New enantiopure bis(thioether) and bis(sulfoxide) ligands from benzothiophene

Article abstract of DOI:10.1002/ejoc.200400547

The C₂-symmetric compound 2,3,2′,3′-tetrahydro-2, 2′-bi(benzo[b]thiophenyl) and three diastereomeric bis(oxide) derivatives can be synthesized in a few steps from benzo[b]-thiophene by oxidative homocoupling of (R)-2,3-dihydro-benzo[b]thiophene 1-oxide. This new family of enantiopure bis(thioether) and bis(sulfoxide) ligands forms stable chelating Pd^II complexes. The fused pentacyclic structure of the complexes imparts a rigid chiral environment around the metal centre. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.

Full text of DOI:10.1002/ejoc.200400547

FULL PAPER
New Enantiopure Bis(thioether) and Bis(sulfoxide) Ligands from
Benzothiophene
David Madec,[a] Francesco Mingoia,[a,b] Cristian Macovei,[a] Guillaume Maitro,[a]
Giuliano Giambastiani,[c] and Giovanni Poli*[a]
Keywords: Oxidative coupling / Palladium / S ligands / Sulfoxides
The C2-symmetric compound 2,3,2Ј,3Ј-tetrahydro-2,2Ј-
bi(benzo[b]thiophenyl) and three diastereomeric bis(oxide)
derivatives can be synthesized in a few steps from benzo[b]-
thiophene by oxidative homocoupling of (R)-2,3-dihydro-
benzo[b]thiophene 1-oxide. This new family of enantiopure
bis(thioether) and bis(sulfoxide) ligands forms stable chelat-
ing PdII complexes. The fused pentacyclic structure of the
complexes imparts a rigid chiral environment around the me-
tal centre.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
Introduction
The field of asymmetric catalysis is witnessing an ever-
growing interest and several highly efficient catalytic meth-
ods are nowadays known in the literature. Despite these
positive results, knowledge in this field is still limited and
much work will be needed to make this methodology a
comprehensive and well-established technique. In this con-
text, the nature of the ancillary ligands used for a given
metal-catalysed process is central, with chiral P- and N-
based ligands occupying an incontestable leading position.
Despite the vast knowledge on sulfur–metal interactions in
coordination chemistry,[1] the use of S-based ligands in ca-
talysis appears to be still rather underdeveloped. Indeed,
bis(thioether)s have only been sporadically reported in the
literature in the context of asymmetric catalysis, and are
usually associated with modest enantioselectivities.[2,3] Such
a drawback is often due to the loss of stereohomogeneity
of the chelate complexes as a result of rapid epimerisation
at the sulfur (stereogenic) centres. Nonetheless, stereocon-
trol at the sulfur atom can be forced in special cases, such
as under stereoelectronic assistance, as recently demon-
strated by Khiar et al.[4] Furthermore, related studies in-
volving bis(sulfoxide)s, although of high potential interest,
have so far been virtually neglected.[5]
Scheme 1. New approach for the preparation of SCCS-type ligands
Results and Discussion
In this paper we describe our results in the development
of a new family of enantiopure SCCS chiral ligands of po-
tential interest for asymmetric catalysis. More specifically,
we thought that homocoupling of 2,3-dihydrobenzo[b]thio-
phene 1-oxide (C Ǟ B), followed by sulfoxide reduction (B
Ǟ A) might enable an easy entry to such a new class of
enantiopure SCCS ligands (Scheme 1).[6]
Since this particular type of coupling involves the preser-
vation of the pre-existing stereogenic centres at sulfur, as
well as the concomitant generation of two new ones, the
enantiomeric purity of the starting sulfoxide was expected
to be central not only to obtain enantiopure products, but
also to minimize the amount of possible homocoupled dia-
stereomers.[7] Accordingly, commercially available benzo[b]-
