Simple and practical one-step synthesis of new 1,3-dienic δ-sultones from terminal alkynes and some synthetic applications of these compounds

Article abstract of DOI:10.1080/17415993.2010.537339

1,3-Dienic δ-sultones 4,6-diaryl-[1,2]oxathiine 2,2-dioxides were synthesized via a one-step reaction of arylalkynes with dioxane sulfotrioxide. The reactivity of various alkynes in this reaction was investigated. The resulting sultones were brominated with Br₂ or N-bromosuccinimide regioselectively to sulfur and subsequently coupled with phenylacetylene using Sonogashira conditions.

Full text of DOI:10.1080/17415993.2010.537339

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Simple and practical one-step synthesis
of new 1,3-dienic δ-sultones from
terminal alkynes and some synthetic
applications of these compounds
Jens Gaitzsch a b , Victor Rogachev a c , Peter Metz a , Victor D.
Filimonov c , Martin Zahel a & Olga Kataeva a
a Department of Chemistry, Technische Universität Dresden,
Bergstrasse 66, 01069, Dresden, Germany
b Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße
6, 01069, Dresden, Germany
c Department of Organic Chemistry, Tomsk Polytechnic University,
Leninstr. 30, 634050, Tomsk, Russia
Version of record first published: 10 Dec 2010.
To cite this article: Jens Gaitzsch, Victor Rogachev, Peter Metz, Victor D. Filimonov, Martin Zahel
& Olga Kataeva (2011): Simple and practical one-step synthesis of new 1,3-dienic δ-sultones from
terminal alkynes and some synthetic applications of these compounds, Journal of Sulfur Chemistry,
32:1, 3-16
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Journal of Sulfur Chemistry
Vol. 32, No. 1, February 2011, 3–16
Simple and practical one-step synthesis of new 1,3-dienic
δ-sultones from terminal alkynes and some synthetic
applications of these compounds
Jens Gaitzscha,b, Victor Rogacheva,c*, Peter Metza, Victor D. Filimonovc, Martin Zahela
and Olga Kataevaa#
aDepartment of Chemistry, Technische Universität Dresden, Bergstrasse 66, 01069 Dresden, Germany;
bLeibniz-Institut für Polymerforschung Dresden e.V., Hohe Straße 6, 01069 Dresden, Germany;
cDepartment of Organic Chemistry, Tomsk Polytechnic University, Leninstr. 30, 634050 Tomsk, Russia
(Received 10 September 2010; final version received 31 October 2010)
1,3-Dienic δ-sultones 4,6-diaryl-[1,2]oxathiine 2,2-dioxides were synthesized via a one-step reaction of
arylalkynes with dioxane sulfotrioxide. The reactivity of various alkynes in this reaction was investigated.
The resulting sultones were brominated with Br2 or N-bromosuccinimide regioselectively α to sulfur and
subsequently coupled with phenylacetylene using Sonogashira conditions.
Ph
O
O
O
S2
S2
S2
Br
Ar
[SO3]
[Br2]
O
O
O
Ar
Ar
Ar
Ar
Ar
Ar
Keywords: alkynes; dioxane sulfotrioxide; δ-sultones; bromination; Sonogashira coupling
1. Introduction
Sultonesareimportantheterocycliccompoundsinorganicsynthesis(1, 2)andmedicinalchemistry
(3). Recently developed powerful methodologies for the generation of these cyclic sulfonates
include the intramolecular Diels–Alder reaction (4), ring closing metathesis (5), Pd-catalyzed
intramolecular coupling reaction (6), Rh-catalyzed C–H insertion (7), and Rh-catalyzed carbene
cyclization cycloaddition cascade (8). However, a general method for the synthesis of 1,3-dienic δ-
sultones has not been described yet. We have previously investigated a simple synthesis of the 1,3-
dienicδ-sultone4,6-diphenyl-[1,2]oxathiine2,2-dioxideusinganovelreactionofphenylacetylene
with sulfuric acid or dioxane sulfotrioxide (9, 10) and also a practical synthesis of 1,2-diketones
via oxidation of 1,2-diaryl substituted alkynes with dioxane sulfotrioxide under similar conditions
*Corresponding author. Email: victor.rogachev@gmail.com
#X-ray diffraction analysis.
ISSN 1741-5993 print/ISSN 1741-6000 online
© 2011 Taylor & Francis
DOI: 10.1080/17415993.2010.537339
http://www.informaworld.com

4
J. Gaitzsch et al.
Figure 1. Synthesis of sultones 2a–2g from arylalkynes 1a–1g. Reaction conditions: (a) dioxane sulfotrioxide 3 (1
equiv.), dioxane/CHCl3, 1:1 (v/v) (Table 1); (b) trimethylsilyl chlorosulfonate 4 (1 equiv.), addition of 4 over 5 min
(Table 2).
(11). Here we communicate a further study on the one-step heterocyclization of arylalkynes with
sulfur trioxide to give new 4,6-diaryl substituted 1,3-dienic δ-sultones as well as some synthetic
applications of these compounds.
2. Results and discussion
We found earlier that treatment of phenylacetylene 1a with dioxane sulfotrioxide (12) gave a better
yield of sultone 2a as compared to the reaction with sulfuric acid and oleum (10). Therefore,
dioxane sulfotrioxide was used in further experiments. In order to determine the scope of the
reaction and to achieve a better understanding of its pathway, sulfonation of a series of substituted
phenylacetylenes was undertaken. The influence of substituents on the reactivity of the substrate
and on the yields of the products was investigated. Gratifyingly, our method to synthesize sultone
Table 1. Synthesis of 1,3-dienic δ-sultones from alkynes 1a–1h and dioxane sulfotrioxide 3 in
dioxane/CHCl3 1:1 (v/v).
Substrate
R
T
Reaction time (h)
Product (yield, %)
1a
1b
1c
1d
1e
1g
1h
H
p-Me
p-Cl
m-Cl
p-MeO
p-Ph
Reflux
Reflux
3.5
4.5
4.5
60
2a (40)
2b (38)
2c (38)
2d (40)
2e (8)
Reflux
0 ◦C to rt
0 ◦C to rt
Reflux
7.5a
4
2g (13)
2h (0)
p-NO2
0 ◦C to rt or reflux
4–22
Note: aAddition of a solution of 3 in dioxane/CHCl3 1:1 (v/v) at 0 ◦C over 3 h.

