Synthetic strategies for preparing BEDT-TTF derivatives functionalised with metal ion binding groups

Article abstract of DOI:10.1039/b606715h

The syntheses of BEDT-TTF (ET) derivatives with potential metal ion binding pyridyl, bipyridyl and terpyridyl groups is achieved either by stepwise construction of the organosulfur core or via reactions of hydroxymethyl-ET for which a cheap and efficient

Full text of DOI:10.1039/b606715h

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www.rsc.org/njc | New Journal of Chemistry
Synthetic strategies for preparing BEDT-TTF derivatives functionalised
with metal ion binding groups
Qiang Wang,a Peter Day,b Jon-Paul Griffiths,a Hui Niea and John D. Wallis*a
Received (in Durham, UK) 11th May 2006, Accepted 29th August 2006
First published as an Advance Article on the web 2nd October 2006
DOI: 10.1039/b606715h
The syntheses of BEDT-TTF (ET) derivatives with potential metal ion binding pyridyl, bipyridyl
and terpyridyl groups is achieved either by stepwise construction of the organosulfur core or via
reactions of hydroxymethyl-ET for which a cheap and efficient four step route is reported. The
tosylate of hydroxymethyl-ET, reported for the first time, undergoes nucleophilic substitutions
with pyridyl, bipyridyl- and terpyridyl-thiolates to give new donors. The X-ray crystal structures
of two substituted ET derivatives show considerable deviation of the organosulfur donor system
from planarity by bending about the short molecular axis of the ET group.
been electrocrystallised to a radical cation salt,19 both phos-
Introduction
phine and nitrogen centres in 8,20 and dithiolates as in neutral
paramagnetic systems such as 9.21
The radical cation salts of bis(ethylenedithio)tetrathiafulva-
lene (BEDT-TTF or ET) 1, have been extensively studied
because of their wide variety of electrical properties,1 including
the occurrence of superconductivity in salts such as
ET2[Cu(SCN)2] and ET2(ICl2).2 Substituted derivatives of
ET are more difficult to prepare, however a number of
mono-, di- and tetrasubstituted materials are now reported,3
and some of their radical cation salts have been studied.4
Materials with novel combinations of electrical and magnetic
properties are a current theme of research in which a transition
metal ion provides a magnetic centre.5 The latter may feature
in the anion, as in Day’s paramagnetic superconductor (ET)4
[Fe(oxalate)3] ꢀ H2O ꢀ C6H5CN,6 the Kobayashis’ radical ca-
tion salts of BETS 2 with FeX4ꢁ (X = Cl, Br) whose electrical
properties can be changed by an external magnetic field,7 and
Coronado’s salts of partially oxidized layers of ET8 or BETS9
with chromium(III)/manganese(II) oxalate networks as
anions, which shows almost independent conducting
and ferromagnetic behaviour. Complex anions such as
[Cr(III)(phen)(NCS)4]ꢁ and [trans-M(isoquinoline)2(NCS)4]ꢁ
(M = Cr(III) or Fe(III)) have also been used10 with TTF11,12
and ET12,13 and other donors.14 In contrast, attachment of the
metal binding group, notably pyridine or bipyridine centres, to
the donor has been developed in a number of cases. For
We have been involved in attaching the metal binding ligand
to the ET framework and we have communicated the synth-
eses of donors such as donors 10–12.22 Here we describe the
synthetic approaches to racemic donors 13–18 either by step-
wise construction of the molecule, or from hydroxymethyl-ET
which can be functionalised by either tosylation and substitu-
tion or by ester formation. An efficient four step synthesis of
racemic hydroxymethyl-ET is also described. Several donors
with pyridine rings directly attached to an ET or EOET
framework 19–21 have been reported.23,24
Synthesis of ET derivatives
The ligands 1322 and 14 were prepared initially by syntheses
involving typically five steps according to the general scheme
developed earlier in this laboratory and illustrated in Scheme
1. The mercaptobipyridine groups were introduced at the third
step of the synthesis. Trithione 2225 was cyclised with allyl
alcohol to give the hydroxymethyl thione 23, which was
tosylated using 1.5 equivalents of tosyl chloride in pyridine
to give 24 in an overall yield of 62% from 22. The 6-mercapto-
and 4-mercaptobipyridines 25 and 26 were synthesized in
several steps via the corresponding halobipyridines. 6-Bro-
mo-2,20-bipyridine was prepared by reaction of 6-bromo-2-
lithiopyridine with ethyl 2-pyridylsulfoxide.26 2,20-Bipyridine
was converted in two steps to 4-nitro-2,20-bipyridine-N-oxide
which was reacted with acetyl chloride and phosphorus
trichloride27 to give 4-chlorobipyridine, which was found to
be superior to the chlorination of the N-oxide of 2,20-bipyr-
idine which requires a tedious separation of 4- and 6-chloro
isomers.28 The mercaptobipyridines were obtained by heating
the halobipyridine with sodium hydrogen sulfide, potassium
hydroxide and DMF which, compared with the earlier pro-
cedure using hydrogen sulfide as the source of sulfur,28 was
much more reproducible, took much less time and doubled the
yield to typically 80% for this step. Reaction of tosylate 24
with the sodium salt of each mercaptobipyridine in DMF
furnished thiones 27 and 28 in yields of 70–73%. Subsequent
example, Ouahab has reported radical cation salts of 3,15
a
TTF conjugated to a pyridine through an alkene; Batail and
Avarvari have reported a series of N-pyridyl- and N-2,20-
bipyridyl-TTF and EDT-TTF-carboxamides such as 4 and
5,16 and Pilkington has included bipyridyl metal binding sites
as bridges in molecules such as 6 which link a TTF to a
verdazyl radical.17 Other metal binding centres utilised include
phosphines,18 as in the molybdenum complex 7 which has
a School of Biomedical and Natural Sciences, Nottingham Trent
University, Clifton Lane, Nottingham, UK NG11 8NS. E-mail:
john.wallis@ntu.ac.uk
b The Davy-Faraday Research Laboratory, The Royal Institution of
Great Britain, 21 Albemarle St., London, UK W1S 4BS. E-mail:
pday@ri.ac.uk
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exchange of thione sulfur for oxygen using mercuric acetate
gave oxo compounds 29 (93%) and 30 (97%), which were
cross coupled with the unsubstituted thione 3125 in triethyl
phosphite at 90–100 1C to give ligands 13 (46%) and 14 (54%)
after separation from homo-coupled products by chromato-
graphy. The overall yields of each ligand from the trithione 22
were 18% (13) and 24% (14).
cycloaddition of trithione 22 with allyl acetate gives the
thione 36 (72%) which is converted to the oxo compound 37
in 90% yield. Cross coupling with unsubstituted thione 31
gave acetyloxymethyl-ET 38 in 70% yield after separation
from homocoupled products. Finally, hydrolysis of the
acetate gave HMET 39 in 96% yield. This represents the most
efficient synthesis of racemic HMET reported to date. The
preparation of HMET 39 has been reported by Zhu30 and
ourselves31 in five step syntheses in which the hydroxyl group
is protected with a TBDMS group. The new route is shorter
and considerably cheaper, and full experimental details are
provided.
