Convenient methods for synthesis of C2-symmetric diphenyltetrahydrothiophenes

Article abstract of DOI:10.1055/s-0028-1088123

Racemic and optically pure (-)-(3R,4R)-3,4-diphenyltetrahydrothiophene, (+)-(2S,5S)-2,5-diphenyltetrahydrothiophene, and (-)-(3S,6S)-3,6-diphenyl-1,2- dithiane were synthesized by use, in the crucial steps, of the easy-to-handle borane systems tetrabutylammonium borohydride-iodine and tetrabutylammonium borohydride-iodomethane. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-0028-1088123

PAPER
1739
Convenient Methods for Synthesis of C2-Symmetric Diphenyltetrahydro-
thiophenes
Synthesis of
C
-Symm
a
etric Diphe
r
nyltetrah
i
ydroth
a
iophenes ppan Periasamy,* Gurubrahamam Ramani, Gopal P. Muthukumaragopal
2
School of Chemistry, University of Hyderabad, Hyderabad, AP 500046, India
Fax +91(40)23012460; E-mail: mpsc@uohyd.ernet.in
Received 18 December 2008; revised 14 January 2009
Ph
Ph
Ph
Ph
Abstract: Racemic and optically pure (–)-(3R,4R)-3,4-diphenyltet-
rahydrothiophene, (+)-(2S,5S)-2,5-diphenyltetrahydrothiophene,
Ph
Ph
Ph
Ph
S
and (–)-(3S,6S)-3,6-diphenyl-1,2-dithiane were synthesized by use,
in the crucial steps, of the easy-to-handle borane systems tetra-
butylammonium borohydride–iodine and tetrabutylammonium
borohydride–iodomethane.
S
S
S
S
( )-1
(–)-1
(+)-2
(–)-3
Figure 1
Key words: diphenyltetrahydrothiophenes,
3,6-diphenyl-1,2-
dithiane, asymmetric reduction, tetrabutylammonium borohydride,
sulfur heterocycles
to-handle tetrabutylammonium borohydride–iodine or
tetrabutylammonium borohydride–iodomethane system
in anhydrous tetrahydrofuran provides ( )-2,3-diphenyl-
butane-1,4-diol (6) in 75% or 74% yield, respectively.
Further conversion into the corresponding ditosylate 7 by
use of p-toluenesulfonyl chloride and pyridine followed
by cyclization with sodium sulfide nonahydrate gives ( )-
1 in 91% yield.16
Chiral ligands containing sulfide moieties are useful for
many asymmetric transformations, such as asymmetric
epoxidations,1 catalytic asymmetric cyclopropanation of
electron-deficient alkenes,2 electrophilic sulfenylation of
unsaturated carbon–carbon bonds,3 and aziridination of
N-electron-withdrawn imines.4 They are useful for the
synthesis of chiral alcohols and amines from organobo-
ranes,5 the synthesis of certain carbocycles6 and function-
alized N-heterocycles,7 as well as the synthesis of
biologically active molecules such as iso-agatharesinol,8
swainsonine,9 a side chain of Taxol,10 and the anti-inflam-
matory agents11 neobenodine, cetirizine, and CDP-840.
Previously, a simple protocol for accessing chiral C2-sym-
metric 3,4-diphenylpyrrolidines via reduction of 2,3-
diphenylsuccinic acid derivatives by use of the sodium
borohydride–iodine reagent system was reported from
this laboratory.12 More recently, it was reported that the
reagent systems tetrabutylammonium borohydride–
iodine13a and tetrabutylammonium borohydride–
iodomethane13b give better yields in borane reductions.
Herein, we report simple, convenient methods for the
preparation of both racemic and optically pure (–)-
(3R,4R)-3,4-diphenyltetrahydrothiophene [( )-1 and (–)-
1], (+)-(2S,5S)-2,5-diphenyltetrahydrothiophene [(+)-
2],14 and (–)-(3S,6S)-3,6-diphenyl-1,2-dithiane [(–)-3]
(Figure 1) by use of these modified borane reagent sys-
tems in crucial steps in the synthesis.