thiophene (1) was converted into the corresponding 2,3-di-
[a]
Laboratoire de Chimie Organique, UMR 7611, Université P. et
M. Curie,
4 Place Jussieu, B. P. 183, 75252 Paris Cedex 05, France
Fax: (internat.) +33-1-4427-7567
E-mail: giovanni.poli@upmc.fr
[b]
On leave from: ISMN-CNR, sez. Palermo,
Via U. La Malfa 153, 90146 Palermo, Italy
CNR, ICCOM, Florence Research Area,
[c]
Via Madonna del Piano, 50019 Sesto Fiorentino, Firenze, Italy hydrobenzo[b]thiophene 4 by reproduction and/or optimi-
552
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejoc.200400547
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Enantiopure Bis(thioether) and Bis(sulfoxide) Ligands
FULL PAPER
Scheme 2. Preparation of (R)-2,3-dihydrobenzo[b]thiophene 1-ox-
ide (5); reagents and conditions: (i) m-CPBA, CHCl3, room temp.,
19 h (90%); (ii) H2, 1 atm, 10% Pd/C (quant.); (iii) LiAlH4, Et2O,
reflux, 4 h (77%); (iv) H2, 30 atm, [RuII(triphos)(MeCN)3(OTf)2],
THF, 100 °C (96%); (v) CPO, H2O2, pH 5 buffer, room temp., 22 h
(90%, 98% ee)
Scheme 3. Synthesis of bis(sulfoxide)s 6–8; reagents and conditions:
(i) a: LDA, THF, –78 °C. b: CuCl2, –78 °C Ǟ room temp. c: O2,
76%, 1:1:1 diastereomeric ratio
sation of known synthetic routes (Scheme 2). Oxidation of
1 with m-chloroperbenzoic acid (m-CPBA) afforded the
corresponding sulfone 2, which was quantitatively hydroge-
nated to give 2,3-dihydrobenzo[b]thiophene 1,1-dioxide (3).
Treatment of the latter with an excess of LiAlH4 gave the
desired 2,3-dihydrobenzo[b]thiophene 4.[8] Alternatively, hy-
drogenation of 1 in the presence of [RuII(triphos)(MeCN)3-
(OTf)2], according to Bianchini’s protocol,[9] gave the de-
sired thioether 4 directly.[10]
Figure 1. ORTEP diagram of bis(sulfoxide) 6
A synthetically useful conversion of thioether 4 into its lute stereochemistry, and, by extension, that of the remain-
corresponding sulfoxide 5 was then necessary. After a few ing one.
disappointing hydroperoxide/TiIV oxidations in the presence
The sulfoxide functions of 6–8 are incorporated into five-
of various chiral ligands, we turned our attention to chloro- membered ring structures. As a consequence, assuming me-
peroxidases (CPOs). Indeed, Allenmark[11] has reported tal coordination through the sulfur atom, only the dia-
that, on the micromolar scale, the CPO isolated from stereomer 6 has the proper geometry for chelation. Tests of
Caldariomyces fumago affords the desired sulfoxide (R)-5 metal complexation confirmed the above speculation. In-
with a 99% ee. Remarkably, the method could be easily deed, addition of an equimolar amount of PdCl2 to 6 in
transposed from an analytical to a preparative scale (1500- CH2Cl2 afforded a new complex, which could be easily
fold scale-up) simply by using a commercially available monitored by TLC analysis and isolated as a yellow-orange
CPO. Accordingly, multigram oxidation of 4 gave the de- solid. Unfortunately, all attempts to obtain crystals suitable
sired sulfoxide (R)-5 in 90% yield and 98% ee.
for an X-ray diffraction analysis failed. However, compari-
Homocoupling of (R)-5 turned out be very tricky. In- son of the SO absorption bands in the IR spectrum of 6
deed, we soon realized that the lithium anion of 5, gener- (1020 cm–1) with those of its palladium(ii) complex 12
ated by deprotonation with LDA in THF at –78 °C, suffers (1150 cm–1) clearly indicated coordination through sulfur.[5]
ring opening above –50 °C. Furthermore, treatment of the As expected, treatment of diastereomer 7 under identical
above anion at –78 °C with CuCl2, and subsequent warm- conditions did not afford results consistent with the discrete
ing,[12] gave only tiny amounts of the homocoupled product formation of a chelated palladium(ii) complex.