This synthetic route provides oxo compounds 29 and 30
which can be cross-coupled with alternative thiones to give
further bipyridine-substituted donors. Nevertheless, it could
be more convenient to be able to introduce the metal binding
group right at the end of the synthesis, especially if the metal
binding moiety is expensive, or difficult to make. In addition,
when we tried to make the ligand 15 containing a 40-mercapto-
2,20: 60,200-terpyridine group by the route above, the final step
of the synthesis was problematic. 40-Mercaptoterpyridine 33
was prepared from the commercially available chloro com-
pound 32 and sodium hydrogen sulfide in DMF in quantita-
tive yield. Constable reported the first details of this
compound recently.29 Reaction of the tosylated thione 24 with
the sodium salt of the mercaptoterpyridine 33 gave the thione
34 in 69% yield and this product was converted to the oxo
compound 35 in 67% yield. However, purification of the
donor 15, from the reaction of oxo compound 35 with the
unsubstituted thione 31 in triethyl phosphite, required several
chromatographic separations and gave a very low yield of the
donor. Thus, we developed a different approach (Scheme 2)
involving nucleophilic substitution on tosyloxymethyl-ET 40
to prepare donor 15.
Tosylation of HMET was only possible by use of a large
excess of tosyl chloride in pyridine over 20 h which gave the
product 40 in 85% yield. Use of just two equivalents of tosyl
chloride gave no product after 24 h, and at least seven
equivalents are necessary for this reaction to succeed. We
measured the X-ray crystal structure of this tosylate to look
for any feature which might give clues to the difficulty in the
tosylation. In fact the structure is particularly unusual, since it
shows that the tosyl group is bent back over the ET system
(Fig. 1); the closest intramolecular contacts between the ET
and tosyl group (ca. 3.5–3.6 A) involve the methyl carbon and
sp2 carbon atoms of the unsubstituted ‘‘half’’ of the ET
system. However, there is no charge transfer interaction; the
crystal colour is typical of an ET derivative, and in solution
the UV/visible spectrum shows no remarkable features. Both
tosyl and ET units are involved in the molecular stacking
(Fig. 2): the phenyl rings stack face to face (separation 3.44 A)
and these pairs then stack with some overlap between adjacent
ET moieties (separation 3.80 A). There is one rather close
intermolecular Sꢀ ꢀ ꢀS contact between dithiole rings of
3.3884(17) A. The ET moiety is significantly non-planar even
in the heterocyclic core of the molecule. Thus, the best planes
defined by the sulfur and sp2 carbon atoms of the two
Synthesis of HMET and its tosylate
We have developed a method of preparing hydroxymethyl-ET,
HMET, in four steps from trithione 22 in an overall yield of
44% utilising an acetyl protecting group (Scheme 2). Thus,
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dithiolodithiin units lie at 33.75(5)1 to each other. The sub-
stituted dihydrodithiin ring adopts a half chair conformation
while for the unsubstituted ring both sp3 carbon atoms deviate
to the same side of the ring plane. There is some disorder in the
structure with ca. 13% of molecules preferring a slightly
different conformation; the ET and methylphenyl groups
occupy similar positions, but in the minor component the
tosyloxymethyl sidechain is attached to the other carbon of the
ethylene bridge. In both structures the sidechain adopts a
pseudoaxial orientation with respect to the ET group. The
sluggishness of the reaction between HMET and tosyl chloride
may just be due to the HMET molecules being stacked in
solution and so access to the hydroxyl group is hindered.
There is no similar difficulty in tosylation the hydroxymethyl
thione 23.
Reaction of the sodium salt of 40-mercaptoterpyridine 33
with the tosylated donor 40 in DMF over 48 h at room
temperature gave the terpyridyl-ET derivative 15 in 65% yield
after chromatography, and thus avoiding the difficulties of the
previous synthesis. Ligand 14 was also prepared by reaction of
the appropriate bipyridinethione 26 with the tosylated HMET
in a yield of 65%. The overall yields of 14 from trithione by
this route or the stepwise route discussed earlier are very
similar. However, when a range of derivatives is being made,
it may be simpler to make a large amount of the tosylated
donor, and then react it with the required nucleophiles. The
tosylated donor was also reacted with the sodium salt of 2,6-
diacetyl-4-mercaptopyridine, to give the pyridyl substituted
donor 16 in 70% yield. The X-ray structure of 16 is shown in
Fig. 3. The pyridyl group is not bent back over the ET moiety
as in the tosylate, but the sidechain is extended away from the
ET to which it attaches by a pseudo-axial connection. The
pyridyl substituent remains roughly parallel to the ET group-
ing. The latter shows some deviations from planarity (Fig. 4);
the planes of the two dithiolodithiin sections, as defined by
their four sulfur atoms, lie at 24.18(1)1. In the substituted
dihydrodithiin ring both sp3 carbon atoms are displaced to the
same side of the plane defined by the other four atoms, the
substituted atom carbon by less than the methylene carbon
atom (0.543 cf. 1.151 A). In the unsubstituted dihydrodithiin
ring only one of the sp3 carbon atoms is strongly displaced
from the plane of the four other atoms (by 0.711, cf. ꢁ0.107
A). Further substitution reactions on tosylated HMET will
find applications for preparing a range of substituted ET
derivatives.
The facile synthesis of HMET 39 now opens up access to
further functionalised derivatives e.g. by esterification. Thus,
DCC coupling of HMET with pyridinecarboxylic acids gave
new donors substituted with binding groups, 17 and 18, in
reasonable yields (ca. 50%), with considerable potential for
preparation of further materials. Furthermore, this route was
taken to attach other heterocyclic moieties e.g. a thiophene in
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Scheme 1
41 which could also be used to bring additional electrical
Experimental
properties on polymerisation.
General
NMR spectra were measured on a JEOL JNM-EX270 spectro-
meter at 270 MHz for 1H and at 67.8 MHz for 13C using CDCl3
as solvent, and measured in p.p.m. downfield from TMS, unless
otherwise stated. IR spectra were recorded on a PerkinElmer
Spectrum RX 1 FT-IR spectrometer in cmꢁ1. Mass spectra were
recorded at the EPSRC National Mass Spectrometry Centre at
Swansea University. X-ray diffraction datasets were measured
by the EPSRC National Crystallography Service at Southamp-
ton University. Chemical analysis data were obtained from the
Microanalytical Laboratory, University of Nottingham. Flash
chromatography was performed on 40–63 silica gel (Merck).
In summary, routes to the synthesis of a number of ET
derivatives with metal binding groups are described. The
approach via HMET in particular has the potential for pre-
paring substrates for multifunctional materials by attachment
of the ET unit to molecular systems bringing additional
properties. We are currently studying the coordination chem-
istry of the new donors reported here.
5,6-Dihydro-5-(hydroxymethyl)-1,3-dithiolo-[4,5-b]-1,4-dithiin-
2-thione 2330
A suspension of allyl alcohol (15 ml, 0.22 mol) and trithione
2225 (27.8 g, 0.14 mol) in toluene (600 ml) was heated to reflux
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Scheme 2
for 4 h. After cooling to room temperature the reaction
mixture was filtered, and the solid washed with ethanol.
