Formation of 3-sulfanylcoumarins by SnPh3OH-promoted cyclization of 3-aryl-2-sulfanylpropenoic acids

Article abstract of DOI:10.1002/ejic.200500237

Reaction of SnPh₃OH with 3-(2-hydroxyphenyl)sulfanylpropenoic acid [H₂(o-hpspa)] yielded [SnPh₃(SC)], where SC is deprotonated 3-sulfanylcoumarin (3-sulfanyl-2H-1-benzopyran-2-one, HSC), by a cyclization process. Similarly, when 3-(2-hydroxy-5-bromophenyl)- and 3-(2-hydroxy-3,5-dibromophenyl)-2-sulfanylpropenoic acids were treated with the same tin hydroxide, the cyclization resulted in [SnPh₃(BrSC)] and [SnPh₃(Br₂SC)], where BrSC and Br₂SC are the new ligands formed from the deprotonation of 3-sulfanyl-6-bromocoumarin and 3-sulfanyl-6,8-dibromocoumarin, respectively. The new compounds were characterized by elemental analysis, multinuclear NMR (¹H, ¹³C and ¹¹⁹Sn) and vibrational spectroscopy, and mass spectrometry. Single-crystal X-ray structures of these complexes all showed that the tin atom is surrounded by three phenyl C atoms and the S and O atoms of the bidentate ligand in a distorted trigonal-bipyramidal environment. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200500237

FULL PAPER
Formation of 3-Sulfanylcoumarins by SnPh3OH-Promoted Cyclization of
3-Aryl-2-Sulfanylpropenoic Acids
Pedro Álvarez-Boo,[a] José S. Casas,[b] María D. Couce,[a] Vanesa Fernández-Moreira,[a]
Eduardo Freijanes,[a] Emilia García-Martínez,[a] José Sordo,*[b] and
Ezequiel Vázquez-López[a]
Keywords: Tin / Triphenyltin complexes / 3-(2-hydroxyphenyl)-2-sulfanylpropenoic acids / 3-sulfanylcoumarin /
X-ray diffraction
Reaction of SnPh3OH with 3-(2-hydroxyphenyl)sulfanylprop-
enoic acid [H2(o-hpspa)] yielded [SnPh3(SC)], where SC is
deprotonated 3-sulfanylcoumarin (3-sulfanyl-2H-1-benzopy-
ran-2-one, HSC), by a cyclization process. Similarly, when 3-
(2-hydroxy-5-bromophenyl)- and 3-(2-hydroxy-3,5-dibro-
mophenyl)-2-sulfanylpropenoic acids were treated with the
same tin hydroxide, the cyclization resulted in [SnPh3(BrSC)]
and [SnPh3(Br2SC)], where BrSC and Br2SC are the new li-
gands formed from the deprotonation of 3-sulfanyl-6-bromo-
coumarin and 3-sulfanyl-6,8-dibromocoumarin, respectively.
The new compounds were characterized by elemental analy-
sis, multinuclear NMR (1H, 13C and 119Sn) and vibrational
spectroscopy, and mass spectrometry. Single-crystal X-ray
structures of these complexes all showed that the tin atom is
surrounded by three phenyl C atoms and the S and O atoms
of the bidentate ligand in a distorted trigonal-bipyramidal
environment.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
ticular those substituted at positions 3 or 4 of the pyrone
cycle), have bacteriostatic and rodenticide applications.[2–4]
Introduction
In previous work,[1] treatment of 3-(phenyl)-2-sulfanyl-
propenoic acid (H2pspa) with SnPh3OH in the presence of
diisopropylamine afforded the compound [Q][SnPh3(pspa)]
(Q = diisopropylammonium), which showed antibacterial
activity against Staphylococcus aureus and, although minor,
against Escherichia coli. In an effort to synthesize a more
soluble product with similar activity we have now prepared
the 3-(2-hydroxyphenyl)-2-sulfanylpropenoic acid [H2(o-
hpspa)]. However, reaction of this compound with
SnPh3OH yielded the unexpected complex [SnPh3(SC)],
where SC is deprotonated 3-sulfanylcoumarin. Formation
of the same product in the absence of diisopropylamine
showed that the amine played no role in the reaction.
Coumarin (1,2-benzopyrone, Scheme 1) is a natural
product present in plants with widespread use in foodstuffs
and cosmetic products. Furthermore, this substance is used
in medicine as an anticoagulant. Coumarin derivatives (in par-
Scheme 1.