along with some α-chlorinated and α,β-unsaturated sulfox-
BH3 ·THF reduction of bis(sulfoxide)s 6–8 gave the cor-
ides in a very irreproducible way. Bubbling oxygen through responding bis(thioether)s 9–11 (Scheme 4). Analysis of
the mixture after CuCl2 addition[13] did not improve these their optical rotatory power clearly evidenced the enantio-
results. After much effort we finally discovered that careful meric relationship between 9 and 10, as well as the meso
warming of the reaction mixture to room temperature after structure of 11.[14]
CuCl2 addition, followed by oxygen bubbling, gave the
three expected diastereomers 6, 7 and 8 in a 1:1:1 ratio and (thioether)s was performed next. Separate treatment of 9
with a reproducible yield of 76% (Scheme 3). and 11 with PdCl2 in CH2Cl2 at room temperature afforded
A check of the coordinating/chelating abilities of the bis-
Diastereomer 8 could be easily detected on the basis of the corresponding chelated complexes 13 and 14
its (more complex) 13C NMR spectrum; the two remaining (Scheme 5), whose structures were determined by X-ray dif-
dissymmetric isomers show only half the number of signals. fraction analysis (Figure 2 and Figure 3, respectively).
Additionally, a single-crystal X-ray diffraction structure of Interestingly, no epimerisation at the stereogenic sulfur
the more polar diastereomer 6 (Figure 1) unveiled its abso- centres appears to be possible in complex 13.
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553

G. Poli et al.
FULL PAPER
Figure 3. ORTEP diagram of complex 14
Scheme 4. Synthesis of bis(thioether)s 9–11; reagents and condi-
tions: (i) BH3 ·THF, THF, 0 °C Ǟ room temp. (quant.)
chelated structures, which can create a well-defined asym-
metric or dissymmetric “chiral space” around a metal, a
feature that is of obvious potential interest for asymmetric
catalysis. Extension of the present method to the homo-
coupling of additional enantiopure sulfoxides and studies
of asymmetric catalysis are planned for the future.
Experimental Section
General Remarks: Diethyl ether and THF were distilled from so-
dium benzophenone ketyl; dichloromethane and diispropylamine
were distilled from CaH2. All other reagents and solvents were used
1
without further purification. H NMR (400 MHz) and 13C NMR
(100 MHz) were recorded with a Bruker ARX-400 spectrometer
using the residual peak of deuterated chloroform (δ = 7.27 ppm for
1H and = 77.14 ppm for 13C) as internal standard. IR spectra were
recorded with a Bruker Tensor 27 (pike) instrument and only the
strongest or structurally most important peaks are listed. Optical
rotations were measured with a Perkin–Elmer 343 polarimeter. An-
alytical HPLC was performed with a Waters liquid chromatograph
using Chiralcel OJ column. Chromatographic purifications were
conducted using 40–63 µm or 15–40 µm silica gel and analytical
TLC was performed on Merck precoated silica 60-F254 plates.
Scheme 5. Preparation of complexes 12–14; reagents and condi-
tions: (i) PdCl2, CH2Cl2, room temp. (quant.)