Combined washings and filtrate were evaporated and the
residue purified by flash chromatography (SiO2, EtOAc) to
furnish 23 as an yellow oil (26.7 g, 73%) which solidified on
standing, dH: 3.96 (2H, m, CH2OH), 3.84 (1H, m, 5-H), 3.39
(1H, dd, J = 13.4, 2.8 Hz, 6-Ha), 3.32 (1H, dd, J = 13.4, 6.7
Hz, 6-Hb), 1.80 (1H, br, OH), dC: 210.2 (CQS), 125.5, 123.7
(30a- & 70a-C), 64.4 (CH2OH), 39.8 (5-C), 33.1 (6-C).
nitrogen. The solution was added to ice water (200 ml) and
filtered. The solid was dissolved in DCM and washed with
water (200 ml), 4 M HCl (3 ꢃ 200 ml) and brine (100 ml)
before being dried over MgSO4. Concentration in vacuo
yielded the product 24 as a brown solid, (13.65 g, 85%), mp
114–116 1C, dH: 7.80 (2H, d, J = 8.2 Hz, 20-,60-H), 7.32 (2H, d,
J = 8.2 Hz, 30-,50-H), 4.30 (1H, dd, J = 10.4, 9.7 Hz, CHaO),
4.12 (1H, dd, J = 10.4, 6.2 Hz, CHbO), 3.91 (1H, m, 5-H), 3.28
(2H, d, J = 3.7 Hz, 6-H2), 2.41 (3H, s, CH3); dC: 207.0 (2-C),
145.3 (10-C), 132.0 (40-C), 130.1 (20-, 60-C), 128.0 (30-, 50-C),
122.2, 121.1 (3a, 7a-C), 68.5 (CH2O), 40.2 (5-C), 30.5 (6-C),
21.7 (CH3); nmax (KBr): 1594, 1482, 1359, 1191, 1122, 1001,
999, 965, 824, 809, 790, 665, 567, 549, 516; found C: 38.4, H:
3.0%, C13H12O3S6 requires C: 38.2, H: 3.0%.
5,6-Dihydro-5-(40-methybenzenesulfonyloxy)-methyl-1,3-
dithiolo-[4,5-b]-1,4-dithiin-2-thione 24
Alcohol 23 (10.00 g, 39.4 mmol), tosyl chloride (11.23 g, 59
mmol) and dry pyridine (40 ml) were stirred overnight under
6-Mercapto-2,20-bipyridine 25
6-Bromo-2,20-bipyridine26 (1.24 g, 5.28 mmol) and solid KOH
(0.87 g, 15.5 mmol) were added to a suspension of sodium
hydrogen sulfide (3.1 g, 55.2 mmol) in DMF (80 ml). The
mixture was heated to reflux under nitrogen atmosphere over-
night. After cooling to RT, the mixture was filtered and the
filtrate was concentrated under reduced pressure to give a
yellow residue. The residue was dissolved in 50 ml H2O, and
neutralised with diluted HCl (2 M). The yellow precipitate was
collected and re-dissolved in CH2Cl2, and washed twice with
H2O. The organic phase was separated and dried over MgSO4.
Removal of solvent afforded 6-mercapto-2,20-bipyridine28 as a
yellow solid (0.77 g, 78%). dH: 12.28 (1H, br, NH), 8.61 (1H, d,
Fig. 1 Molecular structure of tosyloxymethyl-ET 40.
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Fig. 2 Crystal packing for tosyloxymethyl-ET 40 looking down the a axis.
J = 4.7 Hz, 60-H), 7.79 (2H, m, 4-,40-H), 7.48 (1H, d, J = 8.7 Hz,
30-H), 7.28 (2H, m, 3-,50-H), 7.14 (1H, d, J = 8.2 Hz, 5-H); dC:
179.5 (6-C), 149.5 (2-C), 146.7 (20-C), 144.3 (60-C), 138.3 (40-C),
137.8 (4-C), 133.3 (3-C), 125.7 (30-C), 121.3 (50-C), 110.8 (5-C).
(1H, d, J = 4.7 Hz 600-H), 8.20 (1H, d, J = 7.9 Hz, 300-H), 8.06
(1H, d, J = 7.8 Hz, 30-H), 7.76 (1H, dt, J = 7.8, 1.7 Hz, 400-H),
7.52 (1H, t, J = 7.8 Hz, 40-H), 7.18 (1H, dd, J = 7.4, 5.0 Hz,
500-H), 7.13 (1H, d, J = 7.9 Hz, 50-H), 4.07 (1H, m, 5-H), 3.84
(1H, dd, J = 14.1, 4.7 Hz, 6-Ha), 3.48 (1H, dd, J = 14.1, 9.6
Hz, 6-Hb), 3.40 (2H, m, 5-CH2Sbipy); dC (100 MHz): 207.4 (2-
C), 155.7 (20-,60-C), 155.1 (200-C), 149.1 (600-C), 137.2 (40-C),
136.9 (400-C), 123.9 (3a-C), 122.5 (500-C), 122.4 (7a-C), 121.6
(50-C), 120.7 (300-C), 117.3 (30-C), 41.9 (5-C), 33.7 (5-C), 32.7
(CH2Sbipy); nmax (KBr): 1576, 1555, 1480, 1443, 1419, 1140,
1061, 983, 773, 740; m/z: (EI) 425 ([M + H]+, 100%); HRMS:
(EI) found [M + H]+ 424.9403, C16H12N2S6 requires 424.9402.
5,6-Dihydro-5-(20,200-bipyridin-60-ylthiomethyl)-1,3-dithiolo-
[4,5-b]-1,4-dithiin-2-thione 27
Sodium hydride (0.31 g, 50% dispersion in oil, 6.5 mmol) was
added to a solution of 6-mercapto-2,20-bipyridine (1.23 g, 6.5
mmol) in dry DMF (20 ml). After 40 min of stirring a solution
of tosylate 24 (2.60 g, 6.5 mmol) in dry DMF (10 ml) was
added and the resulting mixture was stirred under nitrogen for
25 h. The solution was concentrated in vacuo, and the residue
partitioned between DCM and water. The organic layer
separated and dried over MgSO4. Purification by flash chro-
matography on silica (8 : 1 cyclohexane : EtOAc) yielded 27 as
a red solid, (1.88 g, 70%), mp 117–120 1C, dH (400 MHz): 8.58
5,6-Dihydro-5-(20,200-bipyridine-60-thiomethyl)-1,3-dithiolo-
[4,5-b]-1,4-dithiin-2-one 29
To a solution of thione 27 (0.30 g, 0.71 mmol) in chloroform (5
ml) was added glacial acetic acid (2 ml) and then mercury(II)
Fig. 3 X-ray structure of 16.
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Fig. 4 X-ray structure of 16.
acetate (0.57 g, 1.78 mmol). This was stirred for 2 h before
being filtered. The filtrate was collected and diluted with water
(20 ml). The solution was neutralised with sodium bicarbonate
and the organic layer separated and dried over MgSO4.