The synthesis of 3-sulfanylcoumarin had been previously
carried out by Shi et al.[5] by reacting 5-(o-hydroxybenzyli-
dene)rhodanine with hydrazine hydrate in EtOH at 80 °C.
In this paper, we describe the formation of tin() com-
plexes containing this deprotonated species as well as its 6-
[a] Departamento de Química Inorgánica, Universidade de Vigo,
36200 Vigo, Spain
[b] Departamento de Química Inorgánica, Universidade de Santi-
ago de Compostela,
15782 Santiago de Compostela, Spain
E-mail: qijsordo@usc.es
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
Scheme 2.
Eur. J. Inorg. Chem. 2005, 4425–4429
DOI: 10.1002/ejic.200500237
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J. Sordo et al.
FULL PAPER
Scheme 3.
bromo- and 6,8-dibromo derivatives which resulted from within the range of 2.12–2.18 Å reported for other tri-
the cyclization of 2-sulfanylpropenoic acids (Scheme 2), to- phenyltin compounds.[6] On the other hand, the Sn–S bond
gether with their structural study by means of X-ray diffrac- length [2.4691(10) Å] is slightly greater than the sum of the
tion and characterisation by vibrational and NMR spec- covalent radii of tin and sulphur atoms (2.42 Å),[7] but
troscopy. We chose Br-substituted derivatives in an effort to within the range reported for triphenyltin thiolates (2.405–
examine the influence of relatively bulky and electronega- 2.481 Å).[6,8–10] The most remarkable bond length around
tive atoms in the aromatic moiety of the acids on the cycli- the tin atom is the long (even for an apical position) Sn–O
zation process.
distance [2.589(2) Å], which is greater than the sum of their
covalent radii (2.13 Å),[7] though smaller than the sum of
their van der Waals radii (3.70 Å)[7] and in the range that
has confidently been reported to indicate Sn–O bonding.[11]
This long bond length denotes a weak interaction between
these atoms and is in line with the short C–O distance of
1.215(4) Å, indicating that the C=O bond is only slightly
altered upon coordination [d(C=O) = 1.20 Å].[7]
Results and Discussion
Synthesis of [SnPh3(L)] (L = SC, BrSC, Br2SC)
The reaction of the complex formation is shown in
Scheme 3.
In the Experimental Section we describe the reactions
carried out with excess SnPh3OH. Besides these conditions,
the reaction was also explored in a 1:1 mol ratio of reac-
tants in the presence and absence of diisopropylamine in
EtOH solution. In all cases, the solid isolated was deter-
mined to be the same sulfanylcoumarin derivative.
The reactions of H2(Br2-o-hpspa) with Zn(OAc)2,
Cd(OAc)2, Pb(OAc)2 and SnR2O (R = Me, Et, Bu, Ph) were
also explored. In all cases, the solids isolated have stoichio-
metries corresponding to the 3-aryl-2-sulfanylpropenoic
acid derivatives. For example, the reaction of H2(Br2-o-
hpspa) with SnMe2O afforded a solid with the analytical
data C 26.4, H 1.9, S 6.3%; [SnMe2(Br2-o-hpspa)] requires
C 26.4, H 2.0, S 6.4%, while [SnMe2(SC)2] requires C 29.3,
H 1.5, S 7.8%. Further work to elucidate the role of the
metal in the cyclization process is in progress. In order to
explore the behaviour of [SnPh3(SC)] in acidic medium,
HOOCCF3(aq.) was used as a proton source; no formation
of free sulfanylcoumarin was detected.
Figure 1. Displacement ellipsoid plot for [SnPh3(SC)] with the
atom numbering scheme. Ellipsoids at 30% probability.
