Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates

Article abstract of DOI:10.1002/ejoc.201500420

The thioacetate group is extensively employed as an anchoring group for attachment of molecules onto gold surfaces or between electrodes in molecular electronics. On account of its ready hydrolysis, it is often incorporated in the last step of a synthetic

Full text of DOI:10.1002/ejoc.201500420

FULL PAPER
DOI: 10.1002/ejoc.201500420
Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates
Martyn Jevric,*[a] Anne Ugleholdt Petersen,[a] Mads Mansø,[a]
Anders Østergaard Madsen,[a] and Mogens Brøndsted Nielsen*[a]
Keywords: Synthetic methods / Acetylation / Click chemistry / Bismuth / Protecting groups / Molecular electronics
The thioacetate group is extensively employed as an anchor- butyl thioether end-cap(s) was prepared, including mo-
ing group for attachment of molecules onto gold surfaces or
between electrodes in molecular electronics. On account of
its ready hydrolysis, it is often incorporated in the last step of
a synthetic sequence from the corresponding tert-butyl thio-
ether. Here we present a particularly convenient method for
this conversion using AcCl in combination with Bi(OTf)3,
which is known as an environmentally friendly salt. A large
variety of redox-active and photoactive substrates with tert-
lecules incorporating dithiafulvene, dicyanoethylene, di-
hydroazulene, fulleropyrrolidine, and triazole units, and suc-
cessfully subjected to a BiIII promoted conversion into prod-
ucts with thioacetate end-cap(s). The azide group could also
withstand these conditions, which allowed us to prepare S-
(4-azidophenyl) ethanethioate that presents a convenient
building block for subsequent CuAAC reactions.
Introduction
known procedure employing catalytic bromine,[4] in both
cases in the presence of acetyl chloride. Alternatively, the
thioacetate can be introduced by the treatment of an aryl
halide with potassium thioacetate under cross-coupling
conditions.[5] Nevertheless, not all functional groups present
in the molecular wire/transistor may be compatible with
these conditions, and as the demands for more specific and
sometimes more complicated structures increase, so do the
needs to develop alternative methods for the StBu to SAc
conversion.
Bismuth(III) salts have been shown to be versatile cata-
lysts in organic transformations, facilitating a wide variety
of reactions and have been tagged as green reagents, due to
non-toxic and environmentally safe properties.[6] This reac-
tivity can be ascribed to the weak shielding of the outer f
electrons, thus giving this non-toxic heavy metal salt Lewis
acidic character, and thus it is capable of such transforma-
tions as carbon–carbon bond formation in Friedel–Crafts
type chemistry, and both deprotection and formation of
acetals, amongst others. More pertinent to our interests, re-
actions that have been reported are the deprotection of tert-
butyl ethers connected to either furan or thiophene (1) by
using either catalytic bismuth triflate [Bi(OTf)3] or bismuth
chloride, furnishing the lactone or thiolactone (2), respec-
tively, in high yields (Scheme 1).[7] It has also been found
that bismuth(III) salts provide a gentle non-toxic methodol-
ogy to effect deprotection of thioacetals, where otherwise
such reagents as boron trifluoride or mercury salts need be
employed.[8] From these observations, it can be seen that
BiIII salts exhibit an affinity for both oxygen and sulfur lone
pairs. The drive for the development of a new, versatile
methodology to transform tert-butyl thioethers to their cor-
Scientific advances in nanotechnology have allowed for
the construction of elaborate and miniaturized devices in-
corporating small organic molecules and supramolecular
assemblies to perform certain functions, such as electrical
conductivity, photoactivity, catalysis, and redox activity
(charge reservoirs), just to mention a few. Organic mol-
ecules integrated into molecular junctions in the field of
molecular electronics[1] have required an additional design
requirement for the secure and reliable anchoring of the
molecule to electrodes or upon a 2-dimensional surface.
Typically gold is used in such devices, due to its high sta-
bility and conductive properties. Several anchoring groups
have been used; nonetheless, a thiol (thiolate) seems to be
one of the most robust functional groups for the connection
of an organic molecule to gold.[2] Unfortunately, the thiol
moiety is susceptible to aerial oxidation and thus has to be
typically liberated from the labile protected thioacetate in
situ. To the dismay of synthetic chemists in this field, the
thioacetate group is not tolerant to many reaction condi-
tions. For this reason, the tert-butyl thioether has often
been used to mask the thiol during harsh synthetic transfor-
mations until a terminal step, where the thioacetate can be
generated from the tert-butyl thioether by treatment with
either the Lewis acid boron tribromide[3] or from a lesser
[a] Department of Chemistry, University of Copenhagen,
Universitetsparken 5, 2100 Copenhagen Ø, Denmark
E-mail: jevric.m@gmail.com
mbn@kiku.dk
http://chem.ku.dk/research_sections/solarenergy/
organicsynthesis/
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201500420.
Eur. J. Org. Chem. 2015, 4675–4688
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4675