Journal of Sulfur Chemistry
5
Table 2. Synthesis of 1,3-dienic δ-sultones from alkynes 1a–1h and trimethylsilyl chlorosulfonate
4 in dioxane/CHCl3 1:1 (v/v).
Substrate
R
T
Reaction time (h)
Product (yield, %)
1a
1b
1c
1d
1e
1f
H
p-Me
p-Cl
0 ◦C to rt
0 ◦C to rt
24
48
24
60
66
66
4
4–22
2a (34)
2b (47)
2c (38)
2d (14)
2e (45)a
2f (28)b
2g (38)
2h (0)
0 ◦C to rt
m-Cl
0 ◦C to rt
p-MeO
o-MeO
p−Ph
p-NO2
−78 ◦C to rt
−78 ◦C to rt
Reflux
1g
1h
0 ◦C to rt or reflux
Notes: aReaction in CHCl3/dioxane/CH2Cl2 1:3:3 (v/v/v).
bReaction in dioxane/CH2Cl2 1:2 (v/v).
2a from alkyne 1a with dioxane sulfotrioxide 3 at reflux could easily be extended to the conversion
of alkynes 1b and 1c to sultones 2b and 2c, respectively, whereas the transformation of 1d to 2d
proceeded best at lower temperature (Figure 1, Table 1).
Acetophenones 5a–5g (ca. 5%), 1,3,5-triarylbenzenes 6a–6g (5–10%), and unidentified
compounds of high polarity were also isolated by flash chromatography from the reaction mixture
as by-products of the sulfonation of 1a–1g. The 1,3,5-substitution of 6a–6g was confirmed by
NMR analysis of all products and by X-ray diffraction analysis of 6b.1 Sulfonic acid 7a (ca. 7%)
was additionally obtained from the product mixture derived from 1a.
Methoxy derivatives 1e and 1f could not be converted into the corresponding sultones 2e and
2f under these conditions due to the higher reactivity of these substrates. On the other hand, a
decrease in the reaction temperature to 0 ◦C and slower addition of the solution of 3 to the solution
of 1e resulted in the formation of sultone 2e in 8% yield. Apparently, electron-rich arylalkynes
need lower temperatures for conversion to sultones 2. However, further decrease in the reaction
temperature below 0 ◦C was not possible due to the insolubility of dioxane sulfotrioxide 3 in the
cold solvent. The 4-phenyl derivative 1g showed a rather low reactivity with dioxane sulfotrioxide
3 (13% of 2g with 87% conversion of starting alkyne). Unfortunately, 4-nitrophenylacetylene 1h
could not be converted into sultone 2h. At 0 ◦C, alkyne 1h was recovered, whereas an increased
temperature resulted in decomposition of 1h.
In anotherseriesof experiments, liquid trimethylsilyl chlorosulfonate (4) indioxane/chloroform
solutionwasusedinsteadof 3. Itiswellknownthat 4 canbeusedasanequivalentofSO3(13). Slow
addition of 4 to the substrate and dioxane caused formation of 3 in situ at low temperature and thus,
ensured mild reaction conditions excluding areas with high concentration of SO3. With this SO3
source, sultones 2a–2d were synthesized from the corresponding alkynes 1a–1d in 14–47% yields
(Figure 1, Table 2). Slow addition of 4 to a solution of 1e in dioxane/chloroform/dichloromethane
at −78 ◦C allowed the preparation of sultone 2e in 45% yield. Here, dichloromethane was added
as a co-solvent to avoid solidification of the reaction mixture at low temperature. Under similar
conditions, alkyne 1f was also converted into sultone 2f, albeit in a lower yield of 28%, probably
due to the steric hindrance caused by the o-methoxy group. Sultones 2e and 2f were unstable to
air, but could be safely stored in a chloroform solution. The biphenyl alkyne 1g reacted rather
reluctantly with 4 at rt (7% of 2g with 46% conversion of starting compound), but at reflux sultone
2g was formed in 38% yield. Similar to the reaction of 1h with 3, no sultone formation was noted
after treatment of this electron-deficient substrate with reagent 4.
The proposed mechanism of this heterocyclization is shown in Figure 2. We presume that
alkyne 1 is first sulfonated with SO3 to afford a highly reactive β-sultone existing in the cyclic I
and zwitterionic II form. Subsequent addition of a further equivalent of alkyne 1 to this β-sultone
then gives the stable δ-sultone 2. In conclusion, a range of monosubstituted arylalkynes 1a–1h
were investigated in a heterocyclization reaction with SO3 to give δ-sultones. The reactivity of

6
J. Gaitzsch et al.
Figure 2. Proposed mechanism of the heterocyclization of alkynes to give δ-sultones.
Figure 3. Relative reactivity of compounds 1a–1h in the reaction with SO3 sources 3 and 4 based on the M and I effects
of the substituents.
3 and 4 toward the alkynes investigated is similar, but not identical. The relative reactivity of
these compounds toward the SO3 sources 3 and 4 is depicted in Figure 3. Alkynes 1a–1d and 1g
react readily with sulfonating agents 3 and 4 at room temperature or above, while the electron-
rich methoxy derivatives 1e and 1f only give the desired products in decent yields at very low
temperatures using 4 as the SO3 source. Due to the presence of the electron-withdrawing nitro
group in the para position of the phenyl ring, acetylene 1h neither gave a sultone with 3 or 4.
Figure 4. Bromination of δ-sultones 2a–2g. Reaction conditions: (a) Br2 (1.5 equiv.), CHCl3, reflux; (b) NBS
(1.05 equiv.), CHCl3, rt.
Table 3. Bromination of δ-sultones 2a–2g with Br2 or NBS
Substrate
R
Bromine source
Reaction time (min)
Product (yield, %)
2a
2b
2c
2d
2e
2f
H
p-Me
p-Cl
Br2
Br2
Br2
90
45
120
60
60
60
8a (95)
8b (97)
8c (96)
8d (98)
8e (95)
8f (74)
8g (70)
m-Cl
Br2
p-MeOa
o-MeOa
p−Ph
NBS
NBS
Br2
2g
45
Note: aReaction at rt.

Journal of Sulfur Chemistry
7
These results underpin an electrophilic attack at the alkyne moiety in the course of this sultone
generating reaction.
In the next part of our studies, we investigated some synthetic applications of the new 1,3-dienic
δ-sultones. These investigations commenced with bromination of sultone 2a, which is readily
available (9). The reaction of δ-sultone 2a was carried out at 60 ◦C in chloroform with one or
more equivalents of bromine. The regioselectivity of this overall vinylic substitution process can
readily be rationalized. Only attack of a positive bromine source at the carbon α to sulfur in 2a
generates a highly delocalized carbenium ion, which in turn undergoes elimination of a proton
to afford product 8a. To our delight, we observed an almost quantitative yield and virtually no
side products, also using an excess of Br2. Further investigation of this bromination reaction led
Figure 5. X-ray diffraction analysis of 8a.
Figure 6. X-ray diffraction analysis of 8c.

