New recoverable organoselenium catalyst for hydroperoxide oxidation of organic substrates

Article abstract of DOI:10.1080/00397910801997793

New benzisoselenazol-3(2H)-one covalently bounded to a silica support was synthesized and characterized. It was used as an effective, selective, and easy-to-regenerate catalyst for t-BuOOH and H2O2 oxidation of alkyl arenes to alkyl aryl ketones, aromatic aldehydes to arene carboxylic acids, and sulfoxides and/or sulfones. Copyright Taylor & Francis Group, LLC.

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New Recoverable
Organoselenium Catalyst for
Hydroperoxide Oxidation of
Organic Substrates
Halina Wójtowicz a , Grażyna Soroko a & Jacek
Młochowski a
a Department of Organic Chemistry, Faculty of
Chemistry, Wrocław University of Technology,
Wrocław, Poland
Version of record first published: 12 Jun 2008.
To cite this article: Halina Wójtowicz, Grażyna Soroko & Jacek Młochowski
(2008): New Recoverable Organoselenium Catalyst for Hydroperoxide Oxidation of
Organic Substrates, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 38:12, 2000-2010
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Synthetic Communications1, 38: 2000–2010, 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910801997793
New Recoverable Organoselenium Catalyst for
Hydroperoxide Oxidation of Organic Substrates
ꢀ
Halina Wojtowicz, Graz˙yna Soroko, and Jacek Młochowski
Department of Organic Chemistry, Faculty of Chemistry,
Wrocław University of Technology, Wrocław, Poland
Abstract: New benzisoselenazol-3(2H)-one covalently bounded to a silica
support was synthesized and characterized. It was used as an effective, selective,
and easy-to-regenerate catalyst for t-BuOOH and H2O2 oxidation of alkyl arenes
to alkyl aryl ketones, aromatic aldehydes to arene carboxylic acids, and sulfoxides
and=or sulfones.
Keywords: Catalysts; Hydrogen peroxide; Organoselenium compounds;
Oxidation; tert-Butyl hydroperoxide
Covalent immobilization of homogeneous catalysts on solid silica or
polymer support has received considerable recent attention in organic
synthesis. The best prospective catalysts can be easily recovered from
the reaction mixture and reused.[1] In an ideal case, the catalyst immobi-
lized on solid support should combine the advantages of its homogeneous
precursor and heterogeneous material. Moreover, the immobilization of
homogeneous catalysts potentially allows their adaptation for continu-
ous-flow-type processes. Use of this type of catalyst as promoter of
hydrogen peroxide and tert-butyl hydroperoxide (TBHP) oxidation of
various groups of organic substrates should fulfill requirements of green
chemistry.[2–4] The most common homogeneous catalysts for oxidation
of organic substrates are transition-metal complexes. Some of them have
been recently successfully immobilized on solid support and used as
heterogeneous easily recoverable oxygen-transfer catalysts.[2,5] Although
Received in the U.K. July 2, 2007
Address correspondence to Jacek Młochowski, Department of Organic Chem-
´
istry, Faculty of Chemistry, Wrocław University of Technology, Wyb. Wyspians-
kiego 27, 50-370 Wrocław, Poland. E-mail: jacek.mlochowski@pwr.wroc.pl
2000

Organoselenium Catalyst for Hydroperoxide Oxidation
2001
during the past three decades, a variety of selenium compounds have been
employed as stoichiometric oxidants[6] or oxygen-transfer catalysts,[7] to
our knowledge only one of them has been used as solid supported oxi-
dant[8] and another was immobilized on a polystyrene support.[9]
Most recently, in our laboratory, open-chain selenenamide bounded
