Oxidations of alkenes with hypervalent iodine reagents: An alternative ozonolysis of phenyl substituted alkenes and allylic oxidation of unsubstituted cyclic alkenes

Article abstract of DOI:10.1016/j.tetlet.2014.02.076

Unsaturated CC double bonds with a phenyl substituent can be cleaved with iodylbenzene and iodosylbenzene to give carbonyl compounds. It is believed that the reactions occur via a radical pathway. The allylic oxidation of cyclic alkenes lacking a phenyl substituent was achieved in acetonitrile/water mixture (3:1) also using iodylbenzene and iodosylbenzene.

Full text of DOI:10.1016/j.tetlet.2014.02.076

Tetrahedron Letters 55 (2014) 2230–2232
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Oxidations of alkenes with hypervalent iodine reagents: an
alternative ozonolysis of phenyl substituted alkenes and allylic
oxidation of unsubstituted cyclic alkenes
⇑
Ufuk Atmaca, Hande K. Usanmaz, Murat Çelik
Department of Chemistry, Faculty of Science, Atatürk University, Erzurum 25240, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Unsaturated C@C double bonds with a phenyl substituent can be cleaved with iodylbenzene and iodosyl-
benzene to give carbonyl compounds. It is believed that the reactions occur via a radical pathway. The
allylic oxidation of cyclic alkenes lacking a phenyl substituent was achieved in acetonitrile/water mixture
(3:1) also using iodylbenzene and iodosylbenzene.
Received 25 June 2013
Revised 1 February 2014
Accepted 20 February 2014
Available online 28 February 2014
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Allylic hydroperoxide
Oxidative cleavage
Hypervalent iodine
Ozonolysis
Alkenes
Carbonyl groups, both as ketones or aldehydes, are accessible by
many synthetic routes,1 either as intermediates or as final prod-
ucts.2 Ozonolysis is generally accepted as a standard method for
this direct transformation of alkenes into carbonyl compounds.3,4
However, safety hazards, especially on a large scale, and the need
for both special equipment and reducing agents (Me2S or Zn/AcOH)
make this reaction complex.5 Oxygen donor oxidants such as RuO4
and OsO4 are generally employed in the catalytic cleavage of ole-
fins, but these are toxic and costly.6
corresponding allylic hydroperoxides (2a–d) and carbonyl com-
pounds (4a–l).
Exposure of cyclohexene (1a) to iodosylbenzene (PhIO)
(1.1 equiv) in acetonitrile/water (4:1) and aerial O2 resulted in
allylic oxidation of the double bond in 24 h at room temperature:
a labile allylic hydroperoxide (2a)11 was produced in 81% yield
(Table 1). As the reactivity of our novel oxidation system using
Table 1
Hypervalent iodine(III) compounds, such as [bis(trifluoroacet-
oxy)iodo)benzene] (PIFA) and iodosylbenzene (PhIO), and
iodine(V) compounds, such as iodylbenzene (PhIO2), have been
used extensively in organic synthesis owing to their low toxic-
ity, ready availability and easy handling.7 We previously reported
the synthesis of vicinal cis-diols of C@C double bonds using
[bis(trifluoroacetoxy)iodo)benzene].8 Nowadays, the development
of safe (green) procedures for cleavage of C@C double bonds
is highly desirable.5 Ochiai and co-workers have successfully
synthesized hydroxy-k3-iodane (PhI(OH)BF4.18C6) in the pres-
ence of HBF4/H2O.3 We report herein the oxidation of olefins
with iodosylbenzene9 and iodylbenzene10 at room temperature
in the absence of any additive or catalyst, resulting in the
Allylic oxidation with iodosylbenzene (PhIO) and iodylbenzene (PhIO2)
Yield
Entry
1
Substrate
Product
PhIO
81
PhIO2
88
Ref.
11
OOH
2a
2b
1a
1b
OOH
2
3
78
67
81
76
11
12
OOH
OOH
1c
1d
2c
2d
4
58
65
11
⇑
Corresponding author. Tel.: +90 442 231 4390; fax: +90 442 236 0948.
E-mail address: mcelik@atauni.edu.tr (M. Çelik).
http://dx.doi.org/10.1016/j.tetlet.2014.02.076
0040-4039/Ó 2014 Elsevier Ltd. All rights reserved.