Concentration in vacuo yielded 29 as a beige solid, (0.27 g,
93%), mp 120–123 1C, dH (400 MHz): 8.61 (1H, dm, J = 4.6
Hz, 600-H), 8.27 (1H, dd, J = 7.9, 1.0 Hz, 300-H), 8.11 (1H, dd,
J = 7.6, 1.0 Hz, 30-H), 7.78 (1H, dt, J = 7.8, 1.7 Hz, 400-H),
7.59 (1H, dt, J = 7.9, 1.0 Hz, 40-H), 7.26 (1H, ddd, J = 7.6,
5.0, 1.3 Hz, 500-H), 7.17 (1H, d, J = 7.8 Hz, 50-H), 4.11 (1H, m,
5-H), 3.97 (1H, dd, J =14.0, 4.4 Hz, 6-Ha), 3.55 (3H, m, 6-Hb,
CH2Sbipy); dC (100 MHz): 188.5 (2-C), 155.9 (60-C), 155.8 (20-
C), 155.3 (200-C), 149.2 (600-C), 137.3 (40-C), 136.9 (400-C), 123.9
(500-C), 122.5 (50-C), 120.7 (300-C), 117.3 (30-C), 112.2, 112.1 (sp2
C), 43.6 (5-C), 33.8 (6-C, CH2Sbipy); nmax (KBr): 1656, 1618,
1558, 1556, 1529, 1506, 1433, 1384, 1260, 1212, 1145, 1097,
1020, 861, 804, 774, 462; m/z: (CI) 409 ([M]+, 100%); HRMS:
(CI) found [M + H]+ 408.963, C16H12NOS5 requires 408.963.
night. After cooling to RT, the mixture was filtered and the
filtrate was concentrated under reduced pressure to give a
yellow residue. The residue was dissolved in 50 ml H2O, and
neutralised with diluted HCl (2 M). The yellow precipitate was
collected and re-dissolved in CH2Cl2, and washed twice with
H2O. The organic phase was separated and dried over MgSO4.
Removal of solvent afforded 2628 as a yellow solid (1.27 g,
80%), mp 162–164 1C, dH (400 MHz): 11.20 (1H, br, NH),
8.62 (1H, dd, 5.0, 0.9 Hz, 60-H), 8.09 (1H, d, J = 1.8 Hz, 3-H),
7.92 (1H, d, J = 7.8 Hz, 30-H), 7.85 (1H, dt, J = 1.3, 7.8 Hz,
40-H), 7.53 (1H, d, J = 6.4 Hz, 6-H), 7.46 (1H, dd, J = 6.4, 1.8
Hz, 5-H), 7.40 (1H, dd, J = 7.3, 5.1 Hz, 5-H); dC (DMSO-d6,
100 MHz): 191.3 (CQS), 149.5 (60-C), 148.3 (20-C), 139.8
(2-C), 138.2 (40-C), 133.7 (6-C), 129.6 (5-C), 126.4 (3-C), 125.6
(50-C), 121.3 (30-C); nmax (KBr): 3413 br, 3053 br, 1606, 1564,
1458, 1411, 1353, 1300, 1210, 1115, 1088, 1051, 993, 824, 781,
713, 606; m/z: (ES+) 189 [M + H]+; found C: 63.3, H: 4.1, N:
14.8%, C10H8N2S requires C: 63.8, H: 4.3, N: 14.9%.
(200,20 0 0 -Bipyridin-600-ylthiomethyl)-ET 13
5,6-Dihydro-5-(20,200-bipyridine-40-ylthiomethyl)-1,3-dithiolo-
[4,5-b]-1,4-dithiin-2-thione 28
A suspension of oxo compound 29 (0.34 g, 0.83 mmol) and
unsubstituted thione 3125 (0.36 g, 1.60 mmol) in dry triethyl
phosphite (15 ml) was heated to 90 1C under nitrogen for 6 h.
The solution was allowed to cool and concentrated in vacuo.
The residue was purified by flash chromatography on silica (1 :
6 EtOAc : cyclohexane) to yield 13 as an orange solid, (0.53 g,
46%), mp 100–103 1C, dH (400 MHz): 8.60 (1H, ddd, J = 5.0,
1.7, 1.0 Hz, 60 0 0 -H), 8.28 (1H, td, J = 7.9. 1.0 Hz, 30 0 0 -H), 8.10
(1H, dd, J = 7.8, 1.0 Hz, 500-H), 7.78 (1H, dt, J = 7.7, 1.7 Hz,
40 0 0 ꢁH), 7.58 (1H, t, J = 7.8 Hz, 400-H), 7.25 (1H, ddd, J =
7.5, 4.7, 1.2 Hz, 50 0 0 -H), 7.12 (1H, dd, J = 7.9, 0.7 Hz, 300-H),
4.02 (1H, m, 5-H), 3.86 (1H, dd, J = 13.9, 4.5 Hz, 6-Ha), 3.39
(1H, dd, J = 14.0 9.7 Hz, 6-Hb), 3.33 (1H, dd, J = 13.5, 5.2
Hz, CHaSbipy), 3.24 (1H, dd, J = 13.5, 3.2 Hz, CHbSbipy),
3.22 (4H, s, 50-,60-H2); dC (100 MHz): 156.2 (200-C), 156.0 (600-
C), 155.5 (20 0 0 -C), 149.2 (60 0 0 -C), 137.3 (40 0 0 -C), 137.1 (400-C),
124.0 (300-C), 122.5 (30 0 0 -C), 120.9 (500-C), 117.2 (50 0 0 -C), 113.9,
113.9, 113.3, 112.8 (sp2 C), 42.5 (5-C), 33.9 (6-C), 33.4
(CH2Sbipy), 30.2 (50-,60-C); nmax (KBr): 2920, 1654, 1575,
1508, 1410, 1246, 1137, 770; m/z: (APCI) 585 [M + H]+
(57%), 425 (45%), 156 (100%). HRMS: (EI) found [M + H]+
584.8881, C21H16N2S9 requires 584.8878.
Sodium hydride (0.26 g, 50% dispersion in oil, 5.40 mmol) was
added to a solution of 4-mercapto-2,20-bipyridine 26 (0.95 g,
5.05 mmol) in dry DMF (20 ml). After stirring for 40 min, a
solution of tosylate 24 (2.06 g, 5.05 mmol) in dry DMF (20 ml)
was added and the mixture was stirred under nitrogen for 27 h.
The solvent was removed under vacuum and the residue was
portioned between CH2Cl2 and water. The organic phase was
separated and dried over MgSO4. Purification by flash chro-
matography on silica (CH2Cl2/MeOH: 9.5/0.5) gave the pro-
duct 28 as a yellow solid (1.57g, 73%) mp 73–75 1C, dH: 8.61
(1H, td, J = 4.9, 0.8 Hz, 600-H), 8.45 (1H, d, J = 5.2 Hz, 60-H),
8.33 (1H, d, J = 7.9 Hz, 300-H), 8.28 (1H, d, J = 1.7 Hz, 30-H),
7.75 (1H, dt, 7.4, 1.6 Hz, 400-H), 7.25 (1H, m, 500-H), 7.11 (1H,
dd, J = 5.2, 2.0 Hz, 50-H), 3.80 (1H, m, 5-H), 3.39 (4H, m, 5-
CH2S, 6-H2); dC: 207.4 (CQS), 156.4 & 155.2 (20-,200-C), 149.2
& 149.1 (60-,600-C), 147.3 (40-C), 137.0 (400-C), 124.2 (500-C),
121.9 & 121.5 (3a-,7a-C), 121.4 & 121.3 (300-,50-C), 118.4 (30-
C), 41.2 (5-C), 35.0 & 32.7 (5-CH2, 6-C); nmax (KBr): 1569,
1559, 1532, 1442, 1379, 1056 787, 729, 702, 512; m/z: (EI) 424
([M]+, 100%); HRMS: (CI) found 423.9315 [M]+,
C16H12N2S6 requires 423.9319.
