1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate: An efficient reagent for synthesis of Β-nitrato alcohols

Article abstract of DOI:10.1080/00397910902898593

A simple and efficient method for the ring opening of epoxides to-hydroxy nitrates has been achieved in the presence of ammonium nitrate and 1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate.

Full text of DOI:10.1080/00397910902898593

This article was downloaded by: [UQ Library]
On: 16 June 2015, At: 01:17
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954
Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,
UK
Synthetic Communications: An
International Journal for Rapid
Communication of Synthetic
Organic Chemistry
Publication details, including instructions for
authors and subscription information:
http://www.tandfonline.com/loi/lsyc20
1,4-
Bis(triphenylphosphonium)-2-
butene Peroxodisulfate: An
Efficient Reagent for Synthesis
of β-Nitrato Alcohols
Rashid Badri a & Maryam Gorjizadeh a
a Department of Chemistry, College of Science ,
Chamran University , Ahvaz, Iran
Published online: 29 Oct 2009.
To cite this article: Rashid Badri & Maryam Gorjizadeh (2009) 1,4-
Bis(triphenylphosphonium)-2-butene Peroxodisulfate: An Efficient Reagent for
Synthesis of β-Nitrato Alcohols, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 39:23, 4239-4248, DOI:
10.1080/00397910902898593
To link to this article: http://dx.doi.org/10.1080/00397910902898593
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the
information (the “Content”) contained in the publications on our platform.
However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness,
or suitability for any purpose of the Content. Any opinions and views

expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the
Content should not be relied upon and should be independently verified with
primary sources of information. Taylor and Francis shall not be liable for any
losses, actions, claims, proceedings, demands, costs, expenses, damages,
and other liabilities whatsoever or howsoever caused arising directly or
indirectly in connection with, in relation to or arising out of the use of the
Content.
This article may be used for research, teaching, and private study purposes.
Any substantial or systematic reproduction, redistribution, reselling, loan,
sub-licensing, systematic supply, or distribution in any form to anyone is
expressly forbidden. Terms & Conditions of access and use can be found at
http://www.tandfonline.com/page/terms-and-conditions

Synthetic Communications1, 39: 4239–4248, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910902898593
1,4-Bis(triphenylphosphonium)-2-butene
Peroxodisulfate: An Efficient Reagent for
Synthesis of b-Nitrato Alcohols
Rashid Badri and Maryam Gorjizadeh
Department of Chemistry, College of Science, Chamran University,
Ahvaz, Iran
Abstract: A simple and efficient method for the ring opening of epoxides to
b-hydroxy nitrates has been achieved in the presence of ammonium nitrate and
1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate.
Keywords: 1,4-Bis(triphenylphosphonium)-2-butene peroxodisulfate, epoxide,
b-hydroxy nitrate, regioselectivity, ring opening
INTRODUCTION
Epoxides (oxiranes) are a useful class of precursors in organic synthesis.
The epoxide ring can easily be cleaved by a variety of nucleophilic
reagents, forming regio- and stereoselective ring-opened products, espe-
cially b-substituted alcohols.[1] However, there are few applications of
the nitrate ion as the nucleophile for these reactions.[2] b-Hydroxy
nitrates as functionalized alkyl nitrates, which are useful intermediates
in organic synthesis,[3] have been prepared in low yields through the reac-
tion of oxiranes with concentrated nitric acid[4] or by nitration of halohy-
drines with silver nitrates.[5] Recently, some methods for the synthesis of
b-hydroxy nitrates based on the reaction of epoxides with tetranitro-
methane,[6] ceric ammonium nitrate (CAN),[7] nitric oxide (NO) in air,[8]
Received January 24, 2009.
Address correspondence to Rashid Badri, Chemistry Department, Faculty of
Sciences, Shahid Chamran University, Ahvaz 61357-4-3169, Iran. E-mail:
rashidbadri@yahoo.com
4239

