Reactions of organocobaloximes with aryldisulfonyl chlorides

Article abstract of DOI:10.1016/j.jorganchem.2004.01.001

Photochemical reactions of benzyl, heteroaromaticmethyl and allylcobaloximes with aryldisulfonyl chlorides yield symmetrical disulfones. Allyl cobaloximes yield allyldisulfones as the major product whereas bibenzyl is the major product in benzylcobaloximes. A time dependent ¹H NMR studies show that bibenzyl is formed from O -benzyldimethylglyoxime - a predominant product in the initial stage of the reaction.

Full text of DOI:10.1016/j.jorganchem.2004.01.001

Journal of Organometallic Chemistry 689 (2004) 1102–1109
www.elsevier.com/locate/jorganchem
Reactions of organocobaloximes with aryldisulfonyl chlorides q
*
B.D. Gupta , V. Vijaikanth
Department of chemistry, Indian Institute of Technology, Kanpur 208016, India
Received 20 October 2003; accepted 19 January 2004
Dedicated to Prof. M. Tada, Waseda University, Japan
Abstract
Photochemical reactions of benzyl, heteroaromaticmethyl and allylcobaloximes with aryldisulfonyl chlorides yield symmetrical
disulfones. Allyl cobaloximes yield allyldisulfones as the major product whereas bibenzyl is the major product in benzylcobaloximes.
1
A time dependent H NMR studies show that bibenzyl is formed from O-benzyldimethylglyoxime – a predominant product in the
initial stage of the reaction.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Organocobaloximes; Disulfonyl chlorides; SH2 reactions; Disulfone; Bibenzyl-O-benzyldimethylglyoxime; 1H NMR studies
1. Introduction
[26c]. Sulfonyl group is a synthetically useful functional
group and has recently been reported as potential ste-
reoinducer [28]. It has also been utilized for carbon–
carbon bond formation as carbonyl group equivalents
for many synthetic transformations [29]. In particular,
benzyl and allyl sulfones have been used in many or-
ganic transformations [30]. Allylic aryl sulfones serve as
valuable intermediates in the carbon–carbon bond for-
mation via alkylation of sulfonyl anion [31]. Disulfones
find application in polymerization reactions [32] and in
natural product synthesis [33].
Since little information is known on the synthesis of
disulfones, we have carried out the reaction of organo-
cobaloximes with aryldisulfonyl chlorides, ClO2S–Ar–
SO2Cl, having two reactive SO2–Cl bonds. The aim of
the study is (i) to gain more insight into the SH2/SH20
reaction with two reactive free radical centers, (ii) to
understand the mechanism of the formation of bibenzyl
and (iii) to develop a general method for the synthesis of
symmetrical disulfones, RO2S–Ar–SO2R.
The use of organocobalt complexes to mediate or
catalyze the organic reactions has grown tremendously
in the last few years [1]. There are several type of reac-
tions where cobalt complexes have played a prominent
role as stoichiometric reagents or catalysts [2–5]. In
particular the application of organocobaloximes in or-
ganic synthesis is well documented in the literature [6–8].
Organocobaloximes have recently been used for the
synthesis of sulfones [9], for example allyl [10–15], ben-
zyl [16–18], heteroaromaticmethyl [17,19], allenyl
[20,21], propargyl [20,21] and alicyclic phenyl sulfone
[20–25] have been synthesized.
Sulfone functionality is ubiquitous in nature where it
serves several important roles [26]. Recently, it has been
identified as HIV-1 non-nucleoside reverse transcriptase
inhibitor, which led to the idea of developing novel
synthetic sulfones [27]. Several synthetic methodologies
have appeared in which sulfone is involved as an acti-
vating group and its use as intermediates in total syn-
thesis of many natural products has become a classic
q The preliminary account of this work has been published (B.D.
Gupta, V. Singh, K. Qanungo, V. Vijaikanth and R.S. Sengar, J.
Organomet. Chem. 582 (1999) 279).
* Corresponding author. Tel.: +91-512-2597046; fax: +91-512-
2597436.
E-mail address: bdg@iitk.ac.in (B.D. Gupta).
2. Results and discussion
Benzyl (1–5), heteroaromaticmethyl (6–8) and allyl
(9–11) cobaloximes are reacted with disulfonyl chlo-
rides, 4,40-biphenyldisulfonyl chloride (A) and 2,4-mes-
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.01.001

B.D. Gupta, V. Vijaikanth / Journal of Organometallic Chemistry 689 (2004) 1102–1109
1103
itylenedisulfonyl chloride (B) in 1:2 molar ratio in di-
chloromethane at 0 °C under anaerobic and photolytic
condition. A smooth reaction takes place and is com-
plete within 3 h to give a mixture of products, disulfone,
dimer and O-organodimethyl glyoxime (dmgH ether).
The ratio and yield of these products depends on the
nature of the cobaloxime, reaction time and the reaction
conditions (Schemes 1 and 2 Table 1).
Benzyl cobaloxime (1) on reaction with A forms di-
sulfone 1a and bibenzyl 1c in 15% and 52% yield, re-
spectively. A similar reaction occurs with cobaloximes 2
and 3 to yield disulfones (2a and 3a) and the substituted
bibenzyl (2c and 3c). However no disulfone is formed with
4 and 5, only the dimer products (4c and 5c) are isolated.
B reacts in a similar way with cobaloximes 1–5 to give a
mixture of disulfones (1b–5b) and bibenzyl (1c–5c) in
varying yields. No disulfone is formed in the reaction with
5. The amount of bibenzyl formed is always more than
the disulfone. In the reaction of B with 1 and 3, dmgH
ether 1d and 3d are also formed in low yield (<5%).