to a silica support was a catalyst for hydroperoxide oxidation of alde-
hydes, benzylamines, and azometine compounds.[10]
In our previous work, we have been particularly interested in the
activity of Ebselen [(2-phenyl)benzisoselenazol-3(2H)-one] (1) because
this compound and other heterocyclic selenenamides interact with bioac-
tive oxygen species in a biomimetic way.[11–13] We used 1 as a promoter
for hydrogen peroxide and t-butyl hydroperoxide oxidation of different
common groups of organic compounds to show evidence that Ebselen
is an efficient oxygen-transfer homogeneous catalyst for hydroperoxide
oxidation of a broad spectrum of organic substrates such as alkylarenes,
aromatic aldehydes, sulfides, benzylamines, and azomethine groups.[14–19]
Moreover, in many cases, Ebselen is a more efficient and selective
oxygen-transfer catalyst than other selenium compounds.[4,7] We demon-
strated that Ebselen and its analogs acted via active intermediates—
peroxyselenuranes.[16] It should be noted that contrary to inorganic and
volatile selenium compounds, benzisoselenazolones are inodorous and
nontoxic, thus their use is safe even on a larger scale.[13,20]
RESULTS AND DISCUSSION
In this work, we designed and synthesized a new selenium heterogeneous
catalyst 2 named Halicat, having a cyclic selenenamide moiety bounded
to a solid silica support by a propylene group. We expected that catalytic
activity of this new material would be similar to the activity of its homo-
geneous precursor and that it should be easily separated from the reac-
tion mixture by filtration and reusable.
The key substrates used for preparation of the catalyst were 2-(chlor-
oseleno)benzoyl chloride (3) and 3-(aminopropyl)triethoxysilane (4). The
reaction proceeded via tandem selenenylation–acylation of amino group
in 4 by dichloride 3. 2-(3-Propyltriethoxysilyl)benzisoselenazol-3(2H)-one
(5) was hydrolyzed with hydrochloric acid in an ethanol–water solution
to give the final product 2 (Scheme 1). It was a sand-like amber-colored
solid, insoluble in water and common organic solvents and only sparingly
soluble in hotꢀdimethylsulfoxide (DMSO). It did not melt at temperatures
1
less than 360 C. The signals in H NMR spectrum of 2 observed in the
range 7.4–8.03 ppm were characteristic for benzene ring protons whereas
the signal 861 ppm in 77Se NMR spectrum was the evidence for an

ꢀ
H. Wojtowicz et al.
2002
Scheme 1.
isoselenazole ring.[21] In the IR spectrum, absorbance at 1690 cmꢁ1
ꢁ1
(C O), 1430 cm and 1002 cmꢁ1 (Si-C) was present. Elemental analysis
=
(C,H,N,Se) corresponded to a general formula (C10H10NO4SeSi)n.
In this work, Halicat was successfully used for hydrogen peroxide
and t-butyl hydroperoxide oxidation in three model reactions: TBHP oxi-
dation of alkylarenes 6 to alkylaryl ketones 7, TBHP oxidation of benzal-
dehydes 8 to benzoic acids 9, and hydrogen peroxide oxidation of sulfides
10 to sulfoxides 11 and=or sulfones 12. The results were compared with
these when Ebselen was a catalyst under the same reaction conditions.
Three alkyl aromatic hydrocarbons 6 were oxidized to correspond-
ing alkylaryl ketones 7 with 80% TBHP as stoichiometric oxidant (1.2
molar equivalent), in the presence of Halicat (Scheme 2) similar to that
reported earlier for other catalysts.[14] For comparison, Ebselen was
used as a reference catalyst. The results, given in Table 1, show that
catalytic effectiveness of Halicat and Ebselen (1) is similar. The
reaction was highly selective, and 1-acenaphthenone (7aa), acetophenone
(7b), and benzophenone (7c) were isolated as sole products in almost
Scheme 2. R ¼ Me (6b, 7b); R ¼ Ph (6c, 7c).