Bu4NBH4
Ph
Ph
CH2OH
CH2OH
Ph
Ph
CO2Me
CO2Me
TiCl4, Et3N
I2 or MeI
OMe
CH2Cl2, –45 °C
Ph
THF
O
6
5
4
80%
75% (using I2)
74% (using MeI)
pyridine
TsCl
Ph
Ph
Ph
CH2OTs
Na2S•9H2O
EtOH
S
Ph
CH2OTs
7
( )-1
91%
85%
Scheme 1 Synthesis of ( )-3,4-diphenyltetrahydrothiophene [( )-1]
(–)-(3R,4R)-3,4-Diphenyltetrahydrothiophene [(–)-1] is
readily prepared by a similar synthetic protocol starting
from (R)-(+)-1,1¢-binaphthalene-2,2¢-diyl bis(phenylace-
tate) (9), which, in turn, is easily accessed by the reaction
of phenylacetic acid with 1,1¢-binaphthalene-2,2¢-diol (8)
(Scheme 2). Diester 9 is converted into the intramolecu-
larly coupled diester (–)-(R,R,R)-10 in 80% yield in the
presence of titanium(IV) chloride–triethylamine.17 Subse-
quent reduction of 10 with tetrabutylammonium borohy-
dride–iodine or tetrabutylammonium borohydride–
iodomethane gives (–)-(2R,3R)-2,3-diphenylbutane-1,4-
diol [(–)-6] in 71% or 75% yield, respectively. We ob-
served that these reducing systems give better yields than
the sodium borohydride–iodine system for the reduction
of 10. Direct reduction of 10 to (–)-6 is necessary, since
the hydrolysis of (–)-(R,R,R)-10 when potassium hydrox-
( )-3,4-Diphenyltetrahydrothiophene [( )-1] is readily
accessed by the synthetic protocol outlined in Scheme 1.
Dimethyl ( )-2,3-diphenylsuccinate (5) is prepared in
80% yield from methyl phenylacetate in the presence of
titanium(IV) chloride–triethylamine in dichloromethane
at –45 °C.15 Subsequent reduction of diester 5 by the easy-
SYNTHESIS 2009, No. 10, pp 1739–1743
x
x.
x
x
.
2
0
0
9
Advanced online publication: 14.04.2009
DOI: 10.1055/s-0028-1088123; Art ID: Z28108SS
© Georg Thieme Verlag Stuttgart · New York

1740
M. Periasamy et al.
PAPER
O
O
O
O
Ph
Ph
Ph
Ph
BnCOOH
TiCl4, Et3N
O
O
O
O
OH
OH
DCC, DMAP
CH2Cl2, –45 °C
8
9
10
75%
80%
Bu4NBH4
I2 or MeI
THF
Ph
Ph
Ph
TsOH2C
Ph
Ph
Ph
Na2S•9H2O
EtOH
TsCl
pyridine
CH2OTs
(–)-7
84%
HOH2C
CH2OH
(–)-6
S
(–)-1
91%, 99% ee
71% (using I2)
75% (using MeI)
Scheme 2 Synthesis of (–)-(3R,4R)-3,4-diphenyltetrahydrothiophene [(–)-1]
ide in methanol is used leads to racemization of the result- riched by use of L-proline and boric acid to give (+)-
ing 2,3-diphenylsuccinic acid. Diol (–)-6 is tosylated with (1R,4R)-diol 13 in 98% ee.20 The (+)-(1R,4R) diol 13
p-toluenesulfonyl chloride–pyridine to give (–)-7 in 84% (98% ee) was mesylated with methanesulfonyl chloride–
yield; ditosylate (–)-7 is cyclized in the presence of sodi- triethylamine in anhydrous dichloromethane to give
um sulfide nonahydrate in refluxing ethanol to give (–)- (1R,4R)-1,4-bis(methanesulfonyloxy)-1,4-diphenylbutane
(3R,4R)-3,4-diphenyltetrahydrothiophene [(–)-1] (91%). (14) in 82% yield.21 Finally, (+)-(2S,5S)-2,5-diphenyltet-
The structure of (–)-1 was further confirmed by X-ray rahydrothiophene [(+)-2] was obtained in 80% yield by
crystal structure analysis. The ORTEP diagram is given in the reaction of 14 with sodium sulfide nonahydrate in
Figure 2.
dimethyl sulfoxide.14 Its structure was further confirmed
by X-ray crystal structure analysis. The ORTEP diagram
of (+)-2 is given in Figure 3.