Furfuryl cobaloxime 6, on reaction with A and B
exclusively forms the disulfones 6a and 6b in 57% and
44% yield, respectively. No other organic product is
formed (Scheme 1, Table 1). However, the reactions of
the disulfonyl chlorides with cobaloximes 7 and 8
proceed differently. For example, A on reaction with 7
forms the disulfone 7a exclusively whereas no disulfone
is formed with 8. The only products isolated in the
latter are the dimer 8c and the dmgH ether 8d. On the
other hand, B on reaction with cobaloximes 7 and 8
forms the disulfones 7b, 8b; dimers 7c, 8c and dmgH
ethers 7d, 8d.
The disulfonyl chloride A and B react with allyl (9)
and crotyl (10) cobaloximes 9 and 10 to yield the cor-
responding disulfones, 9a, 9b, 10a and 10b in 72–99%
yield (Scheme 2, Table 1). No other product is formed.
a-Pinenyl cobaloxime 11, however, forms the disulfone
11a in 37% yield with A and no disulfone with B. Dimer
11c and dmgH ether 11d are the only products isolated.
ClCoIII(dmgH)2Py is the main inorganic product iso-
lated in these reactions and no attempt has been made to
characterize the other water-soluble inorganic products.
Many observations are made from independent re-
actions. (a) The reactions do not proceed in dark. (b) All
the organocobaloximes are stable in solution under inert
atmosphere in the absence of aryldisulfonyl chloride. (c)
The reaction of A with PhCH2Co(dmgH)2L (L ¼ 4-t-bu-
Py) under photochemical condition is complete in 3 h
and forms bibenzyl (79%), dmgH ether (2%) and di-
sulfone (1%). when L is 4-cyanopyridine, the same re-
Scheme 1.

1104
B.D. Gupta, V. Vijaikanth / Journal of Organometallic Chemistry 689 (2004) 1102–1109
Scheme 2.
Table 1
Organic products from the reaction of organocobaloximes (1–11) with aryldisulfonyl chlorides (A and B)
RCo
Disulfonyl chloride
Disulfone
Dimer
Dmg–ether
1
A
B
1a (15)
1b (5)
1c (52)
1c (90)
1d (–)
1d (2)
2
3
A
B
2a (3)
2b (4)
2c (61)
2c (60)
2d (–)
2d (–)
A
B
3a (21)
3b (12)
3c (52)
3c (45)
3d (–)
3d (3)
4
A
B
4a (–)
4b (4)
4c (78)
4c (8)
4d (1)
4d (–)
5
A
B
5a (–)
5b (–)
5c (86)
5c (57)
5d (–)
5d (–)
6
A
B
6a (57)
6b (44)
6c (–)
6c (–)
6d (–)
6d (–)
7
A
B
7a (64)
7b (12)
7c (–)
7c (7)
7d (–)
7d (5)
8
A
B
8a (–)
8b (20)
8c (15)
8c (26)
8d (6)
8d (15)
9
A
B
9a (72)
9b (86)
–
–
–
–
10
11
A
B
10a (99)
10b (85)
–
–
–
–
A
B
11a (37)
–
11c (34)
11c (35)
11d (7)
action takes 10 h to complete and yields bibenzyl (31%),
dmgH ether (2%) and disulfone (1%). The reaction of A
with 1 in the presence of two equivalents of pyridine
yields bibenzyl (80%) in 5 h. (d) The reaction of A with
PhCH2Co(dpgH)2Py requires 5 h to complete and yields
bibenzyl (50%) and disulfone (4%).

B.D. Gupta, V. Vijaikanth / Journal of Organometallic Chemistry 689 (2004) 1102–1109
1105
All the reactions are free radical in nature as inferred
from the experimental observations and the nature of
products formed. Since the Co–C bond in organocoba-
loximes is weak (17–30 kcal molꢀ1) and photolabile, it
can be cleaved even at wavelength above 360 nm [34].
Tungsten lamp and glass apparatus are, therefore, ade-
quate for preparative photolysis experiments. Arene-
sulfonyl chlorides have previously been identified as
chain-propagating species in many organic reactions of
alkenes as well as in the reaction with organocobaloxi-
mes [35]. Cobaloxime (II), a d7 species, formed during
the homolysis of Co–C bond has been observed to be a
good leaving group [35c,35d].
The general characteristics of the reaction of organo-
cobaloximes 1–11 with aryldisulfonyl chloride, A and B
are similar to the reaction of the same substrates with
arylsulfonyl chloride described earlier by us [15–18]. We
believe that a similar mechanism might be operating here.
The most surprising result in the present study is the
lack of formation (or a low yield) of disulfone in the
reaction of benzyl cobaloximes (1–5) with A or B. Bib-
enzyl is the major or the only product isolated in such
cases. Since benzylcobaloxime in the absence of A or B is
stable under inert conditions, the formation of such a
high proportion of bibenzyl is very surprising. It sug-
gests that simple homolysis of the Co–C bond followed
by dimerisation of the benzyl radicals cannot be the only
pathway for its formation. In order to rationalize the
Fig. 2. Time dependent 1H NMR spectra of the reaction of 1 with
p-toluenesulfonyl chloride.
ether (1d) disappears. The amount of disulfone, how-
ever, remains constant during the course of the reaction
(Fig. 1). So, only disulfone and bibenzyl are isolated at
the end of the reaction (Table 1). The reaction of 4-
methoxybenzyl cobaloxime (4) with A, monitored by 1H
NMR, also shows the similar result.
