Selective and mild oxidation of sulfides to sulfoxides by oxodiperoxo molybdenum complexes adsorbed onto silica gel

Article abstract of DOI:10.1016/S0040-4020(01)00969-3

Aliphatic and aromatic sulfides, ketosulfides, sulfinyl acids and esters, and olefinic sulfides were oxidized to sulfoxides using oxodiperoxo complexes of molybdenum coated on silica gel (150 ? pore size) in very high yields. Complete chemoselectivity was observed for the oxidation of all functional sulfides. Sulfones were, however, the main products of the reaction when the complexes were not coated on silica gel. The influence of silica gel as the support of these reactions was also investigated and it was demonstrated that it alters the reactivity of the complex but it is not responsible for the excellent chemoselectivity of the complexes. The complex [MoO(O₂)₂(pyrazole) (H₂O)] proved to be more reactive than [MoO(O₂)₂(Opyr) (H₂O)].

Full text of DOI:10.1016/S0040-4020(01)00969-3

TETRAHEDRON
Pergamon
Tetrahedron 57 22001) 9669±9676
Selective and mild oxidation of sul®des to sulfoxides by
oxodiperoxo molybdenum complexes adsorbed onto silica gel
a
Fabiana Batigalhia, Marcelo Zaldini-Hernandes, Antonio G. Ferreira, Ivani Malvestiti
a
a
b
Ã
and Quezia B. Cassa,p
a
Â
Departamento de Quõmica, Universidade Federal de SaÄo Carlos, Cx. Postal 676, 13565-905 SaÄo Carlos, SP, Brazil
b
Â
Departamento de Quõmica Fundamental, Universidade Federal de Pernambuco, Recife, PE, Brazil.
Received 25 June 2001; accepted 3 October 2001
AbstractÐAliphatic and aromatic sul®des, ketosul®des, sul®nyl acids and esters, and ole®nic sul®des were oxidized to sulfoxides using
Ê
oxodiperoxo complexes of molybdenum coated on silica gel 2150 A pore size) in very high yields. Complete chemoselectivity was observed
for the oxidation of all functional sul®des. Sulfones were, however, the main products of the reaction when the complexes were not coated on
silica gel. The in¯uence of silica gel as the support of these reactions was also investigated and it was demonstrated that it alters the reactivity
of the complex but it is not responsible for the excellent chemoselectivity of the complexes. The complex [MoO2O2)22pyrazole) 2H2O)]
proved to be more reactive than [MoO2O2)22Opyr) 2H2O)]. q 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
2. Results and discussion
The use of diperoxo complexes of molybdenum for ole®n
epoxidation is well established1±3 and since sul®de oxi-
dation can be achieved with reagents used for ole®n epoxi-
dation, the use of these complexes for these purpose was
examined.
Molybdenum 2VI) oxodiperoxo complexes such as shown in
Fig. 1 [MoO2O2)22Opyr) 2H2O)] and [MoO2O2)22Pyrazole)
2H2O)], complexes 2I) and 2II), respectively, are stoichio-
metric reagents. They were prepared by stoichiometric
reaction of the ligands with molybdic acid and hydrogen
peroxide by the procedure described by Mimoun et al.1
Shurig mentions the use of molybdenum 2VI) oxodiperoxo
complexes for oxidation of sul®des,2,3 but to our knowledge
there is only a single reported study of the use of these
complexes for the preparation of sulfoxides, the paper of
the Caro®glio group4 on the oxidation of thioanisole by
hydrogen peroxide catalyzed by Mo2VI) in presence of
b-cyclodextrin-based ligands.
Both complexes were obtained as yellow powder after
concentration of the reaction mixture and according to the
Mimoun1 procedure these complexes were dried in the
presence of phosphorus pentoxide. Infrared and ultraviolet
spectra and microanalysis were used to characterize them
2see Section 4).
Although there are a large number of procedures for oxi-
dation of sul®des to sulfoxides, few of them are highly
chemoselective and able to stop at the sulfoxide level.5
The series of sul®des selected for these studies is shown in
Fig. 2. The series includes aliphatic and aromatic sul®des
21±3), ketosu®des 24±12), sul®nyl acids and esters 213±18),
and ole®nic sul®des 219±27).6±11
In this paper we report an ef®cient oxidation using molyb-
denum 2VI) oxodiperoxo complexes coated on silica gel for
conversion of sul®des to sulfoxides. Complete chemoselec-
tivity was observed in the reactions of the oxodiperoxo
molybdenum complexes used for all functional sul®des
investigated, including alkenes.
The oxidation reaction was preliminarily investigated for
the sul®des 21)±23) using the complex 2I). The reactions
Keywords: mild oxidation; oxodiperoxo molybdenum complexes; silica
gel; sul®de.
p
Corresponding author. Tel.: 155-16-260-8208; fax: 155-16-260-8350;
e-mail: quezia@dq.ufscar.br
Figure 1. Structures of the aquo 2N-oxo of pyridine) and of aquo 2pyrazol)
molybdenum 2VI) oxodiperoxo complexes.
0040±4020/01/$ - see front matter q 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020201)00969-3

9670
F. Batigalhia et al. / Tetrahedron 57 32001) 9669±9676
Figure 2. The structures of the used sul®des.
were carried out using methanol:acetonitrile 21:1 v/v) as
solvent, however, under these reaction conditions the main
products were the corresponding sulfones.
the complexes to the sul®des. Even when a 2:1 molar ratio
of the complexes to the sul®de was used the reactions
stopped at the sulfoxide stage. Leaving the reactions for a
further period of time made little change to the products
formed.
The use of heterogeneous organic reactions by immobiliz-
ing the reagent on porous solids has been proved success-
ful.12±16 The effect of silica gel as support for these reaction
was thus investigated by coating complex 2I) to silica gel
The results obtained show that complex 2II) reacts about
twice as fast as the reactions involving complex 2I). Fig. 3
shows the pro®le of the oxidation reaction of benzyl phenyl
sul®de with both complexes exemplifying the greater
reactivity of complex 2II). In one case, with sul®de 2, oxi-
dation at the stated condition of the reaction with complex
2II) gave unwanted sulfone as a major product. However,
conducting the reaction at lower temperature 2220 8C) this
oxidation was controlled and sulfoxide function was again
obtained selectively 2see Table 1 entry 2). Traces of sulfones
were observed for the reaction of complex 2II) with all
others sul®des when the reactions were carried out at 0 8C.