8
J. Gaitzsch et al.
Figure 7. Sonogashiracouplingofbromosultones8a–8g withphenylacetylene 1a. Reactionconditions:(a)1a (2equiv.),
PdCl2, PPh3, CuI, THF/Et3N, 2:1 (v/v), reflux.
Table 4. Sonogashira coupling of bromo sultones 8a–8g with phenylacetylene 1a.
Substrate
R
Reaction time (h)
Product (yield, %)
8a
8b
8c
8d
8e
8f
H
p-Me
p-Cl
17.5
19
19
18.5
24
18
9a (90)
9b (55)
9c (65)
9d (70)
9e (98)
9f (98)
9g (69)
m-Cl
p-MeO
o-MeO
p−Ph
8g
19
to a general method for functionalization of 1,3-dienic δ-sultones 2. To this end, sultones 2b–2d
and 2g were treated with bromine to give the corresponding bromo sultones 8b–8d and 8g,
respectively, in 70–98% yield with complete regioselectivity (Figure 4, Table 3). The structure
of products 8 was confirmed by spectroscopic data and X-ray diffraction analysis of bromo
sultones 8a (Figure 5) and 8c (Figure 6).1 Methoxy-activated sultones 2e and 2f gave mixtures
of more highly brominated unstable products with bromine. Fortunately, products 8e and 8f
were readily available by treatment of 2e or 2f with 1 equiv. of N-bromosuccinimide (NBS) at
room temperature in 95 and 74% yield, respectively. In contrast to the starting material 2f, the
brominated compound 8f was stable when exposed to air.
Bromo sultones 8a–8g are useful substrates for further functionalizations. Thus, subsequent
treatment of these compounds with phenylacetylene under Sonogashira conditions provided the
internal alkynes 9a–9g in high yields (Figure 7, Table 4).
3. Conclusion
Insummary, wehaveestablishedanewmethodtosynthesize1,3-dienicδ-sultones, basedonearlier
work (9, 10). The scope was expanded to include various substituents at the phenyl residue. We
optimized the reaction conditions, especially temperature and SO3 source, by adjusting them for
each substrate individually. All sultones were generated in moderate yields up to 47%, however,
in a single operation. Furthermore, we have shown that these sultones could be functionalized
with complete regioselectivity in excellent yields. Bromination only occurred at the carbon atom
adjacent to the sulfur atom, and a subsequent Sonogashira coupling with phenylacetylene was
carried out in good yields.

Journal of Sulfur Chemistry
9
4. Experimental
4.1. General
All reactions requiring exclusion of moisture were run under argon using flame-dried glassware.
Solvents were dried by distillation from Na (dioxane), P2O5 (CHCl3), or by passing through acti-
vated alumina (CH2Cl2). Solvent mixtures are reported as v/v ratios. All commercially available
compounds were used as received unless stated otherwise. Starting alkynes were synthesized
from the corresponding aryl bromides by two-step procedures via Sonogashira coupling with
2-methyl-3-butyn-2-ol (14) with subsequent cleavage using anhydrous KOH and 18-crown-6 in
benzene for the retro Favorski reaction (15) (alkynes 1b, 1c, 1e–1h) or with ethynyltrimethylsi-
lane with subsequent cleavage using KOH in methanol/diethyl ether (16) (alkyne 1d). Sulfur (VI)
oxide was distilled from 60% oleum or a P2O5/H2SO4 mixture (1:2, mol/mol) and converted
into dioxane sulfotrioxide by a known method (12). Flash chromatography: Merck silica gel 60
(40–63 μm). Thin-layer chromatography: Merck silica gel 60 F254 plates with UV visualization
of the spots. Melting points: Kleinfeld Labortechnik Electrothermal IA 9100 apparatus. 1H and
13C NMR: Bruker DRX-500 (1H: 500 MHz, 13C: 126 MHz, CDCl3, δ (ppm), calibrated to the
residual resonance of the solvent) or else Bruker AC-300 (1H: 300 MHz, 13C: 75.4 MHz, CDCl3,
δ (ppm), calibrated to the residual resonance of the solvent), s = singlet, d = doublet, t = triplet,
m = multiplet, psd = pseudo-doublet. Mass spectra: Hewlett Packard 5890 GC coupled with a
Hewlett Packard 5972 detector and Agilent 6890N GC coupled with an Agilent 5973N detec-
tor (GC/MS, m/z, 70 eV), or else Hewlett Packard 1100 – Bruker EsquireIon Trap (ESI/APCI,
m/z, 10–50V). FT-IR spectra: Nicolet 205 and Nicolet Avatar 360 spectrometer (ν, cm−1). X-ray
diffraction analysis: Nonius Kappa CCD diffractometer equipped with a molybdenum fine-focus
sealed tube.
4.2. Preparation of sultones 2a–2d and 2g from arylalkynes 1a–1d and 1g with dioxane
sulfotrioxide 3 (general procedure 1)
The arylalkyne 1a–1d or 1g (2.5 mmol) was dissolved in a CHCl3/dioxane mixture (4 mL, 1:1) in
a 10-mL flask at rt. Dioxane sulfotrioxide 3 (0.420 g, 2.5 mmol) was added, and the mixture was
stirred under reaction conditions as shown in Table 1. After cooling to rt, the reaction mixture was
filtered through a silica gel layer (2 cm) eluting with ethyl acetate. The volatiles were removed in
vacuo, and the products were purified by column chromatography with pentane/ethyl acetate.
4.3. Preparation of sultones 2a–2d and 2g from arylalkynes 1a–1d and 1g with
trimethylsilyl chlorosulfonate 4 (general procedure 2)
The arylalkyne 1a–1d or 1g (2.5 mmol) was dissolved in a CHCl3/dioxane mixture (6 mL, 1:1) in
a 10-mL flask and cooled to 0 ◦C. Trimethylsilyl chlorosulfonate 4 (0.472 g, 2.5 mmol) was added
dropwise at this temperature. Then the cooling bath was removed, and the mixture was stirred
under reaction conditions as shown in Table 2. The resulting mixture was filtered at rt through a
silica gel layer (2 cm) eluting with ethyl acetate. The volatiles were removed in vacuo, and the
products were purified by column chromatography with pentane/ethyl acetate.
4.4. Preparation of sultones 2e and 2f from arylalkynes 1e and 1f (general procedure 3)
The methoxyphenylethyne 1e or 1d (2.5 mmol) was dissolved in CH2Cl2 (10 mL) in a 50-mL
flask at rt. Dioxane (7 mL) and CHCl3 (3 mL) were added, and the solution was cooled to −78 ◦C.