1H NMR monitoring experiment on the previously
reported reaction of benzylcobaloxime with ArSO2Cl
[17] gives identical result. All the three products are
formed in the initial stage and later dmgH ether product
gets consumed as the reaction progresses (Fig. 2). This
confirms that the formation of dmgH ether and its
conversion into bibenzyl is a general phenomenon in the
reaction of benzyl cobaloxime with arylsulfonyl chlo-
rides. The extent of formation of bibenzyl and dmgH
ether is a function of reaction time; if it is run longer all
the dmgH ether will convert to bibenzyl.
1
results we have studied the progress of reaction by H
NMR. The 1H NMR spectra of the organic products in
the reaction of A with benzylcobaloxime 1 has been
measured at different time intervals (Fig. 1). The result
shows that the disulfone 1a, bibenzyl 1c and dmgH ether
1d are formed in the initial stage of the reaction with 1d
as the predominant product. As the reaction progresses,
the amount of bibenzyl increases at the cost of dmgH
ether and finally the peak corresponding to the dmgH
It is difficult to pinpoint the exact mechanism of the
conversion of dmgH ether to bibenzyl. The cleavage of
benzyl–O bond into iminoxyl and benzyl radical occurs
under the photolysis conditions. A recent report has
shown that benzophenone–O-benzyloxime forms biben-
zyl by the free radical dimerization of the benzyl radicals,
produced as a result of the homolysis of the benzyl–O
bond, when heated in a sealed tube at 200 °C [36]. The
preferential cleavage of C–O bond (bond energy 68 kcal/
mol) over N–O bond (48 kcal/mol) may be attributed to
the resonance stabilization of benzyl radicals.
We have also observed that the reaction of A with 1
under thermal condition (refluxing dichloromethane and
diffused light) is slow and remains incomplete even after
10 h. DmgH ether (1d, 20%) and bibenzyl (1c, 2%) are
the only organic products isolated. No disulfone is
formed. Johnson et al. [11] have also made similar
observation earlier. It is, therefore, clear that dmgH
ether is formed in both thermal and photochemical
Fig. 1. Time dependent 1H NMR spectra of the reaction of 1 with A.

1106
B.D. Gupta, V. Vijaikanth / Journal of Organometallic Chemistry 689 (2004) 1102–1109
conditions, but the decomposition of dmgH ether to
bibenzyl occurs only under photochemical condition.
All our efforts to improve the yield of disulfone have
failed. For example, the use of a stronger base than
pyridine and carrying out the reaction in the presence
of excess free pyridine, the modifications partially
successful in increasing the yield of sulfones in the re-
action of RSO2Cl with benzyl cobaloximes [17] have
failed in the present case. The distinct difference
might be due to the higher stability of the disulfonyl
diradical.
The use of bulky equatorial ligand, dpgH in place of
dmgH, has been shown to be more selective and more
reactive in exo-selective Diels–Alder reactions and in
radical alkyl–alkenyl cross-coupling reactions [37,38].
This also does not improve the yield of the disulfone in
the present study.
ginning. The absence of any cross-coupling product
supports the concerted mechanism.
3. Conclusions
Symmetrical disulfones are formed in the reaction of
organocobaloximes with aryldisulfonyl chlorides. The
reactions are more complicated as compared to the re-
actions of the same organocobaloximes with monos-
ulfonyl chlorides. Allyl cobaloximes yield disulfones in
good yield whereas bibenzyl is the major product in
benzyl cases. 1H NMR studies have confirmed that
bibenzyl is formed from O-benzyldimethylglyoxime, a
product in the initial stage of the reaction. The conver-
sion of O-benzyldimethylglyoxime to bibenzyl has been
reported for the first time.
Two more factors have been considered to increase
the yield of the disulfone (i) by increasing the nucleo-
philicity of the cobalt bound CH2 group and hence in-
creasing the rate of SH2 reaction and (ii) to inhibit/retard
the electron transfer process [17] responsible for the
formation of dmgH ether. The introduction of a meth-
oxy group in the m- or p-position, known to increase the
reactivity of cobalt bound CH2group towards electro-
philes [39], does not make any significant improvement
in the disulfone formation in the present study. The
yield, however, is visibly improved in the reaction of A
or B with furfuryl (6) and 2-thienylmethyl (7) coba-
loximes, where the Co–CH2 bond is more nucleophilic
than the Co–benzyl bond. As observed earlier, the
RCoIII–RCoIV potential is high (compared to benzyl)
that inhibits the formation of intermediate RCoIV [39].
Allyl cobaloximes have always been observed to be far
more reactive towards the electrophilic radicals as
compared to the benzyl cobaloximes [14].
The disulfone may arise by the SH2/SH20 attack
(concerted or stepwise) of the sulfonyl radical at the
alpha carbon in benzyl cobaloxime (or c carbon in allyl).
This generates cobaloxime (II) that forms part of a chain
reaction by abstracting a chlorine atom from aryl-
disulfonyl chloride A or B to give the sulfonyl radical
[40]. Cobaloxime (II) and ArSOÅ2 are known to act as
propagating species [17]. We, however, can not rule out
the participation of some ancillary process in which the
disulfone is formed by the coupling of benzyl radical
with sulfonyl radical. The absence of monosulfone
product supports the concerted process.
4. Experimental
4.1. General instrumental and experimental techniques
used
The synthesis of all the organocobaloximes has been
reported earlier [10,14,17,41]. Silica gel (ACME, 100–
200 mesh size) was used in the column chromatography.