Ê
2Davisil, 150 A pore size) in a weight ratio of 40% of
complex to silica.
The adsorbed complex 2I) was then used to react with the
sul®des 21) to 23), using methanol:acetonitrile 21:5 v/v) as
the reaction solvent. The complex was added using a solid
addition ¯ask and it was done in portions over a 20 min
period. The reactions were followed by thin layer and/or
gas chromatography. The main products, this time, were
the sulfoxides.
Based on these preliminary results the reactivity of both
complexes was investigated. Table 1 shows the results of
the oxidation reactions under optimized conditions for the
sul®des series 21) to 227), using both molybdenum 2VI)
oxodiperoxo complexes coated on silica Davisil in a
nominal weight ratio of 40%. The reaction conditions
were optimized for each sul®de with respect to temperature
and reaction time.
The geometrical and electronic structures of these com-
plexes were theoretically investigated at the ab initio
level.16 Good correlation was found between experimental
and the calculated geometrical parameters. The relationship
between the reactivity of these complexes and their
coordination number was also established.
The electronic properties of these complexes were also
studied.17,18 The electronic af®nity values computed for
complex 2I) was 2.24 eV while for complex 2II) it was
The reactions were carried out based on a 1:1 molar ratio of

F. Batigalhia et al. / Tetrahedron 57 32001) 9669±9676
9671
Table 1. Results of the oxidations of sul®des 21)±227) with supported
complexes 2I) and 2II)
The results presented in Table 1 show also that the oxidation
of sul®des to the corresponding sulfoxides has been
achieved with complete chemoselectivity in the presence
of a variety of functional groups. It is important to notice
that molybdenum 2VI) oxodiperoxo complexes have been
used, in solution, ef®ciently as stoichiometric reagents for
the oxidation of various organic substrates such as ketones,
aliphatic amines and ole®ns.1±3
Complex 2I)a
Complex 2II)a
Sul®de
Sulfoxide 2%)
Time 2h)
Sulfoxide 2%)
Time 2h)
1
97
96
97
88
91
93
97
92
91
97
95
91
92
86
96
97
98
96
83
95
94
98
92
93
97
94
96
23
11
13
7
10
8
6
9
7
6
10
15
7
14
6
12
8
11
3
92
95
97
74
87
92
87
86
84
96
97
90
85
80
92
95
96
94
85
93
91
98
89
90
95
93
94
12
7
6
5
8
6
4
6
5
3
8
11
3
9
5
6
6
8
1
8
5
7
10
8
9
7
5
2b
3
4
5
6
7
8
9
Trying to establish if the silica was working as a slow-
releasing agent and if it was also responsible for the
observed chemoselectivity, the reactions of complex 2II)
with the sul®des 2, 4, 13, 19 and 25 were examined.
Complex 2II) was selected since it was more reactive than
complex 2I) and the selected sul®des are representatives of
the classes of sul®des investigated.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
A comparison was made of the standard reaction conditions
with the one using the complex 2II) coated to silica added all
at once at the beginning of the reaction and by the use of
the non-coated complex added as in the standard reaction
protocol.
15
9
15
16
15
12
12
9
The graphics at Fig. 4 shows the pro®les of the oxidations of
sul®de 4 at the three examined conditions and illustrates the
results found for the other four sul®des also investigated.
When the reactions were carried out as the standard reaction
protocol only the corresponding sulfoxides were formed
2Fig. 42a)), however, just by altering the addition condition
of the complex, sulfones were also formed 2Fig. 42b)).
The use of complex 2II) not coated to silica gel and added
into portions at 20 min period as in the standard reaction
protocol, showed that the use of the silica is important in the
reactivity of the complex but not in the chemoselectivity of
the reactions. The results for the non-supported reagent 2Fig.
42c)), show that sulfones were formed almost as the sole
products of the reactions. However, no epoxidation or
Bayer±Villeger products, were obtained at this reaction
conditions for any of the functional sul®des.
a
Supported form of the complexes 2I) and 2II).
Complexes added at 220 8C.
b
2.93 eV. The comparison of the electronic af®nity of both
complexes would suggest that complex 2II) should be more
reactive towards nucleophiles than the complex 2I). This
predictive behavior was con®rmed by the experimental
results shown on Table 1.
The sul®des 11, 12 and 18 formed the corresponding
sulfoxides, as expected, as a diastereomeric mixture. The
yields given in Table 1 for these sulfoxides are for the
diastereomeric mixtures.
To demonstrate the utility of the procedure described here, a
Figure 3. The pro®le of the oxidation of benzyl phenyl sul®de.

9672
F. Batigalhia et al. / Tetrahedron 57 32001) 9669±9676
addition of hydrogen peroxide and then the ligand to the
isolated and dried residues of a previous reaction; followed
by the addition of a 3 M aqueous solution of sulfuric acid as
in the protocol for preparing the complexes. The reconsti-
tuted reagents is then dried in presence of phosphorus
pentoxide before use. The reconstituted complex 2I) was
used with success for the oxidation of benzyl phenyl sul®de
affording the sulfoxide in 95% isolated yield.
3. Conclusions
The results presented on this paper demonstrated that
molybdenum 2VI) oxodiperoxo complexes such as shown
in Fig. 1 when coated to silica gel can be used for the
ef®cient selective preparation of sulfoxides. Sulfones can
be prepared using the complexes uncoated to silica gel.
The excellent chemoselectivity of these complexes towards
the sulfur group, the high yields obtained and the wide
application associated with the easy manipulation makes
them a good choice for the use in the oxidation of functional
sul®des.
4. Experimental
4.1. General
IRspectra were recorded on a BOMEM MB-Series spectro-
meter and are reported in wavenumbers 2cm21).
UV±Vis spectra were obtained on a Hitachi instrument in a
silica cuvette. Samples for UV±Vis were dissolved in
distilled water.