10 J. Gaitzsch et al.
Trimethylsilyl chlorosulfonate 4 (0.472 g, 2.5 mmol) dissolved in 1:1 dioxane/CH2Cl2 (1 mL)
was added to the alkyne solution dropwise over 30 min at −78 ◦C. The resulting mixture was
stirred for 3 h at this temperature and warmed slowly to rt. After stirring for 60 h, the reac-
tion mixture was filtered through a silica gel layer (ca. 3 cm) eluting with ethyl acetate. The
volatiles were removed in vacuo, and the products were purified by column chromatography with
pentane/ethyl acetate.
4.4.1. 4,6-Diphenyl-[1,2]-oxathiine 2,2-dioxide (2a)
Column chromatography with pentane/ethyl acetate (5:1). Yield: see Tables 1 and 2. Pale yellow
1
crystalline compound, m.p. 158 ◦C. Rf = 0.32 (pentane/ethyl acetate, 5:1). H NMR: 6.73 (s,
1H), 6.79 (s, 1H), 7.46–7.62 (m, 8H), 7.79–7.83 (m, 2H). 13C NMR: 102.23 (CH), 113.12 (CH),
125.09 (2 CH), 126.81 (2 CH), 129.00 (2 CH), 129.30 (2 CH), 130.78 (CH), 130.90 (C), 131.43
(CH), 135.56 (C), 147.65 (C), 156.51 (C). MS (ESI): 285 [M+H]+, 302 [M+NH4]+. IR: 528,
562, 582, 605, 682, 727, 754, 790, 855, 932, 1005, 1041, 1076, 1164, 1224, 1251, 1281, 1345,
1398, 1420, 1450, 1494, 1541, 1578, 1627, 1652, 1696, 1735, 3069, 3093. Elemental analysis:
calc. for C16H12O3S: C 67.59, H 4.25, S 11.18; found: C 67.77, H 4.17, S 11.19. For X-ray
crystallographic data, see our previous work (17).
4.4.2. 4,6-Ditolyl-[1,2]-oxathiine 2,2-dioxide (2b)
Column chromatography with pentane/ethyl acetate (5:1). Yield: see Tables 1 and 2. Pale yellow
solid, m.p. 189 ◦C. Rf = 0.37 (pentane/ethyl acetate, 5:1). 1H NMR: 2.40 (s, 6H), 6.65 (s, 1H),
6.67 (s, 1H), 7.24–7.29 (m, 4H), 7.44 (psd, J = 9.0 Hz, 2H), 7.68 (psd, J = 9.0 Hz, 2H). 13C
NMR: 21.32 (CH3), 21.48 (CH3), 101.37 (CH), 111.80 (CH), 125.84 (2 CH), 126.86 (2 CH),
128.19 (C), 129.66 (2 CH), 129.92 (2 CH), 132.67 (C), 141.20 (C), 141.98 (C), 147.61 (C),
156.56 (C). MS (ESI): 313 [M+H]+, 642 [2M+NH4]+. IR: 544, 591, 639, 670, 707, 743, 771,
794, 820, 861, 929, 1004, 1020, 1047, 1126, 1156, 1187, 1230, 1250, 1292, 1345, 1414, 1450,
1510, 1536, 1570, 1621, 2921, 3076. Elemental analysis: calc. for C18H16O3S: C 69.21, H 5.16,
S 10.26; found: C 69.95, H 5.17, S 10.84.
4.4.3. 4,6-Di(4-chlorphenyl)-[1,2]-oxathiine 2,2-dioxide (2c)
Column chromatography with pentane/ethyl acetate (5:1). Yield: see Tables 1 and 2. Pale yellow
solid, m.p. 200 ◦C. Rf = 0.29 (pentane/ethyl acetate, 5:1). 1H NMR: 6.66 (s, 1H), 6.73 (s, 1H),
7.45–7.49 (m, 6H), 7.74 (psd, J = 9.0 Hz, 2H). 13C NMR: 102.11 (CH), 113.61 (CH), 127.17
(2 CH), 128.12 (2 CH), 129.22 (C), 129.41 (2 CH), 129.66 (2 CH), 133.80 (C), 137.25 (C),
137.90 (C), 146.41 (C), 155.78 (C). MS (ESI): 353 [M+H]+, 370 [M+NH4]+, 391 [M+K]+,
727 [2M+Na]. IR: 537, 570, 595, 630, 673, 706, 722 749, 775, 828, 861, 929, 1004, 1048, 1091,
1121, 1159, 1223, 1251, 1288, 1349, 1407, 1459, 1487, 1532, 1560, 1590, 1620, 1912, 2959,
3078. Elemental analysis: calc. for C16H10Cl2O3S: C 54.41, H 2.85, S 9.08; found: C 53.72, H
2.91, S 8.51.
4.4.4. 4,6-Di(3-chlorphenyl)-[1,2]-oxathiine 2,2-dioxide (2d)
Column chromatography with pentane/ethyl acetate (5:1). Yield: see Tables 1 and 2. Pale yellow
solid, m.p. 137–138 ◦C. Rf = 0.34 (pentane/ethyl acetate, 5:1). 1H NMR: 6.69 (s, 1H), 6.76 (s,
1H), 7.40–7.54 (m, 6H), 7.69 (d, J = 7.5 Hz, 1H), 7.78 (s, 1H). 13C NMR: 102.67 (CH), 114.56
(CH), 124.01 (CH), 124.99 (CH), 125.90 (CH), 126.95 (CH), 130.33 (CH), 130.65 (CH), 130.91