M. Jevric, A. U. Petersen, M. Mansø, A. Ø. Madsen, M. B. Nielsen
FULL PAPER
responding thioacetates encouraged us to investigate the ditionally, structures 8a and 11a incorporate electron-
possibility to employ a BiIII salt together with acetyl chlor- donating, redox-active dithiafulvene (DTF) units, which
ide.[9]
have also found interest in molecular electronics; for exam-
ple, a large selection of cruciform-like molecular wires with
DTF groups has recently been studied in break-junctions
and at self-assembled monolayers on gold.[11] Compound
12a has a central dihydroazulene (DHA) unit which acts as
a photoswitch, undergoing light-induced ring-opening to a
vinylheptafulvene (VHF);[12] this conversion has been
shown to be accompanied by electrical conductance switch-
ing.[13]
Scheme 1. Lead reaction (top) and the focus of this work (bottom).
Results and Discussion
Treatment of a series of tert-butyl thioether derivatives
(3a–12a and various functionalized fullerenes) with cata-
lytic Bi(OTf)3 was the focus of this study (Figure 1). This
Synthesis of Thioether Substrates
Stemming from the bromide 13, which could be routinely
consisted of a combination of simple aryl derivatives with synthesized on a large scale from commercially available 4-
functionalization in the para position (I), a host of double bromothiophenol,[3a] a host of different compounds was
thioethers (II) and additionally some fullerene/tert-butyl made (Scheme 2), where some of this chemistry has been
thioether hybrid compounds (III). Indeed, fullerene itself previously reported. Thus, preparation of compounds 3a,[4]
has also been shown to anchor to gold surfaces[10] and the 4a,[14] and 5a[15] followed standard procedures. Aldehyde
hope was that this approach could lend itself to the synthe- 14[3a] was the precursor for addition of both electron poor
sis of materials with two different anchoring groups. Ad- and rich olefin derivatives. A Knoevenagel condensation
Figure 1. Substrates for probing the Bi(OTf)3 catalyzed conversion of tert-butyl thioethers into thioacetates.
4676
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4675–4688

Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates
Scheme 2. Synthetic outline for preparation of 3a–8a; TIPS = triisopropylsilyl, TBAF = tetrabutylammonium fluoride.
with malononitrile in the presence of basic alumina gave
alkene 7a in high yield. On the other hand, a phosphite-
mediated coupling with the 1,3-dithiol-2-thione 15[16] could
be used to affix a DTF unit to the aryl by also creating a
carbon–carbon double bond, thus furnishing 8a in excellent
yield, in analogy to a recent protocol.[17] Taking the pre-
viously reported boronic acid 16[18] in methanol and sub-
jecting it to treatment with sodium azide in the presence of
copper acetate afforded azide 6a in high yield, using a litera-
ture procedure for a related compound.[19]
Molecules with two sulfur end-caps were also targeted,
allowing for anchoring to electrodes at both ends
(Scheme 3). A homo-coupling reaction of 4a under palla-
dium catalysis and conducted in the presence of air gave
butadiyne 9a,[20] whilst a CuI-catalyzed alkyne-azide cyclo-
addition (CuAAC) reaction[21] using 0.1 equivalents of cop-
per iodide formed triazole 10a in moderate yield. DTF con-
taining derivative 8a could be treated with an excess of ele-
mental iodine to afford 11a, which contained both two
DTF units and two tert-butyl thioether groups. All these
compounds were fully characterized using NMR spec-
troscopy and elemental analyses agreed with their respective
calculated values. Compound 12a incorporating the DHA
unit was made according to a previously published pro-
Scheme 3. Synthesis of dimeric thioethers 9a–11a.
cedure.[15]
Aldehyde 14 could be carried over into other synthetic
transformations. Thus, subjecting it to a standard 1,3-di- was to provide the fullerene derivatives with superior solu-
polar cycloaddition reaction with C60, a Prato reaction,[22] bility in a broad range of solvents. It was also of interest to
using two different amino acids (17 and 18) produced fuller- investigate a hybrid system, which had an increased dis-
ene derivatives 19a and 20a. Compound 19a was derived tance between the two potential anchoring groups. For this
from the commercially available amino acid N-ethylglycine purpose, a third fullerene derivative was synthesized in a
17. In the case of derivative 20a, the tailor-made amino acid two-step procedure. A Prato reaction with the known 4-
18, which had been previously used by us,[23] was success- ethynylbenzaldehyde 21[24] yielded fulleropyrrolidine 22,
fully employed. The advantage of using such an amino acid which, bearing a phenylacetylenic unit, was subsequently
Eur. J. Org. Chem. 2015, 4675–4688
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4677