U. Atmaca et al. / Tetrahedron Letters 55 (2014) 2230–2232
2231
Table 2
PhIO
H2O
PhIO2
Oxidative cleavage reaction of olefins with iodosylbenzene (PhIO) and iodylbenzene
(PhIO2)
Yield (%)
air
OOH
H
OH
I
OH
O
I
OH
I
O
I
Entry
1
Substrate
Product
PhIO
70
PhIO2
75
Ref.
15
I
+
OOH
Ph
OH
Ph
Ph
O
Ph
Ph
O
Ph
Ph
O
i
ii
iii
3a
Ph
4a
PhIO
OHC
O
Ph
OH
I
OH
I
O
2
3
77
74
80
80
16
16
3b
Ph
OHC
4b
I
O
Ph
O
Ph
OH
v
iv
Ph
3c
O
H
Ph
4c
OHC
PhIO or PhIO2
H2O,air
OOH
Ph
3d
Ph
3e
O
OOH
Ph
OHC
O
4
5
6
75
68
65
81
72
70
17
18
radical scavenger
4d
2a
1a
Scheme 1. Proposed mechanism for the synthesis of allylic hydroperoxides.
Ph
CHO
4e
iodylbenzene is similar to that of iodosylbezene, we investigated
the oxidation of olefins with iodylbenzene in the hope of obtaining
allylic hydroperoxides and carbonyl compounds in good yields.
Scheme 1 shows a proposed mechanism for the synthesis of
cyclohexene hydroperoxide (2a). The reaction starts with the dis-
solution of iodyl- or iodosylbenzene in water in the presence of
aerial oxygen. The hydrate form of iodosylbenzene, which has lim-
ited solubility in water, produces oxodiphenyldiiodine compound
ii. The conversion of iodine(V) into iodine(III) was previously dis-
cussed in the literature.13 Next, radical iii is generated from the
reaction between oxodiphenyldiiodine ii and triplet oxygen (from
air) at room temperature. The radical iii can abstract the relatively
weak allylic CAH proton from cyclohexene and the cyclohexenyl
radical is formed. The cyclohexenyl radical reacts with a aerial oxy-
gen to give the allylic hydroperoxide.14 It is much more likely that
the cyclohexenyl radical captures oxygen, rather than the hydro-
peroxide radical. In order to study the effect of the radical mode,
we oxidized cyclohexene with the radical scavenger, 2,4,6-tri-
tert-butylphenol, under the same conditions, but no oxidized prod-
uct was detected. The allylic hydroperoxides (entries 1–4) were not
observed in reactions of iodosylbenzene and iodylbenzene in the
absence of air oxygen (Scheme 1).
Ph
O
a
—
Ph
4f
CHO
3f
O
3g
Ph
Ph
4g
7
8
64
69
75
76
5
5
Ph
Ph
Ph
H
H
H
O
O
3h
Ph
4g
4g
Ph
9
65
72
5
3i
Ph
CHO
CHO
4h
3j
10
11
66
67
73
76
3
CHO
CHO
3k
19
4i
OMe
OMe
CHO
4j
3l
12
70
76
20
a
Compound 4f has not been reported.
We next investigated the reactivity of cyclic benzylic systems3a–f
and benzylic olefins 3g–l (Table 2), since these compounds have a
high tendency to undergo oxidative cleavage of the C@C double
bonds. When 1-phenyl-1-cyclobutene (3a) was reacted with iodyl-
benzene in acetonitrile/water (4:1) at room temperature, carbonyl
compound 4a15 was produced selectively in 75% yield (Table 2).
Dibenzylic olefins 3e,f (Table 2) (entries 5 and 6) reacted with
iodylbenzene and iodosylbenzene and produced the ring cleavage
compounds as the sole products. The structures of the products were
established by comparison with the spectral data in the literature.
The reaction of styrene (3g) with iodyl- and iodosylbenzene fol-
lowed by chromatography on silica gel with ethyl acetate/hexane
(1:3) gave benzaldehyde (4g) in 64–75% yield (entry 7). We also
examined the reactions of cis- and trans-stilbenes (3h,i) (entries
8 and 9) with iodylbenzene and iodosylbenzene in acetonitrile/
water (4:1). Spectroscopic studies (1H NMR and 13C NMR) revealed
that the reaction mixture consisted of one product. The structures
were determined by comparison of the spectral data with those de-
scribed in the literature, except for entry 6.
OOH
H
Ph
I
Ph
I
Ph
O
O
PhIO/H2O/air
O
O
Ph
Ph
( )n
or
( )n
vi
( )n
vii
PhIO2/H2O/air
3a-l
Ph
OH
I
PhIO or PhIO2
H2O/air
Ph
O
( )n
4a-l
Scheme 2. Proposed mechanism for the synthesis of carbonyl compounds.
O
Ph
( )n
O
iv
radical scavenger
3a-l
vii is formed in the first step. The favoured formation of vii is
well-established in the literature.9 In the proposed mechanism,
we believe that the benzylic radical has high-stability and plays a
key role in the synthesis of carbonyl compounds.
In conclusion, we have developed an effective method for the
oxidative cleavage of C@C double bonds by using iodyl or iodosyl
Scheme 2 shows a proposed mechanism for the oxidative cleav-
age of the double bonds. We assume that radical vi adds to the
benzylic double bonds and a five-membered cyclic intermediate