All solvents were distilled and dried prior to use. Melt-
ing points were recorded on a FISHER-JOHNS appa-
ratus and all the values were uncorrected. UV–vis
spectra were recorded on a Shimadzu 160-A Spectro-
1
photometer. H NMR spectra were recorded on JEOL
PMX-60 instrument and in JEOL-JNM LAMBDA 400
model spectrometer in CDCl3 using TMS as internal
reference. 13C{1H} NMR spectra were recorded on a
JEOL-JNM LAMBDA 400 model spectrometer in
CDCl3. IR spectra were recorded from 4000–400 cmꢀ1
on a Bruker FT-IR-Vector 22 model. They were re-
corded in solid state as KBr pellets. Elemental analysis
was carried out using a Thermoquest CE instruments
CHNS-O elemental analyzer.
4.2. General procedure for the photochemical reaction
A solution of aryldisulfonyl chloride (1 mmol in 30
ml of dichloromethane) was degassed for 30 min, and
organocobaloxime (2 mmol) was added to it. The reac-
tion mixture was cooled to 0 °C and irradiated using
2 ꢁ 200 W tungsten lamps. The progress of the reaction
was monitored using TLC in ethyl acetate. On comple-
tion, the mixture was concentrated and the organic
compounds were separated by flash chromatography.
The organic products were further separated by column
chromatography. In some cases, a white solid product
insoluble in chloroform was formed.
The reaction of a 1:1 mixture of allyl (9) and benzyl
(1) cobaloximes or a 1:1 mixture of allyl (9) and furfuryl
(6) cobaloximes with A, does not form any cross-cou-
pling-organic product. The only products formed are the
1
corresponding disulfones and bibenzyl. The H NMR
monitoring of this reaction shows that these are the only
products formed from the beginning itself. The extent of
allyl disulfone formation, however, is more in the be-

B.D. Gupta, V. Vijaikanth / Journal of Organometallic Chemistry 689 (2004) 1102–1109
1107
4.3. General procedure for the cross-reaction
Disulfone 7a: White solid; m.p. 218–220 °C; 1H NMR
(400 MHz) d: 4.58 (s, 4H, CH2SO2), 6.92–6.95 (m, 2H,
Ar), 7.27–7.30 (m, 4H, Ar), 7.68–7.81 (m, 8H, Ar);
13C{1H} NMR (100.6 MHz) d: 57.3 (CH2SO2), 127.3
(Ar), 127.7 (Ar), 127.9 (Ar), 128.3 (Ar), 129.5 (Ar), 130.4
(Ar), 137.2 (Ar), 144.5 (Ar); UV kmax 250.6 nm
(log e 4:46), 269.2 nm (log e 4:51); IR m 1313 and 1151
cmꢀ1; Anal. Calc. for C22H18O4S4: C, 55.70; H, 3.80; S,
27.00. Found: C, 55.73; H, 3.82; S, 27.09%.
The same procedure as outlined above, except that a
1:1 mixture of allyl cobaloxime and benzyl cobaloxime
or allyl cobaloxime and furfuryl cobaloxime was used.
1
4.4. H NMR monitoring: general procedure
A 3.0 ml aliquot of the reaction mixture was taken
out at regular time interval. The total organic product in
each fraction was separated by flash chromatography
Disulfone 9a: White solid; m.p. 146 °C; 1H NMR (400
MHz) d: 3.88 (d, J ¼ 4:6 Hz, 4H, CH2SO2), 5.21 (d,
J ¼ 16:8 Hz, 2H, CH2@C), 5.38 (d, J ¼ 9:6 Hz, 2H,
CH2@C), 5.83–5.85 (m, 2H, @CH–C), 7.80 (d, J ¼ 6:8
Hz, 4H, Ar) 7.99 (d, J ¼ 6:4 Hz, 4H, Ar); 13C{1H}
NMR (100.6 MHz) d: 60.9 (CH2SO2), 124.5 (Ar), 125.0
(Ar), 128.0 (Ar), 129.3 (Ar), 138.2 (Ar), 144.4 (Ar); UV
kmax 266.4 nm (log e 4:56); Anal. Calc. for C18H18O4S2:
C, 55.70; H, 3.80; S, 27.00. Found: C, 55.70; H, 3.82; S,
27.08%.
1
and was analyzed further by H NMR spectroscopy.
1
Disulfones were characterized by H, 13C{1H} NMR
spectroscopy and elemental analysis. UV and IR spectra
were recorded for representative examples. The dimers
1
and dmgH ether were characterized by H NMR spec-
troscopy and were compared with the known samples
from another study. The characteristics of disulfones
obtained are given below.
Disulfone 1a: White solid; m.p. 202–204 °C; 1H NMR
(400 MHz) d: 4.37 (s, 4H, –CH2SO2), 7.14 (d, J ¼ 7:2
Hz, 4H, Ar), 7.26–7.36 (m, 6H, Ar), 7.69 (d, J ¼ 8:8 Hz,
4H, Ar), 7.75 (d, J ¼ 8:0 Hz, 4H, Ar); 13C{1H} NMR
(100.6 MHz) d: 62.9 (CH2SO2), 127.8 (Ar), 127.9 (Ar),
128.6 (Ar), 128.7 (Ar), 129.6 (Ar), 130.9 (Ar), 138.4 (Ar),
143.7 (Ar), 144.1 (Ar), 146.0 (Ar); Anal. Calc. for
C26H22O4S2: C, 67.53; H, 4.76; S, 13.85. Found: C,
67.49; H, 4.78; S, 13.80%.