M. Jevric, A. U. Petersen, M. Mansø, A. Ø. Madsen, M. B. Nielsen
FULL PAPER
Scheme 4. Synthesis of fullerene derivatives 19a, 20a, and 23a.
reacted in a CuAAC reaction to form triazole 23a in good was the case for converting 7a into 7b (Entry 8). Meanwhile,
yield (Scheme 4).
the reaction of the DTF derivative 8a, despite leaving the
contents of the vessel stirring for 3 hours in the presence of
0.25 equiv. of Bi(OTf)3 (Entry 9), gave only small amounts
of desired product 8b. In this case, the DTF unit also was
susceptible to a side reaction where some acetylation of the
fulvene had occurred giving rise to products 25 and 26 (Fig-
ure 2). Formation of these side-products could be sup-
pressed by increasing the catalyst loading; thus, using
0.5 equiv. of Bi(OTf)3 in 30 min gave 8b in fair yield (Entry
10). The reaction for the formation of the double thioacet-
ate 9b[28] worked efficiently well with similar loading (Entry
11), and this product conveniently precipitated from the re-
action mixture. The yield could be somewhat improved
when the reaction was conducted in neat acetonitrile (Entry
12). On the other hand, using a similar loading of Bi(OTf)3
resulted in an incomplete reaction of 10a into 10b (Entry
13; products 27a,b shown in Figure 2 where only one SAc
had been formed were also identified), but with a stoichio-
metric amount of Bi(OTf)3 the reaction was driven to com-
pletion (Entry 14). The triazole seemed to hinder the reac-
tivity and this was also evidenced by reactions upon the
fullerene derivatives (in CH3CN/toluene/o-DCB, 2:1:2).
With Bi(OTf)3 loadings corresponding to 0.2–0.3 equiv., the
reactions of fullerene derivatives 19a and 20a gave little to
no reaction (Entries 18 and 20), but this hindrance could be
overcome by raising the Bi(OTf)3 loading to 1.5–1.6 equiv.
Finally, the reaction of triazole-fullerene thioether 23a in
the presence of 2 equiv. of Bi(OTf)3 afforded 23b in low
yield (Entry 22), where unfortunately significant amounts
of starting material were isolated and in this case ac-
BiIII-Catalyzed Acetylations
With a host of substrates in hand, the acetylation of
these compounds was examined using Bi(OTf)3 (Table 1,
Scheme 5). A general set of conditions was employed where
a solvent mixture of acetonitrile and toluene in 2:1 ratio
was used in the presence of an excess of acetyl chloride
in order to trap the air sensitive thiol. By using 0.2 molar
equivalents (equiv.) of Bi(OTf)3, product 3b could be
formed in 78% yield (Entry 1). However, lowering the cata-
lyst loading to 0.1 equiv. resulted in an incomplete reaction,
whether it was run for 30 minutes or 3 hours (Entries 2 and
3), suggesting that the catalyst was probably deactivated
within half an hour. The starting material could be con-
sumed with a loading of 0.1 equiv. (Entry 4) when the reac-
tion was performed in CH2Cl2 and in the presence of a
small amount of acetic acid, but with the desired product
forming in very low yield. Under these conditions, the
major product 24a (Figure 2) corresponded to the loss of
the silyl protecting group and addition of hydrogen chloride
across the triple bond of the terminal acetylene. Conversion
of 4a and 5a yielded 4b[25] and 5b[26] in medium to good
yields, respectively (Entries 5 and 6). Conversion of 4a to
4b was complicated by a partial side reaction by addition
of TfOH across the alkyne resulting in an inseparable mix-
ture of 4b and the vinyl triflate 24b;[27] this mixture was also
very unstable neat. Reaction of azide 6a with 0.2 equiv. of
catalyst (Entry 7) afforded thioacetate 6b in high yield as
4678
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4675–4688

Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates
companied by significant decomposition. The structures of
10a and 7b were confirmed by X-ray crystallographic analy-
sis (Figure 3). The larger Bi(OTf)3 loadings needed for the
triazole substrates may be the result of undesired coordina-
tion between BiIII and the triazole unit. Several examples
of triazoles acting as ligands towards metal ions are
known[29] as are complexes between BiIII and ligands with
nitrogen donor atoms.[30] Yet, maybe more important, the
triazole should become protonated by any triflic acid pres-
ent [generated from Bi(OTf)3], and as we shall see below
this acid also promotes the acetylation reaction. For C60
Prato adduct substrates, protonation of the pyrrolidine unit
may also play an inhibiting role.
Table 1. Bi(OTf)3 catalyzed acetylation reactions; see Scheme 5.
Entry[a] Substrate Equiv. Bi(OTf)3
Time [h]
Product(s) [%][b]
1
2
3
3a
3a
3a
3a
4a
5a
6a
7a
8a
8a
9a
9a
10a
0.2
0.1
0.1
0.1
0.2
0.2
0.2
0.2
0.25
0.5
0.5
0.5
0.5
0.5
0.5
3
24
0.5
1
0.5
0.5
3
0.5
0.5
1
3b (78)
3a (35) 3b (55)
3a (21) 3b (58)
3b (10) 24a (30)
4b (40) 24b (9)[d]
5b (47)
4[c]
5
6
7
8
9
10
11
12[f]
13
Figure 2. Side-products.
6b (82)
7b (86)
8b (7) 25 (19) 26 (4)
8b (55)
9b (63)[e]
9b (95)[e]
2
10a (61) 27a/27b (27)
10b (12)
14
15
16
10a
11a
12a
12a
19a
19a
20a
20a
23a
1.0
1.0
0.9
0.9
0.3
1.5
0.2
1.6
2.0
0.5
0.5
0.5
0.5
2
0.5
2
0.5
0.5
10b (97)
11b (78) 28 (9)
12b (84)
17[f]
18[g]
19[g]
20[g]
21[g]
22[g]
12b (88)
19a (80) 19b (10)
19a (13) 19b (77)
20a (95) 20b (0)
20b (89)
Figure 3. Top: Molecular structure of 10a (crystals grown from
CH2Cl2/heptane). Space group: C2. There is some disorder in the
triazole unit; the C and N atoms connected to the benzene rings
are superimposed, thus contributing 50% each in both positions.
Bottom: Molecular structure of 7b (crystals grown from acetone/
heptane). Space group: P21/c. There is some disorder in the methyl
group, where the hydrogen atoms can be placed in two positions.
For both structures, the thermal ellipsoids are shown at the 50%
probability level. CCDC-1055456 (for 10a) and -1055455 (for 7b)
contain the supplementary crystallographic data. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
23a (23) 23b (24)
[a] All reactions were performed in a mixture of CH3CN/toluene
(2:1) (if not otherwise stated) in an excess of acetyl chloride, with
the exception of Entry 4. [b] Unless otherwise stated, yields (in
brackets) are isolated yields from column chromatography. [c] The
reaction was performed in CH2Cl2/toluene (2:1), with added acetic
acid. [d] Products isolated as a mixture; yields are based on ratios
determined by 1H NMR spectroscopy. [e] The reaction products
were isolated by filtration. [f] No toluene was used as a co-solvent
(i.e., neat MeCN was used); the reaction was conducted under
ultra-sonication in Entry 12 (but not in 17). [g] Solvent system:
CH3CN/toluene/o-DCB (2:1:2). o-DCB = ortho-dichlorobenzene.
strong Lewis acids resulted in ring-opening reaction to the
corresponding vinylheptafulvalene (VHF), which otherwise
is a light-driven process (Scheme 6).[31] This can lead to
isomerization for DHA molecules with substituents in the
seven-membered ring as the VHF can isomerize between Z
and E configurations, before returning to a DHA, as illus-
trated in Scheme 6. Indeed, with the substituent residing
upon the DHA 7-position, as is the case for 12a, the BBr3/
AcCl protocol resulted in an inseparable mixture of 7- and
Scheme 5. For substrates and conditions, see Table 1.
A previous report featured the treatment of the photo- 6-substituted DHA isomers. Gratifyingly, this regioisomeric
switch DHA 12a with boron tribromide in order to facili- phenomenon was not observed when Bi(OTf)3 was em-
tate the functional group transformation of the tert-butyl ployed, and the desired transformation to the product 12b
thioethers to the corresponding thioacetates.[15] Prior to this could be effected rapidly with a catalyst loading of 91%
work, it had been found that the treatment of DHA with (Table 1, Entry 16), while in the case of the former protocol,
Eur. J. Org. Chem. 2015, 4675–4688
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4679