Journal of Sulfur Chemistry 11
(CH), 131.53 (CH), 132.39 (C), 135.28 (C), 135.44 (C), 137.00 (C), 146.08 (C), 155.34 (C). MS
(ESI): 353 [M+H]+, 370 [M+NH4]+, 727 [2M+Na]+. IR: 548, 560, 587, 649, 666, 689, 747,
777, 806, 823, 851, 882, 933, 1044, 1083, 1165, 1228, 1255, 1274, 1356, 1422, 1473, 1535, 1563,
1620, 1653, 1697, 1733, 3064, 3091. Elemental analysis: calc. for C16H10Cl2O3S: C 54.41, H
2.85, S 9.08; found: C 54.41, H 3.16, S 7.75.
4.4.5. 4,6-Di(4-methoxyphenyl)-[1,2]-oxathiine 2,2-dioxide (2e)
Column chromatography with pentane/ethyl acetate (3:1). Yield: see Tables 1 and 2. Pale yellow
solid, m.p. 162–163 ◦C (decomp.). Slowly decomposes on the air at rt with the building of pink
1
products. Rf = 0.34 (pentane/ethyl acetate, 3:1). H NMR: 3.87 (s, 6H), 6.60 (s, 2H), 6.97–
7.01 (m, 4H), 7.51 (psd, J = 9.0 Hz, 2H), 7.75 (psd, J = 9.0 Hz, 2H). 13C NMR: 55.47 (CH3),
55.49 (CH3), 100.40 (CH), 110.22 (CH), 114.41 (2 CH), 114.61 (2 CH), 123.49 (C), 127.72 (2
CH), 127.84 (C), 128.33 (2 CH), 147.39 (C), 156.38 (C), 161.71 (C), 162.17 (C). MS (ESI): 345
[M+H]+, 362 [M+NH4]+, 361 [M+OH]−, 705 [2M+OH]−.
4.4.6. 4,6-Di(2-methoxyphenyl)-[1,2]-oxathiine 2,2-dioxide (2f)
Column chromatography with pentane/ethyl acetate (3:1).Yield: see Tables 1 and 2.Yellow solid,
1
m.p. 127–128 ◦C. Rf = 0.32 (pentane/ethyl acetate, 3:1). H NMR: 3.88 (s, 3H), 3.92 (s, 3H),
6.80 (s, 1H), 6.97–7.10 (m, 4H), 7.15 (s, 1H), 7.37–7.46 (m, 3H), 7.82 (d, J = 7.8 Hz, 1H). 13
C
NMR: 55.62 (CH3), 55.69 (CH3), 109.33 (CH), 111.41 (CH), 111.59 (CH), 116.08 (CH), 120.03
(C), 120.86 (CH), 120.98 (CH), 125.06 (C), 129.00 (CH), 129.70 (CH), 131.44 (CH), 131.81
(CH), 145.50 (C), 151.41 (C), 157.11 (C), 157.55 (C). MS (ESI): 345 [M+H]+, 362 [M+NH4]+,
706 [2 M+NH4]+. IR: 548, 565, 587, 600, 613, 672, 707, 731, 747, 777, 808, 830, 856, 926,
994, 1019, 1055, 1127, 1157, 1184,1206, 1242, 1272, 1299, 1341, 1432, 1458, 1486, 1532, 1575,
1598, 1623, 2839, 2945, 2998, 3127. Elemental analysis: calc. for C18H16O5S: C 62.78, H 4.68,
S 9.81; found: C 61.58, H 4.63, S 8.88.
4.4.7. 4,6-Di(biphenyl-4-yl)-[1,2]-oxathiine 2,2-dioxide (2g)
Column chromatography with pentane/ethyl acetate (10:1). Yield: see Tables 1 and 2. Yellow
solid, m.p. 213 ◦C. Rf = 0.32. 1H NMR: 6.78 (s, 1H), 6.83 (s, 1H), 7.41–7.52 (m, 6H), 7.63–7.67
(m, 6H), 7.71–7.75 (m, 4H), 7.90 (psd, J = 7.4 Hz, 2H). 13C NMR: 101.97 (CH), 112.70 (CH),
126.40 (2 CH), 127.14 (4 CH), 127.32 (2 CH), 127.63 (2 CH), 127.94 (2 CH), 128.15 (CH),
128.22 (CH), 129.00 (2 CH), 129.01 (2 CH), 129.69 (C), 134.29 (C), 139.67 (C), 139.70 (C),
143.75 (C), 144.23 (C), 147.26 (C), 156.38 (C). MS (ESI): 437 [M+H]+. IR: 568, 603, 635, 694,
747, 761, 834, 863, 933, 1003, 1049, 1074, 1161, 1226, 1291, 1340, 1408, 1484, 1515, 1535,
1560, 1600, 1623, 1697, 1724, 2850, 2922, 3026, 3078. Elemental analysis: calc. for C28H20O3S:
C 77.04, H 4.62, S 7.35; found: C 76.67, H 4.16, S 7.15.
4.4.8. 1,3,5-Tritolylbenzene (6b)
Yield 5% by the general procedure 1. Yellow solid. Rf = 0.85 (pentane/ethyl acetate, 5:1).
1H NMR: 2.42 (s, 9H), 7.16–7.98 (m, 15H). 13C NMR: 21.78 (3 CH3), 127.84 (6 CH),
129.31 (6 CH), 130.19 (6 CH), 137.89, (3 C), 139.06 (3 C), 142.83 (3 C). MS (GC–MS): 348
(100) [M]+.