Organoselenium Catalyst for Hydroperoxide Oxidation
2003
Table 1. Results of oxidation of arenes 6 to alkylaryl ketones 7 with t-BuOOH
(1.2 molar eq.)=HALICAT (2) and Ebselen (1)a
Product
Recovered
catalyst
2 (%)
Substrate React. Conversion
6
Yield
(%)b
Mp=bp
Lit.
time (h)
(%)
7
(ꢀC) mp=bp (ꢀC)
6a
6ac
6b
6c
6c
6c
48
30
120
48
72
120
95 (96) 7aa 88 (90) 119–120
100 (99) 7aa 79 (82)d
124[22]
202[23]
96
97
95
98
98
98
98 (89) 7b 100 (96)e
202
39 (80) 7c 97 (95)
82 (98) 7c 99 (99)
96 (97) 7c 100 (98)
47–49 48–49[23]
aData for Ebselen are given in parentheses.
bIsolated yield based on the converted substrate.
cTBHP used in 2.5 molar eq.
dAccompanied by acenaphtoquinone (7ab) 21%, mp 248–251 ꢀC (249–252 ꢀC[23]).
eAfter 24 h.
quantitative yields, although the reaction was faster in the presence of
Ebselen. Nevertheless, Halicat seems to be better catalyst because it
can be simply, almost quantitatively, recovered from the reaction mixture
by filtration and reused.
We found that the conversion of 6c under the standard reaction
conditions remained high even after five runs. A slight loss of activity
of regenerated catalyst after each run took place. When the catalyst
was regenerated five times, conversion of 6c to 7c decreased to 82%.
Halicat was also used as an oxygen-transfer catalyst for t-butyl
hydroperoxide oxidation of carbonyl group in aromatic aldehydes
such as benzaldehyde 8a and those substituted in the para position with
electron-donating groups (8b,c) or electron-withdrawing groups (8d,e).
Under the same reaction conditions as used for oxidation of alkylarenes,
arenecarboxylic acids 9 were produced exclusively from aromatic
aldehydes, whereas the products of the competitive Baeyer–Villiger reac-
tion such as phenols or their formyl esters were not formed (Scheme 3,
Table 2).
Moreover, we found that Halicat effectively catalyzed hydrogen per-
oxide oxidation of sulfides 10 to sulfoxides 11 and=or sulfones 12. The
results strongly depend on the reactivity of the substrate and amount
of the oxidant (Scheme 4).
When 30% aqueous H2O2 was used in a stoichiometric amount, sulf-
oxides 11a–c were produced as sole products although conversion of the

ꢀ
H. Wojtowicz et al.
2004
Scheme 3. R ¼ H (8a, 9a); R ¼ Me (8b, 9b); R ¼ OMe (8c, 9c); R ¼ Br (8d, 9d);
R ¼ NO2 (8e, 9e).
substrate differed. Conversion of the most reactive t-butyl methyl sulfide
(10a) was almost quantitative, and sulfoxide 11a was formed exclusively.
Less reactive substrates 10b,c were converted under the same reaction
conditions to sulfoxides 11b,c in only 54–56% yields. Oxidation of sulfide
10b with hydrogen peroxide, used in 2.5 molar excess, resulted in the
mixture of sulfoxide 11b and sulfone 12b where 11b was a major product.
In the similar condition, more active sulfide 10a was oxidized exclusively
to the sulfone 12a, whereas the oxidation of 10c stopped on the sulfo-
xide 11c (Scheme 4, Table 3).
In conclusion, we have presented in this work a silica-supported
benzisoselenazol-3(2H)-one (Halicat) as a prospective new organocatalyst
for hydroperoxide oxidation of different organic compounds. Its catalytic
effectiveness has been demonstrated with TBHP oxidation of alkylarenes
to alkyl aryl ketones and aromatic aldehydes to arenecarboxylic acids
as well as with the hydrogen peroxide oxidation of sulfides to sulfoxides
and=or sulfones. The conversion of the substrate and reaction selectivity
are similar to those when Ebselen, one of the most effective organosele-
nium catalysts, is used. But in contrast to Ebselen, heterogeneous Halicat
Table 2. Results of oxidation of aromatic aldehydes 8 to arenecarboxylic acids 9
with t-BuOOH (1.2 molar eq.)=HALICAT (2) and Ebselen (1)a
Product
Recovered
catalyst
2 (%)
Substrate React. Conversion
(%)
Yield
(%)b
Mp
(ꢀC)
Lit.