The bond angles around the metal atom are indicative of
the distortion from the regular trigonal-bipyramidal geome-
try. Thus, for instance, C(11)–Sn–S = 95.36(9)°, C(31)–Sn–
C(11) = 105.09(12)° and C(21)–Sn–C(11) = 105.23(12)° (in-
stead of 90°); C(31)–Sn–C(21) = 113.77(13)°, C(31)–Sn–S
= 115.41(9)° and C(21)–Sn–S = 118.47(9)° (instead of
120°). The bond angles involving the two donor atoms of
the sulfanylcoumarin ligand have values quite different
Crystal Structures
[SnPh3(SC)]
Tin Coordination Sphere
Figure 1 shows the structure of the compound and the from that expected for a regular polyhedron, namely:
numbering scheme, and Table 1 lists the significant bond C(31)–Sn–O(11) 78.01(10)°, C(21)–Sn–O(11)
=
=
lengths and angles. The tin atom is coordinated to three 83.50(11)° and, specially, S–Sn–O(1) = 73.08(6)°, which are
phenyl C atoms and to the S and O donor atoms of the considerably narrower than the theoretical 90° angle be-
SC ligand, which results a distorted trigonal-bipyramidal cause of the bite of the SC ligand. Nevertheless, according
environment in which O(1) and C(11) are apical. The equa- to Addison’s τ-criterion,[12] (τ = 0.83) we can state that the
torial C atoms are closer to Sn than the apical carbon, as coordination polyhedron is much closer to a trigonal bi-
expected in this type of polyhedron; i.e. for the apical C pyramid (τ = 1) than to a square pyramid (τ = 0).
atom: Sn–C(11) = 2.154(3) Å, for the equatorial C atoms:
The general features of the tin kernel are similar to those
Sn–C(21) = 2.137(3), Sn–C(31) = 2.131(3) Å – all three are found in triphenyltin sulfanylcarboxylates,[1] in which an
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 4425–4429

SnPh3OH-Promoted Cyclization of 3-Aryl-2-sulfanylpropenoic Acids
FULL PAPER
Table 1. Selected bond lengths [Å] and angles [°] for the prepared stance, carboxylic acid signal found in the spectra of the
complexes with estimated standard deviations in parentheses.
parent sulfanylpropenoic acids (between 13 and 11 ppm) is
absent in the spectra of the tin derivatives due to cycliza-
tion. In addition, no signal attributable to the SH proton is
observed in the spectra of any of these complexes. The 13C
NMR spectra for these complexes are consistent with those
for other 3-substituted, 6-bromo-3-substituted or 6,8-di-
bromo-3-substituted coumarins.[15]
[SnPh3(SC)]
[SnPh3(BrSC)]·EtOH
[SnPh3(Br2SC)]
Sn–C(31)
Sn–C(21)
Sn–C(11)
Sn–S
Sn–O(1)
S–C(2)
O(1)–C(1)
C(31)–Sn–C(21)
C(31)–Sn–C(11)
C(21)–Sn–C(11)
C(31)–Sn–S
C(21)–Sn–S
C(11)–Sn–S
C(31)–Sn–O(1)
C(21)–Sn–O(1)
C(11)–Sn–O(1)
S–Sn–O(1)
C(2)–S–Sn
2.131(3)
2.137(3)
2.154(3)
2.4691(10)
2.589(2)
1.758(3)
2.124(4)
2.123(4)
2.146(4)
2.4540(10)
2.784(3)
1.751(4)
2.143(7)
2.129(7)
2.170(7)
2.470(2)
2.666(5)
1.750(7)
1.200(8)
119.7(3)
103.9(3)
105.9(3)
115.8(2)
112.78(18)
94.25(19)
81.9(2)
The 119Sn NMR spectra show a singlet at about
–101 ppm. This value for the chemical shift falls in the
range proposed for a tetra-coordinated tin centre,[16,17]
which seems to indicate the loss of the five-coordinate na-
ture upon dissolution. This signal slightly shifts upfield as
the temperature increases from 230 to 330 K, but no split-
ting occurs.
1.215(4)
1.205(4)
113.77(13)
105.09(12)
105.23(12)
115.41(9)
118.47(9)
95.36(9)
78.01(10)
83.50(11)
168.04(11)
73.08(6)
118.56(14)
106.26(14)
108.64(14)
112.17(11)
115.47(10)
91.76(10)
77.56(12)
83.74(12)
161.95(11)
70.73(6)
80.5(2)
167.0(2)
72.77(12)
107.4(2)
115.7(5)
105.87(13)
116.7(2)
108.49(12)
113.3(2)
Experimental Section
C(1)–O(1)–Sn
Methods and Materials: Triphenyltin() hydroxide, rhodanine and
diisopropylamine (Aldrich-Chemie) were used as supplied. Elemen-
tal analyses were performed with a Carlo Erba 1108 apparatus.
Melting points were determined using a GallenKamp MFB-595
apparatus. The IR spectra were recorded on a Bruker IFS 66v FT-
IR spectrometer, and the Raman spectra were recorded with the
same spectrometer using an FRA-106 accessory. NMR spectra
SCCO donor fragment is also present; the main difference
lies in the Sn–O bond length, which is longer in this case.
