Reactions of (1,3,3-trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl chloride with some S- and O-nucleophiles

Article abstract of DOI:10.1080/10426500902856412

The sterically crowded 3,3-trichloro-2,2,4,4-tetramethylcyclobutanethione (2c) easily reacts with phosphorus pentachloride in CCl4 yielding the relatively stable (1,3,3-trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl chloride (3c). The reactions of 3c wi

Full text of DOI:10.1080/10426500902856412

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Reactions of (1,3,3-
Trichloro-2,2,4,4-
tetramethylcyclobutyl)sulfenyl
Chloride with Some S- and O-
Nucleophiles
a
Marta Woźnicka a , Grzegorz Mlostoń & Heinz
Heimgartner b
a Department of Organic and Applied Chemistry ,
University of Łódź , Łódź, Poland
b Institute of Organic Chemistry , University of
Zürich , Zürich, Switzerland
Published online: 28 Apr 2009.
To cite this article: Marta Woźnicka , Grzegorz Mlostoń & Heinz Heimgartner
(2009) Reactions of (1,3,3-Trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl Chloride
with Some S- and O-Nucleophiles, Phosphorus, Sulfur, and Silicon and the Related
Elements, 184:5, 1314-1322, DOI: 10.1080/10426500902856412
To link to this article: http://dx.doi.org/10.1080/10426500902856412
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Phosphorus, Sulfur, and Silicon, 184:1314–1322, 2009
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500902856412
Reactions of (1,3,3-Trichloro-2,2,4,4-
tetramethylcyclobutyl)sulfenyl Chloride with Some
S- and O-Nucleophiles
1
1
´
´
Marta Woznicka, Grzegorz Mloston,
and Heinz Heimgartner2
1Department of Organic and Applied Chemistry, University of Lꢀ o´dz´,
Lꢀ o´dz´, Poland
2Institute of Organic Chemistry, University of Zu¨rich, Zu¨rich,
Switzerland
The sterically crowded 3,3-trichloro-2,2,4,4-tetramethylcyclobutanethione (2c) eas-
ily reacts with phosphorus pentachloride in CCl yielding the relatively stable
4
(1,3,3-trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl chloride (3c). The reactions
of 3c with benzylsulfane (4) and thiocamphor (5) occur with elimination of HCl
leading to the unsymmetrical disulfanes 6 and 9. In the case of the sulfenates 10
and 12, which are formed as intermediates in the reactions of 3c with propargyl and
allyl alcohol, respectively, the subsequent [2,3]-sigmatropic rearrangement yields
the corresponding sulfoxides 11 and 13.
Keywords Diorganyldisulfanes; oxygen nucleophiles; sigmatropic rearrangements;
sulfenyl chlorides; sulfur nucleophiles
INTRODUCTION
The synthesis and reactions of thiocarbonyl compounds, especially
thioketones, is a significant topic in our ongoing research. In gen-
eral, thioketones are rather unstable compounds,1 and there is a lim-
ited number of aliphatic and cycloaliphatic representatives, which
can be handled without special precautions. It is well documented
that sterically crowded and non-enolizable thioketones are relatively
Received 14 January 2008; accepted 30 January 2008.
Dedicated to Professor Marian Mikolꢀajczyk, CBMiM PAN in Lꢀ o´dz´, Poland, on the
occasion of his 70th birthday.
The authors thank the Rector of the University of Lꢀ o´dz´ for a grant (G. M. and M. W.)
and F. Hoffmann-La Roche AG, Basel for generous support (H. H.).
Address correspondence to G. Mloston´, Department of Organic and Applied
Chemistry, University of Lꢀ o´dz´, Narutowicza 68, PL 90-136 Lꢀ o´dz´, Poland. E-mail:
gmloston@uni.lodz.pl
1314