4240
R. Badri and M. Gorjizadeh
Scheme 1.
zirconyl nitrate,[9] and bismuth nitrate[2a] were reported. Unfortunately,
some of these methods are not always fully satisfactory and suffer from
disadvantages such as long reaction times, poor regioselectivity, using
of expensive or sensitive reagents, and poor yields. Thus, a better method
for ring opening of epoxides with nitrate ions is still required (Scheme 1).
Peroxodisulfate ion is an excellent and versatile oxidant, used mostly
for the oxidation of compounds in aqueous solution.[10] In spite of the
great convenience of using K2S2O8, Na2S2O8, or (NH4)2S2O8 and rela-
tively high oxidation potential, many oxidation reactions by peroxodisul-
fate do not proceed at a convenient rate. This can be largely attributed to
the rate-limiting homolysis, which has activation energy of approximately
30 Kcal=mol. Thus, certain limitations may be observed with these
reagents. The decomposition of the peroxodisulfate ion requires strong
mineral acids and heavy-metal ions[11] as catalysts, and also protic and
polar solvents are needed, so the modification of K2S2O8, Na2S2O8, or
(NH4)2S2O8 has received much attention recently.[12]
RESULTS AND DISCUSSION
In continuation of our studies on the application of peroxodisulfate in
organic synthesis,[13] we report a mild and efficient method for the ring
opening of oxiranes. Thus, 1,4-bis(triphenylphosphonium)-2-butene
peroxodisulfate was readily prepared by adding an aqueous solution of
potassium peroxodisulfate to a solution of 1,4-bis(triphenylphosphonium)-
2-butene dichloride in water. It is a very stable, white solid that can be
stored for months without losing its activity. It is soluble in acetonitrile,
methanol, dichloromethane, chloroform, and ethyl acetate and slightly
soluble in CCl4 and diethyl ether (Scheme 2).
In our initial work, a variety of oxiranes were treated with appropri-
ate amounts of 1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate

1,4-Bis(triphenylphosphonium)-2-butene Peroxodisulfate
4241
Scheme 2.
and NH4NO3 in three different conditions: (a) solid-state condition in the
presence of silica gel as a surface activator, (b) microwave irradiation,
and (c) reflux condition using acetonitrile as the most convenient solvent.
The first two conditions, which were carried out with different amounts
of substrates and microwave power, were not fruitful. With conventional
reflux condition, the reaction with all used oxiranes in acetonitrile pro-
ceeded smoothly and selectively, and b-hydroxy nitrate in 80–92% yields
were obtained. These results are summarized in Table 1. We conducted
the same reactions with all epoxides listed in Table 1 at the same reaction
conditions in the presence of K2S2O8 as the oxidant and found that mix-
tures of possible hydroxyl nitrates and unidentified products were
formed. The yields of isolated b-hydroxy nitrates were especially poor,
and the reaction times were longer than in the case of oxidant 2. Also,
the saturated form of compound 2 was prepared either via hydrogenation
of compound 1 followed by (Clꢀ ! S2O82ꢀ) exchange or the reaction of
1,4-dichlorobutane with triphenylphosphine followed by anion exchange.
Utilizing this saturated oxidant for the ring opening of epoxides caused
long reaction times and smaller yields than unsaturated oxidant 2. As
mentioned, both procedures, using K2S2O8 and the saturated form of
oxidant 2, were not attractive because of their very low solubility in reac-
tion medium and the probable lack of fixed cis orientation of saturated
oxidant compared to oxidant 2. To determine the optimum condition
for our procedure, the conversion of styrene oxide to the corresponding
b-hydroxy nitrate in the presence of 1,4-bis(triphenylphosphonium)-
2-butene peroxodisulfate as an oxidant in acetonitrile was investigated.
The optimum molar ratio of the oxidant to epoxide was found to be
0.6:1 mmol. When the nitrate ion was added to several unsymmetrical
epoxides as shown in Scheme 1, formation of two isomeric products (I
and II) was possible. Except for the reaction of styrene oxide (Table 1,
entry 1), in which the ring opening occurred at the benzylic ring position
and predominantly produced the primary alcohol, the reaction of the
other unsymmetrical epoxides (Table 1, entries 2–5, 8, and 9) were highly
regioselective. The products formed by cleavage at the unsubstitued ring

4242
R. Badri and M. Gorjizadeh
Table 1. Reaction of various epoxides with ammonium nitrate in the presence of
1,4-bis(triphenylphosphonium)-2-butene peroxodisulfate as oxidanta
Time Yield
(h)
No.
1
Substrate
Product (s)
(%)
80
(15:85)b
1
2
3
4
3
82
90
92
2
2.5
5
2
87
6
7
8
1
85
83
87
1.5
2.5
9
1.5
90
aProducts were identified by comparison of their physical and spectral data
with those of authentic samples.
bAccording to GC analysis.