1H NMRand 13C NMRspectra were recorded on a Bruker
9.4 and 4.7 T DRX-400 MHz and ARX 200 MHz spectro-
meter, respectively, in a 5 mm probe at 303 K. Samples
were dissolved in CDCl3 and TMS was used as an internal
standard. All hydrogen spectra were obtained with spectral
width 8117 Hz, pulse width 10.5 ms, acquisition time 4.0 s,
relaxation delay 1.0 s and the number of scan adjusted to
have a good signal to noise ratio 28±32 scans). The spectra
were processed using zero ®lling and Gaussian window
function 2LBˆ22 and GBˆ2) when necessary. All 13C
NMRspectra were recorded using PENDANT pulse
sequence with 1.2 s acquisition time, pulse width 10.0 ms,
sweep width 13513 Hz and relaxation delay 1.5 s. The
spectra were processed using exponential multiplications
with LBˆ1.0 Hz.
Figure 4. Graphics showing oxidation pro®les of the ketosul®de 24) with
complex 2II) 21:1 molar ratio): 2a) Standard oxidation protocol, 2b) complex
2II) added all at once at the beginning of the reaction and 2c) non-coated
complex added under the conditions of the standard reaction protocol. No
sulfone was formed at condition 2a).
All signals were expressed as ppm down®eld from tetra-
methylsilane used as an internal standard 2d value).
Splitting patterns are designated as s 2singlet), d 2doublet),
t 2triplet), dt 2double triplet), q 2quartet), dq 2double quartet),
m 2multiplet).
hundred fold scale reactions were carried out at the standard
reaction conditions for the oxidations of 4-2bromophenyl)
methyl sul®de, benzyl phenyl sul®de and allyl methyl
sul®de. The sulfoxides were isolated in 90, 91 and 75%
yields, respectively. The oxidation reaction of 4-2bromo-
phenyl) methyl sul®de was carried out at 220 8C while
for the other two sul®des at 210 8C.
Microanalysis were recorded on a Fisons Instruments,
model EA 1108ÐCHNS±O.
Â
Melting points were measured using a Microquõmica
apparatus model MQAPF-301 and are uncorrected.
The used complex can be reconstituted on the silica by the

F. Batigalhia et al. / Tetrahedron 57 32001) 9669±9676
9673
The reactions were monitored by thin layer chromatography
2TLC) using precoated silica gel Merck Kiesegel 60F254
210±40 m) plates and developed in the indicated solvent
systems.
UV 2lmax, nm): 210, 256; IR2 nmax, KBr, cm21): 3346, 3118,
1472, 1203, 967, 837, 583, 535. Calcd for [MoO52OPy)
2H2O)]: %C, 20.76; %H, 2.42; %N, 4.84. Found: %C,
20.81; %H, 2.30; %N, 4.92.
The silica gel used in the oxidation reactions as solid
support for the complexes was Davisil 2200±425 mesh
4.2.2. Molybdenum %VI) %oxo diperoxo)-pyrazole %II).
Molybdenum 2VI) oxide; 21.48 g; 13 mmol); 30% v/v
aqueous solution hydroperoxide 212 mL); pyrazole
21.46 g; 13 mmol); 3 M aqueous solution of sulfuric acid
H2SO4 25 mL). Yield: 1.65 g 273%); Yellow powder; UV
2lmax, nm): 235, 252; IR2 nmax, KBr, cm21): 3318, 955, 871,
610, 518. Calcd for [MoO52Pyrazole) 2H2O)]: %C, 13.74;
%H, 2.29; %N, 10.69. Found: %C, 13.85; %H, 2.33; %N,
10.57.
Ê
particle size and 150 A pore size).
The sul®des 21)±23), 213) and 219) were purchased from
Aldrich 2Milwaukee, USA). Sul®des 24)±29) were donated
by the group of Dr Liliana Marzorati while sul®des
220)±224) by the group of Prof Hans Viertler 2Instituto de
Â
Quõmica, Universidade de S. Paulo, SaÄo Paulo, SP, Brazil).
The sul®des 225)±227) were donated to us by the group of
Â
Dr Miguel J. Dabdoub Paz 2Departamento de Quõmica,
Faculdade de Filoso®a, Ciencias e Letras de RibeiraÄo
4.2.3. General procedure for coating the molybdenum
complexes on silica gel on a 40% ratio. Silica gel
21.15 g) was re¯uxed in anhydrous THF 210 mL) for 1 h
at 858C. Then the solubilized complex 20.80 g) in hot
methanol 230 mL) was slowly added to the silica under
re¯ux. The reaction mixture was kept under re¯ux for a
further 3 h. After cooling, it was concentrated in vacuum
and dried in a vacuo oven at 608C for one day. Coated
Complex 2I): IR2 nmax, KBr, cm21): 3447, 3118, 1474,
1212, 833. Coated complex 2II): IR2 nmax, KBr, cm21):
3423, 1619, 1464, 1208, 960, 850, 529.
Ã
Preto, Universidade de SaÄo Paulo, RibeiraÄo Preto, SP). All
the above cited sul®des were prepared in accordance with
the literature work.6±9 The sul®de 215) was prepared by the
reaction of sul®de 213) with diazomethane while sul®des
216) and 218) were prepared in accordance with the works
of Burgess and Henderson.10,11
Methanol and acetonitrile 2HPLC grade, Mallinckrodt
Baker, St. Louis, Missouri, USA) were used as received.
THF was re¯uxed with copper 2I) chloride, dried and
distilled under KOH and stored over sodium metal.
