncan, M. P. J. Chem.
Soc., Perkin Trans. 1 1987, 559; (b) Kalyani, D.; Deprez, N. R.; Desai, L. V.;
Sanford, M. S. J. Am. Chem. Soc. 2005, 127, 7330; (c) Phipps, R. J.; Gaunt, M. J.
Science 2009, 323, 1593; (d) Dohi, T.; Kato, D.; Hyodo, R.; Yamashita, D.; Shiro,
M.; Kita, Y. Angew. Chem., Int. Ed. 2011, 50, 3784; (e) Skucas, E.; MacMillan, D.
W. C. J. Am. Chem. Soc. 2012, 134, 9090; (f) Tolnai, G. L.; Ganss, S.; Brand, J. P.;
Waser, J. Org. Lett. 2013, 15, 112; (g) Gonzalez, D. F.; Brand, J. P.; Mondiere, R.;
Waser, J. Adv. Synth. Catal. 2013, 355, 1631.
HO
1
O
83a (87)d,8e
6
7
O
HO
3
.
For selected examples, see; (a) Yoshimura, A.; Middleton, K. R.; Luedtke, M. W.;
Zhu, C.; Zhdankin, V. V. J. Org. Chem. 2012, 77, 11399; (b) Guerard, K. C.;
Guerinot, A.; Bouchard-Aubin, C.; Menard, M.-A.; Lepage, M.; Beaulieu, M. A.;
Canesi, S. J. Org. Chem. 2012, 77, 2121; (c) Loudon, G. M.; Radhakrishna, A. S.;
Almond, M. R.; Blodgett, J. K.; Boutin, R. H. J. Org. Chem. 1984, 49, 4272; (d)
Miyamoto, K.; Sakai, Y.; Goda, S.; Ochiai, M. Chem. Commun. 2012, 982; (e)
Moriyama, K.; Ishida, K.; Togo, H. Org. Lett. 2012, 14, 946.
For selected examples, see; (a) Tian, J.; Gao, W.-C.; Zhou, D.-M.; Zhang, C. Org.
Lett. 2012, 14, 3020; (b) McMurtrey, K. B.; Racowski, J. M.; Sanford, M. S. Org.
Lett. 2012, 14, 4094; (c) Souto, J. A.; Becker, P.; Iglesias, A.; Muniz, K. J. Am.
Chem. Soc. 2012, 134, 15505.
2
3
8
65a (74)d,8d
9
O
79b (62)d,8d
4.
10
11
O
5. For selected examples, see; (a) Ochiai, M.; Takeuchi, Y.; Katayama, T.; Sueda, T.;
Miyamoto, K. J. Am. Chem. Soc. 2005, 127, 12244; (b) Dohi, T.; Maruyama, A.;
Yoshimura, M.; Morimoto, K.; Tohma, H.; Kita, Y. Angew. Chem., Int. Ed. 2005,
61b (58)d,8e
4
4
4, 6193; (c) Rodriguez, A.; Moran, W. J. Org. Lett. 2011, 13, 2220; (d) Farid, U.;
12 O
Wirth, T. Angew. Chem., Int. Ed. 2012, 51, 3462; (e) Farid, U.; Malmedy, F.;
Claveau, R.; Albers, L.; Wirth, T. Angew. Chem., Int. Ed. 2013, 52, 7018; (f) Uyanik,
M.; Okamoto, H.; Yasui, T.; Ishihara, K. Science 2010, 328, 1376.
. Koser, G. F. Aldrichim. Acta 2001, 34, 89.
O
13
O
6
5
6
97c (99)d,9a
7. Justik, M. W.; Koser, G. F. Tetrahedron Lett. 2004, 45, 6159.
8
.
For a review concerning iodine(III)-mediated ring contractions, see; (a) Silva, L.
F., Jr. Molecules 2006, 11, 421; For examples, see; (b) Silva, L. F., Jr.; Craveiro, M.
V. Org. Lett. 2008, 10, 5417; (c) Carneiro, V. M. T.; Ferraz, H. M. C.; Vieira, T. O.;
Ishikawa, E. E.; Silva, L. F., Jr. J. Org. Chem. 2010, 75, 2877; (d) Siqueira, F. A.;
Ishikawa, E. E.; Fogaca, A.; Faccio, A. T.; Carneiro, V. M. T.; Soares, R. R. S.; Utaka,
A.; Tebeka, I. R. M.; Bielawski, M.; Olofsson, B.; Silva, L. F., Jr. J. Braz. Chem. Soc.