[8,15]
Benzo[b]thiophene 1,1-Dioxide (2):
m-Chloroperbenzoic acid
(70%, 31.4 g, 0.127 mol, 2.5 equiv.) was added portionwise to a
solution of benzo[b]thiophene (6.83 g, 0.051 mol) in chloroform
(350 mL) at room temperature with vigorous stirring. The mixture
was allowed to stir overnight at the same temperature. Then, a satu-
rated aqueous NaHCO3 solution (1 L) was added and the aqueous
layer was extracted with dichloromethane (3 × 200 mL). The col-
lected organic layers were dried, and the solvent was removed in
vacuo. Crystallization from ethanol afforded white crystals (7.60 g,
1
90% yield). H NMR (CDCl3, 400 MHz): δ = 6.73 (d, J = 7.1 Hz,
1 H), 7.23 (d, J = 7.1 Hz, 1 H), 7.38 (dd, J = 6.6, J = 1.5 Hz, 1
H), 7.51–7.60 (m, 2 H), 7.73 (d, J = 7.1 Hz, 1 H) ppm. 13C NMR
(CDCl3, 100 MHz): δ = 121.3, 125.5, 130.6, 130.8, 131.2, 132.5,
133.7, 136.7 ppm. MS (CI/NH3): m/z = 201 [MN2H7+], 184
Figure 2. ORTEP diagram of complex 13
Conclusions
[MNH4+], 137. IR (powder): ν = 3115, 3060, 1550, 1450, 1445,
˜
In conclusion, we have presented an easy preparation of
a new family of practically enantiopure SCCS-type ligands
[bis(sulfoxide)s and bis(thioether)s] starting from commer
cially available benzo[b]thiophene. The key steps in the syn-
thesis are the successful microgram-to-multigram scale-up
of a highly enantioselective CPO-catalysed thioether-to-sulf-
oxide oxidation, and the CuII-mediated homocoupling re-
action of an α-lithiosulfoxide. The bis(sulfoxide)s and bis-
1280, 1265, 1190, 1145, 1120, 865, 765, 750 cm–1. M.p. 141–143 °C.
[8,15b]
2,3-Dihydrobenzo[b]thiophene 1,1-Dioxide (3):
Hydrogenation
of benzo[b]thiophene 1,1-dioxide (2) (7.30 g, 0.044 mol) was ac-
complished under a pressure of 1 atm of hydrogen over 24 h in
500 mL of ethanol as the solvent and with 0.1 g of 10% palladium-
on-charcoal catalyst. Evaporation of the solvent, after filtration of
the catalyst through a Celite pad, gave white crystals of 3 (7.30 g,
quant.). 1H NMR (CDCl3, 400 MHz): δ = 3.40 (t, J = 7.1 Hz, 2
(thioether)s thus obtained afford rigid pentacyclic metal- H), 3.51 (t, J = 7.1 Hz, 2 H), 7.39 (d, J = 7.6 Hz, 1 H), 7.48 (t, J
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Eur. J. Org. Chem. 2005, 552–557

Enantiopure Bis(thioether) and Bis(sulfoxide) Ligands
FULL PAPER
= 7.6 Hz, 1 H), 7.59 (t, J = 7.6 Hz, 1 H), 7.75 (d, J = 7.6 Hz, 1 H) (benzo[b]thiophenyl) 1,1Ј-Dioxide (7) and (1R,2S,1Ј R,2ЈR)-2,3,2Ј,3Ј-
ppm. 13C NMR (CDCl3, 100 MHz): δ = 25.5, 50.7, 121.6, 127.4,
Tetrahydro-2,2Ј-bi(benzo[b]thiophenyl) 1,1Ј-Dioxide (8): A THF
128.9, 133.6, 137.3, 139.0 ppm. MS (CI/NH3): m/z = 186 [MNH4+], (2 mL) solution of the sulfoxide 5 (100 mg, 0.664 mmol) was added
104. IR (CHCl ): ν = 3120, 3060, 1280, 1150, 705 cm–1. M.p. 88–
dropwise to a stirred solution of lithium diisopropylamide
˜
3
89 °C.
(0.723 mmol, 1.1 equiv.) in THF (2 mL) at –78 °C. After 5 min at
the same temperature dry, powdered cupric chloride (115 mg,
0.855 mmol, 1.3 equiv.) was added to the yellow solution and, after
25 min, the resulting brown mixture was warmed to room tempera-
ture. A dry oxygen stream was then bubbled through the green
solution over 90 min. An aqueous 1.0 m HCl solution (5 mL) was
then added to the resulting green suspension and the aqueous layer
was extracted with chloroform (3 × 5 mL). The collected organic
layers were washed with an NH4Cl/NH3 (2:1) aqueous solution (3
× 5 mL) and brine (5 mL), then dried with anhydrous magnesium
sulfate. The solvent was removed in vacuo and the residue was puri-
fied by flash chromatography (gradient of elution: ethyl acetate/
cyclohexane, 80:20 Ǟ ethyl acetate Ǟ ethyl acetate/methanol, 95:5)
to afford, in order of elution, 7 (25 mg, 25% yield), 8 (25 mg, 25%
yield) and 6 (26 mg, 26%).