Sulfenyl Chloride and S- or O-Nucleophiles
1315
FIGURE 1 Nonenolizable, cycloaliphatic thioketones 1, 2 and α-chlorosulfenyl
chlorides 3.
stable, and for this reason, adamantanethione (1)2 and also 2,2,4,4-
tetramethylcyclobutanethiones 2a,b3,4 are models of choice for studies
on the reactivity of the C=S group (Figure 1).
In the last two decades, thioketones 1 and 2a,b were extensively ex-
plored as dipolarophiles and as precursors of so called “sulfur-centered
1,3-dipoles,” such as thiocarbonyl ylides,5 S-sulfides,6 S-imides,7 and
S-oxides.8 In a recent article, the preparation of a new stable cy-
cloaliphatic thioketone, 2c, was described.9 Thioketones 2a,b easily
add Cl2 to yield stable α-chlorosulfenyl chlorides 3a,b.10 Similarly,
treatment of thioketone 2c with PCl5 in CCl4, gave the sulfenyl chlo-
ride 3c.9 In the same article, some reactions of 3c with non-enolizable
thioketones and selected nucleophiles such as diethyl phosphite and
thioacetic acid were described. The present report is focused on the
results obtained in reactions of 3c with benzylsulfane (4), enolizable
thiocamphor (5), and allyl as well as propargyl alcohol.
RESULTS AND DISCUSSION
The crude α-chlorosulfenyl chloride 3c reacted with benzylsulfane (4) in
the presence of Et3N at room temperature within a few minutes to yield,
unexpectedly, a mixture of the disulfane 6 and dibenzyldisulfane (7)
(Scheme 1). Based on the intensities of the signals of the CH2 groups in
the 1H NMR spectrum of the crude mixture located at 3.57 (7) and 4.15
ppm (6), the ratio was estimated to ca. 1:2. All attempts to separate this
mixture chromatographically led to the decomposition of 6, and only 7
could be isolated. In a second experiment, in the absence of Et3N, the
disulfane 7 was formed in small amount, and 6 could be isolated by
crystallization of the mixture from petroleum ether. This result con-
firms that 3c, in analogy to earlier published reactions with 3a,b,10,11
easily undergoes substitution with S-nucleophiles at the S-atom.
Under analogous reaction conditions, in the presence of Et3N, the col-
ored organic solution of thiocamphor (5) turned colorless after 10 min.

1316
M. Woz´nicka et al.
SCHEME 1
1
The typical workup by crystallization led to colorless crystals. The H
NMR spectrum of this material showed a doublet at 6.18 ppm, which
is characteristic for camphen-2-yl sulfides (see, e.g.12,13). In addition,
the 13C NMR spectrum revealed the presence of two sp2-C atoms (d at
135.1 and s at 141.5 ppm). The spectroscopic data fit well with struc-
ture 9 (Scheme 1). It is likely that the mechanism of the formation of
9 involves the initial formation of the ion pair 8 via nucleophilic sub-
–
stitution of Cl at the S-atom, followed by deprotonation. On the other
hand, involvement of the enol of 5 can also be taken into account.
The reaction of 3c with propargyl alcohol was carried out at ca. 5◦C
in the presence of Et3N. After ca. 1 h, the conversion was complete, and
1
the product was isolated as a colorless solid. The H NMR spectrum
indicated that the molecule contains an allenyl fragment. Furthermore,
the presence of four signals for methyl groups is evidence that the
molecule is no more symmetric. These data point out that the isolated
product is an isomer of the expected propargyl sulfenate. Based on the
spectroscopic data, the structure of the allenyl S-oxide 11 was confirmed
(Scheme 2).
We propose that the nucleophilic substitution leads to the propar-
gyl sulfenate 10, which spontaneously undergoes a [2,3]-sigmatropic
rearrangement to give 11. This type of rearrangement was previously
reported for reactions of propargyl alcohol with variably substituted
halomethyl sulfenyl chlorides (e.g.14) and for the reaction with 3a.11