1
4
15
O
81c (84)d,7
17
1
6
2
011, 22, 1795; (e) Ahmad, A.; Silva, L. F., Jr. Synthesis 2012, 44, 3671; (f) Silva, L.
F., Jr.; Siqueira, F. A.; Pedrozo, E. C.; Vieira, F. Y. M.; Doriguetto, A. C. Org. Lett.
007, 9, 1433.
a
.
(
i) PhI, mCPBA, TsOH H
2
O, HFIP/CH
2
Cl
2
(1:6), 30 min; (ii) 22 equiv
H
H
2
O,
O,
2
substrate; (iii) NaBH
4
.
b
.
9. (a) Justik, M. W.; Koser, G. F. Molecules 2005, 10, 217; (b) Silva, L. F., Jr.;
Vasconcelos, R. S.; Nogueira, M. A. Org. Lett. 2008, 10, 1017.
(
(
i) PhI, mCPBA, TsOH H
2
.
O, TFE/CH
2
Cl
2
(1:1), 30 min; (ii) substrate.
Cl (1:6), 30 min; (ii) 22 equiv
c
i) PhI, mCPBA, TsOH H
2
O, HFIP/CH
2
2
2
10. Vasconcelos, R. S.; Silva, L. F., Jr.; Giannis, A. J. Org. Chem. 2011, 76, 1499.
substrate.
11. Koser, G. F.; Relenyi, A. G.; Kalos, A. N.; Rebrovic, L.; Wettach, R. H. J. Org. Chem.
d
Reported yield when the reaction was carried out with commercially available
Koser’s reagent.
1982, 47, 2487.
12. Prakash, O.; Kumar, M.; Kumar, R. Tetrahedron 2010, 66, 5827.
1
1
3. Morimoto, K.; Nakae, T.; Yamaoka, N.; Dohi, T.; Kita, Y. Eur. J. Org. Chem. 2011,
326.
4. For a leading reference about fluoroalcohols and hypervalent iodine, see; (a)
Dohi, T.; Yamaoka, N.; Kita, Y. Tetrahedron 2010, 66, 5775; For reviews about
fluoroalcohols, see: (b) Begue, J. P.; Bonnet-Delpon, D.; Crousse, B. Synlett 2004,
6
Acknowledgment
We thank CAPES, FAPESP, CNPq, and STINT for financial support.
18; (c) Shuklov, I. A.; Dubrovina, N. V.; Börner, A. Synthesis 2007, 2925.
1
1
1
5. (a) Merritt, E. A.; Carneiro, V. M. T.; Silva, L. F., Jr.; Olofsson, B. J. Org. Chem.
2010, 75, 7416; (b) Yamamoto, Y.; Togo, H. Synlett 2005, 2486.
6. (a) Uyanik, M.; Akakura, M.; Ishihara, K. J. Am. Chem. Soc. 2009, 131, 251; (b)
Purohit, V. C.; Allwein, S. P.; Bakale, R. P. Org. Lett. 2013, 15, 1650.
Supplementary data
Supplementary data (spectroscopic data and experimental pro-
cedures) associated with this article can be found, in the online
version, at http://dx.doi.org/10.1016/j.tetlet.2013.08.012.
7. Hossain, M. D.; Ikegami, Y.; Kitamura, T. J. Org. Chem. 2006, 71, 9903.
18. (a) Ferraz, H. M. C.; Carneiro, V. M. T.; Silva, L. F., Jr. Synthesis 2009, 385; (b)
Ferraz, H. M. C.; Silva, L. F.; Vieira, T. O. Tetrahedron 2001, 57, 1709.
1
9. (a) English, J.; Cavaglieri, G. J. Am. Chem. Soc. 1943, 65, 1085; (b) Jensen, B. L.;
Slobodzian, S. V. Tetrahedron Lett. 2000, 41, 6029.
References and notes
20. For examples, see; (a) Banks, H.; Ziffer, H. J. Org. Chem. 1982, 47, 3743; (b)
Anderson, A. M.; Blazek, J. M.; Garg, P.; Payne, B. J.; Mohan, R. S. Tetrahedron
Lett. 2000, 41, 1527; (c) Kulasegaram, S.; Kulawiec, R. J. J. Org. Chem. 1994, 59,
1
.
For books, see; (a) Varvoglis, A. Hypervalent Iodine in Organic Synthesis;
Academic Press: San Diego, 1996; (b) Hypervalent Iodine Chemistry. In Topics
in Current Chemistry; Wirth, T., Ed.; Springer: Heidelberg, 2003. Vol. 224; For
7195.
2
1. Kirkiacharian, B. S.; Koutsourakis, P. G. Synth. Commun. 1993, 23, 737.