[8]
2,3-Dihydrobenzo[b]thiophene (4). Method A:
A suspension of
2,3-dihydrobenzo[b]thiophene 1,1-dioxide (3) (1 g, 5.95 mmol) in
dry diethyl ether (45 mL) was added to a suspension of LiAlH4
(2.03 g, 53.49 mmol, 9 equiv.) in dry diethyl ether (45 mL) at room
temperature. The reaction mixture was refluxed for 4 h, then cooled
to 0 °C. The excess of hydride was decomposed by dropwise ad-
dition of water (10 mL), and the resultant white precipitate dis-
solved in dilute hydrochloric acid (4 m, 250 mL). The aqueous layer
was extracted with diethyl ether (3 × 100 mL). The collected or-
ganic layers were dried, and the solvent was removed in vacuo. The
crude product was purified by flash chromatography (pentane) to
afford 2,3-dihydrobenzo[b]thiophene as a colorless oil (0.622 g,
77% yield).
Method B: [9] A solution of [Ru(triphos)(CH3CN)3](OTf)2 (100 mg,
0.2 mol%) and benzo[b]thiophene (6 g, 44.7 mmol) in THF (45 mL)
was placed in a 60 mL Parr reactor under nitrogen. After pressuriz-
ing with hydrogen to 30 bar at room temperature, the mixture was
heated to 100 °C with stirring (750 rpm). After 24 h the reactor was
cooled to room temperature, depressurised, and the contents of the
reactor were transferred into a flask. The solvent was evaporated
under reduced pressure and then the residue was washed with pen-
tane (50 mL) and filtered through a cotton pad. The solvent was
evaporated under reduced pressure to afford 4 as a colourless oil
(5.87 g, 96% yield). 1H NMR (CDCl3, 400 MHz): δ = 3.31–3.44
(m, 4 H), 7.08 (td, J = 7.6, J = 1.0 Hz, 1 H), 7.19 (td, J = 7.6, J =
1.0 Hz, 1 H), 7.28 (dd, J = 7.6, J = 1.0 Hz, 1 H), 7.31 (d, J =
7.1 Hz, 1 H) ppm. 13C NMR (CDCl3, 100 MHz): δ = 33.4, 36.3,
122.2, 124.2, 124.5, 127.4, 140.1, 141.6 ppm. MS (CI/NH3): m/z =
6: 1H NMR (CDCl3, 400 MHz): δ = 3.35 (dd, J = 16.4, J = 6.3 Hz,
2 H), 3.87 (dd, J = 16.4, J = 6.8 Hz, 2 H), 3.99 (m, 2 H), 7.39–7.56
(m, 6 H), 7.78 (d, J = 7.6 Hz, 2 H) ppm. 13C NMR (CDCl3,
100 MHz): δ = 35.1, 70.9, 126.3, 126.9, 129.1, 132.6, 140.5, 143.2
ppm. MS (CI/NH3): m/z = 320 [MNH4+], 303 [MH+], 287, 271.
HRMS: m/z calculated for C16H15O2S2 303.0513 [MH+]; found
303.0515. IR (powder): ν = 1470, 1450, 1065, 1020, 750 cm–1.
˜
[α]2D5 = –140.3 (c = 0.7, CHCl3). M.p. 180–182 °C.
7: 1H NMR (CDCl3, 400 MHz): δ = 3.51 (dd, J = 15.2, J = 4.6 Hz,
2 H), 3.80–3.98 (m, 4 H), 7.42–7.58 (m, 6 H), 7.91 (d, J = 7.6 Hz,
2 H) ppm. 13C NMR (CDCl3, 100 MHz): δ = 35.2, 58.7, 126.0,
127.5, 128.6, 132.9, 143.6, 144.2 ppm. MS (CI/NH3): m/z = 320
[MNH4+], 303 [MH+], 285, 267. IR (powder): ν = 1460, 1070, 1010,
˜
750 cm–1. [α]2D5 = +53.4 (c = 0.5, CHCl3). M.p. 156–160 °C.