4-Mercapto-2,20-bipyridine 26
5,6-Dihydro-5-(20,200-bipyridine-40-ylthiomethyl)-1,3-dithiolo-
[4,5-b]-1,4-dithiin-2-one 30
Sodium hydrogen sulfide (4.95 g, 88.4 mmol) was suspended in
DMF (50 ml), to it was added 4-chloro-2,20-bipyridine27 (1.61
g, 8.43 mmol) and solid KOH (1.39 g, 24.8 mmol). The
mixture was heated to reflux under nitrogen atmosphere over-
Mercuric acetate (2.17 g, 6.81 mmol) was added to a solution
of thione 28 (1.15 g, 2.72 mmol) in CHCl3 (20 ml) and glacial
acetic acid (10 ml) and the mixture stirred for 4 h. The yellow
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filtrate was diluted with water (50 ml), and saturated aqueous
NaHCO3 was added to bring the pH to 8–9. The organic phase
was separated and washed with water, followed by drying over
MgSO4. The product 30 was obtained as a yellow waxy solid
(1.08 g, 97%), dH: 8.61 (1H, td, J = 4.9, 0.9 Hz, 600-H), 8.44
(1H, d, 5.2 Hz, 60-H), 8.32 (1H, d, J = 8.2 Hz, 300-H), 8.27 (1H,
d, J = 2.0 Hz, 30-H), 7.76 (1H, m, 400-H), 7.27 (1H, m, 500-H),
7.11 (1H, dd, J = 5.2, 1.9 Hz, 50-H), 3.81 (1H, m, 5-H), 3.41
(2H, m) & 3.51 (2H, m) (5-CH2, 6-H2); dC: 189.0 (2-C), 156.3
& 155.2 (20-,200-C), 149.2 & 149.1 (60-,600-C), 147.5 (40-C), 137.0
(400-C), 124.2 (500-C), 121.4 (300-,50-C), 118.5 (30-C), 112.4 &
112.3 (3a-,7a-C), 42.8 (5-C), 35.1 & 33.8 (5-CH2 & 6-C); nmax
(KBr): 1675, 1568, 1552, 1444, 1377, 785; m/z: (EI) 408 [M]+;
HRMS: (EI) found 407.9550 [M]+, C16H12N2OS5 requires
407.9548.
acetate (9.11 g, 28.5 mmol). A white precipitate could be seen
to form almost immediately. The mixture was stirred for 2 h,
filtered and the solid residue washed with chloroform. The
combined filtrates were collected and neutralised with sodium
hydrogen carbonate. The organic layer was collected, washed
with water, dried over MgSO4 and concentrated to yield 37
(2.88 g, 90%) as a beige solid; mp 76–79 1C; dH: 4.34 (m, 2H
CH2O), 3.92 (m, 1H, 5-H), 3.32 (dd, 1H, J = 13.6, 3.2 Hz, 6-
Ha), 3.18 (dd, 1H, J = 13.6, 5.9 Hz, 6-Hb), 2.04 (s, 3H,
COCH3); dC: 188.4 (OQCS2), 170.3 (OC(O)CH3), 113.5, 113.0
(3a-, 7a-C), 64.5 (CH2O), 43.2 (5-C), 32.4 (6-C), 20.7
(C(O)CH3); nmax (KBr): 2917, 1743, 1670, 1634, 1382, 1361,
1250, 1216, 906, 894, 855, 764, 646, 467; m/z: (EI+) 280 ([M]+,
100%); HRMS: (EI) found 279.9362 [M]+, C8H8O3S4 requires
279.9356.
(200,20 0 0 -Bipyridine-400-ylthiomethyl)-ET 14
Acetyloxymethyl-ET 38
A suspension of oxo compound 30 (1.08 g, 2.65 mmol) and the
unsubstituted thione 3125 (1.19 g, 5.30 mmol) in dry triethyl
phosphite (20 ml) was heated at 100 1C under nitrogen for 8 h.
The mixture was allowed to cool and concentrated in vacuo.
The residue was purified by flash chromatography on silica
(CH2Cl2/MeOH: 9.5/0.5) to yield the product 14 as a yellow
solid (0.84 g, 54%), mp 137–139 1C, dH (400 MHz): 8.67 (1H,
ddd, J = 5.1, 1.8, 0.9 Hz, 60 0 0 -H), 8.43 (1H, dd, J = 5.2, 0.6
Hz, 600-H), 8.37 (1H, d, J = 7.8 Hz, 30 0 0 -H), 8.33 (1H, d, J =
1.6 Hz, 300-H), 7.82 (1H, dt, J = 7.8, 1.8 Hz, 40 0 0 -H), 7.32 (1H,
ddd, J = 7.8, 5.1, 1.1 Hz, 50 0 0 -H), 7.17 (1H, dd, J = 5.2, 1.8
Hz, 500-H), 3.80 (1H, m, 5-H), 3.37 (4H, m, 6-H2, 5-CH2), 3.28
(4H, s, 50-,60-H2); dC (100 MHz): 156.3 & 156.2 (200-,20 0 0 -C),
149.2 (60 0 0 -C), 149.1 (600-C), 147.8 (400-C), 137.0 (40 0 0 -C), 124.1
(50 0 0 -C), 121.5 (30 0 0 -C), 121.3 (500-C), 118.5 (300-C), 41.5 (5-C),
35.0 & 33.3 (5-CH2, 6-C), 30.2 (50-,60-C); nmax (KBr): 1571,
1555, 1534, 1446, 1410, 1379, 787; m/z: (ES) 585 [M + H]+;
found C: 43.2, H: 2.6, N: 4.6%, C21H16N2S9 requires C: 43.1,
H: 2.8, N: 4.8%.
A mixture of oxo compound 37 (2.83 g, 10.1 mmol) and
unsubstituted thione 3125 (4.51 g, 20.1 mmol) was heated in
triethyl phosphite (50 ml) to 80 1C under N2 for 20 h to give an
orange solution. Triethyl phosphite was removed by distilla-
tion in vacuo and the residue purified by flash chromatography
on silica gel eluting with 5 : 1 cyclohexane : ethyl acetate to
yield a red solid which was recrystallised from methanol to
yield 38 (3.21 g, 70%) as a orange solid; mp 111–112 1C; dH
(400 MHz): 4.26 (2H, d, J = 7.3 Hz, ꢁCH2O), 3.81 (1H, m, 5-
H), 3.22 (4H, s, 50-, 60-H2), 3.17 (1H, dd, J = 13.2, 3.2 Hz, 6-
Ha), 3.09 (1H, dd, J = 13.2, 5.8 Hz, 6-Hb), 2.01 (3H, s, CH3);
dC (100 MHz): 170.4 (CQO), 113.9, 113.8, 112.0, 111.2 (sp2-
C), 64.6 (CH2O), 41.9 (5-C), 32.1 (6-C), 30.1 (50-, 60-C), 20.7
(CH3); nmax (KBr): 2917, 1743, 1670, 1634, 1382, 1361, 1250,
1216, 906, 894, 855, 764, 646; m/z: (ES) 456 ([M]+, 25%), 88
(100%); HRMS: (ES) found 456.8676 [M + H]+, C13H12O2S8
requires 456.8678.