12 J. Gaitzsch et al.
4.5. Bromination of sultones 2a–2d and 2g (general procedure 4)
Sultone 2a–2d or 2g (0.5 mmol) was dissolved in CHCl3 (15 mL) in a two-necked flask equipped
with a water condenser. Bromine (0.75 mmol, 1.5 equiv.) was added, and the reaction mixture was
stirred at 65 ◦C bath temperature. HBr gas was removed from the reaction mixture by a gentle
argon flow. After 1 h, the reaction mixture was cooled, and the volatiles were removed in vacuo.
The residue was dissolved in ethyl acetate, filtered through a 2-cm silica gel layer, and the solvent
was removed in vacuo.
4.5.1. 3-Bromo-4,6-diphenyl-[1,2]-oxathiine 2,2-dioxide (8a)
Yield: see Table 3. Pale yellow solid, m.p. 144–145 ◦C. Rf = 0.34 (pentane/ethyl acetate, 5:1). 1H
NMR: 6.50 (s, 1H), 7.44–7.55 (m, 8H), 7.73–7.76 (m, 2H). 13C NMR: 105.62 (CH), 108.61 (C),
125.63 (2 CH), 128.03 (2 CH), 128.85 (2 CH), 129.06 (2 CH), 129.92 (CH), 130.12 (C), 131.47
(CH), 136.16 (C), 145.96 (C), 154.03 (C). MS (ESI): 380 [M+NH4]+. IR: 556, 609, 626, 676,
695, 753, 788, 804, 856, 888, 919, 957, 1014, 1038, 1072, 1100, 1187, 1236, 1287, 1372, 1419,
1447, 1473, 1485, 1493, 1621, 1654, 1697, 1733, 2922, 3004, 3031, 3087. Elemental analysis:
calc. for C16H11BrO3S: C 52.91, H 3.05, S 8.83; found: C 52.82, H 2.80, S 9.01. X-ray: Figure 5.1
4.5.2. 3-Bromo-4,6-ditolyl-[1,2]-oxathiine 2,2-dioxide (8b)
Yield: see Table 3. Pale brown solid, m.p. 145–146 ◦C. Rf = 0.39 (pentane/ethyl acetate, 5:1).
1H NMR: 2.41 (s, 3H), 2.43 (s, 3H), 6.44 (s, 1H), 7.25–7.32 (m, 4H), 7.38 (psd, J = 8.3 Hz,
2H), 7.63 (psd, J = 8.3 Hz, 2H). 13C NMR: 21.41 (CH3), 21.52 (CH3), 104.97 (CH), 107.51 (C),
125.61 (2 CH), 127.43 (C), 128.04 (2 CH), 129.46 (2 CH), 129.77 (2 CH), 133.55 (C), 140.19 (C),
142.13 (C), 146.10 (C), 154.16 (C). MS (ESI): 391 [M+H]+; 408 [M+NH4]+. IR: 561, 588, 616,
643, 699, 741, 782, 813, 894, 958, 1011, 1030, 1099, 1123, 1175, 1192, 1273, 1312, 1369, 1409,
1502, 1540, 1753, 1606, 1623, 1684, 1734, 1916, 2857, 2920, 2956, 3033. Elemental analysis:
calc. for C18H15BrO3S: C 55.25, H 3.86, S 8.29; found: C 54.87, H 3.35, S 8.99.
4.5.3. 3-Bromo-4,6-di(4-chlorphenyl)-[1,2]-oxathiine 2,2-dioxide (8c)
1
Yield: see Table 3. Dark yellow solid, m.p. 149 ◦C. Rf = 0.32 (pentane/ethyl acetate, 5:1). H
NMR: 6.42 (s, 1H), 7.40–7.50 (m, 6H), 7.67 (psd, J = 8.6 Hz, 2H). 13C NMR: 105.49 (CH),
109.38 (C), 126.90 (2 CH), 128.49 (C),129.26 (2 CH), 129.49 (4 CH), 134.31 (C), 136.29 (C),
137.94 (C), 144.78 (C), 153.30 (C). MS (ESI): 448/450/452 [M+NH4]+. IR: 684, 725, 755, 777,
845, 880, 946, 996, 1014, 1077, 1098, 1163, 1182, 1238, 1290, 1380, 1426, 1459, 1476, 1507,
1568, 1592, 1645, 1674, 1704, 1869, 2009, 2030, 2056, 2851, 2927, 2981, 3064, 3296. Elemental
analysis: calc. for C16H9BrCl2O3S: C 44.47, H 2.10, S 7.42; found: C 44.12, H 1.93, S 7.05.
X-ray: Figure 6.1
4.5.4. 3-Bromo-4,6-di(3-chlorphenyl)-[1,2]-oxathiine 2,2-dioxide (8d)
Yield: see Table 3. Pale brown solid, m.p. 146–147 ◦C. Rf = 0.37 (pentane/ethyl acetate, 5:1).
1H NMR: 6.45 (s, 1H), 7.34–7.50 (m, 6H), 7.62 (d, J = 7.5 Hz, 1H), 7.71 (s, 1H). 13C NMR:
106.01 (CH), 110.33 (C), 123.75 (CH), 125.64 (CH), 126.26 (CH), 128.06 (CH), 130.19 (CH),
130.31 (CH), 130.42 (CH), 131.59 (CH), 131.72 (C), 134.99 (C), 135.40 (C), 137.49 (C), 144.39
(C), 152.90 (C). MS (ESI): 448/450/452 [M+NH4]+. IR: 536, 557, 585, 615, 656, 691, 736,
786, 852, 880, 899, 914, 960, 1038, 1078, 1191, 1238, 1276, 1320, 1378, 1421, 1473, 1564, 1592,

Journal of Sulfur Chemistry 13
1621, 1697, 2924, 3080. Elemental analysis: calc. for C16H9BrCl2O3S: C 44.47, H 2.10, S 7.42;
found: C 44.14, H 2.30, S 7.12.
4.5.5. 4,6-Di(biphenyl-4-yl)-3-brom-[1,2]-oxathiine 2,2-dioxide (8g)
Yield: see Table 3. Yellow solid, m.p. 166 ◦C. Rf = 0.40 (pentane/ethyl acetate, 5:1). 1H NMR:
6.57 (s, 1H), 7.37–7.52 (m, 6H), 7.56–7.74 (m, 10H), 7.83 (psd, J = 8.0 Hz, 2H). 13C NMR:
105.45 (CH), 108.33 (C), 126.12 (2 CH), 127.09 (2 CH), 127.15 (2 CH), 127.47 (2 CH), 127.66
(2 CH), 128.04 (CH), 128.24 (CH), 128.64 (2 CH), 128.90 (C), 128.98 (4 CH), 134.94 (C), 139.55
(C), 139.86 (C), 142.86 (C), 144.26 (C), 145.70 (C), 153.91 (C). MS (ESI): 517 [M+H]+, 534
[M+NH4]+, 539 [M+Na]+. IR: 539, 564, 580, 638, 693, 729, 763, 788, 829, 893, 959, 1004,
1035, 1076, 1099, 1118, 1187, 1239, 1278, 1331, 1376, 1420, 1458, 1485, 1516, 1557, 1624,
1731, 1924, 2853, 2926, 3031, 3064. Elemental analysis: calc. for C28H19BrO3S: C 65.25, H
3.72, S 6.22, found: C 65.27, H 3.52, S 5.96.
4.5.6. Bromination of sultones 2e and 2f (general procedure 5)
Sultone 2e or 2f (0.1 mmol) was dissolved in CHCl3 (15 mL). NBS (0.019 g, 0.105 mmol) was
added, and the reaction mixture was stirred at rt.After 1 h, the volatiles were removed in vacuo. The
residue was dissolved in ethyl acetate and filtered through a 2-cm silica gel layer. The solvent was
removed in vacuo, and the products were purified by column chromatography with pentane/ethyl
acetate (3:1).
4.5.7. 3-Bromo-4,6-di(4-methoxyphenyl)-[1,2]-oxathiine 2,2-dioxide (8e)
Yield: see Table 3. Pale yellow solid, m.p. 127–128 ◦C. Slowly decomposed when exposed to
air at rt with formation of pink products. Rf = 0.38 (pentane/ethyl acetate, 3:1). 1H NMR: 3.86
(s, 3H), 3.87 (s, 3H), 6.35 (s, 1H), 6.94–7.01 (m, 4H), 7.44 (psd, J = 9.0 Hz, 2H), 7.67 (psd,
J = 9.0 Hz, 2H). 13C NMR: 55.38 (CH3), 55.47 (CH3), 104.03 (CH), 105.89 (C), 114.06 (2 CH),
114.47 (2 CH), 122.53 (C), 126.91 (2 CH), 129.79 (2 CH), 133.71 (C), 145.87 (C), 153.89 (C),
160.71 (C), 162.19 (C). MS (ESI): 423 [M+H]+.
4.5.8. 3-Bromo-4,6-di(2-methoxyphenyl)-[1,2]-oxathiine 2,2-dioxide (8f)
Yield: see Table 3. Pale brown solid, m.p. 142–143 ◦C. Rf = 0.35 (pentane/ethyl acetate, 3:1). 1H
NMR: 3.97 (s, 6H), 7.00 (s, 1H), 7.05–7.17 (m, 4H), 7.36–7.40 (m, 1H), 7.49–7.58 (m, 2H), 7.92
(dd, J = 7.9 and 1.7 Hz, 1H). 13C NMR: 55.62 (CH3), 55.65 (CH3), 110.08 (C), 111.21 (CH),
111.42 (CH), 111.48 (CH), 119.19 (C), 120.64 (CH), 120.89 (CH), 125.53 (C), 128.63 (CH),
129.51 (CH), 131.06 (CH), 132.02 (CH), 144.75 (C), 150.07 (C), 156.09 (C), 157.47 (C). MS
(ESI): 423 [M+H]+, 440 [M+NH4]+, 864 [2M+NH4]+. IR: 528, 574, 612, 652, 683, 747, 784,
806, 835, 852, 896, 956, 1008, 1045, 1084, 1122, 1186, 1245, 1289, 1370, 1433, 1458, 1473, 1490,
1529, 1611, 1632, 1729, 2839, 2966, 3015, 3117. Elemental analysis: calc. for C18H15BrO5S: C
51.08, H 3.57, S 7.58; found: 50.89, H 3.32, S 7.32.
4.6. Sonogashira coupling of bromo sultones 8a–8f (general procedure 6)
Starting sultone 8a–8f (0.2 mmol) was dissolved in THF (4 mL) and triethylamine (2 mL) in a
two-necked flask equipped with a water condenser. Phenylacetylene 1a (0.4 mmol) and triph-
enylphosphine (0.025 mmol) were added, and the reaction mixture was stirred at rt. After 5 min,