4.2.4. Methyl phenyl sulfoxide: a typical protocol. To a
stirred solution at 2108C of methyl phenyl sul®de 21)
250 mg; 0.402 mmol) in methanol/acetonitrile 21:5 v/v)
22.5 mL), the coated complex 2I) 2290 mg; 0.402 mmol),
was added in portions using a solid addition ¯ask over a
20 min period. After addition, the reaction was warmed to
room temperature and stirred for 23 h The reaction was
followed by TLC and GC. Then, the solids were removed
using a sintered glass funnel. A saturated solution of sodium
hydrogen carbonate 210 mL) was added to the ®ltrate and
then it was extracted with dichlorometane 23£10 mL). The
organic phase was separated, dried over anhydrous sodium
sulfate and concentrated in vacuum. The sulfoxide was
isolated as a colorless oil in 97% yield after purifying by
column chromatography using hexane/ethyl acetate 21:1
v/v) as solvent. IR2 nmax, KBr, cm21): 3004, 2922, 1647,
1431, 1037, 957, 751, 690, 530. 1H NMR2400 MHz;
CDCl3, d): 2.73 2s, 3H); 7.49±7.57 2m, 3H); 7.61±7.68
Sul®des and sulfoxides were puri®ed by column chromato-
graphy on Silica Gel 60 270±230 MeshÐASTM), available
from Merck 2Darmstadt, Germany).
Organic solutions were concentrated under vacuum on
Buchi and Fisaton, evaporator at 20±40 mmHg.
GC analysis was carried out using a GCÐ17 instrument
with a capillary column DB-5 and hydrogen as a carrying
gas. Samples for GC were dissolved in ethyl acetate.
4.2. General procedure for the preparation of
molybdenum %VI) oxodiperoxo complexes
Molybdenum 2VI) oxide was added in portions to an
aqueous hydroperoxide solution 230% v/v), at 08C, under
constant stirring. After most of the molybdenum oxide
had dissolved, the yellow solution was treated with
1 equiv. of the ligand.
2m, 2H). 13C NMR250 MHz; CDCl , d): 43.35; 122.90;
3
128.78; 130.45; 145.13. Calcd for C7H8OS: %C, 59.91;
%H, 5.70; %S, 22.82. Found: %C, 59.98; %H, 5.88; %S,
22.73.
The mixture was stirred for 1 h at room temperature, and
then, a 3 M aqueous solution of sulfuric acid was added. A
yellow precipitate formed and then ®ltered through a
sintered glass funnel; the solid residue was washed with a
solution 1:1 v/v of petroleum ether/2-propanol and concen-
trated in vacuum. The complexes were recrystallized in
2-propanol at 708C and dried in a vacuum oven at 608C in
presence of phosphorus pentoxide for 2 days.
4.2.5. 4-%Bromophenyl) methyl sulfoxide. Isolated as a
colorless solid: mp 74±768C; IR2 nmax, KBr, cm21): 2993,
2906, 1649, 1557, 1039, 942, 811, 680, 505. H NMR
2400 MHz; CDCl3, d): 2.72 2s,3H); 7.51 2d, 1H, Jˆ
8.7 Hz); 7.68 2d, 1H, Jˆ8.7 Hz). 13C NMR250 MHz;
CDCl3, d): 43.74; 124.37; 124.60; 149.37; 153.16. Calcd
for C7H7BrOS: %C, 38.33; %H, 3.19; %S, 14.60. Found:
%C, 38.54; %H, 3.08; %S, 14.41.
1
4.2.1. Molybdenum %VI) %oxo diperoxo)-pyridine-N-
oxide %I). Molybdenum 2VI) oxide 22.06 g; 19 mmol);
30% v/v aqueous solution hydroperoxide 218 mL), pyridine
N-oxide 22.03 g; 19 mmol), 3 M aqueous solution of sul-
furic acid 25 mL). Yield: 3.21 g 287.2%). Yellow powder;
4.2.6. Benzyl phenyl sulfoxide. Isolated as a white solid:
mp 121±1228C; IR2 nmax, KBr, cm21): 2990, 1443, 1030,
743, 684, 480. 1H NMR2400 MHz; CDCl 3, d): 3.98 2d, 1H,
Jˆ12.6 Hz); 4.08 2d, 1H, Jˆ12.6 Hz); 6.95±7.00 2m, 2H);

9674
F. Batigalhia et al. / Tetrahedron 57 32001) 9669±9676
7.20±7.31 2m, 3H); 7.35±7.50 2m, 5H). 13C NMR250 MHz;
CDCl3, d): 63.39; 124.26; 128.09; 128.29; 128.68; 128.99;
130.20; 130.99; 142.63. Calcd for C13H12OS: %C, 72.12;
%H, 5.54; %S, 14.79.Found: %C, 72.32; %H, 5.57; %S,
14.93.
4.2.13. 1-Phenylsul®nyl-3,3-dimethyl-2-butanone. Iso-
lated as a yellow oil. IR2 nmax, KBr, cm21): 2965, 1705,
1580, 1470, 1060, 741, 690, 481. H NMR2400 MHz;
CDCl3, d): 1.05 2s, 9H); 3.85 2d, 1H, Jˆ15.3 Hz); 4.21 2d,
1H, Jˆ15.3 Hz); 7.20 2m, 5H). 13C NMR250 MHz; CDCl 3,
d): 26.60; 42.34; 65.28; 127.55; 129.05; 130.22; 135.54;
209.28. Calcd for C12H16O2S: %C, 64.28; %H, 7.14; %S,
14.28. Found: %C, 64.32; %H, 7.16; %S, 14.26.
1
4.2.7. 1-Phenylsul®nyl-2-propanone. Isolated as a white
solid: mp 74±768C; IR2 nmax, KBr, cm21): 3056, 2907,
1711, 1352, 1034, 739. H NMR2400 MHz; CDCl , d):
1
3
2.24 2s, 3H); 3.79 2d, 1H, Jˆ13.7 Hz); 3.86 2d, 1H, Jˆ
13.7 Hz); 7.52±7.58 2m, 3H); 7.64±7.68 2m, 2H). Calcd
for C9H10O2S: %C, 59.34; %H, 5.49; %S, 17.58. Found:
%C, 59.54; %H, 5.41; %S, 17.30.