1
137 [MH+], 136 [M+], 135, 121, 108, 91. IR (neat): ν = 3070, 2950,
8: H NMR (CDCl3, 400 MHz): δ = 3.29–3.39 (m, 1 H), 3.43 (dd,
˜
1590, 1465, 1450, 1430, 1260, 1125, 1065, 750 cm–1.
J = 16.3, J = 6.6 Hz, 1 H), 3.74 (dd, J = 16.3, J = 6.6 Hz, 1 H),
4.01–4.15 (m, 2 H), 4.20 (dd, J = 16.3, J = 7.1 Hz, 1 H) 7.42–7.60
(m, 6 H), 7.84 (d, J = 7.1 Hz, 1 H), 7.90 (d, J = 7.6 Hz, 1 H) ppm.
13C NMR (CDCl3, 100 MHz): δ = 35.9, 37.0, 63.1, 69.5, 126.4,
126.6, 126.8, 127.5, 128.6, 128.9, 132.5, 133.3, 140.5, 143.5, 143.7,
144.7 ppm. MS (CI/NH3): m/z = 320 [MNH4+], 303 [MH+], 285,
[11,16]
(R)-2,3-Dihydrobenzo[b]thiophene 1-Oxide (5):
An aqueous
H2O2 solution (6.30 mL of 35% v/v H2O2 in 43.70 mL of distilled
water, 73.6 mmol, 2 equiv.) was added dropwise by means of a sy-
ringe pump (flow rate: 3.2 mL h–1) to an emulsion of 2,3-dihydro-
benzo[b]thiophene (4) (5 g, 36.8 mmol) and CPO (540 µL,
22314 u mL–1, 12064 u) in 0.1 m citrate buffer (pH 5.0, 1 L) at room
temperature, with vigorous stirring. Six hours after the end of the
addition, the reaction was treated with a saturated Na2SO3 aqueous
solution (300 mL), and the aqueous layer was extracted with ethyl
acetate (4 × 300 mL) and then with chloroform (2 × 300 mL). The
collected organic layers were dried, and the solvent was removed
in vacuo. The residue was purified by flash chromatography (gradi-
ent of elution: ethyl acetate Ǟ ethyl acetate/methanol, 95:5) to af-
ford 5 as a pure, white solid (5.035 g, 90% yield). 1H NMR (CDCl3
400 MHz): δ = 3.23–3.42 (m, 3 H), 3.83–3.95 (m, 1 H), 7.40–7.56
(m, 3 H), 7.85 (d, J = 7.6 Hz, 1 H) ppm. 1H NMR (C6D6,
400 MHz): δ = 2.25–2.39 (m, 2 H), 2.57–2.64 (m, 1 H), 3.07–3.14
(m, 1 H), 6.77 (d, J = 7.6 Hz, 1 H), 6.85 (t, J = 7.6 Hz, 1 H), 6.95
(td, J = 7.6, J = 1.0 Hz, 1 H), 7.50 (d, J = 7.6 Hz, 1 H) ppm. 13C
NMR (CDCl3, 100 MHz): δ = 31.6, 52.9, 126.1, 126.9, 128.4, 132.4,
143.3, 145.0 ppm. MS (CI/NH3): m/z = 170 [MNH4+], 153 [MH+],
267. IR (powder): ν = 1465, 1445, 1060, 1015, 760 cm–1. [α]25
=
˜
D
–17.4 (c = 0.9, CHCl3). M.p. 172–174 °C.
General Procedure for the Preparation of Bis(thioether) Ligands:
BH3 ·THF (0.8 mL, 1.0 m in THF, 0.8 mmol, 6 equiv.) was added
to a dry THF (3 mL) solution of bis(sulfoxide) (40 mg, 0.13 mmol)
at room temperature. After 15 h stirring the mixture was cooled to
0 °C and a saturated aqueous NH4Cl solution (4 mL) was added
slowly. The aqueous layer was then extracted with diethyl ether (3 ×
5 mL). The combined organic layers were washed with an aqueous
saturated NaHCO3 solution (5 mL) and brine (5 mL), dried with
anhydrous magnesium sulfate and evaporated under reduced pres-
sure. Flash chromatography (cyclohexane/dichloromethane, 95:5)
of the resulting crude product afforded the pure bis(thioether)
ligand as a white solid.