Disulfone 2a: White solid; m.p. 200–202 °C; 1H NMR
(400 MHz) d: 2.34 (s, 6H, CH3), 4.32 (s, 4H, CH2SO2),
7.02 (d, J ¼ 8:4 Hz, 4H, Ar), 7.09 (d, J ¼ 8:0 Hz, 4H,
Ar), 7.67 (d, J ¼ 8:0 Hz, 4H, Ar), 7.74 (d, J ¼ 8:0 Hz,
4H, Ar); 13C{1H}NMR (100.6 MHz) d: 21.2(CH3), 62.6
(CH2SO2), 124.8 (Ar), 127.8 (Ar), 129.4 (Ar), 129.5 (Ar),
130.7 (Ar), 138.1 (Ar), 138.9 (Ar), 144.3 (Ar); Anal.
Calc. for C28H26O4S2: C, 68.57; H, 5.31; S, 13.06.
Found: C, 68.50; H, 5.30; S, 12.98%.
Disulfone 3a: White solid; m.p. 178–180 °C; 1H NMR
(400 MHz) d: 3.72 (s, 6H, OCH3), 4.33 (s, 4H, CH2SO2),
6.69 (s, 4H, Ar), 6.87 (d, J ¼ 8:0 Hz, 2H, Ar), 7.18 (t,
J ¼ 8:0 Hz, 2H, Ar), 7.66 (d, J ¼ 8:4 Hz, 4H, Ar), 7.75
(d, J ¼ 8:4 Hz, 4H, Ar); 13C{1H} NMR (100.6 MHz) d:
55.2 (OCH3), 62.9 (CH2SO2), 114.8 (Ar), 116.1 (Ar),
123.2 (Ar), 127.8 (Ar), 129.2 (Ar), 129.5 (Ar), 129.6 (Ar),
137.9 (Ar), 144.4 (Ar), 159.6 (Ar); UV kmax 269.2 nm
(log e 4:43). Anal. Calc. for C28H26O6S2: C, 68.57; H,
5.31; S, 13.06. Found: C, 68.50; H, 5.28; S, 13.00%.
Disulfone 6a: White solid; m.p. 188–190 °C; 1H NMR
(400 MHz) d: 4.48 (s, 4H, CH2SO2), 6.35–6.37 (m, 4H,
Ar), 7.33 (s, 2H, Ar), 7.73 (d, J ¼ 8:4 Hz, 4H, Ar), 7.83
(d, J ¼ 8:4 Hz, 4H, Ar); 13C{1H} NMR (100.6 MHz) d:
56.0 (CH2SO2), 111.28 (Ar), 112.4 (Ar), 128.0 (Ar),
129.3 (Ar), 138.2 (Ar), 142.2 (Ar), 143.9 (Ar), 144.5 (Ar);
UV kmax 269.4 nm (log e 4:33); IR (KBr) m 1314 and
1156 cmꢀ1; Anal. Calc. for C22H18O6S2: C, 59.73; H,
4.07; S, 14.48. Found: C, 59.70; H, 4.00; S, 14.40%.
Disulfone 10a: White solid; m.p. 107 °C; H NMR
1
(400 MHz) d: 1.49 (d, J ¼ 6:8 Hz, 6H, CH3) 3.76–3.80
(m, 2H, CH–SO2), 5.15 (d, J ¼ 17:2 Hz, 2H, CH2@C),
5.32 (d, J ¼ 10:4 Hz, 2H, CH2@C), 5.82–5.91 (m, 2H,
@CH–C), 7.79 (d, J ¼ 8:0 Hz, 4H, Ar), 7.96 (d, J ¼ 8:0
Hz, 4H, Ar); 13C{1H} NMR (100.6 MHz) d: 12.9 (CH3),
60.9 (CHSO2), 122.1 (Ar), 127.8 (Ar), 130.1 (Ar), 131.0
(Ar), 136.7 (Ar), 144.3 (Ar); UV kmax 267.4 nm
(log e 4:50); Anal. Calc. for C20H22O4S2: C, 61.54; H,
5.64; S, 16.41. Found: C, 61.49; H, 5.60; S, 16.42%.
Disulfone 11a: White solid; m.p. 96 °C; 1H NMR (400
MHz) d: 0.72 (s, 6H, CH3), 1.21 (s, 6H, CH3), 1.34 (d,
J ¼ 10:4, 2H), 1.79–1.86 (m, 2H), 2.02 (q, J ¼ 5:2, 2H),
2.133 (dd, J ¼ 13:6, 9.6 Hz, 2H), 2.30–2.35 (m, 2H), 2.56
(t, J ¼ 5:6, 2H) 4.33–4.37 (m, 2H) 5.09 (d, J ¼ 2:8, 2H),
5.90 (d, J ¼ 2:4, 2H) 7.80 (dd, J ¼ 8:0,2.0 Hz, 4H), 8.08
(dd, J ¼ 6:8,1.6 Hz, 4H); 13C{1H} NMR (100.6 MHz) d:
20.6 (CH3), 26.2, 26.5, 27.6, 39.6, 41.5, 52.7, 58.6
(CHSO2), 113.5, 128.8, 129.8, 139.1, 141.9, 144.4; UV
kmax 269.2 nm (log e 4:48); IR m 1314 and 1146 cmꢀ1
;
Anal. Calc. for C32H38O4S2: C, 69.82; H, 6.91; S, 11.64.
Found: C, 69.78; H, 6.92; S, 11.62%.