4.2.14. 3-Phenylsul®nyl-2-butanone. Isolated as a yellow
oil. IR2 nmax, KBr, cm21): 3063, 2928, 1709, 1580, 1443,
1157, 1060, 746, 488. H NMR2400 MHz; CDCl , d):
1
3
diastereoisomer A: 1.36 2d, 3H, Jˆ7.1 Hz); 2.19 2s, 3H);
3.71 2q, 1H, Jˆ7.1 Hz); 7.49±7.56 2m, 5H); diastereoisomer
B: 1.31 2d, 3H, Jˆ7.1 Hz); 2.24 2s, 3H); 3.80 2q, 1H, Jˆ
7.1 Hz); 7.56±7.73 2m, 5H). 13C NMR250 MHz; CDCl 3, d):
14.14; 26.34; 51.80; 127.92; 129.00; 132.58; 132.71;
205.18. Calcd for C10H12O2S: %C, 61.22; %H, 6.12; %S,
16.32. Found: %C, 61.30; %H, 6.08; %S, 16.30.
4.2.8. 1-%Phenylsul®nyl)acetophenone. Isolated as
a
yellow solid: mp 78±808C; IR2 nmax, KBr, cm21): 3059,
2912, 1675, 1081, 1045, 749. H NMR2400 MHz; CDCl ,
1
3
d): 4.29 2d, 1H, Jˆ14.2 Hz); 4.56 2d, 1H, Jˆ14.2 Hz);
7.42±7.53 2m, 5H); 7.56±7.62 2m, 1H); 7.67±7.72 2m,
2H); 7.85±7.90 2m, 2H). 13C NMR250 MHz; CDCl , d):
3
65.72; 124.03; 128.56; 129.13; 131.33; 133.91; 135.70;
143.02; 191.20. Calcd for C14H12O2S: %C, 68.85; %H,
4.92; %S, 13.11. Found: %C, 68.94; %H, 4.86; %S, 13.03.
4.2.15. 2-%Phenylsul®nyl)cyclopentanone. Isolated as a
brown oil. IR2 nmax, KBr, cm21): 3059, 2963, 2897, 1738,
1443, 1083, 1043, 825, 750, 694. H NMR2400 MHz;
1
CDCl3, d): diastereoisomer A: 1.86±1.98 2m, 4H); 2.26±
2.44 2m, 2H); 3.58 2t, 1H, Jˆ3.8 Hz); 7.25±7.33 2m, 3H);
7.45±7.48 2m, 2H); diastereoisomer B: 1.99±2.20 2m, 4H);
2.69±2.98 2m, 2H); 3.67 2t, 1H, Jˆ3.8 Hz); 7.25±7.33 2m,
4.2.9. 1-Phenylsul®nyl-4-methyl acetophenone. Isolated
as a white solid: mp 62±648C; IR2 nmax, KBr, cm21):
2947, 2835, 1657, 1025, 733. H NMR2400 MHz; CDCl ,
1
3
d): 2.41 2s, 3H); 4.26 2d, 1H, Jˆ14.1 Hz); 4.55 2d, 1H, Jˆ
3H); 7.45±7.48 2m, 2H). 13C NMR250 MHz; CDCl , d):
3
14.1 Hz); 7.22±7.27 2m, 2H); 7.47±7.52 2m, 3H); 7.67±7.71
22.14; 31.88; 50.13; 58.40; 128.56; 129.01; 130.01; 131.55;
137.31; 217.80. Calcd for C11H12O2S: %C, 63.46; %H, 5.76;
%S, 15.38. Found: %C, 63.45; %H, 5.70; %S, 15.41.
2m, 2H); 7.75±7.80 2m, 2H). 13C NMR250 MHz; CDCl ,
3
d): 21.65; 41.14; 126.98; 128.80; 129.01; 129.36; 130.42;
132.95; 134.98; 144.37; 193.71. Calcd for C15H14O2S: %C,
69.76; %H, 5.42; %S, 12.40. Found: %C, 69.86; %H, 5.57;
%S, 12.50.
4.2.16. Phenylsul®nyl acetic acid. Isolated as a white solid:
mp 63±658C; IR2 nmax, KBr, cm21): 3279, 2965, 2889,
1723, 1421, 1076, 1040, 825, 750, 694. H NMR2400
1
4.2.10. 1-Ethylsul®nyl-4-methyl acetophenone. Isolated
as a yellow solid: mp 54±558C; IR2 nmax, KBr, cm21):
2928, 1954, 1670, 1605, 1410, 1014, 812, 447. H NMR
2400 MHz; CDCl3, d): 1.40 2t, 3H, Jˆ7.5 Hz); 2.43 2s,
3H); 2.83 2dq, 1H, Jˆ7.5, 13.3 Hz); 2.99 2dq, 1H, Jˆ7.5,
13.3 Hz); 4.25 2d, 1H, Jˆ14.2 Hz); 4.42 2d, 1H, Jˆ
14.2 Hz); 7.25±7.33 2m, 2H); 7.84±7.90 2m, 2H). 13C
MHz; CDCl3, d): 3.78 2d,1H, Jˆ13.6 Hz); 3.90 2d, 1H,
Jˆ13.6 Hz); 7.52±7.58 2m, 3H); 7.66±7.72 2m, 2H). 13C
NMR250 MHz; CDCl 3, d): 36.65; 127.29; 129.20;
130.14; 134.52; 175.91. Calcd for C8H8O3S: %C, 52.11;
%H, 4.34; %S, 17.37. Found: %C, 52.20; %H, 4.30; %S,
17.41.
1
NMR250 MHz; CDCl , d): 14.11; 21.55; 26.21; 36.66;
3
4.2.17. Phenylsul®nyl acrylic acid. Isolated as a white
solid: mp 102±1048C; IR2 nmax, KBr, cm21): 3458, 2972,
2891, 1725, 1612, 1423, 1060, 1013, 825, 750, 694. H
128.85; 129.18; 129.26; 132.78; 143.94; 194.12. Calcd for
C11H14O2S: %C, 62.86; %H, 6.67; %S, 15.23. Found: %C,
62.94; %H, 6.57; %S, 15.26.
1
NMR2400 MHz; CDCl 3, d): 5.62 2d, 1H, Jˆ15.0 Hz);
7.90 2d, 1H, Jˆ15.0 Hz); 7.20±7.25 2m, 1H); 7.35±7.44
4.2.11. 1-Methylsul®nyl-2-propanone. Isolated as
a
2m, 2H); 7.47±7.52 2m, 2H). 13C NMR250 MHz; CDCl ,
3
yellow solid: mp 59±608C; IR2 nmax, KBr, cm21): 2974,
2922, 1725, 1093, 1032, 511. H NMR2400 MHz; CDCl ,
d): 112.44; 128.49; 129.48; 131.23; 135.93; 152.98; 170.83.