Figure 2 ORTEP representation of the crystal structure of (–)-1;
thermal ellipsoids are drawn at 35% probability and all the hydrogens
are omitted for the sake of clarity
Figure 3 ORTEP representation of the crystal of structure (+)-2; ther-
mal ellipsoids are drawn at 35% probability and all the hydrogens are
omitted for the sake of clarity
The chiral (+)-(2S,5S)-2,5-diphenyltetrahydrothiophene
[(+)-2] is synthesized by the protocol outlined in Scheme
3. (E)-1,4-Diphenylbut-2-ene-1,4-dione (11) is prepared
in 74% yield by Friedel–Crafts acylation of benzene with
fumaryl chloride.18 Subsequent reduction of 11 with
tin(II) chloride/hydrogen chloride in ethanol gives 1,4-
diphenylbutane-1,4-dione (12) in 76% yield.19 Diketone
12 is reduced with tetrabutylammonium borohydride–
iodine in the presence of a chiral oxazaborolidine system
in anhydrous tetrahydrofuran to give (+)-(1R,4R)-1,4-
diphenylbutane-1,4-diol (13) in 90% yield and 90% ee.
We observed that in this case better yields are obtained
when a smaller amount of tetrabutylammonium borohy-
dride (0.8 equiv) is used compared to sodium borohydride
(2.2 equiv).13b,c The nonracemic diol 13 (90% ee) was en-
Surprisingly, (–)-(3S,6S)-3,6-diphenyl-1,2-dithiane [(–)-
3] was formed in 85% yield when the reaction of 14 with
sodium sulfide nonahydrate was carried out in ethanol as
solvent (Scheme 3). Such sulfur–sulfur-bond-containing
compounds were previously reported to be obtained from
the reaction of bromoisobutyrophenone and sodium sul-
fide in ethanol.22 Disulfides are useful synthons, as the
sulfur–sulfur bond can be cleaved by numerous nucleo-
philes and electrophiles, and is also prone to oxidation.23
The structure of compound 3 was further confirmed by X-
ray crystal structure analysis. The ORTEP diagram is giv-
en in Figure 4.24
Synthesis 2009, No. 10, 1739–1743 © Thieme Stuttgart · New York

PAPER
Synthesis of C2-Symmetric Diphenyltetrahydrothiophenes
1741
i) Bu4NBH4
I2 or MeI
OH
O
O
(S)-DPP, B(OMe)3
SnCl2, HCl
EtOH
Ph
OH
Ph
Ph
Ph
Ph
Ph
ii) (S)-proline, B(OH)3
O
O
11
12
76%
13
74%
90%, 90% ee (using I2)
88%, 90% ee (using MeI)
(enriched to 98% ee)
MsCl
Et3N
CH2Cl2
OMs
Na2S•9H2O
DMSO
Na2S⋅9H2O
Ph
OMs
Ph
Ph
Ph
Ph
Ph
S
EtOH
S
S
(+)-2
80%, 99% ee
14
(–)-3
82%
85%, 98% ee
Scheme 3 Synthesis of (+)-(2S,5S)-2,5-diphenyltetrahydrothiophene [(+)-2] and (–)-(3S,6S)-3,6-diphenyl-1,2-dithiane [(–)-3]
mixture was extracted with EtOAc (2 × 20 mL). The combined or-
ganic extracts were washed with aq NaHCO3 (15 mL), H2O (10
mL), and brine (10 mL) and dried (Na2SO4). The solvent was re-
moved and the product was purified by column chromatography
(silica gel, 100–200 mesh, hexane–EtOAc, 80:20) and recrystal-
lized from hexane.