Hydroxymethyl-ET (HMET) 39
A solution of ester 38 (0.65 g, 1.40 mmol) in THF (10 ml) and
20% HCl solution (5 ml) was stirred under N2 for 24 h. The
solution was neutralised by the addition of solid NaHCO3.
The organic layer was collected, washed with brine and dried
over Na2SO4. Removal of solvent yielded 3930.31 (0.56 g, 96%)
as an orange solid, mp 178–181 1C (dec.); dH: 3.74 (3H, m,
CH2OH & 5-H), 3.32 (4H, s, 50-, 60-H2), 3.30 (1H, dd, J =
13.5, 5.0 Hz, 6-Ha), 3.22 (1H, dd, J = 13.5, 3.4 Hz, 6-Hb), 1.58
(1H, s, OH); dC: 114.5, 113.5, 113.0, 111.2, 111.1 (sp2-C), 63.9
(CH2OH), 45.5 (5-C), 31.7 (6-C), 30.1 (50-, 60-C); nmax (KBr):
2918, 1409, 1284, 1259, 1055, 1000, 909, 886, 772; m/z: (EI)
414 [M]+.
5-Acetyloxymethyl-5,6-dihydro-[1,3]dithiolo[4,5-b][1,4]dithiine-
2-thione 36
A suspension of trithione 22 (4.97 g, 25.3 mmol) and allyl
acetate (4.10 g, 41 mmol) in toluene (100 ml) was heated to
reflux for 12 h then cooled and filtered. The solid residue was
washed with chloroform and the combined filtrates collected,
decolourised with charcoal then purified by flash chromato-
graphy on silica gel eluting with 1 : 1 cyclohexane : ethyl
acetate to yield 36 (5.4 g, 72%) as a red oil; dH: 4.36 (m, 2H,
CH2O), 3.94 (m, 1H, 5-H), 3.34 (dd, 1H, J = 13.6, 3.2 Hz,
6-Ha), 3.26 (dd, 1H, J = 13.6, 5.7 Hz, 6-Hb), 2.08 (s, 3H,
COCH3); dC: 207.5 (CQS), 170.3 (CQO), 122.2, 122.1 (3a-,
7a-C) 64.3 (CH2O), 42.4 (5-C), 31.3 (6-C), 20.7 (CH3); nmax
(film): 2923, 2848, 1738, 1487, 1379, 1219, 1057, 8921, 786;
m/z: (EI+) 296 ([M]+, 100%); HRMS: (EI) found 295.9134
[M]+, C8H8O2S5 requires 295.9127.
Tosyloxymethyl-ET 40
Hydroxymethyl-ET 39 (0.28 g, 0.68 mmol) and tosyl chloride
(1.21 g, 6.30 mmol) were dissolved in dry pyridine (15 ml), and
the solution stirred for 20 h under nitrogen. The solution was
added to iced water (40 ml) and the yellow precipitate collected
by filtration, and washed with H2O and MeOH. The solid was
redissolved in CH2Cl2, and washed with aqueous HCl (2 M)
and then H2O. The organic phase was dried over MgSO4, and
the solution evaporated to give the product 40 as an orange
5-Acetyloxymethyl-5,6-dihydro-[1,3]dithiolo-[4,5-b]
[1,4]dithiine-2-one 37
To a solution of thione 36 (3.37 g, 11.4 mmol) in chloroform
(40 ml) was added glacial acetic acid (10 ml) and mercuric
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solid (0.33 g, 85%), mp 60–62 1C, dH: 7.71 (2H, d, J = 8.5 Hz,
Ar-H2), 7.29 (2H, d, J = 8.5 Hz, Ar-H2), 4.22 (1H, t, J = 10.1
Hz, CHbO), 4.07 (1H, dd, J = 10.1, 5.1 Hz, CHaO), 3.82 (1H,
m, 5-H), 3.22 (4H, s, 50-,60-H2), 3.18 (2H, m, 6-H2), 2.40 (3H,
s, CH3); dC: 145.4 (400-C), 132.2 (100-C), 130.1 (300-,500-C), 128.0
(200-,600-C), 113.9, 113.5 & 112.8 (sp2-C), 68.9 (CH2O), 40.8
(5-C), 31.2 (6-C), 30.1 (50-,60-CH2), 21.7 (CH3); nmax (KBr):
1358, 1187, 1171, 1088, 953, 912, 808, 767, 668, 569, 549; m/z:
(EI) 568 ([M]+, 100%); Found C: 37.9, H: 2.7%, C18H16O3S9
requires C: 38.0, H: 2.8%.
solution of tosyloxymethyl-ET (0.68 g, 1.20 mmol) in dry
DMF (15 ml) was added and the mixture was stirred under
nitrogen for 48 h. Solvent was removed under vacuum and the
residue was portioned between CH2Cl2 and water. The organic
phase was separated and dried over MgSO4. Removal of
solvent afforded a brown residue which was purified by flash
chromatography on silica (CH2Cl2/MeOH: 9.5/0.5) to give the
product as a yellow solid. Yield, 0.44 g, 65%.
4-Mercapto-2,6-diacetylpyridine
4-Chloro-2,6-diacetylpyridine32 (0.57 g, 2.88 mmol) and solid
KOH (0.48 g, 8.6 mmol) were added to a suspension of sodium
hydrogen sulfide (1.56 g, 28.0 mmol) in DMF (50 ml). The
mixture was heated to reflux under nitrogen atmosphere for 62
h. After cooling to room temperature, the mixture was filtered
and the filtrate was concentrated under reduced pressure to
give a brown residue. The residue was dissolved in H2O
(15 ml), and neutralised with diluted HCl (2 M). The yellow
precipitate was collected by filtration and re-dissolved in
CH2Cl2, and the bright yellow solution was washed with
H2O and brine, respectively. The organic phase was separated
and dried over MgSO4. Removal of solvent afforded the title
product as a brown solid which was used for next step without
further purification (0.40 g, 70%). mp 92–95 1C. dH(400
MHz): 7.95 (2H, s, 3-,5-H), 3.80 (1H, s, SH), 2.70 (6H, s,
2 ꢃ CH3); dC (100 MHz): 199.0 (2 ꢃ CQO), 152.5 (2-,6-C),
147.1 (4-C), 123.3 (3-,5-C), 25.6 (2 ꢃ CH3); nmax (KBr): 1699,
1571, 1412, 1360, 1308, 1230, 892, 806, 608, 499; m/z: (ES+)
196 [M + H]+, 218 [M + Na]+; HRMS: (CI) found 196.0428
[M + H]+, C9H10NO2S requires 196.0427.