Calcd for C9H8O3S: %C, 55.10; %H, 4.08; %S, 16.32.
Found: %C, 55.00; %H, 4.18; %S, 16.41.
1
3
d): 2.27 2s, 3H); 3.83 2d, 1H, Jˆ13.7 Hz); 3.92 2d, 1H,
Jˆ13.7 Hz); 6.21 2s, 3H). Calcd for C4H8O2S: %C, 40.00;
%H, 6.67; %S, 26.67. Found: %C, 40.10; %H, 6.70; %S,
26.50.
4.2.18. Methyl 2-%phenylsul®nyl)acetate. Isolated as a
yellow oil. IR2 nmax, KBr, cm21): 2927, 1736, 1444, 1045,
749, 691, 487. 1H NMR2400 MHz; CDCl 3, d): 3.72 2s, 3H);
3.68 2d, 1H, Jˆ13.6 Hz); 3.86 2d, 1H, Jˆ13.6 Hz); 7.52±
7.59 2m, 3H); 7.66±7.73 2m, 2H). Calcd for C9H10O3S: %C,
54.54; %H, 5.05; %S, 16.16. Found: %C, 54.45; %H, 5.16;
%S, 16.26.
4.2.12. 1-Ethylsul®nyl-2-propanone. Isolated as a white
solid: mp 44±468C; IR2 nmax, KBr, cm21): 2930, 1713,
1451, 1177, 1022, 754, 610. H NMR2400 MHz; CDCl ,
1
3
d): 1.33 2t, 3H); 2.75 2m, 2H); 2.29 2s, 3H); 3.61 2d, 1H,
Jˆ13.6 Hz); 3.73 2d, 1H, Jˆ13.6 Hz). 13C NMR250 MHz;
CDCl3, d): 14.20; 26.09; 27.62; 41.63; 203.87. Calcd for
C5H10O2S: %C, 44.77; %H, 7.46; %S, 23.88. Found: %C,
44.86; %H, 7.57; %S, 23.93.
4.2.19. Ethyl 2-%phenylsul®nyl)butanoate. Isolated as a
yellow oil. IR2 nmax, KBr, cm21): 2984, 1734, 1454, 1160,
1079, 1048, 854, 755. 1H NMR2400 MHz; CDCl 3, d): 1.21

F. Batigalhia et al. / Tetrahedron 57 32001) 9669±9676
9675
2t, 3H, Jˆ7.1 Hz); 1.49 2s, 6H); 4.11 2q, 2H, Jˆ7.12 Hz);
7.28±7.40 2m, 3H); 7.45±7.50 2m, 2H). 13C NMR250 MHz;
CDCl3, d): 13.99; 25.84; 50.84; 61.00; 128.56; 129.25;
131.52; 136.72; 173.76. Calcd for C12H16O3S: %C, 60.00;
%H, 6.67; %S, 13.33. Found: %C, 60.10; %H, 6.57; %S,
13.26.
4.2.25. 2-Cyclopentenyl benzyl sulfoxide. Isolated as a
white solid: mp 58±608C; IR2 nmax, KBr, cm21): 2928,
2840, 1650, 1449, 1027, 971, 767, 695, 479. H NMR
1
2400 MHz; CDCl3, d): 1.80±1.89 2m, 2H); 2.16±2.21 2m,
2H); 2.21±2.30 2m, 2H); 2.50±2.53 2m, 2H); 2.65±2.78 2m,
2H); 3.95 2d, 1H, Jˆ12.8 Hz); 4.05 2d, 1H, Jˆ12.8 Hz);
5.36±5.38 2m, 1H); 7.26±7.41 2m, 5H). 13C NMR250
MHz; CDCl3, d): 23.34; 23.96; 32.46; 35.04; 49.25;
58.37; 125.72; 128.39; 129.01; 129.80; 130.02; 141.06.
Calcd for C14H18OS: %C, 71.79; %H, 7.69; %S, 13.67.
Found: %C, 71.86; %H, 7.66; %S, 13.50.
4.2.20. Ethyl %phenylsul®nyl)ethanoate. Isolated as a
yellow oil. IR2 nmax, KBr, cm21): 2982, 1734, 1582, 1476,
1028, 743, 479. 1H NMR2400 MHz; CDCl 3, d): 1.21 2t, 3H,
Jˆ7.2 Hz); 3.68 2d, 1H, Jˆ13.6 Hz); 3.85 2d, 1H, Jˆ
13.6 Hz); 4.15 2q, 2H, Jˆ7.2 Hz); 7.52±7.57 2m, 3H);
7.66±7.73 2m, 2H). 13C NMR250 MHz; CDCl , d): 13.99;
4.2.26. 4-Pentenyl benzyl sulfoxide. Isolated as a yellow
solid: mp 46±488C; IR2 nmax, KBr, cm21): 3076, 2920,
2850, 1633, 1493, 1450, 1024, 913, 768, 699, 483, 388.
1H NMR2400 MHz; CDCl 3, d): 1.80±1.92 2m, 2H);
2.10±2.25 2m, 2H); 2.54±2.61 2m, 2H); 3.94 2d, 1H,
Jˆ12.9 Hz); 4.03 2d, 1H, Jˆ12.9 Hz); 4.99 2dq, 1H,
Jˆ1.2, 10.3 Hz); 5.01 2dq, 1H, Jˆ1.6, 17.0 Hz); 5.73 2ddt,
1H, Jˆ6.7, 10.3, 17.0 Hz); 7.26±7.31 2m, 2H); 7.33±7.41
3
36.65; 61.42; 126.87; 128.93; 129.94; 134.96; 169.56. Calcd
for C10H12O3S: %C, 56.60; %H, 5.66; %S, 15.09. Found:
%C, 56.54; %H, 5.59; %S, 15.00.