(2R,2ЈR)-2,3,2Ј,3Ј-Tetrahydro-2,2Ј-bi(benzo[b]thiophenyl) (9): Syn-
thesised from 6 in quantitative yield. 1H NMR (CDCl3, 400 MHz):
δ = 3.21 (dd, J = 15.9, J = 3.9 Hz, 2 H), 3.42 (dd, J = 15.9, J =
7.1 Hz, 2 H), 4.06–4.15 (m, 2 H), 7.03 (td, J = 7.3, J = 1.3 Hz, 2
H), 7.09–7.23 (m, 6 H) ppm. 13C NMR (CDCl3, 100 MHz): δ =
39.4, 55.0, 122.1, 124.5, 124.7, 127.7, 138.5, 140.1 ppm. MS (CI/
NH3): m/z = 288 [MNH4+], 271 [MH+]. HRMS: m/z calculated for
136. IR (powder): ν = 1465, 1440, 1410, 1120, 1025, 790, 770 cm–1.
˜
M.p. 54 °C. ee: 98% [determination by HPLC, column Chiralcel
OJTM; temperature column: 35 °C. UV detection λ = 220 nm; elu-
ent: hexane/ethanol, 85:15, flow rate: 1 mL/ min; t 7.40 min (S)
R
9.25 min (R)]. [α]2D5 = –310 (c = 1.5, acetone).
(1R,2R,1ЈR,2ЈR)-2,3,2Ј,3Ј-Tetrahydro-2,2Ј-bi(benzo[b]thiophenyl)
1,1Ј-Dioxide (6), (1R,2S,1Ј R,2ЈS)-2,3,2Ј,3Ј-Tetrahydro-2,2Ј-bi- C H S 271.0615 [MH+]; found 271.0614. IR (powder): ν = 3060,
˜
16 15
2
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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G. Poli et al.
FULL PAPER
Table 1. Crystallographic data and structure refinement for 6, 13 and 14
6
13
14
Empirical formula
Formula mass
Crystal color
Crystal system
Space group
a [Å]
C16H14O2S2
302.42
C16H14Cl2PdS2
447.72
colourless
trigonal
P32 (no. 145)
14.710(7)
14.710(7)
19.617(9)
–
C16H14Cl2PdS2, CH2Cl2
532.66
colourless
monoclinic
P21 (no. 4)
8.003(1)
7.9984(8)
11.212(2)
102.94(1)
699.4(2)
2
orange
monoclinic
P21/c (no. 14)
11.3275(6)
12.673(3)
13.416(2)
95.74(1)
1916.3(5)
4
b [Å]
c [Å]
β [°]
Volume [Å3]
Z
3676(3)
9
Radiation type
Wavelength [Å]
Density [g cm–1]
µ [mm–1]
Temperature [K]
Size [mm]
Mo-K
0.710730
1.44
0.378
295
0.04 × 0.12 × 0.5
plate
Mo-Kα
0.710730
1.82
1.707
295
0.04 × 0.04 × 0.25
stick
Mo-Kα
0.710730
1.85
1.741
295
0.20 × 0.20 × 0.30
block
α
Shape
Reflections measured
Independent reflections
Rint
θmin, θmax
hmin, hmax
kmin, kmax
lmin, lmax
Refinement
R-factor
Weighted R-factor
∆ρmin
4469
2729
0.11
9314
6442
0.16
17994
3758
0.11
2, 26.00
–13, 13
–15, 14
–16, 16
on F
0.0440
0.0498
1, 27.48
–10, 6
–10, 6
–11, 14
on F
0.0448
0.0445
–0.40
1, 25.02
–16, 15
–17, 16
–23, 21
on F
0.141[17]
0.131
–2.23
–1.11
∆ρmax
0.57
1.93
0.89
Reflections used
σ(I) limit
Number of parameters
Goodness-of-fit
Flack parameter
1809
1.80
183
1.099
5240
3.00
329
1.103
2032
2.00
204
1.094
0.05(12)
0.04(13)
–
2930, 2870, 1585, 1460, 1445, 1120, 1090, 1060, 945, 730 cm–1.