mp (ꢀC)
8
time (h)
9
8a
8b
8c
8d
8e
72
72
72
20
72
96 (96)
99 (95)c
9a 88 (90) 121–123 121–123[23]
9b 100 (96)e 181–182 180–182[23]
94
97
95
93
95
99 (100)c 9c 97 (95) 182–184 182–185[23]
95 (98)
99 (100)
9d 99 (99) 252–254 252–254[23]
9e 100 (98) 239–243 239–245[23]
aData for Ebselen are given in parentheses.
bIsolated yield based on the converted substrate.
cReaction time 48 h.

Organoselenium Catalyst for Hydroperoxide Oxidation
2005
Scheme 4. R1 ¼ Me, R2 ¼ t-Bu (10a, 11a, 12a); R1 ¼ Me, R2 ¼ 4-NO2C6H4
(10b, 11b, 12b); R1, R2 ¼ Ph (10c, 11c, 12c).
can be easily recovered from the reaction mixture by filtration and reused.
The catalyst can be easily prepared by hydrolysis of 2-(3-propyltriethoxy-
silyl)benzisoselenazol-3(2H)-one (5) obtained from 3-(aminopropyl)-
triethoxysilane (4) and 2-(chloroseleno)benzoyl chloride (3).
EXPERIMENTAL
The reaction products presented in Tables 1–3 were analysed using a
Hewlett-Packard 5890=II apparatus with capilary column HP-1 (25 m,
0.22 mm). Melting points were determined on a digital melting-point
1
apparatus Electrothermal IA 91100. H NMR spectra were measured
with a Bruker DRX 300-MHz spectrometer (DMSO-d6, TMS); 13C
and 77Se NMR spectra were taken with a Bruker AvanceTM 600-MHz
Table 3. Results of oxidation of sulfides 10 with H2O2=HALICAT (2) and
Ebselen (1)a,b
Product
Recovered
catalyst
2 (%)
Substrate
10
Conversion
(%)
Yield
(%)c
Yield
(%)c
11
12
10ad
10ae
10bd
10be
10cd
10ce
95 (99)
100 (99)
98 (99)
39 (99)
82 (99)
100 (99)
11a
11a
11b
11b
11c
11c
100 (90)
— (8)
100 (98)
54 (15)
100 (85)
100 (100)
12a
12a
12b
12b
12c
12c
— 15
100 (92)
— (—)
46 (85)
— (15)
— (—)
91
96
93
94
95
92
aData for Ebselen are given in parentheses.
bReaction time for H2O2=HALICAT 2 h; for H2O2=ebselen 0.5 h.
cYield determined by GC, based on the converted substrate.
d1.2 mol of H2O2.
e2.5 mol of H2O2.

ꢀ
H. Wojtowicz et al.
2006
spectrometer (DMSO-d6, Me2Se). IR (KBr pellets) was measured with a
Perkin-Elmer 2000 FT spectrometer.
t-Butyl hydroperoxide (80% in di-t-butyl peroxide=water 3:2),
hydrogen peroxide (30% in water), 3-(aminopropyl)triethoxysilane, and
solvents were purchased from Aldrich Chem. Co. and Fluka and used
as received without additional purifications.