Sulfenyl Chloride and S- or O-Nucleophiles
1317
SCHEME 2
In the case of the reaction of 3c with allyl alcohol under the same
1
conditions (CH2Cl2, Et3N, 5◦C), the H NMR spectrum of the crude
mixture evidenced the presence of two products. One of them, showing
four signals for methyl groups located between 1.40 and 1.95 ppm and
the characteristic pattern of multiplets for an allyl residue, was the ex-
pected allyl sulfoxide 13 (Scheme 3). The second product was identified
as the known thiocarbonyl S-oxide (sulfine) 14.9 Both products were
isolated as pure substances after chromatographic separation (TLC,
ratio ca. 2:1).
SCHEME 3

1318
M. Woz´nicka et al.
The formation of 13 results from a [2,3]-sigmatropic rearrangement
of the initially formed allyl sulfenate 12. The precursor of the unex-
pected 14 is either 12 or 13, which, by elimination of allyl chloride, can
be transformed into the sulfine 14. However, the isolated sulfoxide 13 is
a stable compound, and, therefore, it is more likely that the elimination
of the allyl cation from 12 leads to 14. The different results obtained
with propargyl alcohol can be explained by the enhanced stability of
the allyl cation in comparison with the propargyl cation. The thereby
–
formed sulfenate ion stabilizes by elimination of Cl .
CONCLUSIONS
The present study showed that α-chlorosulfenyl chloride 3c easily re-
acts with S- and O-nucleophiles such as benzylsulfane (4), thiocamphor
(5), propargyl, and allyl alcohol. The reactions with the S-nucleophiles
4 and 5 occur with elimination of HCl and lead to disulfanes 6 and 7,
respectively. We propose that these reactions are initiated by the nucle-
ophilic attack of the S-nucleophile at the S-atom of the sulfenyl chloride
group by substitution of chloride. In an analogous manner, the reactions
of 3c with propargyl and ally alcohol gives the sulfenates 10 and 12,
respectively, which, under the reaction conditions, spontaneously re-
arrange to give the corresponding sulfoxides 11 and 13. The proposed
mechanism of these transformations is a [2,3]-sigmatropic rearrange-
ment, which, in the case of the allyl derivative 12, is accompanied by
the competitive elimination of the allyl cation.
EXPERIMENTAL
General
Melting points (mp) were determined in capillary using a Meltemp
1
2 apparatus and are uncorrected. H and 13C NMR spectra were ob-
tained with a Tesla BS 687 (80 and 20 MHz, respectively) or a Bruker
300 (300 and 75 MHz, respectively) spectrometer using TMS (δTMS
=
0) as internal standard. The multiplicity of the 13C signals was elu-
cidated based on the DEPT experiments. IR spectra were registered
with a Nexus spectrophotometer (in KBr). MS (EI or CI) were recorded
using a Finnigan-Mat-90 or Finnigan-SSQ-700 spectrometer. Elemen-
tal analyses were performed by the Analytical Laboratory of the Polish
´ ´
Academy of Sciences (CBMiM) in Lꢀ odz.