( )-2,3-Diphenylbutane-1,4-diol [( )-6]
Yield: 0.9 g (75%); mp 100–101 °C.
IR (KBr): 3290, 3060, 1601 cm–1.
1H NMR (400 MHz, CDCl3): d = 2.2 (br s, 2 H), 3.1–3.4 (m, 2 H),
3.8–4.1(m, 4 H), 6.8–6.95 (m, 4 H), 7.0–7.2 (m, 6 H).
Figure 4 ORTEP representation of the crystal structure of (–)-3;
thermal ellipsoids are drawn at 35% probability and all the hydrogens
are omitted for the sake of clarity
13C NMR (100 MHz, CDCl3): d = 51.03, 65.5, 126.5, 128.1, 128.6,
Since the chiral tetrahydrothiophene derivatives 1 and 2
and 1,2-dithiane 3 are readily prepared from simple and
readily accessible reagents, the methods described here
have considerable potential for further synthetic exploita-
tion.
140.6.
(–)-2,3-Diphenylbutane-1,4-diol [(–)-6]
Yield: 0.85 g (71%); 98% ee; [a]D25 –48.0 (c 0.404, CHCl3) {(Lit.16
[a]D25 –48.2 (c 0.249, CHCl3)}.
Use of Tetrabutylammonium Borohydride–Iodomethane for
the Reduction of Diester 10; Typical Procedure
TiCl4 (Spectrochem, India) and (R)-(+)-1,1¢-bi(2-naphthol)
(Gerchem, Hyderabad) were used as obtained. CH2Cl2 was distilled
over CaH2 and dried over 4-Å molecular sieves. THF was used
freshly distilled over benzophenone/sodium. Melting points were
determined on a Superfit capillary point apparatus and are uncor-
rected. IR (KBr) spectra were recorded on a Jasco FT-IR model
Diester 10 (2.6 g, 5 mmol) and Bu4NBH4 (6.168 g, 24 mmol) were
mixed in anhyd THF (60 mL) under N2 in a two-necked septum-
capped round-bottom flask. MeI (3.4 g, 1.5 mL, 24 mmol) dissolved
in anhyd THF (30 mL) was added under N2 at 0 °C over 1 h; the
mixture was stirred at 25 °C for 4 h and refluxed for 12 h. It was then
cooled to 25 °C and the excess hydride was carefully quenched with
3 N HCl (10 mL). After the gas evolution had ceased, the reaction
mixture was extracted with EtOAc (2 × 20 mL). The combined or-
ganic extracts were washed with aq NaHCO3 (15 mL), H2O (10
mL), and brine (10 mL) and dried (Na2SO4). The solvent was re-
moved under reduced pressure and the product was purified by col-
umn chromatography (silica gel, 100–200 mesh, hexane–EtOAc,
80:20) and recrystallized from hexane.
1
5300 spectrometer with polystyrene as reference. The H (400
MHz) and 13C (100 MHz) NMR spectra of samples in CDCl3, with
TMS as internal standard, were recorded on a Bruker Avance 400
spectrometer. Optical rotations were measured on an Autopol II au-
tomatic polarimeter at 25 °C. TLC analyses were carried out on
plates coated with silica gel (hexane–EtOAc mixtures); spots were
developed in an I2 chamber. For column chromatographic separa-
tions under gravity, column-grade silica gel (100–200 and 230–400
mesh) was employed.
(–)-2,3-Diphenylbutane-1,4-diol [(–)-6]
Yield: 0.9 g (75%); 98% ee; mp 100–101 °C; [a]D25 –48.0 (c 0.560,
Use of Tetrabutylammonium Borohydride–Iodine for the
Reduction of Diester 5; Typical Procedure
CHCl3) {Lit.16 [a]D25 –48.2 (c 0.249, CHCl3)}.