Disulfone 1b: White solid; m.p. 172–174 °C; 1H NMR
(400 MHz) d: 2.27 (s, 6H, CH3), 2.87 (s, 3H, CH3), 4.39
(s, 4H, CH2SO2), 6.88 (s, 1H, Ar), 7.11 (d, J ¼ 7:2 Hz,
4H, Ar), 7.26–7.36 (m, 6H, Ar); 13C{1H} NMR (100.6
MHz) d: 19.3 (CH3), 23.7 (CH3), 62.7 (CH2SO2), 127.4
(Ar), 128.7 (Ar), 129.1 (Ar), 131.0 (Ar), 136.1 (Ar), 136.3
(Ar), 143.3 (Ar), 146.3 (Ar); UV kmax 245.0 nm
(log e 3:88), 284.0 nm (log e 3:19), 291.8 nm (log e 3:19);
Anal. Calc. for C23H24O4S2: C, 64.49; H, 5.61; S, 14.95.
Found: C, 64.51; H, 5.52; S, 14.92%.
Disulfone 2b: White solid; m.p. 168–170 °C; 1H NMR
(400 MHz) d: 2.29 (s, 6H, CH3), 2.32 (s, 6H, CH3), 2.88
(s, 3H, CH3), 4.35 (s, 4H) 6.89 (s, 1H, Ar), 6.99 (d,
J ¼ 8:4 Hz, 4H, Ar), 7.09 (d, J ¼ 7:6 Hz, 4H, Ar);
13C{1H} NMR (100.6 MHz) d: 19.4 (CH3), 21.2 (CH3),

1108
B.D. Gupta, V. Vijaikanth / Journal of Organometallic Chemistry 689 (2004) 1102–1109
23.7 (CH3), 62.5 (CH2SO2), 124.3 (Ar), 128.3 (Ar), 128.9
(Ar), 129.5 (Ar), 130.9 (Ar), 136.3 (Ar), 139.2 (Ar), 146.2
(Ar); Anal. Calc. for C25H28O4S2: C, 65.79; H, 6.14; S,
14.04. Found: C, 65.77; H, 6.10; S, 14.00%.
(100.6 MHz) d: 19.6 (CH3), 24.1 (CH3), 61.0 (CH2SO2),
123.8, 125.4, 136.7, 142.5, 145.6; UV kmax 243.0 nm
(log e 3:67), 282.8 (log e 3:04), 291.0 (log e 3:05); Anal.
Calc. for C15H20O4S2: C, 54.88; H, 6.10; S, 19.51.
Found: C, 54.90; H, 6.14; S, 19.50%.
Disulfone 10b: White solid; m.p. 94 °C; 1H NMR (400
MHz) d: 1.52–1.55 (m, 6H, CH3), 2.70 (s, 6H, CH3),
3.10 (s, 3H, CH3) 3.87–3.91 (m, 2H, CHSO2), 5.07–5.14
(m, 2H, CH2@C), 5.28 (t, J ¼ 9:2 Hz, 2H, CH2@C),
5.76–5.87 (m, 2H, @CH–C), 7.12 (s, 1H, Ar); 13C{1H}
NMR (100.6 MHz) d: 12.0, 12.2, 19.5, 19.6, 24.2,
64.3(CHSO2), 122.5, 122.6, 130.74, 130.9, 136.0, 136.7,
136.8, 142.7, 142.9, 145.8, 145.9; UV kmax 244.6 nm
(log e 3.72), 283.0 (log e 3:17), 291.2 (log e 3:18); Anal.
Calc. for C17H24O4S2: C, 57.30; H, 6.74; S, 17.98.
Found: C, 57.22; H, 6.70; S, 18.02%.
Disulfone 3b: White solid; m.p. 156–158 °C; 1H NMR
(400 MHz) d: 2.32 (s, 6H, CH3), 2.85 (s, 3H, CH3), 3.71
(s, 6H, OCH3), 4.35 (s, 4H, CH2SO2), 6.62–6.67 (m, 4H,
Ar), 6.85–6.88 (m, 2H, Ar), 6.91 (s, 1H, Ar), 7.12–7.20
(m, 2H, Ar); 13C{1H} NMR (100.6 MHz) d: 19.4, 23.6
(CH3), 55.2 (OCH3), 62.7 (CH2SO2), 114.8 (Ar), 116.4
(Ar), 121.1 (Ar), 123.2 (Ar), 128.6 (Ar), 129.7 (Ar), 136.2
(Ar), 143.4 (Ar), 146.2 (Ar), 159.6 (Ar); Anal. Calc. for
C25H28O6S2: C, 61.48; H, 5.74; S, 13.11. Found: C,
61.52; H, 5.70; S, 13.15%.
Disulfone 4b: White solid; m.p. 80 °C; 1H NMR
(CDCl3, 400 MHz) d: 2.34 (s, 6H, CH3), 2.87 (s, 3H,
CH3), 3.79 (s, 6H, OCH3), 4.36 (s, 4H, CH2SO2), 6.78–
6.81 (m, 4H, Ar), 6.93–7.05 (m, 5H Ar); 13C{1H} NMR
(100.6 MHz) d: 19.7 (CH3), 23.4 (CH3), 55.3 (OCH3),
62.1 (CH2SO2), 114.1 (Ar), 114.2 (Ar), 119.1 (Ar), 121.2
(Ar), 131.4 (Ar), 132.3 (Ar), 136.0 (Ar), 142.0 (Ar);
Anal. Calc. for C25H28O6S2: C, 61.48; H, 5.74; S, 13.11.
Found: C, 61.45; H, 5.72; S, 13.10%.
Acknowledgements
We thank DST for funding this project. Vijaikanth
thanks CSIR, India for the SRF fellowship.