1,4-Bis(triphenylphosphonium)-2-butene Peroxodisulfate
4243
Scheme 3.
position, and in each case only one isomer was obtained. Also in the case
of cyclic epoxides (Table 1, entries 6 and 7), the reaction was completely
antistereoselective, and only trans products were obtained. The coupling
constant of the vicinal hydrogens is different in anti and syn products.
The structures and configurations of the products were confirmed by
comparison of their spectral values with those reported earlier.[9,2c] It is
noteworthy that the reaction medium was almost neutral, so that some
sensitive functional groups such as the carbon–carbon double bond
remained intact (Table 1, entries 5 and 8). The possible mechanism of
the oxidation reaction using the peroxodisulfate mechanism might be
as follows: the sulfate anion radical gains an electron from epoxide and
oxidizes the ring to a cation radical. This radical reacts with NH4NO3
to form the corresponding product (Scheme 3).
In conclusion, we have developed a novel and efficient protocol
for the synthesis of b-nitrato alcohols with NH4NO3 using 1,4-
bis(triphenylphosphonium)-2-butene peroxodisulfate as oxidant. This
method offers several advantages, including high conversions, short reac-
tion times, and good isolated yields, which make it useful and attractive
process for the ring opening of epoxides.
EXPERIMENTAL
All products were characterized by comparison of their physical data and
1
infrared (IR), H NMR, and 13C NMR spectra with authentic samples.
The IR spectra were recorded on a Bomem Fourier transform (FT)–IR
spectrometer. 1H NMR and 13C NMR spectra were taken on a
400-MHz Broucker spectrometer. 1,4-Bis(triphenylphosphonium)-2-butene

4244
R. Badri and M. Gorjizadeh
peroxodisulfate was prepared, and other chemicals were purchased from
the Merck Chemical Company in Darmstadt, Germany.
Preparation of 1,4-Bis(triphenylphosphonium)-2-butene Dichloride (1)
Triphenylphosphine (2.62 g, 10 mmol) was added to a solution of
1,4-dichlorobutene (0.63 g, 5 mmol) in CHCl3 (10 mL) in a 50-mL,
round-bottomed flask equipped with a magnetic stirrer and a reflux con-
denser. The reaction mixture was refluxed for 2.5 h. The solution was
cooled to room temperature, and then diethyl ether was added dropwise
until an oily product was separated. The ether was removed by decanta-
tion, and acetone (40 mL) was added. Stirring the acetone solution for
40 min afforded a white precipitate, which was filtered, washed with acet-
one, and then dried. Yield 80%, mp 278–279ꢁC. IR (KBr): t ¼ 3053, 2755,
1613, 1575, 1478, 1437, 754, 693, 556 (cmꢀ1).13C NMR (CDCl3):
d ¼ 20.7, 120.8, 132.15, 134.2, 137.01, 140.17.1H NMR (CDCl3): d ¼ 5.7
(dd, 4 H), 6.3 (m, 2 H), 7.79–8 (m, 30 H).
Preparation of 1,4-Bis(triphenylphosphonium)-2-butene Peroxodisulfate (2)
A solution of K2S2O8 (0.54 g, 2 mmol) in H2O (5 mL) was prepared in a
25-ml, round-bottomed flask with a magnetic stirrer. Compound 1
(1.298 g, 2 mmol) was added to this solution, and the reaction mixture
was stirred at ambient temperature for 3 h. The resulting white precipitate
was filtered, washed with distilled water (10 mL), and dried in vacuo.
Yield 78%, mp 205–208ꢁC. IR (KBr): t ¼ 3053, 2750, 1623, 1585, 1472,
1437, 750, 724, 689, 556 (cmꢀ1).13C NMR (CDCl3): d ¼ 19.04, 119.45,
130.05, 133.98, 136.91, 138.8.1H NMR (CDCl3): d ¼ 4.7 (dd, 4 H), 5.8
(m, 2 H), 7.68–8 (m, 30 H).
General Procedure for the Preparation of b-Hydroxy Nitrate
1,4-Bis(triphenylphosphonium)-2-butene peroxodisulfate (0.6 mmol) was
added in small portions to a solution of epoxide (1 mmol) and NH4NO3
(2 mmol) in CH3CN=H2O (5=1:30 mL) in a 50-mL, round-bottomed flask
equipped with a condenser and a magnetic stirrer. The reaction mixture
was refluxed for the appropriate time indicated in Table 1. The progress
of the reaction was monitored by thin-layer chromatography (TLC). On
completion of reaction, the reaction mixture was cooled to room tem-
perature and filtered. The solvent was evaporated; water (20 mL) was
added and extracted with diethyl ether (3 ꢂ 15 mL). The combined