2232
U. Atmaca et al. / Tetrahedron Letters 55 (2014) 2230–2232
3. Miyamoto, K.; Tada, N.; Ochiai, M. J. Am. Chem. Soc. 2007, 129, 2772.
4. Paterson, I.; Florence, G. J.; Heimann, A. C.; Mackay, A. C. Angew. Chem., Int. Ed.
2005, 44, 1130.
5. Lara, M.; Mutti, F. G.; Glueck, S. M.; Kroutil, W. Eur. J. Org. Chem. 2008, 3668.
6. Travis, B. R.; Narayan, R. S.; Borhan, B. J. Am. Chem. Soc. 2002, 124, 3824.
7. Yusubov, M. S.; Nemykin, V. N.; Zhdankin, V. V. Tetrahedron 2010, 66, 5745.
8. Celik, M.; Alp, C.; Coskun, B.; Gultekin, M. S.; Balci, M. Tetrahedron Lett. 2006, 47,
3659.
benzene in the presence of water as a safe alternative to ozonoly-
sis. In addition, hypervalent iodine(III) or (V) species (iodosyl- and
iodylbenzene) react with C@C bonds that include no substitutents
on the alkenes to give the corresponding allylic hydroperoxides.
Acknowledgments
9. Zhdankin, V. V. Arkivoc 2009, i, 1–62.
10. Zhdankin, V. V. J. Org. Chem. 2011, 76, 1185–1197.
11. Chambers, R. D.; Sandford, G.; Shah, A. Synth. Commun. 1996, 26, 1861.
12. Inoue, Y.; Ueoka, T.; Hakushi, T. J. Chem. Soc., Perkin Trans. 2 1984, 2053.
13. Richter, H. W.; Cherry, B. R.; Zook, T. D.; Koser, G. F. J. Am. Chem. Soc. 1997, 119,
9614.
We are grateful to the Scientific and Technological Research
Council of Turkey (TUBITAK) for a grant [TBAG-107T390].
Supplementary data
14. Catir, M.; Kilic, H.; Nardello-Rataj, V.; Aubry, J. M.; Kazaz, C. J. Org. Chem. 2009,
74, 4560.
15. Verlhac, J. B.; Pereyre, M.; Quintard, J. P. Tetrahedron 1990, 46, 6399.
16. Hon, Y. S.; Lin, S. W.; Lu, L.; Chen, Y. J. Tetrahedron 1995, 51, 5019.
17. Ghobril, C.; Sabot, C.; Mioskowski, C.; Baati, R. Eur. J. Org. Chem. 2008,
4104.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.tetlet.2014.
02.076.
18. Leroux, J. P.; Desbene, P. L.; Cherton, J. C. J. Heterocycl. Chem. 1981, 18, 847.
19. Sieber, F.; Wentworth, P.; Toker, J. D.; Wentworth, A. D.; Metz, W. A.; Reed, N.
N.; Janda, K. D. J. Org. Chem. 1999, 64, 5188.
References and notes
20. Dadova, J.; Kummel, S.; Feldmeier, C.; Cibulkova, J.; Pazout, R.; Maixner, J.;
Gschwind, R. M.; Konig, B.; Cibulka, R. Chem. Eur. J. 2013, 19, 1066.
1. Uyanik, M.; Ishihara, K. Chem. Commun. 2009, 2086.
2. Mang, H.; Gross, J.; Lara, M.; Goessler, C.; Schoemaker, H. E.; Guebitz, G. M.;
Kroutil, W. Tetrahedron 2007, 63, 3350.