The SC Ligand
The C–C (1.44–1.46 Å) and C–O [1.354(4), 1.382(4) Å]
bond lengths are as expected for a single bond between sp2
carbon atoms, except for the C(12)–C(13) [1.345(5) Å] and
C(1)–O(1) [1.215(4) Å] lengths which indicate some double
bond character.
1
were recorded at room temperature in CDCl3. H and 13C NMR
spectra were obtained with a Bruker AMX300 spectrometer op-
erating at 300.14 and 75.48 MHz, respectively (referenced to
SiMe4). 119Sn NMR spectra were recorded with a Bruker AMX500
apparatus operating at 186.50 MHz (referenced to SnMe4). Down-
field shifts were taken to be positive. Mass spectra were recorded
with a Kratos MS50TC spectrometer connected to a DS90 data
system and operating under EI (70 eV, 250 °C) and FAB conditions
(Xe, 8 eV) using as liquid matrix 3-nitrobenzyl alcohol. Crystallo-
graphic data were recorded at room temperature on a Bruker CCD
Smart apparatus using Mo-Kα radiation (λ = 0.71073 Å). An ab-
sorption correction was made by means of the SADABS pro-
gram,[18] and the structure solution was carried out using the
SHELXS-97 program.[19a] Least-squares full-matrix refinements on
F2 were performed using the program SHELXL97.[19a] Reflection
data for [SnPh3(BrSC)] were corrected for the diffuse scattering as
a result of disordered ethanol molecules by means of the program
[SnPh3(BrSC)]·EtOH and [SnPh3(Br2SC)]
The type of coordination and the bond lengths involving
the tin atom are similar to those discussed above for
[SnPh3(SC)]. As seen in Table 1, the bond lengths around
the metal atom are almost identical in all three compounds.
The only noticeable difference in the metrical data of these
complexes is the Sn–O bond length. Even though the Sn–
O bond lengths are quite different [2.589(2), 2.784(3) and
2.666(5) Å], we can conclude that the presence of one or
two Br atoms on the phenyl ring of the SC ligand does not
induce any significant change in the molecular structure of SQUEEZE,[19b] and the illustrations were obtained with the PLA-
TON package.[19c] Crystal data, details of data collections and re-
the complex.
finements are given in Table 2. The molecular structures of the
complexes are depicted in Figure 1 and Figures S1 and S2 (Sup-
porting Information) and show ellipsoids at 30% probability level.
CCDC reference numbers 265333–265335 contain the supplemen-
Spectroscopic Studies
The vibrational patterns of the complexes have been ana-
tary crystallographic data for this paper. These data can be ob-
lysed in light of their structural study by X-ray diffraction. tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Thus, the position of ν(C=O) is consistent with the weak
Sn–O bond, which is close to that found in inclusion com-
plexes[13] in which a coumarin ligand is hydrogen-bonded
via this group. The band at 360 cm–1, present in both IR
Synthesis of the Compounds: 3-Aryl-2-sulfanylpropenoic acids were
prepared[20] by condensation of the appropriate benzaldehyde with
rhodanine, subsequent hydrolysis in NaOH (1 ) and subsequent
and Raman spectra and attributable to ν(Sn–S), is consis- acidification with aqueous HCl (1 ).
tent with the coordination via the S atom, and νasym(Sn–C)
H2(o-hpspa): From 2-hydroxybenzaldehyde (2.50 g, 10 mmol) as
and νsym(Sn–C) vibrations are located at positions typical
starting material. Colour: yellow. Yield: 1.14 g, 58%. Mp: 140 °C.
IR and (Raman): 1682 vs ν(C=O), 1452 s δ(OH), 1264 s ν(C–O),
2568 m (2568 m) ν(S–H) cm–1. EI (main signals): m/z (%) = 196
of a non-planar SnC3 framework.[1,14]
The 1H NMR spectra agree with the evolution associated
with the cyclization and deprotonation processes. For in- (16) [M+], 178 (40) [M+ – H2O], 150 (100) [M+ – H2O – CO], 133
Eur. J. Inorg. Chem. 2005, 4425–4429
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J. Sordo et al.
FULL PAPER
Table 2. Crystal data and structure refinement for [SnPh3(SC)], [SnPh3(BrSC)]·EtOH and [SnPh3(Br2SC)].