The reference catalyst 1 (Ebselen) was obtained using to the pro-
cedure described in our previous works.[24,25] 2-(Chloroseleno)benzoyl
chloride (3) was prepared via selenylation of diazonium salt of anthranilic
acid followed by treatment of intermediate bis(2-carboxyphenyl) disele-
nide with thionyl chloride.[24,25]
Preparation of 2-(3-Propyltriethoxysilyl)benzisoselenazol-3(2H)-one (5)
The solution of 2-(chloroseleno)benzoyl chloride (3) (0.05 mol, 12.5 g) in
acetonitrile (100 ml) was added dropwise for 30 min to a vigorously stir-
red solution of 3-(aminopropyl)triethoxysilane (4) (0.05 mol, 11.05 g) and
triethylamine (0.11 mol, 15.3 ml) in acetonitrile (150 ml). The mixture was
stirred for 18 h at room temperature. After this period, the solid was fil-
tered off and acetonitrile was evaporated in vacuo. The viscous oily resi-
due was dissolved in dichloromethane (50 ml), and the solution was
washed with water (3 ꢂ 30 ml) and dried with MgSO4. Solvent was evapo-
rated in vacuo. The product (5) was white powder melted at 133–135 ꢀC
(8.02 g), yield 77%. nmax (KBr)=cmꢁ1: 3062 (C-H), 1690–1520 (C O),
=
1430 and 1002 (Si-C), 1110–1020 (Si-O-C); dH (300 MHz, DMSO-
d6)=ppm: 0.56 (t, 2H, J ¼ 8.2 Hz, CH2Si), 1.11 (t, 9H, J ¼ 6.6 Hz,
CH3), 1.65 (m, 2H, CH2), 3.26 (t, 2H, J ¼ 6.6 Hz, CH2N), 3.7 (m, 6H,
CH2CH3), 7.38 (t, 1H, J ¼ 7.2 Hz, ArH), 7.57 (t, 1H, J ¼ 7.5 Hz, ArH),
7.76 (d, 1H, J ¼ 7.8 Hz, ArH), 7.99 (d, 1H, J ¼ 7.4 Hz, ArH); dC
(600 MHz, DMSO-d6)=ppm: 166.8, 139.7, 131.9, 128.5, 127.8, 126.3,
58.1, 45.2, 27.4, 18.6, 9.2; dSe (600 MHz, DMSO-d6)=ppm: 859.4. Anal.
calcd. for C16H25NO4SeSi, %: C, 47.76; H, 6.26; N, 3.48; Se, 19.62.
Found, %: C, 45.92; H, 6.62; N, 4.04; Se, 20.02.
Preparation of 2-(Propylsilicate)benzisoselenazol-3(2H)-one (2)
The solution 5 (0.015 mol, 6.0 g) in ethanol (75 ml), water (50 ml), and
concentrated hydrochloric acid (1 ml) was heated for 5 h under reflux.
Then the reaction mixture was cooled in the ice bath for 2 h. Product
2, insoluble in water, was washed with water by decantation (4 ꢂ 50 ml)
and dried for 5 h at 120 ꢀC. The amber-colored powder did not melt at
less than 360 ꢀC (3.67 g, yield 77%). It was insoluble in common

Organoselenium Catalyst for Hydroperoxide Oxidation
2007
organic solvents (methanol, methylene dichloride, acetonitrile,
tetrahydrofurane, acetone), only sparingly soluble in hot DMSO and
DMF, and well soluble in hot 5% aqueous solution of NaOH.
=
n
max (KBr)=cmꢁ1: 3062 (C-Har), 1690–1520 (C O amide), 1430 and
1002 (Si-C), 1021 (Si-O-Si); dH (300 MHz, DMSO-d6)=ppm: 0.514 (t, 2H,
J ¼ 8.2 Hz, CH2Si), 1.72 (m, 2H, CH2), 3.66 (t, 2H, J ¼ 6.7 Hz, CH2N),
7.4 (t, 1H, J ¼ 6.0 Hz, Ar-H), 7.56 (t, 1H, J ¼ 6.8 Hz, Ar-H), 7.8 (d, 1H,
J ¼ 6.9 Hz, Ar-H), 8.03 (d, 1H, J ¼ 6.8 Hz, Ar-H); dC (600 MHz, DMSO-
d6)=d ppm: 166.9, 139.8, 131.9, 128.5, 127.9, 126.2, 45.3, 22.5, 9.5; dSe
(600 MHz, DMSO-d6), ppm: 861.1. Anal. calcd. for (C10H10NO4SeSi)n,
%: C, 38.10; H, 3.20; N, 4.44; Se, 25.05%. Found, C, 37.96; H, 3.51;
N, 4.43; Se, 25.05.