40-Mercapto-2,20:60,200-terpyridine 33
The compound was prepared quantitatively from 40-chloro-
2,20:60,200-terpyridine 32 following the procedure used for 4-
mercapto-2,20-bipyridine, to give the product 3329 as a bright
yellow solid (99%) , mp 230–235 1C, dH (400 MHz): 12.46 (1H,
br, NH), 8.73 (2H, br d, J = 4.4 Hz, 6-,600-H), 8.06 (2H, s, 30-
,50-H), 7.98 (2H, d, J = 7.9 Hz, 3-,300-H), 7.83 (2H, dt, J = 7.7,
1.1 Hz, 4-,400-H), 7.40 (2H, dd, J = 7.0, 5.1 Hz, 5-,500-H);
d
C (100 MHz): 193.5 (CQS), 149.8 (6-,600-C) , 147.7 (2-,200-C),
139.0 (20-,60-C), 137.7 (4-,400-C), 126.6 (30-,50-C), 125.4
(5-,500-C), 120.5 (3-,300-C); nmax (KBr): 3249, 1607, 1566,
1483, 1462, 1451, 1327, 1265, 1115, 1099, 1077, 1062, 990,
881, 845, 782, 730, 699, 678, 616, 585, 466; m/z: (ES) 266
([M + H]+, 100%).
(200,20 0 0 :60 0 0 ,20 0 0 0 -Terpyridine-40 0 0 -ylthiomethyl)-ET 15
Sodium hydride (0.037 g, 50% dispersion in oil, 0.77 mmol)
was added to a solution of 40-mercapto-2,20:60,200-terpyridine
33 (0.20 g, 0.76 mmol) in dry DMF (8 ml). After stirring for 40
min, a solution of tosyloxymethyl-ET 40 (0.46 g, 0.80 mmol) in
dry DMF (10 ml) was added and the mixture was stirred under
nitrogen for 48 h. Solvent was removed under vacuum and the
residue was portioned between CH2Cl2 and water. The organic
phase was separated and dried over MgSO4. Removal of
solvent afforded a brown residue which was purified by flash
chromatography on silica (CH2Cl2/MeOH: 19/1) to give the
product 15 a yellow solid (0.33 g, 65%), mp 200–202 1C, dH
(400 MHz): 8.62 (2H, ddd, 4.7, 1.8, 0.9 Hz, 600-,60 0 0 0 -H), 8.51
(2H, dd, J = 7.9, 1.0 Hz, 300-,30 0 0 0 -H), 8.31 (2H, s, 30 0 0 -50 0 0 -H),
7.78 (2H, dt, J = 7.8, 1.8 Hz, 400-,40 0 0 0 -H), 7.28 (2H, ddd, J =
7.8, 4.7, 1.0 Hz, 500-,50 0 0 0 -H), 3.81 (1H, m, 5-H), 3.58 (1H, dd,
J = 14.3, 5.0 Hz, 5-CHaSterpy), 3.45 (1H, dd, J = 14.3, 9.7
Hz, 5-CHbSterpy), 3.35 (1H, dd, J = 13.2, 5.1 Hz, 6-Ha), 3.27
(1H, dd, J = 13.2, 3.2 Hz, 6-Hb), 3.21 (4H, s, 50-,60-H2); dC
(100 MHz): 155.4 (200-,20 0 0 -,60 0 0 -,20 0 0 0 -C), 149.1 (600-,60 0 0 0 -C),
148.9 (40 0 0 -C), 137.0 (400-,40 0 0 0 -C), 124.1 (500-,50 0 0 0 -C), 121.4
(300-,30 0 0 0 -C), 118.4 (30 0 0 -,50 0 0 -C), 113.8, 113.0, 112.8, 112.0 &
111.4 (sp2-C), 41.6 (5-C), 34.8 (5-CH2Sterpy), 33.3 (6-C),
30.2 (50-,60-C); nmax (KBr): 1576, 1550, 1467, 1405, 1389,
1259, 808, 782, 730, 673; m/z: (CI) 662 [M + H]+. Found C
45.9, H 2.7, N 5.9%, C26H19N3S9 ꢀ H2O requires C 45.9, H 3.1,
N 6.2%.
(200,600-Diacetylpyridine-400-ylthiomethyl)-ET 16
Sodium hydride (0.023 g, 50% dispersion in oil, 0.48 mmol)
was added to a solution of 4-mercapto-2,6-diacetylpyridine
(0.09 g, 0.46 mmol) in dry DMF (4 ml). After stirring over-
night, a solution of tosyloxymethyl-ET 40 (0.27 g, 0.48 mmol)
in dry DMF (7 ml) was added and the mixture was stirred
under nitrogen for 6 d. Solvent was removed under vacuum
and the brown residue was partitioned between CH2Cl2 and
water. The organic phase was separated and washed with
brine, dried over MgSO4. Removal of solvent afforded a
brown oily residue which was purified by flash chromatogra-
phy on silica eluted with CH2Cl2 and 16 was obtained as an
orange solid (0.19 g, 70%), mp 180–183 1C, dH (400 MHz):
8.00 (2H, s, 300-,500-H), 3.75 (1H, m, 5-H), 3.52 (1H, dd, J =
12.8, 5.0 Hz, 6-Ha), 3.45 (1H, dd, J = 12.8, 7.8 Hz, 6-Hb), 3.32
(2H, d, J = 4.2 Hz, CH2S), 3.28 (4H, s, 50-,60-H2), 2.75 (6H, s,
2 ꢃ CH3); dC (100 MHz): 199.0 (2 ꢃ CQO), 152.6 (200-,600-C),
150.5 (400-C), 121.4 (300-,500-C), 113.8, 112.9, 112.6, 112.5, 101.8
(sp2-C), 41.1 (5-C), 34.9 (6-C), 33.4 (CH2S), 30.1 (50-,60-C),
25.6 (2 ꢃ CH3); nmax (KBr): 1696, 1570, 1408, 1359, 1304,
1260, 1228, 800, 732, 606; m/z: (ES) 591 [M]+; found C: 38.9,
H: 2.8, N: 2.1%. C20H17NO2S9 ꢀ 0.5CH2Cl2 requires: C: 38.9,
H: 2.8, N: 2.2%.
(200,20 0 0 -Bipyridine-400-ylthiomethyl)-ET 14 (from 40)
Nicotinic acid, HMET ester 17
Sodium hydride (0.058 g, 50% dispersion in oil, 1.21 mmol)
was added to a solution of 4-mercapto-2,20-bipyridine (0.22 g,
1.17 mmol) in dry DMF (10 ml). After stirring for 40 min, a
N,N0-dicyclohexylcarbodiimide (0.12 g, 0.6 mmol) was added
to a solution of HMET 39 (0.19 g, 0.46 mmol), picolinic acid
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(0.10 g, 0.6 mmol) and 4-dimethylaminopyridine (5 mg) in dry
dichloromethane (10 ml). The mixture was stirred for 20 h at
RT, after which the mixture was concentrated and purified by
silica gel column chromatography eluting with 5 : 1 cyclohex-
ane : ethyl acetate to yield 17 (0.12 g, 50%) as an orange solid,
mp 175–176 1C; dH (400 MHz, DMSO-d6): 9.12 (1H, dd, J =
2.1, 0.6 Hz, 200-H), 8.82 (1H, dd, J = 4.8, 1.7 Hz, 600-H), 8.33
(1H, dt, J = 7.9, 2.0 Hz , 400-H), 7.58 (1H, ddd, J = 7.9. 4.9,
0.8 Hz, 500-H), 4.55 (1H, dd, J = 11.2, 7.2 Hz, CHaO), 4.49
(1H, dd, J = 11.2, 6.3 Hz, CHbO), 4.33 (1H, m, 5-H), 3.52
(1H, dd, J = 13.6, 5.5 Hz, 6-Ha), 3.44 (1H, dd, J = 13.6, 3.4
Hz, 6-Hb), 3.39 (4H, s, 50-,60-H2); dC (100 MHz, DMSO-d6):
164.3 (CQO), 153.9 (600-C), 150.2 (200-C), 137.0 (400-C), 125.2
(300-C), 123.9 (500-C), 113.2, 112.9, 110.8, 110.0 (sp2-C), 65.1
(CH2O), 41.6 (5-C), 31.5 (6-C), 29.5 (50-.60-C); nmax (KBr):
1723, 1636, 1617 1384, 1276, 1109, 1023 738, 618; m/z: (ES)
520 [M + H]+; HRMS: (ES) found 519.8780 [M + H]+.