Disulfone 6b: White solid; m.p. 158–160 °C; 1H NMR
(400 MHz) d: 2.46 (s, 6H, CH3), 2.88 (s, 3H, CH3), 4.51
(s, 4H, CH2SO2), 6.32–6.35 (m, 4H, Ar), 7.01 (s, 1H,
Ar), 7.33 (d, J ¼ 0:8 Hz, 2H, Ar); 13C{1H} NMR (100.6
MHz) d: 19.2 (CH3), 23.7 (CH3), 55.9 (CH2SO2), 111.4
(Ar), 112.7 (Ar), 136.5 (Ar), 136.6 (Ar), 141.9 (Ar), 144.1
(Ar), 146.1 (Ar); UV kmax 244.8 nm (log e 3.84); Anal.
Calc. for C19H20O6S2: C, 55.88; H, 4.90; S, 15.69.
Found: C, 55.80; H, 4.88; S, 15.70%.
Disulfone 7b: White solid; m.p. 160–162 °C; 1H NMR
(400 MHz) d: 2.40 (s, 6H, CH3), 2.88 (s, 3H, CH3), 4.61
(s, 4H, CH2SO2), 6.91 (d, J ¼ 2:8 Hz, 2H, Ar), 6.94 (s,
1H, Ar), 6.96–6.98 (m, 2H, Ar), 7.30 (d, J ¼ 0:8 Hz, 1H,
Ar), 7.31 (d, J ¼ 0:8 Hz, 1H, Ar); 13C{1H } NMR (100.6
MHz) d: 19.4 (CH3), 23.8 (CH3), 57.2 (CH2SO2), 127.5
(Ar), 127.8 (Ar), 128.0 (Ar), 130.6 (Ar), 135.7 (Ar), 136.4
(Ar), 143.6 (Ar), 146.6 (Ar); Anal. Calc. for
C19H20O4S4: C, 51.82; H, 4.55; S, 29.09. Found: C,
51.80; H, 4.52; S, 29.02%.
Disulfone 8b: White solid; m.p. 162–164 °C; 1H NMR
(400 MHz) d: 2.35 (s, 6H, CH3), 2.89 (s, 3H, CH3), 4.47
(s, 4H, CH2SO2), 6.88 (d, J ¼ 4:8 Hz, 2H, Ar), 6.94 (s,
1H, Ar), 7.09 (d, J ¼ 2:4 Hz, 2H, Ar), 7.25 (s, 2H, Ar);
13C{1H} NMR (100.6 MHz) d: 19.2 (CH3), 23.6 (CH3),
57.3 (CH2SO2), 126.5 (Ar), 127.2 (Ar), 129.1 (Ar), 136.1
(Ar), 136.4 (Ar), 143.1 (Ar), 146.2 (Ar); UV kmax 245.6
nm; Anal. Calc. for C19H20O4S4: C, 51.82; H, 4.55; S,
29.09. Found: C, 51.78; H, 4.50; S, 29.02%.
References
[1] M.E. Welker, Curr. Org. Chem. 5 (2001) 785.
[2] M. Tada, Rev. Heteroatom. Chem. 20 (1999) 97.
[3] Y.K. Chung, Coord. Chem. Rev. 188 (1999) 297.
[4] A.J. Fletcher, S.D.R. Christie, J. Chem. Soc., Perkin Trans. 1
(2000) 1657.
[5] G. Pattenden, Chem. Soc. Rev. 17 (1988) 361.
[6] (a) M. Tada, Y. Hanaoka, J. Organomet. Chem. 616 (2000) 89;
(b) T. Uetake, M. Nishikawa, M. Tada, J. Chem. Soc., Perkin
Trans. 1 (1997) 3591.
[7] (a) L.M. Grubb, K.A. Brown, B.P. Branchaud, Tetrahedron Lett.
39 (1998) 3447;
(b) G. Kettschau, G. Pattenden, Tetrahedron Lett. 39 (1998)
2027;
(c) J.L. Gage, B.P. Branchaud, Tetrahedron Lett. 38 (1997) 7007;
(d) G.B. Gill, G. Pattenden, G.A. Roan, Tetrahedron Lett. 37
(1996) 9369.
[8] (a) C.L.L. Chai, R.C. Johnson, J. Koh, Tetrahedron 58 (2002)
975;
(b) B.M. Richardson, M.E. Welker, J. Org. Chem. 62 (1997) 1299.
[9] (a) M.D. Johnson, Acc. Chem. Res. 16 (1983) 343;
(b) J.C. Walton, Acc. Chem. Res. 31 (1998) 99.
[10] S. Roy, I. Das, K. Bhanuprakash, B.D. Gupta, Tetrahedron 50
(1994) 1847.
[11] A.E. Crease, B.D. Gupta, M.D. Johnson, E. Bialkowska, K.N.V.
Duong, A. Gaudemer, J. Chem. Soc., Perkin I (1979) 2611.
[12] A.E. Crease, M.D. Johnson, J. Am. Chem. Soc. 100 (1978) 8013.
[13] P. Bougeard, M.D. Johnson, J. Organomet. Chem. 206 (1981)
221.
[14] S. Roy, B.D. Gupta, S. Chaklanobis, J. Organomet. Chem. 269
(1984) 201.
Disulfone 9b: White solid; m.p. 156 °C; 1H NMR (400
MHz) d: 2.71 (s, 6H, CH3), 3.10 (s, 3H, CH3), 3.94 (d,
J ¼ 7:6 Hz, 4H, CH2SO2), 5.27 (d, J ¼ 17:2 Hz, 2H,
CH2@C), 5.38 (d, J ¼ 10:4 Hz, 2H, CH2@C), 5.77–5.86
(m, 2H, @CH–C), 7.13 (s, 1H Ar); 13C{1H} NMR
[15] B.D. Gupta, S. Roy, S. Sen, Ind. J. Chem. B 24 (1985) 1032.
[16] B.D. Gupta, M. Kumar, I. Das, M. Roy, Tetrahedron Lett. 27
(1986) 5773.