Sulfenyl Chloride and S- or O-Nucleophiles
1319
Starting Materials
(1,3,3-Trichloro-2,2,4,4-tetramethylcyclobutyl)sulfenyl chloride (3c)
was prepared from 3,3-dichloro-2,2,4,4-tetramethylcyclobutanethione
(2c) by chlorination using PCl5 in CCl4 solution following a protocol in
the literature.9 Benzylsulfane (4), thiocamphor (5), propargyl alcohol,
and allyl alcohol were used as trade reagents. Propargyl alcohol and
allyl alcohol were dried by azeotropic distillation with CH2Cl2 prior to
usage.
Reaction of 3c with Benzylsulfane (4)
A solution of 3c (282 mg, 1 mmol) and 4 (124 mg, 1 mmol) in CH2Cl2
(2 mL) was stirred magnetically at room temperature for 24 h. Then,
the solvent was evaporated and pure product 6 was obtained after
crystallization from petroleum ether.
(Benzyl)(1,3,3-trichloro-2,2,4,4-tetramethylcyclobutyl)disulfide
(6)
Yield: 164 mg (44%), colorless crystals, mp 62–64◦C (petroleum ether,
−20◦C). IR (KBr): 3002 m, 2981 m, 1495 m, 1469 s, 1454 s, 1440 m, 1384
m, 1200 m, 942 m, 865 s, 828 s, 801 m, 704vs, 559 m. 1H NMR (CDCl3): δ =
1.55 (s, 6H, Me), 1.56 (s, 6H, Me), 4.15 (s, 2H, CH2), 7.28 (s, 5H, arom.
H). 13C NMR (CDCl3): δ = 26.2 (Me), 27.2 (Me), 59.9 (Cq), 92.0 (CqCl2),
98.7 (CqS(Cl)), 127.6 (arom. CH), 128.6 (arom. CH), 129.4 (arom. CH),
136.5 (arom. Cq). CI-MS (isobutan): 373 (7), 371 (20, [M+1]+), 335 (75),
333 (100), 123 (10, [C6H5CH2S]+), 91 (5, [C6H5CH2]+). Anal. Calcd. for
C15H19Cl3S2 (369.81): C 48.72, H 5.18, S 17.34. Found: C 48.61, H 5.35,
S 17.43.
Reaction of 3c with Thiocamphor (5)
To a magnetically stirred solution of 3c (282 mg, 1 mmol) in CH2Cl2
(4 mL) at room temperature, a solution of 5 (168 mg, 1 mmol) and tri-
ethylamine (101 mg, 1 mmol) in CH2Cl2 (4 mL) was added, and stirring
was continued for 10 min. Then, the solvent was evaporated, and the
residue was washed with diethyl ether (for the purpose to remove inor-
ganic salts). The product was purified by repeated crystallization from
diethyl ether.

1320
M. Woz´nicka et al.
((1R,4R)-1,7,7-Trimethylbicyclo[2.2.1]hept-2-en-2-yl)(1,3,3-
trichloro-2,2,4,4-tetramethylcyclobutyl)disulfide (9)
Yield: 210 mg (51%), colorless crystals, m.p 123–127◦C (diethyl ether,
−70◦C). IR (KBr): 2953 s, 2870 m, 1470 m, 1451 m, 1441 m, 1385 m,
870 m, 830 m. 1H NMR (CDCl3): δ = 0.78 (s, 3H, Me), 0.82 (s, 3H, Me),
1.06 (s, 3H, Me), 1.53 (s, 3H, Me), 1.54 (s, 3H, Me), 1.56 (s, 3H, Me), 1.59
(s, 3H, Me), 0.87–1.94 (m, 4H, CH2), 2.38 (t, JH,H = 3.6 Hz, 1H, CH),
6.18 (d, JH,H = 3.4 Hz, 1H, C CH). 13C NMR (CDCl3): δ = 11.4 (Me),
19.3 (Me), 19.5 (Me), 25.5 (CH2), 26.1 (Me), 26.3 (Me), 26.9 (Me), 27.1
(Me), 31.5 (CH2), 52.4 (CH), 56.7 (Cq), 57.6 (Cq), 60.0 (Cq), 60.1 (Cq), 90.7
(CqS), 98.8 (CqCl2), 135.1 (C CH), 141.5 (C CH). CI-MS (isobutan): 417
(20), 415 (40, [M+1]+), 413 (38), 379 (75), 377 (100), 252 (10), 167 (15).
Anal. Calcd. for C18H27Cl3S2 (413.90): C 52.23, H 6.58, S 15.49. Found:
C 51.94, H 6.53, S 15.37.
Reaction of 3c with Propargyl Alcohol
To a magnetically stirred and cooled (ice-water bath) solution of 3c
(282 mg, 1 mmol) in CH2Cl2 (2 mL), propargyl alcohol (56 mg, 1 mmol)
dissolved in CH2Cl2 (2 mL) was added. After 10 min, a solution of
triethylamine (101 mg, 1 mmol) in CH2Cl2 (2 mL) was added in small
portions. Stirring was continued at room temperature for 1 h, and the
solvent was evaporated. The oily residue was treated with diethyl ether,
the organic layer was separated, and the solvent was evaporated to
dryness. An analytically pure sample was obtained after crystallization
from petroleum ether.
(Propa-1,2-dienyl)(1,3,3-trichloro-2,2,4,4-
tetramethylcyclobutyl)sulfoxide (11)
Yield: 88 mg (29%), colorless crystals, mp 110–112◦C (petroleum ether).
1
IR (KBr): 3058 m, 2991 m, 2972 m, 1935 m, 1053 s, 881 m, 841 m. H
NMR (CDCl3): δ = 1.43 (s, 3H, Me), 1.48 (s, 3H, Me), 1.56 (s, 3H, Me),
1.88 (s, 3H, Me), 5.28 (dd, 4JH,H = 6.2 Hz, 2JH,H = 14.0 Hz, 1H, C(H)H),
5.36 (dd, 4JH,H = 6.5 Hz, 2JH,H = 14.0 Hz, 1H, C(H)H), 6.19 (dd, 4JH,H
= 6.5 Hz, 4JH,H = 6.2 Hz, 1H, CH ). 13C NMR (CDCl3): δ = 24.9 (Me),
25.3 (Me), 25.4 (Me), 26.1 (Me), 56.7 (Cq), 59.0 (Cq), 81.8 (CH2), 94.0
(CqS), 96.4 (CH), 98.2 (CqCl2), 209.3 (CH C CH2). CI-MS (NH3): 320
(17), 318 (16, [M+NH4]+), 305 (32), 304 (12), 303 (98), 302 (12), 301
(100, [M+1]+). Anal. Calcd. for C11H15Cl3OS (301.66): C 43.80, H 5.01,
S 10.63. Found: C 43.38, H 4.74, S 10.44.