Oxidation of Alkyl Arenes 6 to Alkyl Aryl Ketones 7: General Procedure
The solution of alkyl arene 6 (5 mmol), TBHP (1.14 ml, 10 mmol), and
catalyst 1 (63.5 mg, 0.25 mmol) or 2 (78.8 mg, 0.25 mmol) in t-butyl alco-
hol (5 ml) was stirred at 80 ꢀC until the substrate was exhausted. The reac-
tion progress was controlled by thin-layer chromatography (TLC) using
dichloromethane as an eluent. Reaction times are given in Table 1. After
the reaction was finished, the yellow solid containing 7ab and catalyst 2
was filtered. To the filtrate, a pinch of Pd=asbestos (10%) was added to
decompose peroxides, and solvent was evaporated in vacuo. The crude
solid residue was purified by column chromatography on silica gel (elu-
ent: hexane–ethyl acetate 2:1), to give pure acenaphtenone (7aa) (as white
prisms, 0.67 g, yield 79%, mp 119–120 ꢀC; 124 ꢀC,[22] 121.5–122.5 ꢀC[26]).
The solid containing 7ab was dissolved in hot acetone; the catalyst 2
was filtered off. The pure 7ab crystallized from the filtrate after
cooling was ꢀfiltered andꢀdried in air (yellow prisms, 0.19 g, yield 21%,
mp 248–251 C; 249–252 C[23]).
When alkyl benzenes 6b and 6c were oxidized, the catalyst 2 was
filtered off from the reaction mixture, washed with acetone, dried in air
at 120 ꢀC, and reused in a subsequent run. The filtrate was evaporated
in vacuo. The oily residue 7bꢀwas purified by column chromatography
(oil, 0.61 g, yield 99%, bp 202 C; 202 ꢀC[23]) oꢀr solid 7c was recrystallized
from toluene (0.88 g, yield 96.5%, mp 47–49 C; 48–49 ꢀC[23]).
Oxidation of Aromatic Aldehydes 8 to Aromatic
Acids 9: General Procedure
The solution of aldehyde 8 (5 mmol), TBHP (1.14 ml, 10 mmol), and
catalyst 1 (63.5 mg, 0.25 mmol) or 2 (78.8 mg, 0.25 mmol) in t-butyl

ꢀ
H. Wojtowicz et al.
2008
alcohol (5 ml) was stirred at 80 ꢀC until the substrate disappeared. The
reaction progress was controlled by TLC using dichloromethane as an
eluent. Reaction times are given in Table 2. After the reaction was com-
pleted, the catalyst 2 was filtered off from the reaction mixture, washed
with acetone, and dried in the air at 120 ꢀC. It was reused in a subsequent
run. To the filtrate (or directly to the reaction mixture when 1 was a cata-
lyst) a pinch of Pd=asbestos (10%) was added, and solvent was evapo-
rated in vacuo. The residue recrystallized from the ethanol–water
mixture to give pure 9a–9e (Table 2).