fractometer with graphite monochromated Mo-K radiation. A
α
[α]2D5 = –160 (c = 1.0, CHCl3). M.p. 129–131 °C.
summary of the crystal data, data collection for 6, 13, and 14, and
refinement techniques is given in Table 1. The diffraction data were
reduced using the EvalCCD[18] program package. Absorption cor-
rections were applied using DIFABS.[19] The structures were solved
with SIR92[20] and refined by full-matrix least-squares on F using
the programs of the PC version of CRYSTALS[21] with anisotropic
thermal parameters for non-hydrogen atoms, when sufficient data
were available. Hydrogen atoms were introduced in calculated posi-
tions, and only one overall isotropic displacement parameter was
refined. CCDC-234009 (for 6), -234175 (for 13) and -234010 (for
14) contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_requ-
est/cif.
(2S,2ЈS)-2,3,2Ј,3Ј-Tetrahydro-2,2Ј-bi(benzo[b]thiophenyl) (10): Syn-
thesised from 7 in quantitative yield. Spectroscopic data were iden-
tical to those of 9 except for the specific rotation. [α]2D5 = +159 (c
= 1.0, CHCl3).
meso-2,3,2Ј,3Ј-Tetrahydro-2,2Ј-bi(benzo[b]thiophenyl) (11): Synthe-
1
sised from 8 in quantitative yield. H NMR (CDCl3, 400 MHz): δ
= 3.33 (dd, J = 15.9, J = 3.3 Hz, 2 H), 3.44–3.54 (m, 2 H), 3.81–
3.90 (m, 2 H), 7.07 (td, J = 7.6, J = 1.2 Hz, 2 H), 7.13–7.25 (m, 6
H) ppm. 13C NMR (CDCl3, 100 MHz): δ = 41.5, 54.4, 122.3, 124.6,
125.0, 127.6, 138.4, 139.6 ppm. MS (CI/NH3): m/z = 288 [MNH4+],
271 [MH+]. HRMS: m/z calculated for C16H15S2 271.0615 [MH+];
found 271.0618. IR (powder): ν = 3055, 2945, 2895, 1583, 1460,
˜
1445, 1210, 1115, 1060, 945, 735 cm–1. M.p. 150–153 °C.
General Procedure for the Preparation of Palladium(II) Complexes
12, 13 and 14: An equimolar (0.5 m) mixture of either the bis(sulf-
oxide) 6 or bis(thioether)s 9 or 11 and palladium(ii) chloride was
stirred at room temperature in dichloromethane for 18 h. The sol-
vent was removed in vacuo to leave an orange solid. Crystallisation
of the crude product by slow evaporation of a saturated dichloro-
methane solution afforded the four desired palladium(ii) com-
plexes. Suitable crystals of complexes 13 and 14 could be used for
X-ray analyses. M.p. of 13: 262 °C (dec.); 14: 168–170 °C.
Acknowledgments
We thank Prof. Alexandre Alexakis for fruitful discussions, Dr.
Carine Guyard-Duhayon (CIM2, UPMC) for X-ray analyses,
Alain Valleix for HPLC analyses and Dr. Francesco Vizza
(ICCOM) for a gift of compound 4. CNRS, and COST Action D24
“Sustainable Chemical Processes: Stereoselective Transition Metal-
Catalyzed Reactions” are kindly acknowledged.
X-ray Crystallographic Study: Single crystal X-ray data were col-
lected at room temperature on
a
Nonius KappaCCD dif-
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2005, 552–557

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FULL PAPER
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Received August 2, 2004
Eur. J. Org. Chem. 2005, 552–557
www.eurjoc.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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