[17] B.D. Gupta, M. Roy, S. Roy, M. Kumar, I. Das, J. Chem. Soc.
Perkin 2 (1990) 537.
[18] B.D. Gupta, I. Das, V. Dixit, Ind. J. Chem. A 32 (1993) 762.

B.D. Gupta, V. Vijaikanth / Journal of Organometallic Chemistry 689 (2004) 1102–1109
1109
[19] B.D. Gupta, I. Das, V. Dixit, Ind. J. Chem. A 32 (1993)
1019.
[30] (a) W.-C. Cheng, C. Halm, J.B. Evarts, M.M. Olmstead, M.J.
Kurth, J. Org. Chem. 64 (1999) 8557;
[20] B.D. Gupta, S. Roy, Tetrahedron Lett. 27 (1986) 4905.
[21] B.D. Gupta, S. Roy, J. Chem. Soc., Perkin 2 (1988) 1377.
[22] P. Bougeard, A. Bury, C.J. Cooksey, M.D. Johnson, G.M.
Lampman, J.H. Hungerford, J. Org. Chem. 49 (1984) 1751.
[23] M.R. Ashcroft, P. Bougeard, A. Bury, C.J. Cooksey, M.D.
Johnson, J. Organomet. Chem. 289 (1985) 403.
[24] I. Das, S. Chowdhury, K. Ravikumar, S. Roy, B.D. Gupta, J.
Organomet. Chem. 532 (1997) 101.
(b) B.D. Lenihan, H. Shechter, J. Org. Chem. 63 (1998) 2072;
(c) J. Wildeman, P.C. Borgen, H. Pluim, P.H.F.M. Rouwette,
A.M. Van Leusen, Tetrahedron Lett. 25 (1978) 2213.
[31] P.C. Van Dort, P.L. Fuchs, J. Org. Chem. 62 (1997) 7137.
[32] I. Cho, Prog. Polym. Sci. 25 (2000) 1043.
[33] J.L. Acena, O. Arjona, F. Iradier, J. Plumet, Tetrahedron Lett. 37
(1996) 105.
[34] (a) B.D. Gupta, S. Roy, Inorg. Chim. Acta 146 (1988) 209;
(b) J.F. Endicott, T.L. Netzel, J. Am. Chem. Soc. 101 (1979) 4000;
(c) B.T. Golding, T.J. Kemp, P.J. Sellers, E. Nocchi, J. Chem.
Soc. Dalton Trans. (1977) 1266;
[25] B.D. Gupta, V.V. Kanth, I. Das, Ind. J. Chem. A 39 (2000)
835.
[26] (a) C. Najera, M. Yus, Tetrahedron 55 (1999) 10547;
(b) N.S. Simpkins, Sulphones in Organic Synthesis, Pergamon
Press, Oxford, 1993;
(d) B.P. Hay, R.G. Finke, J. Am. Chem. Soc. 108 (1986) 4820;
(e) J. Halpern, Science 227 (1985) 869;
(c) S. Patai, Z. Rappoport, C. Stirling (Eds.), The Chemistry of
Sulphones and Sulfoxides, Wiley, Chichester, 1988.
[27] (a) M. Artico, R. Silvestri, E. Pagnozzi, B. Bruno, E. Novellino,
G. Greco, S. Massa, A. Ettorre, A.G. Loi, F. Scintu, P.L. Colla, J.
Med. Chem. 43 (2000) 1886;
(f) H. Elroi, D.J. Meyerstein, J. Am. Chem. Soc. 106 (1984) 5540.
[35] (a) P.S. Skell, R.C. Woodworth, J.H. McNamara, J. Am. Chem.
Soc. 79 (1957) 1253;
(b) M.S. Kharasch, R.A. Moser, J. Org. Chem. 17 (1952) 453;
(c) M. Tada, K. Kaneko, J. Org. Chem. 60 (1995) 6635;
(d) B.P. Branchaud, R.M. Slade, Tetrahedron Lett. 35 (1994) 4071.
[36] M.Z.A. Badr, M.M. Aly, S.A. Mahgoub, A.M. Fahmy, A.A.
Atallah, Bull. Chem. Soc. Jpn. 61 (1988) 1779.
(b) M. Artico, R. Silvestri, S. Massa, A.G. Loi, S. Corrias, G.
Piras, P.L. Colla, J. Med. Chem. 39 (1996) 522.
[28] (a) N. Mase, Y. Watanabe, T. Toru, T. Kakumoto, T. Hagiwara,
J. Org. Chem. 65 (2000) 7083;
[37] M.W. Wright, T.L. Smalley Jr., M.E. Welker, A.L. Rheingold, J.
Am. Chem. Soc. 116 (1994) 6777.
(b) N. Mase, Y. Watanabe, T. Toru, Tetrahedron Lett. 40 (1999)
2797;
[38] B.P. Branchaud, Y.L. Choi, Tetrahedron Lett. 29 (1988) 6037.
[39] B.D. Gupta, M. Kumar, S. Roy, Inorg. Chem. 28 (1989) 11.
[40] J.H. Espenson, M.S. McDowell, Organometallics 1 (1982) 1514.
[41] B.D. Gupta, V. Vijaikanth, V. Singh, J. Organomet. Chem. 570
(1998) 1.
(c) E. Marcantoni, S. Cingolani, G. Bartoli, M. Bosco, L. Sambri,
J. Org. Chem. 63 (1998) 3624.
[29] B.M. Trost, Bull. Chem. Soc. Jpn. 61 (1988) 107;
P.D. Magnus, Tetrahedron 33 (1977) 2019.