Compound
[SnPh3(SC)]
[SnPh3(BrSC)]·EtOH
[SnPh3(Br2SC)]
Empirical formula
Molecular weight
Crystal system
Space group
a [Å]
b [Å]
c [Å]
C27H20O2SSn
527.18
monoclinic
P21/n
9.5474(3)
24.5775(8)
10.2597(3)
108.6187(10)
2281.45(12)
4
C29H25BrO3SSn
652.15
C27H18Br2O2SSn
684.98
monoclinic
C2/c
16.3047(16)
10.0204(10)
31.026(3)
91.607(2)
5067.1(9)
8
triclinic
¯
P1
9.4458(10)
9.8333(11)
15.8031(17)
99.854(2)
1397.2(3)
β [°]
Volume [Å3]
Z
2
Density calcd. [g cm–3]
Absorption coefficient [mm–1]
F(000)
1.535
1.233
1056
1.550
2.446
648
1.796
4.267
2656
Crystal size [mm]
θ range for data collection
Limiting indices
0.20×0.25×0.25
1.66–28.27
–12 Յ h Յ 12, –30 Յ k Յ
32, –13 Յ 1 Յ 7
15526
0.43×0.32×0.14
2.14–28.03
–12 Յ h Յ 12, –12 Յ k Յ
10, –20 Յ l Յ 20
8621
0.28×0.21×0.15
2.39–27.99
–21 Յ h Յ 20, –13 Յ k Յ
13, –24 Յ l Յ 40
14715
Reflections collected
Reflections unique, R
5592 [R(int) = 0.0512]
semi-empirical
5592/0/280
6006 [R(int) = 0.0253]
semi-empirical
6006/0/283
5803 [R(int) = 0.0448]
semi-empirical
5803/0/293
Absorption correction
Data/restrictions/parameters
Goodness-of-fit on F2
1.013
0.849
1.116
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
R1 = 0.0435 wR2 = 0.0671
R1 = 0.0892 wR2 = 0.0788
0.476 and – 0.447
R1 = 0.0359 wR2 = 0.0696
R1 = 0.0573 wR2 = 0.0743
0.577 and –0.730
R1 = 0.0581 wR2 = 0.1211
R1 = 0.1101 wR2 = 0.1307
2.850 and –3.077
Largest diff. peak and hole [eÅ–3]
(5) [M+ – COOH], 121 (67) [M+ – H2O–CO–CHO], 90 (41) [M+
–
ppm. C9H6Br2O3S: calcd. C 30.5, H 1.7, S 9.0%; found C 30.7, H
1.6, S 8.8%.
H2O – 2CO – S] 77 (28) [M+ – H2O – 2CO – S– CH]. The MS
1
(FAB) spectrum shows the same signals. H NMR: δ = 12.84 [br.
[SnPh3(SC)]: A solution of SnPh3OH (0.40 g, 1.0 mmol) in 10 mL
of an ethanol/acetone mixture (1:1 v/v) was treated with a solution
of H2(o-hpspa) (0.10 g, 0.5 mmol) in 10 mL of the same solvent.
After stirring and refluxing for 5 h, a beige solid was formed. Yield:
0.32 g, 60%. Mp: 135 °C.. IR and (Raman): 1676 s ν(C=O), 269 s
νasym(Sn–C), 232 s νsym(Sn–C) 361 sh (360 w) ν(Sn–S) cm–1. EI
(main signals): m/z (%) = 528 (3) [M+], 351 (35) [SnPh3], 197 (8)
[SnPh], 120 (6) [Sn]. Besides these signals, the EI spectrum shows
signals for H2(o-hpspa) and its fragments, and the FAB spectrum
s, 1 H, C(1)OH], 7.71 [s, 1 H, C(3)H], 10.07 [s, 1 H, C(5)OH], 6.86
[d, 1 H, C(6)H], 7.27 [1 H, C(7)H], 6.88 [d, 1 H, C(8)H], 7.67 [d, 1
H, C(9)H] ppm. 13C NMR: δ = 168.7 C(1), 139.0 C(2), 132.2 C(3),
120.9 C(4), 153.7 C(5), 116.1 C(6), 131.0 C(7), 123.2 C(8), 129.6
C(9) ppm. C9H8O3S: calcd. C 55.1, H 4.1, S 16.3%; found C 55.6,
H 3.9, S 16.1%.