1,4-Bis(triphenylphosphonium)-2-butene Peroxodisulfate
4245
organic layers were concentrated in vacuo; the resulting product was
directly charged on a small silica-gel column and eluted with a mixture
of ethyl acetate and n-hexane (1:4) to afford the pure product.
1
The IR, H NMR, and 13C NMR spectra data of the products are
listed.
Selected Data
1-Hydroxy-2-phenylethyl Nitrate 1
1
IR: 3365 (OH), 1632 (NO2), 1455 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 2.9 (br s, 1 H), 3.2 (d, 2 H), 5.52 (m, 1 H), 7.2–7.36 (m,
5 H). 13C NMR (100 MHz, CDCl3): d ¼ 67.2 (CH2), 81.6 (CH), 127.2
(2 ꢂ CH), 128.4 (2 ꢂ CH), 131.1 (CH), 141.1 (C).
3-Phenoxy-2-hydroxypropyl Nitrate 2
1
IR: 3389 (OH), 1630 (NO2), 1452 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 3.68 (br s, 1 H), 4.2 (d, 2 H), 4.5 (m, 1 H), 4.9 (d, 2 H),
6.7–7.26 (m, 5 H). 13C NMR (100 MHz, CDCl3): d ¼ 71 (CH2), 73.2
(CH), 74.6 (CH2), 115.2 (2 ꢂ CH), 122.7 (2 ꢂ CH), 131.7 (CH), 162.1 (C).
3-Chloro-2-hydroxypropyl Nitrate 3
1
IR: 3400 (OH), 1640 (NO2), 1435 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 3.35 (br s, 1 H), 3.95 (d, 2 H), 4.88 (m, 1 H), 5.09 (d,
2 H).13C NMR (100 MHz, CDCl3): d ¼ 49 (CH2), 75.2 (CH), 79.2 (CH2).
2-Hydroxy-3-isopropoxypropyl Nitrate 4
1
IR: 3382 (OH), 1632 (NO2), 1467 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 1.3 (d, 6 H), 3.15 (br s, 1 H), 3.85 (m, 1 H), 4.13 (m, 3 H),
4.86 (d, 2 H). 13C NMR (100 MHz, CDCl3): d ¼ 22 (2 ꢂ CH3), 71.2
(CH), 75.6 (CH), 76.1 (CH2), 78.9 (CH2).
3-Nitrato-2-hydroxypropyl Methacrylate 5
1
IR: 3435 (OH), 1626 (NO2), 1280 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 2.1 (s, 3 H), 3.05 (br s, 1 H), 4.38 (m, 1 H), 4.5 (d, 2 H), 5.1
(d, 2 H), 5.7 (d, 1 H), 6.2 (d, 1 H). 13C NMR (100 MHz, CDCl3): d ¼ 18.5
(CH3), 69.2 (CH), 71.6 (CH2), 77.5 (CH2), 128.1 (CH2), 134 (C), 168 (C).