14 J. Gaitzsch et al.
PdCl2 and CuI (both 0.01 mmol) were added, and the reaction mixture was heated at 77 ◦C bath
temperature. After 24 h, the volatiles were removed in vacuo. The residue was dissolved in ethyl
acetate and filtered through a 2-cm silica gel layer. The solvent was removed in vacuo, and the
products were purified by column chromatography with pentane/ethyl acetate (3:1).
4.6.1. 4,6-Diphenyl-3-(phenylethynyl)-1,2-oxathiine 2,2-dioxide (9a)
Yield: see Table 4. Dark yellow solid, m.p. 125–126 ◦C. Rf = 0.30 (pentane/ethyl acetate, 5:1).
1H NMR: 6.64 (s, 1H), 7.12–7.17 (m, 2H), 7.23–7.45 (m, 10H), 7.65–7.71 (m, 3H). 13C NMR:
73.89 (C), 81.53 (C), 102.10 (C), 105.32 (CH), 121.74 (C), 125.76 (CH), 128.41 (3 CH), 128.44
(CH), 128.51 (CH), 128.55 (CH), 128.98 (CH), 129.19 (CH), 130.68 (C), 131.68 (CH), 132.46
(3 CH), 133.75 (CH), 133.96 (CH), 135.80 (C), 147.21 (C), 154.89 (C). MS (ESI): 385 [M+H]+,
402 [M+NH4]+, 407 [M+Na]+, 786 [2M+NH4]+, 791 [2M+Na]+. IR: 541. 571, 585, 647, 662,
682, 702, 748, 766, 826, 865, 908, 926, 1006, 1033, 1075, 1123, 1186, 1238, 1282, 1319, 1369,
1397, 1449, 1478, 1494, 1515, 1613, 1697, 1733, 2186, 3025, 3059. Elemental analysis: calc. for
C24H16O3S: C 74.98, H 4.19, S 8.34; found: C 75.05, H 4.12, S 8.10.
4.6.2. 4,6-Ditolyl-3-(phenylethynyl)-1,2-oxathiine 2,2-dioxide (9b)
1
Yield: see Table 4. Yellow solid, m.p. 65 ◦C. Rf = 0.35 (pentane/ethyl acetate, 5:1). H NMR:
2.34 (s, 3H), 2.37 (s, 3H), 6.59 (s, 1H), 7.18–7.28 (m, 7H), 7.37–7.38 (m, 2H), 7.57–7.62 (m,
4H). 13C NMR: 21.49 (CH3), 21.54 (CH3), 79.93 (C), 101.67 (C), 104.59 (CH), 112.95 (C),
122.02 (C), 125.77 (2 CH), 128.03 (C), 128.38 (2 CH), 128.50 (2 CH), 129.27 (3 CH), 129.76
(2 CH), 131.65 (2 CH), 133.01 (C), 140.78 (C), 142.13 (C), 147.35 (C), 155.05 (C). MS (ESI):
413 [M+H]+, 430 [M+NH4]+. IR: 593, 640, 688, 754, 814, 910, 1004, 1022, 1115, 1180, 1240,
1318, 1371, 1419, 1440, 1457, 1485, 1509, 1558, 1608, 1655, 1733, 2192, 2863, 2921, 3026,
3058. Elemental analysis: calc. for C26H20O3S: C 75.70, H 4.89, S 7.77; found: C 75.45, H 5.02,
S 7.42.
4.6.3. 4,6-Di(4-Chlorphenyl)-3-(phenylethynyl)-1,2-oxathiine 2,2-dioxide (9c)
Yield: see Table 4. Dark yellow solid, m.p. 90–92 ◦C. Rf = 0.31 (pentane/ethyl acetate, 5:1). 1H
NMR: 6.62 (s, 1H), 7.31–7.52 (m, 9H), 7.71 (psd, J = 8.7 Hz, 4H). 13C NMR: 79.29 (C), 103.08
(C), 105.19 (CH), 114.57 (C), 121.47 (C), 127.00 (2 CH), 128.51 (2 CH), 128.98 (2 CH), 129.05
(C), 129.44 (2 CH), 129.75 (CH), 129.89 (2 CH), 131.76 (2 CH),134.07 (C), 136.63 (C), 137.87
(C), 145.60 (C), 154.04 (C). MS (ESI): 470 [M+NH4]+. IR: 552, 581, 605, 631, 687, 752, 781,
822, 907, 1007, 1088, 1121, 1182, 1233, 1373, 1401, 1459, 1485, 1530, 1590, 1621, 1907, 2189,
2853, 2922, 3079. Elemental analysis: calc. for C24H14Cl2O3S: C 63.59, H 3.11, S 7.07; found:
C 63.88, H 3.33, S 6.85.
4.6.4. 4,6-Di(3-Chlorphenyl)-3-(phenylethynyl)-1,2-oxathiine 2,2-dioxide (9d)
Yield: see Table 4. Dark yellow solid, m.p. 43–44 ◦C. Rf = 0.31 (pentane/ethyl acetate, 5:1). 1H
NMR: 6.68 (s, 1H), 7.35–7.53 (m, 9H), 7.59–7.63 (m, 1H), 7.66–7.71 (m, 1H), 7.76–7.79 (m,
2H). 13C NMR: 79.14 (C), 103.69 (C), 105.70 (CH), 115.44 (C), 121.35 (C), 123.84 (CH), 125.72
(CH), 126.63 (CH), 128.51 (2 CH), 128.60 (CH), 129.82 (CH), 130.01 (CH), 130.36 (CH), 130.49
(CH), 131.47 (CH), 131.83 (2 CH), 132.27 (C), 134.70 (C), 135.35 (C), 137.14 (C), 145.04 (C),
153.59 (C). MS (ESI): 453 [M+H]+, 470 [M+NH4]+. IR: 528, 574, 592, 643, 683, 754, 779,
857, 884, 924, 997, 1012, 1079, 1098, 1126, 1168, 1235, 1300, 1375, 1422, 1479, 1507, 1523,