C17H13NO2S8 + H requires 519.8785.
X-Ray crystallography for 16 and 40
Data was collected by the EPSRC National Crystallography
Service on a Bruker-Nonius FR591 diffractometer equipped
with a rotating anode source and CCD camera using Mo Ka
radiation at 120 K, and structures were solved and refined with
SHELXS-97 and refined with SHELXL-97.33
Crystal data for 16. C20H17NO2S9.0.5CH2Cl2, Mr = 634.35,
triclinic, a = 7.8542(1), b = 11.9820(2), c = 14.1992(3) A,
a = 90.439(1), b = 92.745(1), g = 101.822(1)1, V = 1306.2
3
A , Z = 2, P1, Dc = 1.61 g cmꢁ3, m(Mo Ka) = 0.89 mmꢁ1, T
ꢀ
= 120 K, 5986 unique reflections, 5172 with Fo 4 4s(Fo), R =
0.038, wR=0.084. Orange X-ray quality single crystals were
obtained by layering hexane onto a concentrated solution of
the compound in dichloromethane. A molecule of the latter
solvent is included in the crystal structure, and lies near the
centre of symmetry which relates the two chlorine atoms, but
the position of the methylene group is disordered.
Crystal data for 40. C18H16O3S9, Mr = 568.85, triclinic, a =
6.2490(1), b = 11.0486(3), c = 16.4757(4) A, a = 82.167(2),
b = 82.328(2), g = 87.627(2)1, V = 1116.5 A , Z = 2, P1, Dc
Picolinic acid, HMET ester 18
3
ꢀ
Reaction of HMET 39 and picolinic acid, following to the
procedure for 17 above gave 18 (0.13 g, 54%) as an orange
solid; mp 163–165 1C, dH (400 MHz, DMSO-d6): 8.73(1H, d,
J = 4.6 Hz, 600-H), 8.08 (1H, d, J = 7.8 Hz, 300-H), 8.00 (1H,
dt, J = 7.7, 1.2 Hz, 400-H), 7.66 (1H, dd, J = 7.8, 4.6 Hz, 500-
H), 4.49 (1H, dd, J = 11.2, 7.1 Hz, CHaO), 4.42 (1H, dd, J =
11.2, 6.7 Hz, CHbO), 4.32 (1H, m, 5-H), 3.47 (1H, dd, J =
13.5, 5.3 Hz, 6-Ha), 3.42 (1H, dd, J = 13.5, 3.7 Hz, 6-Hb); 3.38
(4H, s, 50-,60-H2); dC (100 MHz, DMSO-d6): 164.1 (CQO),
149.9 (600-C), 147.0 (200-C), 137.5 (400-C), 127.6 (500-C), 125.2
(300-C), 113.3, 113.2, 112.9, 110.8, 110.0 (sp2-C), 65.3 (CH2O),
41.7 (5-C), 31.6 (6-C), 29.5 (50-.60-C); nmax (KBr): 1741, 1723,
1306, 1280, 1277, 1243, 1133, 1087, 771, 740, 699; m/z: (ES)
520 [M + H]+; HRMS: (ES) found 519.8781 [M + H]+.
C17H13NO2S8 + H requires 519.8785.
= 1.69 g cmꢁ3, m (Mo Ka) = 0.91 mmꢁ1, T = 120 K, 5118
unique reflections, 4486 with Fo 4 4s(Fo), R = 0.039, wR =
0.107. Light brown X-ray quality single crystals were obtained
by layering hexane onto a concentrated solution of the com-
pound in CH2Cl2. The structure is disordered 87 : 13 between
two structures in which the ET and 4-CH3C6H4 fragments
occupy very similar positions, but with the different points of
attachment of the tosyloxymethyl sidechain to the ethylene
bridge of the ET moiety.
CCDC reference numbers 616013 and 616014. For crystal-
lographic data in CIF or other electronic format see DOI:
10.1039/b606715h
Acknowledgements
We thank the Leverhulme Trust for a grant (F/01374/B), the
Nottingham Trent University for a studentship (J.P.G.) and
the Chinese Government for an Exchange Scholarship (H.N.).
We thank the EPSRC National Crystallography Service (Prof.
M. B. Hursthouse and staff, University of Southampton) for
datasets and the EPSRC Mass Spectrometry Service (Prof.
A. G. Brenton and staff, University of Swansea) for measure-
ments. We acknowledge the EPSRC Chemical Database
Service at Daresbury34 for access to the Cambridge Structural
Database.35
3-Thienylmethoxyacetic acid, HMET ester 41
To a solution of HMET 39 (0.19 g, 0.46 mmols), (thiophen-3-yl)
methoxyacetic acid (0.10 g, 0.6 mmols) and 4-dimethylamino-
pyridine (0.005 g) in dry dichloromethane (10 ml) was added
N,N0-dicyclohexylcarbodiimide (0.12 g, 0.6 mmols). The mix-
ture was stirred for 20 h at RT, after which the mixture was
concentrated and purified by silica gel column chromatogra-
phy eluting with 5 : 1 cyclohexane : ethyl acetate to yield 41
(0.19 g, 73%) an oily orange solid; dH: 7.26 (1H, dd, J = 3.0,
5.0 Hz, 500-H), 7.19 (1H, br m, 200-H), 7.03 (1H, dd, J = 1.1, 5.0
Hz, 400-H), 4.58 (2H, s, OCH2Ar), 4.32 (2H, d, J = 7.2 Hz,
CH2O), 4.05 (2H, s, C(QO)CH2O), 3.82 (1H, m, 5-H), 3.21
(4H, s, 50-,60-H2), 3.16 (1H, dd, J = 3.5 13.5 Hz, 6-Ha), 3.06
(1H, dd, J = 5.5, 13.5 Hz, 6-Hb); dC: 169.8 (CQO), 137.9 (300-
C), 127.4 (200-C), 126.4 (500-C), 123.8 (400-C), 113.7 (sp2-C), 68.4
(OCH2Ar), 66.7 (C(O)CH2O), 64.7 (CH2O), 41.7 (5-C), 32.5
(6-C), 30.1 (50-, 60-C); nmax (KBr): 2910, 2848, 1744, 1697,
1656, 1401, 1277, 1183, 1158, 1116, 991, 903, 851, 768, 727,
691, 628, 566, 499; m/z: (EI) 569 ([M + H]+, 10%), 230
(100%); HRMS: (EI) found 567.8575 [M]+, C18H16O3S9
requires 567.8580.
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