H2(Br-o-hpspa): From 5-bromo-2-hydroxybenzaldehyde (3.16 g,
10 mmol) as starting material. Colour: yellow. Yield: 2.56 g, 93%.
Mp. 133 °C. IR and (Raman): 1677 vs ν(C=O), 1414 m δ(OH),
1
shows the same metallated signals. H NMR: δ = 7.91 [s, C(4)H],
1278 vs ν(C–O), 2566 w (2575 m) ν(S–H) cm–1. EI (main signals): 7.37–7.22 [m, C(5)H–C(8)H], 7.74–7.72 (m, Pho), 7.41–7.38 (m,
m/z (%) = 275 (36) [M+ – H], 256 (100) [M+ – H – H2O], 228 (97) Phm,p) ppm. 13C NMR: δ = 162.8 C(2), 139.3 C(3), 126.5 C(4),
[M+ – H2O – CO], 230 (95) [M+ – COOH], 168 (26) [M+ – H2O –
2CO – SH], 150 (44) [M+ – COOH – Br], 120 (54) [M+ – H2O–
CO–CHO – Br], 149 (98) [M+ – H2O–CO–Br]. The FAB spectrum
130.1 C(4a), 151.8 C(8a), 116.4 C(8), 126.5 C(7), 120.0 C(6), 124.9
C(5), 140.6 Ci, 136.7 Co, 128.7 Cm, 129.3 Cp ppm. 119Sn NMR: δ
= –100.9 (s) ppm. C27H20O2SSn: calcd. C 61.5, H 3.8, S 6.1%;
found C 61.4, H 3.9, S 6.0%. From the mother liquor of the reac-
tion flask, suitable crystals for X-ray diffraction were isolated.
1
shows the same signals. H NMR: δ = 9.84 [s, 1 H, C(3)H], 10.88
[s, 1 H, C(5)OH], 6.90 [d, 1 H, C(6)H], 7.94 [dd, 1 H, C(7)H], 7.66
[d, 1 H, C(9)H] ppm. 13C NMR: δ = 166.6 C(1)OH, 118.2 C(2)SH,
119.8 C(4), 160.1 C(5), 111.3 C(6), 139.6 C(7), 113.0 C(8), 135.5
C(9) ppm. C9H7BrO3S: calcd. C 39.3, H 2.5, S 11.6%; found C
39.9, H 2.3, S 11.2%.
[SnPh3(BrSC)]: A solution of SnPh3OH (0.29 g, 0.8 mmol) in
10 mL of an ethanol/acetone mixture (1:1 v/v) was treated with a
solution of H2(Br-o-hpspa) (0.10 g, 0.4 mmol) in 10 mL of the same
solvent. After refluxing for 5 h, a brown solid was formed. Yield:
0.19 g, 40%. Mp: 145 °C. IR (Raman): 1686 s ν(C=O), 261 s
H2(Br2-o-hpspa):
From
3,5-dibromo-2-hydroxybenzaldehyde
(3.79 g, 10 mmol) as starting material. Colour: beige. Yield: 3.36 g, νasym(Sn–C), 233 s (235 w) νsym(Sn–C), 359 w (354 w) ν(Sn–S)
95%. Mp: 120 °C. IR and (Raman): 1682 vs ν(C=O), 1448 s δ(OH),
cm–1.EI (main signals): m/z (%) = 607 (2) [M+ + H], 351 (65)
1276 vs ν(C–O), 2565 m (2565 w) ν(S–H) cm–1. EI (main signals): [SnPh3], 307 (7) [HSSnPh2], 197 (80) [SnPh], 121 (9) [SnH], 120
m/z (%) = 354 (25) [M+], 336 (80) [M+ – H2O], 308 (100) [M+
(34) [Sn]. Besides these signals, the EI spectrum shows signals for
H2O – CO], 279 (24) [M+ – H2O–CO–CHO], 227 (46) [M+ – H2O– H2(Br-o-hpspa) and its fragments, and the FAB spectrum shows
–
CO–BrH], 167 (24) [M+ – H2O – 2CO–SH–Br], 148 (21) [M+
–
the same metallated signals. 1H NMR: δ = 7.81 [s, 1 H, C(4)H],
H2O – CO – 2Br], 119 (52) [M+ – H – H2O – 2CO – 2Br]. The 7.71 [d, 1 H, C(5)H], 7.46 [dd, 1 H, C(7)H], 7.41 [d, 1 H, C(8)H],
1
FAB spectrum shows the same signals. H NMR: δ = 9.81 [s, 1 H,
7.70 (d, 6 H, Pho), 7.40 (q, 9 H, Phm,p) ppm. 13C NMR: δ = 162.1
C(3)H], 11.50 [s, 1 H, C(5)H], 7.94 [s, 1 H, C(7)H], 7.67 [d, 1 H, C(2), 119.8 C(3), 121.5 C(4a), 150.6 C(8a), 118.1 C(8), 128.3 C(7),