Journal of Sulfur Chemistry 15
1593, 1619, 1652, 1686, 1732, 2190, 2921, 3066. Elemental analysis: calc. for C24H14Cl2O3S: C
63.59, H 3.11, S 7.07; found: C 63.90, H 3.42, S 6.84.
4.6.5. 4,6-Di(4-methoxyphenyl)-3-(phenylethynyl)-1,2-oxathiine 2,2-dioxide (9e)
1
Yield: see Table 4. Dark yellow oil, Rf = 0.31 (pentane/ethyl acetate, 3:1). H NMR: 3.87 (s,
3H), 3.88 (s, 3H), 6.58 (s, 1H), 6.95–7.04 (m, 4H), 7.30–7.36 (m, 3H), 7.42–7.46 (m, 2H), 7.74
(m, 4H). 13C NMR: 55.40 (CH3), 55.47 (CH3), 80.14 (C), 101.18 (C), 103.51 (CH), 111.43 (C),
113.89 (2 CH), 114.47 (2 CH), 122.09 (C), 123.22 (C), 127.62 (2 CH), 128.09 (C), 128.34 (2
CH), 129.13 (CH), 130.24 (2 CH), 131.53 (2 CH), 147.21 (C), 154.86 (C), 161.24 (C), 162.23
(C). MS (ESI): 445 [M+H]+, 462 [M+NH4]+, 906 [2M+NH4]+, 911 [2M+Na]+. IR: 536, 582,
687, 755, 798, 909, 1024, 1076, 1172, 1228, 1255, 1308, 1369, 1455, 1484, 1509, 1538, 1558,
1571, 1600, 1734, 2192, 2840, 2924, 2961.
4.6.6. 4,6-Di(2-Methoxyphenyl)-3-(phenylethynyl)-1,2-oxathiine 2,2-dioxide (9f)
Yield: see Table 4.Yellow oil, Rf = 0.32 (pentane/ethyl acetate, 3:1). 1H NMR: 3.96 (s, 3H), 3.98
(s, 3H), 7.05–7.20 (m, 4H), 7.28 (s, 1H), 7.35–7.45 (m, 5H), 7.48–7.58 (m, 2H), 7.66 (dd, J = 7.7
and 1.7 Hz, 1H), 7.95 (dd, J = 7.7 and 1.7 Hz, 1H). 13C NMR: 55.55 (CH3), 55.62 (CH3), 77.95
(C), 101.58 (C), 110.41 (2 CH), 111.71 (CH), 115.43 (C), 119.74 (C), 120.30 (CH), 120.89 (CH),
122.09 (C), 125.21 (C), 128.27 (2 CH), 128.78 (CH), 129.08 (CH), 130.06 (CH), 131.27 (CH),
131.58 (2 CH), 131.97 (CH), 146.87 (C), 150.53 (C), 156.89 (C), 157.56 (C). MS (ESI): 445
[M+H]+, 462 [M+NH4]+, 906 [2 M+NH4]+, 911 [2 M+Na]+. IR: 592, 642, 689, 751, 810,
837, 912, 991, 1021, 1049, 1121, 1183, 1247, 1290, 1369, 1396, 1420, 1434, 1458, 1474, 1485,
1528, 1598, 1630, 2194, 2838, 2937, 3068.
4.6.7. 4,6-Di-(Biphenyl-4-yl)-3-(phenylethinyl)-[1,2]-oxathiine 2,2-dioxide (9g)
Yield: see Table 4. Yellow solid, m.p. 189 ◦C. Rf = 0.30 (pentane/ethyl acetate, 5:1). 1H NMR:
6.81 (s, 1H), 7.35–7.37 (m, 3H), 7.42–7.52 (m, 8H), 7.64–7.78 (m, 8H), 7.87–7.91 (m, 4H). 13
C
NMR: 79.87 (C), 102.42 (C), 105.11 (CH), 113.70 (C), 121.85 (C), 126.27 (2 CH), 127.12 (2
CH), 127.18 (2 CH), 127.22 (2 CH), 127.65 (2 CH), 128.06 (CH), 128.24 (CH), 128.44 (2 CH),
128.98 (4 CH), 129.09 (2 CH), 129.45 (CH), 129.49 (CH), 131.71 (2 CH), 134.65 (C), 139.61
(C), 139.94 (C), 143.24 (C), 144.21 (C), 146.77 (C), 154.74 (C). MS (ESI): 537 [M+H]+, 554
[M+NH4]+, 559 [M+Na]+. IR: 545, 583, 632, 684, 725, 748, 761, 783, 836, 907, 1000, 1025,
1114, 1190, 1238, 1298, 1346, 1375, 1396, 1456, 1483, 1512, 1600, 2181, 2845, 2922, 3028,
3057. Elemental analysis: calc. for C36H24O3S: C 80.57 H 4.51 S 5.98 found: C 80.21 H 4.44 S
5.83.
Acknowledgements
Financial support of this work by the DFG (ME 776/15-2) and the Rosa-Luxemburg-Foundation is gratefully
acknowledged.
Note
1. Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the
CambridgeCrystallographicDataCentreassupplementarypublicationnumbersCCDC776086(6b), CCDC776085
(8a), CCDC 776084 (8c).

16 J. Gaitzsch et al.
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