Diester 5 (1.49 g, 5 mmol) and Bu4NBH4 (6.168 g, 24 mmol) were
mixed in anhyd THF (60 mL) under N2 in a two-necked septum-
capped round-bottom flask. I2 (3.048 g, 12 mmol) dissolved in an-
hyd THF (30 mL) was added under N2 at 0 °C over 1 h; the mixture
was stirred at 25 °C for 4 h and refluxed for 12 h. The mixture was
cooled to 25 °C and the excess hydride was carefully quenched with
3 N aq HCl (10 mL). After gas evolution had ceased, the reaction
IR (KBr): 3290, 3060, 1601 cm–1.
1H NMR (400 MHz, CDCl3): d = 2.2 (br s, 2 H), 3.1–3.4 (m, 2 H),
3.8–4.1 (m, 4 H), 6.8–6.95 (m, 4 H), 7.0–7.2 (m, 6 H).
13C NMR (100 MHz, CDCl3): d = 51.03, 65.5, 126.5, 128.1, 128.6,
140.6.
Synthesis 2009, No. 10, 1739–1743 © Thieme Stuttgart · New York

1742
M. Periasamy et al.
PAPER
( )-2,3-Diphenylbutane-1,4-diol [( )-6]
Yield: 0.89 g (74%); mp 100–101 °C.
1H NMR (400 MHz, CDCl3): d = 1.8–2.0 (m, 4 H), 2.6–2.8 (br s, 2
H), 4.7 (m, 2 H), 7.2–7.3 (m, 10 H).
13C NMR (100 MHz, CDCl3): d = 35.1, 74.3, 125.6, 127.0, 128.1,
( )-3,4-Diphenyltetrahydrothiophene [( )-1]
144.6.
Na2S·9H2O (freshly recrystallized from EtOH; 4.8 g, 20 mmol) was
added to ( )-ditosylate 7 (2.63 g, 5 mmol) in EtOH (40 mL), and the
mixture was refluxed for 24 h. H2O (10 mL) was then added and the
mixture was extracted with Et2O (2 × 20 mL). The combined ex-
tracts were dried (Na2SO4) and the solvent was removed under re-
duced pressure. The product was purified by column
chromatography (silica gel, 230–400 mesh, hexane).
When using Bu4NBH4/MeI: Yield: 0.97 g (88%); 90% ee of
(1R,4R); [a]D25 +52.68 (c 0.47, CHCl3) {Lit.21 [a]D25 –58.5 (c 1.01,
CHCl3, > 98% ee) for (1S,4S)}.
(+)-(2S,5S)-2,5-Diphenyltetrahydrothiophene [(+)-2]
Dimesylate 14 (1.990 g, 5 mmol), prepared from (+)-(1R,4R)-diol
13 (98% ee), was taken up in DMSO (15 mL); Na2S·9H2O (freshly
recrystallized from EtOH; 4.8 g, 20 mmol) was added and the mix-
ture was stirred at 5 °C for 24 h. H2O (10 mL) was then added and
the contents were extracted with Et2O (3 × 20 mL). The combined
extracts were concentrated and the product was purified by column
chromatography (silica gel, 230–400 mesh, hexane).
Yield: 1.094 g, (91%); mp 109–110 °C.
1H NMR (400 MHz, CDCl3): d = 3.12–3.17 (m, 2 H), 3.28–3.32 (m,
2 H), 3.48–3.5 (m, 2 H), 7.1–7.26 (m, 10 H).
13C NMR (100 MHz, CDCl3): d = 38.6, 55.8, 126.8, 127.4, 128.5,
140.5.
Yield: 0.96 g (80%); 99% ee; mp 78 °C; [a]D25 +22 (c 0.5, CHCl3).
LCMS: m/z = 241 [M + 1].
HPLC (Daicel Chiralcel OJ-H, i-PrOH–hexane, 20:80, flow rate 1.0
mL/min, 254 nm): tR (S,S) = 28.8 min, tR (R,R) = 42.5 min.