4.2.21. Ethyl 2-%phenylsul®nyl)propanoate. Isolated as a
yellow oil. IR2 nmax, KBr, cm21): 1982, 1730, 1455, 1161,
1053, 754, 695. 1H NMR2400 MHz; CDCl , d): diastereo-
3
isomer A: 1.20 2t, 3H, Jˆ7.1 Hz); 1.48 2d, 3H, Jˆ7.2 Hz);
3.81 2q, 2H, Jˆ7.1 Hz); 4.13 2d, 1H, Jˆ7.2 Hz); 7.50±7.55
2m, 3H); 7.58±7.60 2m, 2H); diastereoisomer B: 1.20 2t, 3H,
Jˆ7.1 Hz); 1.48 2d, 3H, Jˆ7.2 Hz); 3.81 2q, 2H, Jˆ7.1 Hz);
4.11 2d, 1H, Jˆ7.2 Hz); 7.50±7.55 2m, 3H); 7.58±7.60 2m,
2m, 3H). 13C NMR250 MHz; CDCl , d): 21.67; 32.62;
3
50.22; 58.45; 116.10; 119.09; 128.39; 129.01; 130.01;
130.55; 136.82. Calcd for C12H16OS: %C, 69.23; %H,
7.69; %S, 15.38. Found: %C, 69.20; %H, 7.65; %S, 15.41.
2H). 13C NMR250 MHz; CDCl , d): 14.00; 17.32; 45.15;
4.2.27. 2-Cyclohexenyl benzyl sulfoxide. Isolated as a
white solid: mp 66±688C; IR2 nmax, KBr, cm21): 3064,
2931, 2858, 1637, 1490, 1452, 1033, 912, 768, 699, 483,
3
61.00; 127.88; 128.83; 129.05; 132.98; 172.43. Calcd for
C11H14O3S: %C, 58.40; %H, 6.19; %S, 14.16. Found: %C,
58.45; %H, 6.16; %S, 14.26.
1
388. H NMR2400 MHz; CDCl , d): 1.48±1.63 2m, 4H);
3
1.85±1.89 2m, 2H); 1.95±1.99 2m, 2H); 2.15±2.19 2m, 1H);
2.47±2.51 2m, 1H); 2.63±2.70 2m, 2H); 3.95 2d, 1H,
Jˆ12.8 Hz); 4.03 2d, 1H, Jˆ12.8 Hz); 5.40±5.42 2m, 1H);
4.2.22. Allyl methyl sulfoxide. Isolated as a brown oil. IR
2nmax, KBr, cm21): 3088, 3001, 2925, 1649, 1431, 1049,
951, 743. H NMR2400 MHz; CDCl , d): 2.01 2s, 3H);
1
7.25±7.38 2m, 5H). 13C NMR250 MHz; CDCl , d): 22.25;
3
3
3.09 2dt, 2H, Jˆ7.1, 1.1 Hz); 5.08 2dq, 1H, Jˆ1.4,
17.1 Hz); 5.09 2dq, 1H, Jˆ1.1, 10.2 Hz); 5.76 2ddt, 1H,
Jˆ7.1, 10.2, 17.1 Hz). 13C NMR250 MHz; CDCl 3, d):
14.28; 36.86; 116.88; 134.08. Calcd for C4H8OS: %C,
46.08; %H, 7.68; %S, 30.72. Found: %C, 46.10; %H,
7.66; %S, 30.76.
22.80; 25.21; 28.29; 30.45; 49.38; 58.30; 123.41; 128.36;
128.99; 129.70; 130.03; 134.53. Calcd for C15H20OS: %C,
72.58; %H, 8.06; %S, 12.90. Found: %C, 72.59; %H, 8.08;
%S, 12.98.
4.2.28. %Z)-1-Phenylsul®nyl-2-hepthylethene. Isolated as a
yellow oil. IR2 nmax, KBr, cm21): 2927, 2860, 1453, 1038,
738. H NMR2400 MHz; CDCl , d): 0.86±0.91 2m, 3H);
1
4.2.23. 3-Methyl-3-butenyl benzyl sulfoxide. Isolated as a
white solid: mp 48±508C; IR2 nmax, KBr, cm±1): 3077, 2919,
1648, 1445, 1036, 894, 758, 703, 470. 1H NMR2400 MHz;
CDCl3, d): 1.72±1.73 2m, 3H); 2.41±2.48 2m, 2H); 2.66±
2.74 2m, 2H); 3.96 2d, 1H, Jˆ12.9 Hz); 4.06 2d, 1H,
Jˆ12.9 Hz); 4.72±4.73 2m, 1H); 4.80±4.82 2m, 1H);
3
1.23±1.36 2m, 10H); 2.52±2.66 2m, 2H); 6.18±6.24 2m,
1H); 6.62 2dt, 1H, Jˆ6.8, 15.5 Hz); 7.45±7.52 2m, 5H).
13C NMR250 MHz; CDCl 3, d): 14.11; 22.66; 29.06;
29.14; 29.21; 31.86; 122.57; 128.76; 128.95; 129.95;
133.78; 136.62. Calcd for C15H22OS: %C, 72.00; %H,
8.80; %S, 12.80. Found: %C, 72.10; %H, 8.85; %S, 12.78.
7.25±7.39 2m, 5H). 13C NMR250 MHz; CDCl , d): 22.40;
3
30.16; 49.04; 58.40; 112.00; 128.40; 129.02; 129.98;
130.00; 142.46. Calcd for C12H16OS: %C, 69.23; %H,
7.69; %S, 15.38. Found: %C, 69.20; %H, 7.65; %S, 15.41.