Oxidation of Sulfides 10 to Sulfoxides 11 and Sulfones 12
The 30% aqueous hydrogen peroxide (0.69 ml, 6 mmol or 1.41 ml,
12.5 mmol) was added in one portion to a magnetically stirred solution
of sulfide 10 (5 mmol) in methanol (30 ml) containing the catalyst soluted
(1) or suspended (2). The reaction was continued for 0.5 h (cat. 1) or 2 h
(cat. 2) and monitored by TLC (hexane–ethyl acetate 3:1). After this
period, the heterogenous catalyst 2 was filtered off from the reaction
mixture (catalyst 1 remained in solution). When sulfide 10b was oxidized,
the insoluble sulfoxide 11b was separated together with the catalyst and
dissolved in hot methanol (20 ml). The catalyst was removed by filtration,
and pure 11b (white prisms, mp 142–143 ꢀC; 142 ꢀC[27]) crystallized from
the filtrate. When sulfides 10a and 10c were oxidized, the filtrate was
treated with saturated aqueous Na2SO3 (20 ml) to decompose excess
H2O2 and extracted with dichloromethane (3 ꢂ 30 ml). The organic phase
was dried over anhydrous MgSO4 and evaporated in vacuo. The residue
wasꢀrecrystallized from hexane to give pure 11c (white prisms, mp 152–
153 C; 151–153 ꢀC[28] or chromatographed on a silica-gel column
(hexane–ethyl acetate 3:1) to give pure 11ꢀa (oil, ꢀbp 82 ꢀC=18 torr; 82 ꢀC/
18 torr[29]) and 12a (white prisms, mp 83 C, 83 C[27]).
ACKNOWLEDGMENTS
This work was supported by the Polish State Committee for Scientific
Research (Grant 3T09A 003 27).
REFERENCES
1. Gladysz, J. A. Introduction: Recoverable catalysts and reagents—perspective
and prospective. Chem. Rev. 2002, 102, 3215–3216.

Organoselenium Catalyst for Hydroperoxide Oxidation
2009
2. Leadbeater, N. E.; Marco, M. Preparation of polymer-supported ligands and
metal complexes for use in catalysis. Chem. Rev. 2002, 102, 3217–3273.
3. Lu, Z.; Lindner, E.; Mayer, H. R. Applications of sol-gel-processed inter-
phase catalysis. Chem. Rev. 2002, 102, 3543–3577.
ꢀ
4. Młochowski, J.; Brza˛szcz, M.; Chojnacka, M.; Giurg, M.; Wojtowicz, H.
Diaryl diselenides and benzisoselenazol-3(2H)-ones as oxygen-transfer
agents. Arkivoc 2004, 3, 231–238.
5. Fan, Q.-H.; Li, Y.-M.; Chan, A. S. C. Recoverable catalysts for asymmetric
organic synthesis. Chem. Rev. 2002, 102, 3385–3465.
6. Back, T. B. Organoselenium Chemistry: A Practical Approach; T. G. Back
(Ed.); Oxford: Oxford University Press, 1999; chap 5, pp. 93–112.
ꢀ
7. Młochowski, J.; Brza˛szcz, M.; Giurg, M.; Palus, J.; Wojtowicz, H. Selenium
promoted oxidation of organic compounds: Reactions and mechanisms. Eur.
J. Org. Chem. 2003, 4329–4339.
8. Hu, N. X.; Aso, Y.; Otsubo, T.; Ogura, T. Mild and selective oxidations with
polystyrene-bound diaryl selenoxide. Chem. Letters 1985, 603–606.
9. Taylor, R. T.; Flood, L. A. Polystyrene-bound phenylseleninic acid: Catalytic
oxidation of olefins, ketones and aromatic systems. J. Org. Chem. 1983, 48,
5160–5164.
10. Giurg, M.; Brza˛szcz, M.; Młochowski J. Hydroperoxide oxidation of differ-
ent organic compounds catalyzed by silica-supported selenenamide. Polish J.
Chem. 2006, 80, 417–428.
11. Muller, A.; Cadenas, E.; Graf, P.; Sies, H. A novel biologically active sele-
noorganic compound I: Glutathione peroxidase-like activity in vitro and
antioxidant capacity of PZ 51 (Ebselen). Biochem. Pharmacol. 1984, 33,
3235–3240.
12. Mugesh, G.; Singh, K. K. Synthetic organoselenium compounds as antioxi-
dants: Glutathione peroxidase activity. Chem. Soc. Rev. 2000, 29, 347–257.
13. Mugesh, G.; du Mont, W.-W.; Sies, H. Chemistry of biologically important
synthetic organoselenium compounds. Chem. Rev. 2001, 101, 2125–2179.