1H NMR (400 MHz, CDCl3): d = 2.11–2.16 (m, 2 H), 2.58–2.62 (m,
2 H), 4.82–4.86 (m, 2 H), 7.22–7.34 (m, 6 H), 7.46–7.47 (m, 4 H).
(–)-3,4-Diphenyltetrahydrothiophene [(–)-1]
Compound (–)-1 was prepared from ditosylate (–)-7, by following
the procedure described above for ( )-1.
Yield: 1.094 g (91%); 99% ee; mp 109–110 °C; [a]D25 –205 (c 1.08,
CHCl3).
13C NMR (100 MHz, CDCl3): d = 41.0, 54.3, 127.2, 128.4, 142.5.
LCMS: m/z = 241 [M + 1].
HPLC (Daicel Chiralcel OB-H, i-PrOH–hexane, 5:95, flow rate 1.0
mL/min, 254 nm): tR (R,R) = 7.7 min, tR (S,S) = 12.3 min.
1H NMR (400 MHz, CDCl3): d = 3.12–3.17 (m, 2 H), 3.28–3.32 (m,
2 H), 3.48–3.5 (m, 2 H), 7.1–7.26 (m, 10 H).
13C NMR (100 MHz, CDCl3): d = 38.6, 55.8, 126.8, 127.4, 128.5,
140.5.
Anal. Calcd for C16H16S: C, 79.95; H, 6.71; S, 13.34. Found: C,
79.99; H, 6.74; S, 13.53.
(–)-(3S,6S)-3,6-Diphenyl-1,2-dithiane [(–)-3]
Dimesylate 14 (1.99 g, 5 mmol), prepared from (+)-(1R,4R)-diol 13
(98% ee), was taken up in EtOH (20 mL); Na2S·9H2O (freshly re-
crystallized from EtOH; 4.8 g, 20 mmol) was added and the mixture
was stirred at 25 °C for 24 h. H2O (10 mL) was then added and the
mixture was extracted with Et2O (3 × 20 mL). The combined ex-
tracts were concentrated and the product was purified by column
chromatography (silica gel, 230–400 mesh, hexane).
LCMS: m/z = 241 [M + 1].
Anal. Calcd for C16H16S: C, 79.95; H, 6.71; S, 13.34. Found: C,
79.95; H, 6.71; S, 13.64.
(+)-(1R,4R)-1,4-Diphenylbutane-1,4-diol (13)
Yield: 1.16 g (85%); mp 69–70 °C; 98% ee (based on ee of precur-
sor 13). (However, X-ray structure data revealed the absence of the
other enantiomer. Unfortunately, the corresponding racemic mix-
ture could not be resolved by HPLC using the chiral columns OD,
OB, OJ, and AD).
[a]D25 –4.2 (c 0.6, CHCl3).
1H NMR (400 MHz, CDCl3): d = 2.0–2.15 (m, 2 H), 2.53–2.61 (m,
2 H), 4.82–4.86 (m, 2 H), 7.22–7.36 (m, 10 H).
Bu4NBH4 (1.891 g, 7.6 mmol) was placed in a 100-mL three-neck
round-bottom flask under a N2 atmosphere in anhyd THF (20 mL).
To this I2 (0.934 g, 3.68 mmol) in anhyd THF (30 mL) was added
under N2 at 0 °C over 1 h by use of a pressure equalizer. The dibo-
rane generated in situ was trapped as a BH3–THF complex. To this
reagent, a soln of (S)-a,a-diphenyl-2-pyrrolidine methanol [(S)-
DPP; 0.8 mmol] and trimethyl borate (1 mmol) in THF (8 mL)] was
added and the mixture was stirred for 10 min. Then 12 (1 g, 4.6
mmol) dissolved in THF (25 mL) was added slowly to the reaction
mixture with a pressure equalizer over 1 h at 10 °C, and the mixture
was further stirred at 25 °C for 1 h. The reaction mixture was
brought to 25 °C and carefully quenched with 2 N HCl (15 mL). The
organic layer was separated and the aqueous layer was extracted
with Et2O (2 × 20 mL). The combined extracts were washed with
brine (10 mL) and dried (Na2SO4). The solvent was removed under
reduced pressure and the product was purified by column chroma-
tography (silica gel, 100–200 mesh, hexane–EtOAc, 75:25).