4.2.29. %Z)-1-Phenylsul®nyl-2-hexylethene. Isolated as a
white oil. IR2 nmax, KBr, cm21): 2928, 2862, 1455, 1040,
741. 1H NMR2400 MHz; CDCl 3, d): 0.89 2t, 3H, Jˆ
7.0 Hz); 1.25±1.36 2m, 8H); 2.25 2dq, 2H, Jˆ1.4, 7.3 Hz);
5.82 2dt, 1H, Jˆ7.3, 9.2 Hz); 6.18 2dt, 1H, Jˆ1.4, 9.2 Hz);
4.2.24. 5-Phenyl-4-pentenyl benzyl sulfoxide. Isolated as a
yellow solid: mp 49±518C; IR2 nmax, KBr, cm21): 3029,
2927, 1603, 1490, 1123, 1037, 975, 752, 701, 490. H
1
7.25±7.35 2m, 5H). 13C NMR250 MHz; CDCl , d): 14.11;
3
NMR2400 MHz; CDCl , d): 1.56±1.70 2m, 2H); 1.90±
3
22.63; 28.78; 28.95; 29.13; 33.09; 122.48; 128.65; 128.90;
129.03; 133.72; 136.55. Calcd for C14H20OS: %C, 71.18;
%H, 8.47; %S, 13.56. Found: %C, 71.10; %H, 8.57; %S,
13.50.
2.10 2m, 2H); 2.22±2.40 2m, 2H); 3.94 2d, 1H, Jˆ
12.9 Hz); 4.04 2d, 1H, Jˆ12.9 Hz); 6.12 2dt, 1H, Jˆ7.0,
15.8 Hz); 6.40 2dt, 1H, Jˆ1.4, 15.8 Hz); 7.22±7.40 2m,
10H). 13C NMR250 MHz; CDCl 3, d): 20.32; 30.65;
36.57; 52.37; 124.08; 127.19; 127.60; 127.75; 128.99;
129.08; 129.16; 129.29; 132.57; 137.09. Calcd for
C18H20OS: %C, 76.05; %H, 7.04; %S, 11.27. Found: %C,
76.00; %H, 7.08; %S, 11.30.
4.2.30. %Z)-1-Phenylsul®nyl-2-phenylethene. Isolated as a
yellow oil. IR2 nmax, KBr, cm21): 3050, 2888, 1483, 1033,
747. 1H NMR2400 MHz; CDCl 3, d): 6.49 2d, 1H, Jˆ
10.7 Hz); 6.59 2d, 1H, Jˆ10.7 Hz); 7.13±7.52 2m, 10H).

9676
F. Batigalhia et al. / Tetrahedron 57 32001) 9669±9676
4. Bonchio, M.; Caro®glio, T.; Di Furia, F.; Fornasier, R. J. Org.
Chem. 1995, 60, 5986±5988.
Calcd for C14H12OS: %C, 73.68; %H, 5.26; %S, 14.03.
Found: %C, 73.65; %H, 5.30; %S, 14.13.
5. The Chemistry of Sulphones and Sulphoxides, Patai, S.,
Rappaport, Z., Stirling, C., Eds.; Wiley: Chichester, 1988.
6. Lattanzi, A.; Bonadies, F.; Scettri, A. Tetrahedron: Asym-
metry 1997, 8 213), 2141±2151.
4.3. Macroscale oxidation: a typical protocol
4.3.1. 4-%Bromophenyl) methyl sulfoxide. To a stirred
solution at 2208C of 4-2bromophenyl) methyl sul®de 22)
28.13 g; 40 mmol) in methanol/acetonitrile 21:5 v/v)
2650 mL), the coated complex 2I) 228.78 g; 40 mmol), was
added in portions using a solid addition ¯ask over a 20 min
period. After addition, the reaction was warmed to room
temperature and stirred for 13 h. The reaction was followed
by TLC and GC. Then, the solids were removed using
a sintered glass funnel. A saturated solution of sodium
hydrogen carbonate 2500 mL) was added to the ®ltrate and
then it was extracted with dichlorometane 23£500 mL). The
organic phase was separated, dried over anhydrous sodium
sulfate and concentrated in vacuum. The sulfoxide was
isolated as a colorless solid in 90% yield.
7. Reetz, M. T.; Merk, C.; Naberfeid, G.; Rudolph, J.;
Grieberow, N.; Gossard, R. Tetrahedron Lett. 1997, 38 230),
5273±5276.
8. Belleau, B.; Gulini, U.; Gour-Salin, B.; Ahmed, F. R. Can. J.
Chem. 1985, 63, 1268±1274.
Â
9. Guerrero Jr., P. G. PhD Thesis, Departamento de Quõmica,
Ã
Faculdade de Filoso®a Ciencias e Letras de RibeiraÄo Preto,
Universidade de SaÄo Paulo, RibeiraÄo Preto, SP, Brazil, 2000,
377p.
10. Burgess, K.; Henderson, I. Tetrahedron Lett. 1989, 30 228),
3633±3636.
11. Burgess, K.; Henderson, I. Tetrahedron Lett. 1989, 30 233),
4325±4328.
12. Liu, K. T.; Tong, Y. C. J. Org. Chem. 1978, 43 213), 2717±
2718.
Acknowledgements
13. Hashmat Ali, M.; Stevens, W. Synthesis 1997, 764±768.
14. Hashmat Ali, M.; Bohnert, G. J. Synthesis 1998, 1238±1240.
15. Firouzabadi, H.; Abbasi, M. Synth. Commun. 1999, 29 29),
1485±1491.
We thank CNPq, CAPES and Fapesp for ®nancial support
and for grants.
16. Kropp, P. J.; Breton, G. W.; Fields, J. D.; Tung, J. C.; Loomis,
B. R. J. Am. Chem. Soc. 2000, 122, 4280±4285.
17. Hernandez, M. Z. Masters Dissertation, Departamento de
References
Â
Quõmica, Universidade Federal de SaÄo Carlos, SaÄo Carlos,
SP, Brazil, 1998, 129p.
18. Sensato, F. R.; Cass, Q. B.; Longo, E.; Zukerman-Schpector,
1. Mimoun, H.; de Roche, I. S.; Sajus, L. Bull. Chem. Soc. Fr.
1969, 5, 1481±1492.
2. Schuring, V.; Hintzer, K.; Leyrer, U.; Mark, C.; Pitchen, P.;
Kagan, H. B. J. Organomet. Chem. 1989, 370, 81±96.
3. Winter, W.; Mark, C.; Schurig, V. Inorg. Chem. 1980, 19,
2045±2048.
Â
J.; Custodio, R.; Andres, J.; Hernandes, M. Z.; Longo, R. L.
Inorg. Chem. 2001 in press.