ꢀ
14. Giurg, M.; Wojtowicz, H.; Młochowski, J. Hydroperoxide oxidation of azo-
methines and alkylarenes catalyzed by Ebselen. Polish J. Chem. 2002, 76,
537–542.
15. Brza˛szcz, M.; Kloc, K.; Maposah, J.; Młochowski J. Selenium(IV) oxide cat-
alysed oxidation of aldehydes to carboxylic acids with hydrogen peroxide.
Synth. Commun. 2000, 30(24), 4425–4434.
ꢀ
16. Wojtowicz, H.; Brza˛szcz, M.; Kloc, K.; Młochowski, J. Selective oxidation of
aromatic aldehydes to arenecarboxylic acids using ebselen-tert-butyl hydro-
peroxide catalytic system. Tetrahedron 2001, 57, 9743–9748.
17. Brza˛szcz, M.; Kloc, K.; Młochowski, J. Hydroperoxide oxidation of benzyla-
mines catalyzed by selenium compounds. Polish J. Chem. 2003, 77, 1579–1586.
18. Młochowski, J.; Giurg, M.; Kubicz, E.; Said, S. B. Benzisoselenazol-3(2H)-
ones and bis(2-carbamoyl)phenyl diselenides as new catalysts for hydrogen
peroxide oxidation of organic compounds. Synth. Commun. 1996, 26, 291–300.
´
19. Giurg, M.; Wiech, E.; Piekielska, K.; Ge˛bala, M.; Młochowski, J.; Wolanski,
M.; Ditkowski, B.; Peczynska-Czoch, W. A new approach to synthesis of
´

ꢀ
H. Wojtowicz et al.
2010
questiomycin A: Oxidative cyclocondensation of ortho-aminophenol. Polish
J. Chem. 2006, 80, 297–306.
20. Information on Uses, Handling, and Storage of Selenium; Selenium-Tellurium
Development Association, Grimberg, Belgium: 1993.
21. Młochowski, J. 1,2-Selenazoles. In Comprehensive Heterocyclic Chemistry,
3rd ed., A. Katritzky (Ed.); Elsevier: Oxford, 2008; chap 4.07.
22. Sudhakaran, K. V.; Pillai, V. N. Solid-phase polymeric analogs of
chloramine-T and bromamine-T: Preparation and use as synthetic reagents.
Indian J. Chem. Sect. B 1990, 29B(11), 1012–1016.
23. Advancing Science, Handbook of Fine Chemicals; Aldrich: Milwaukee, WI,
2007–2008.
24. Młochowski, J.; Kloc, K.; Syper, L.; Inglot, A. D.; Piasecki, E. Aromatic and
azaaromatic diselenides, benzisoselenazolones, and related compounds as
immunomodulators active in humans: Synthesis and properties. Liebigs
Ann. Chem. 1993, 1239–1244.
25. Palus, J.; Młochowski, J.; Juchniewicz, L. 2,20-Diselenobisbenzoates and 2,20-
diselenobisbenzenesulfonates, new chiral aryl diselenides. Polish J. Chem.
1998, 72, 1931–1936.
26. Stec, Z. A study on decomposition of 1-hydroperoxy-1,2-dihydroacenaphthy-
lene in acidic and basic media. Polish J. Chem. 1994, 68, 727–732.
27. Rozen, S.; Bareket, Y. Oxidation of sulfur-containing compounds with HOFꢃ
CH3CN. J. Org. Chem. 1997, 62, 1457–1462.
28. Landini, D.; Modena, G.; Montanari, F.; Scorrano, G. Reduction and race-
mization of sulfoxides by halide ions in aqueous perchloric acid. J. Am.
Chem. Soc. 1970, 92, 7168–7174.
29. Henbest, H. B.; Reid, J. A. N.; Stirring, C. J. M. The oxidation of ethers and
related compounds, part III. J. Chem. Soc. 1964, 1220–1223.