13C NMR (100 MHz, CDCl3): d = 41.0, 54.3, 127.5, 127.6, 128.5,
142.5.
LCMS: m/z = 273 [M + 1].
Anal. Calcd for C16H16S2: C, 70.54; H, 5.92; S, 23.54. Found: C,
70.56; H, 5.94; S, 23.78.
Acknowledgment
25
Yield: 1 g (90%); mp 63–65 °C; 90% ee; [a]D +52.6 (c 0.25,
We thank the CSIR (New Delhi) for research fellowships to G.B.R.
and G.P.M. DST support through a J. C. Bose National Fellowship
research grant to M.P. is gratefully acknowledged. We also thank
the DST for the 400 MHz NMR facility under the FIST program and
for the National Single-Crystal X-ray Diffractometer facility. Sup-
port of the UGC under the ‘University of Potential for Excellence’
and the Center for Advanced Study (CAS) programs is also grate-
fully acknowledged.
CHCl3) {Lit.21 [a]D25 –58.5 (c 1.01, CHCl3) for (1S,4S)-13}.
HPLC (Daicel Chiralpak AD-H, i-PrOH–hexane, 10:90, flow rate
1.0 mL/min, 254 nm): tR (S,S) = 21 min, tR (R,R) = 22.5 min.
The non-racemic diol 13 (90% ee) was enriched by a reported
procedure20 using L-proline and boric acid; this gave (+)-(1R,4R)-
diol 13 in 98% ee.
IR (KBr): 3339, 3025, 1207, 990 cm–1.
Synthesis 2009, No. 10, 1739–1743 © Thieme Stuttgart · New York

PAPER
Synthesis of C2-Symmetric Diphenyltetrahydrothiophenes
1743
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(23) Parker, A. J.; Kharasch, N. Chem. Rev. 1959, 59, 583.
(24) For compounds 1, 2, and 3, diffraction data were collected
on a Bruker SMART APEX CCD area detector system using
graphite monochromated Mo Ka radiation (l = 0.71073 Å).
Data reduction was carried out with SAINTPLUS, and the
structures were solved and refined with SHELXS-97. All
non-hydrogen atoms were refined anisotropically.
Crystal data for 1 (CCDC 711632): C16H16S, MW = 240.36,
monoclinic, space group: P21, a = 10.363 (2) Å, b = 8.6732
(19) Å, c = 14.857 (3) Å, b = 91.314 (4)°, V = 1335.0(5) Å3,
Z = 4, r = 1.196 Mg·M–3, m = 0.218 mm–1, T = 298 (2) K. Of
the 13820 reflections collected, 5194 were unique
(Rint = 0.0301). Refinement on all data converged at
R1 = 0.0487, wR2 = 0.1107.
References
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Crystal data for 2 (CCDC 711633): C16H16S, MW = 240.35,
monoclinic, space group: P21, a = 13.453 (4) Å, b = 5.7139
(18) Å, c = 17.416 (5) Å, b = 99.656 (5)°, V = 1319.8 (7) Å3,
Z = 4, r = 1.210 Mg·M–3, m = 0.220 mm–1, T = 298 (2) K. Of
the 12428 reflections collected, 4612 were unique
(Rint = 0.0626). Refinement on all data converged at
R1 = 0.0750, wR2 = 0.1969.
Crystal data for 3 (CCDC 711634): C16H16S2, MW = 272.41,
trigonal, space group: P3121, a = 9.2159 (14) Å, b = 9.2159
(14) Å, c = 14.647 (5) Å, a = 90°, b = 90°, g = 120°,
V = 1077.3 (4) Å3, Z = 3, r = 1.260 Mg·M–3, m = 0.350
mm–1, T = 298 (2) K. Of the 6010 reflections collected, 1401
were unique (Rint = 0.0326). Refinement on all data
converged at R1 = 0.0412, wR2 = 0.1092.
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Synthesis 2009, No. 10, 1739–1743 © Thieme Stuttgart · New York