Sulfenyl Chloride and S- or O-Nucleophiles
1321
Reaction of 3c with Allyl Alcohol
A solution of 3c (282 mg, 1 mmol) in CH2Cl2 (2 mL) was stirred magnet-
ically and cooled in an ice-water bath. Anhydrous allyl alcohol (116 mg,
2 mmol) dissolved in CH2Cl2 (2 mL) was added first, and after 10 min, a
solution of triethylamine (101 mg, 1 mmol) in CH2Cl2 (2 mL) was added
dropwise. Stirring was continued for 1 h at room temperature, and the
solvent was evaporated. The residue was washed with diethyl ether (to
remove inorganic salts), and product 13 was separated from the sulfine
149 [isolated as the less polar fraction, 53 mg (23%)] using preparative
layer chromatography and CH2Cl2/petroleum ether 1:1 as the eluent.
An analytically pure sample of 13 was obtained after crystallization
from petroleum ether.
(Prop-2-en-1-yl)(1,3,3-trichloro-2,2,4,4-
tetramethylcyclobutyl)sulfoxide (13)
Yield: 80 mg (46%), colorless crystals, mp 66–70◦C (petroleum ether,
−20◦C). IR (KBr): 2981 m, 1471 m, 1387 m, 1082 m, 1047 s, 995 m,
1
880 m, 838 m, 798 m. H NMR (CDCl3): δ = 1.47 (s, 3H, Me), 1.49 (s,
3H, Me), 1.58 (s, 3H, Me), 1.90 (s, 3H, Me), 3.26–3.33, 3.54–3.62 (2m,
2H, CH2), 5.42–5.49 (m, 2H, CH=CH2), 5.89–6.01 (m, 1H, CH CH2).
13C NMR (CDCl3): δ = 25.1 (Me), 25.3 (Me), 25.4 (Me), 26.1 (Me), 55.3
(CH2), 56.5 (Cq), 58.9 (Cq), 92.6 (CqS), 98.2 (CqCl2), 124.0 (CH CH2),
126.2 (CH CH2). CI-MS (NH3): 307 (37), 305 (99), 303 (100, [M+1]+),
246 (43), 244 (60). Anal. Calcd. for C11H17Cl3OS (303.68): C 43.51, H
5.64, S 10.56. Found: C 43.29, H 5.62, S 10.42.
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