C(9)OH] ppm. 13C NMR: δ = 157.6 C(1)OH, 118.3 C(2)SH, 122.0
117.5 C(6), 132.7 C(5), 140.2 Ci, 136.6 Co, 128.7 Cm, 129.5 Cp ppm.
C(4), 160.1 C(5), 111.3 C(6), 142.4 C(7), 111.8 C(8), 135.3 C(9) 119Sn NMR: δ = –98.1 (s) ppm. C27H19BrO2SSn: calcd. C 53.5, H
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 4425–4429

SnPh3OH-Promoted Cyclization of 3-Aryl-2-sulfanylpropenoic Acids
FULL PAPER
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3.1, S 5.3%; found C 52.6, H 3.3, S 4.6%. From the mother liquor,
crystals of the ethanol solvate suitable for X-ray diffraction were
isolated.
[SnPh3(Br2SC)]: A solution of SnPh3OH (0.20 g, 0.6 mmol) in
10 mL of an ethanol/acetone mixture (1:1 v/v) was treated with a
solution of H2(Br2-o-hpspa) (0.10 g, 0.3 mmol) in 10 mL of the
same solvent. After refluxing for 5 h, a white solid was formed.
Yield: 0.22 g, 54%. Mp: 162 °C. IR (Raman): 1699 s ν(C=O), 273
w νasym(Sn–C), 258 s (255 w) νsym(Sn–C), 361 w ν(Sn–S) cm–1. EI
(main signals): m/z (%) = 609 (31) [M+ + H – Ph], 351 (72) [SnPh3],
308 (17) [SnPh2S + 2H], 197 (93) [SnPh], 120 (43) [Sn]. Besides
these signals, the EI spectrum shows signals for H2(Br2-o-hpspa)
and its fragments, whilst the FAB spectrum shows the signals for
the same metallated fragments as well as another signal at 685 (3)
[M+]. 1H NMR: δ = 7.74 [s, 1 H, C(4)H], 7.42 [d, 1 H, C(7)H], 7.41
[d, 1 H, C(5)H], 7.69 (d, 6 H, Pho), 7.40 (q, 9 H, Phm,p) ppm. 13C
NMR: δ = 161.3 C(2), 122.2 C(3), 127.5 C(4a), 147.6 C(8a), 117.4
C(8), 137.3 C(7), 110.77 C(6), 135.4 C(5), 139.8 Ci, 136.6 Co, 128.7
Cm, 129.6 Cp ppm. 119Sn NMR:
δ = –94.0 (s) ppm.
C27H18Br2O2SSn: calcd. C 47.3, H 2.6, S 4.7%; found C 46.7, H
2.3, S 4.8%. From the mother liquor, suitable crystals for X-ray
diffraction were isolated.
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Supporting Information (see footnote on the first page of this arti-
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Acknowledgments
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tion Program for Area Detector Data”, University of
Göttingen, Germany, 1996.
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Solution and Refinement”, University of Göttingen, Germany,
1997; b) A. L. Spek, Acta Crystallogr., Sect. A 1990, 34, 46; c)
A. L. Spek, PLATON v. 3.04.02, University of Utrecht, The
Netherlands, 2002, http://www.cryst.chem.uu.nl/platon/.
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Received: March 18, 2005
We thank the EU Directorate General for Regional Policies and
the Directorate General for Research of the Spanish Ministry of
Science and Technology for financial support under ERDF pro-
grams (Project BQU2002–04524-C02–02), and the Xunta de Gal-
icia, Galicia (Spain) (Project PGIDIT03PXIC30103PN).
[1] J. S. Casas, A. Castiñeiras, M. D. Couce, M. L. Jorge, U. Russo,
A. Sánchez, R. Seoane, J. Sordo, J. M. Varela, Appl. Or-
ganomet. Chem. 2000, 14, 421 and references cited therein.
Published Online: September 21, 2005
Eur. J. Inorg. Chem. 2005, 4425–4429
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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