4246
R. Badri and M. Gorjizadeh
2-Hydroxycyclohexyl Nitrate 6
1
IR: 3365 (OH), 1633 (NO2), 1439 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 1.3–1.5 (m, 4 H), 1.95 (m, 2 H), 2.25 (m, 2 H), 2.55 (br s,
1 H), 4.18 (m, 1 H), 5.45 (m, 1 H). 13C NMR (100 MHz, CDCl3): d ¼
19.5 (CH2), 20.2 (CH2), 28.4 (CH2), 33.8 (CH2), 70.1 (CH), 78.3 (CH).
2-Hydroxycyclopentyl Nitrate 7
1
IR: 3360 (OH), 1642 (NO2), 1441 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 1.75 (m, 2 H), 1.95–2.14 (m, 4 H), 2.45 (br s, 1 H), 4.28 (m,
1 H), 5.05 (m, 1 H). 13C NMR (100 MHz, CDCl3): d ¼ 19.8 (CH2), 26.2
(CH2), 31.3 (CH2), 80.1 (CH), 81.3 (CH).
3-Allyloxy-2-hydroxypropyl Nitrate 8
1
IR: 3454 (OH), 1631 (NO2), 1377 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 3.09 (br s, 1 H), 3.38 (d, 2 H), 3.85 (d, 2 H), 4.02 (m, 1 H),
4.56 (d, 2 H), 5.29–5.43 (m, 2 H), 5.96 (m, 1 H). 13C NMR (100 MHz,
CDCl3): d ¼ 69.2 (CH), 74.6 (CH2), 75.7 (CH2), 75.9 (CH2), 119.5
(CH2), 140.5 (CH).
3-Butoxy-2-hydroxypropyl Nitrate 9
1
IR: 3360 (OH), 1643 (NO2), 1439 (NO2) (cmꢀ1). H NMR (400 MHz,
CDCl3): d ¼ 0.95 (t, 3 H), 1.41 (six, 2 H), 1.52 (pent, 2 H), 3.04 (br s,
1 H), 3.85 (t, 2 H), 4.03 (m, 2 H), 4.16 (m, 1 H), 4.33 (d, 2 H). 13C
NMR (100 MHz, CDCl3): d ¼ 13.8 (CH3), 19.5 (CH2), 31.9 (CH2), 72.5
(CH2), 72.9 (CH2), 73.6 (CH), 74.1 (CH2).
ACKNOWLEDGMENT
We thank Chamran University for financial support of this work.
REFERENCES
1. (a) Kiasat, A. R.; Badri, R.; Zargar, B.; Sayyahi, S. Poly(ethylene glycol)
grafted onto Dowex resin: An efficient, recyclable, and mild polymer-
supported phase-transfer catalyst for the regioselective azidolysis of epoxides
in water. J. Org. Chem. 2008, 73, 8382–8385.

1,4-Bis(triphenylphosphonium)-2-butene Peroxodisulfate
4247
2. (a) Das, B.; Krishnaiah, M.; Venkateswarlu, K.; Reddy, V. S. Efficient regio-
and stereoselective conversions of oxiranes and aziridines into
(nitrooxy)-substituted alcohols and amines by using bismuth nitrate. Helv.
Chim. Acta 2007, 90, 110–113; (b) Pinto, R. M. A.; Salvador, J. A. R.; Le
Roux, C. Bismuth(III) salts–mediated regioselective ring opening of epoxides:
An easy route to halohydrins and b-hydroxy nitrates. Tetrahedron 2007, 63,
9221–9228; (c) Fan, Y.; Shang, X.; Liu, Z.; Wu, L. Regio- and diastereoselec-
tive ring-opening reaction of epoxides with nitric oxide. Synth. Commun.
2006, 36, 3149–3152.
3. Boschan, R.; Merrow, R. T.; Van Dolah, R. W. The chemistry of nitrate
esters. Chem. Rev. 1955, 55, 485–510.
4. Nichols, P. L.; Magnusson, A. B.; Ingham, J. D. Synthesis of nitric esters by
the addition of nitric acid to the ethylene oxide ring. J. Am. Chem. Soc. 1953,
75, 4255–4258.
5. Marans, N. S.; Zelinski, R. P. 2-Nitratoethyl esters of acrylic, crotonic, and
methacrylic acids. J. Am. Chem. Soc. 1950, 72, 5330–5331.
6. Volkova, Y. A.; Ivanova, O. A.; Budynina, E. M.; Averina, E. B.;
Kuznetsova, T. S.; Zefirov, N. S. Tetranitromethane as an efficient reagent
for the conversion of epoxides into b-hydroxy nitrates. Tetrahedron Lett.
2008, 49, 3935–3938.
7. Iranpoor, N.; Salehi, P. Ammonium nitrate: A mild and efficient reagent for
conversion of epoxides to b-nitrato alcohols. Tetrahedron 1995, 51, 909–912.
8. Liu, Z.; Li, R.; Yang, D.; Wu, L. Ring opening of 2,3-epoxy phenyl ketones
upon reaction with nitric oxide. Tetrahedron Lett. 2004, 45, 1565–1566.
9. Das, B.; Krishnaiah, M.; Venkateswarlu, K. Zirconyl nitrate–mediated regio-
selective ring opening of epoxides and aziridines: An easy synthesis of b-
nitrato-alcohols and sulfonamides. Tetrahedron Lett. 2006, 47, 6027–6029.
10. House, D. A. Kinetics and mechanism of oxidations by peroxydisulfate.
Chem. Rev. 1962, 62, 185–203.
11. Anderson, J. M. Silver(I)-catalyzed oxidative decarboxylation of acids by
peroxydisulfate: Role of silver(II). J. Am. Chem. Soc. 1970, 92, 1651–1659.
12. (a) Hajipour, A. R.; Zahmatkesh, S.; Ruoho, A. E. Synthesis of methyltriphe-
nylphosphonium peroxydisulfate as a mild selective reagent for the oxidation
of alcohols. Synth. Commun. 2006, 36, 71–76; (b) Tajik, H.; Mohammadpoor-
Baltork, I.; Albadi, J. Bromination of some aromatic compounds with
potassium bromide in the presence of benzyltriphenylphosphonium-
peroxodisulfate. Synth. Commun. 2007, 37, 323–328; (c) Tajbakhsh, M.;
Lakouraj, M. M.; Fadavi, A. Allyltriphenylphosphonium peroxodisulfate
(CH2¼CHCH2PPh3)2S2O8: An efficient and convenient reagent for the oxida-
tion of alcohols and silyl and THP-ethers under nonaqueous conditions.
Synth. Commun. 2004, 34, 1173–1181; (d) Firouzabadi, H.; Salehi, P.;
Mohammadpoor-Baltork, I. Tetrakis (pyridine) silver(II) peroxidisulfate,
[Ag(Py)4]S2O8, a reagent for the oxidative transformation. Bull. Chem. Soc.
Jpn. 1992, 65, 2879; (e) Jung, J. C.; Choi, H. C.; Kim, Y. H. Direct facile
tetrahyrofuranylation of alcohols through radical coupling with (Bu4N)2
S2O8. Tetrahedron Lett. 1993, 7, 3581; (f) Mohammadpoor-Baltork, I.;

4248
R. Badri and M. Gorjizadeh
Hajipour, A. R.; Mohammadi, H. Benzytriphenylphosphonium peroxodisul-
fate (PhCH2PPh3)2S2O8, a mild and inexpensive reagent for efficient oxida-
tion of organic compounds under nonaqueous and aprotic conditions. Bull.
Chem. Soc. Jpn. 1998, 71, 1649; (g) Mohammadpoor-Baltork, I.; Hajipour,
A. R.; Aghajari, M. Selective and efficient oxidative deprotection of tri-
methylsilyl and tetrahydropyranyl ethers, etylene acetals, and ketals
with n-butyltriphenylphosphonium peroxodisulfate (BunPPh3)2S2O8. Synth.
Commun. 2002, 32, 1311–1317.
13. (a) Badri, R.; Soleymani, M. Selective oxidation of benzylic substrates to their
corresponding carbonyl compounds with 3,6-bis(triphenylphosphonium)cy-
clohexene peroxodisulfate. Synth. Commun. 2003, 33, 1325–1332; (b) Badri,
R.; Soleymani, M. 3,6-bis(triphenylphosphonium) cyclohexene peroxodisul-
fate as an efficient and mild oxidizing agent for conversion of alkylbenzenes
to corresponding carbonyl compounds. Synth. Commun. 2002, 32, 2385–2389;
(c) Badri, R.; Shalbaf, H.; Heidary, M. A. 3,6-Bis(triphenylphosphonium)cy-
clohexene peroxodisulfate: A highly efficient oxidant for the selective oxida-
tion of benzylic alcohols. Synth. Commun. 2001, 31, 3473–3479.