M. Jevric, A. U. Petersen, M. Mansø, A. Ø. Madsen, M. B. Nielsen
FULL PAPER
a large excess of BBr3 was necessary in order to drive the by column chromatography. This method shows that 6b,
reaction to completion. The 2,7-disubstitution of 12b was conveniently prepared from 6a by using the Bi(OTf)3/AcCl
confirmed by X-ray crystallographic analysis of single crys- protocol as described above, is a useful building block for
tals, but there was significant disorder in the structure (see CuAAC reactions.
SI).
Determination of the Role of BiIII
In order to shed further light on the role of BiIII for the
acetylation, we performed a series of acetylation reactions
on the substrate 3a. The results are summarized in Table 2,
where the first entry corresponds to Entry 1 from Table 1.
First of all, we note that no conversion into 3b is obtained
if 3a is treated with AcCl solely (Entry 2). Thus, any HCl
present in the AcCl reagent is not strong enough to facili-
tate the reaction, even after 24 h. It is likely that TfOH will
be present during the reaction when using Bi(OTf)3 as a
reaction between Bi(OTf)3 and any water would give TfOH
and Bi2O3.[32] Indeed, we found that some of substrate 4a
Scheme 6. Isomerization of substituted DHAs after one ring-open-
ing/ring-closure cycle, which can be induced by a strong Lewis acid was converted into 24b by addition of TfOH. The extent of
(LA).
hydrolysis is difficult to determine (and no precautions to
preclude water were taken during the course of the total
study), but typically our reactions are done with 20 mol-%
Bi(OTf)3 and full hydrolysis would correspond to 60 mol-%
TfOH. TfOH could possibly also be generated using the
Alternative Synthesis via the CuAAC Reaction
In an attempt to get around the large amount of the bis-
muth(III) salt needed for the preparation of 23b and its low
yield of formation, it was decided to investigate the CuAAC
reaction for formation of this fullerene derivative. Indeed,
it was found that treatment of 22 with the azide 6b with
catalytic copper iodide did form 23b in good yield
(Scheme 7) and the product could be conveniently purified
tBu carbocation released from 3a as a proton source. We
therefore performed reactions with AcCl and various equiv-
alents of TfOH (Entries 3–5). These experiments clearly
show that TfOH is capable of effecting the reaction. With
0.6 equiv. of TfOH (Entry 4), corresponding to the maxi-
mum amount possible when using 0.2 equiv. of Bi(OTf)3,
the product 3b was isolated in a significant yield of 46%,
but lower still than the one obtained with Bi(OTf)3 (78%;
Entry 1). Entries 6 and 7 show that BiCl3 also has some
activity, albeit not as high as Bi(OTf)3. Thus, it took 24 h
to reach a yield of 68% of 3b. These experiments signal that
BiIII is not the only species responsible for the high yield
obtained in Entry 1. Substituting AcCl for AcOAc resulted
in no product formation when using BiCl3 (Entry 8), but
around 30% with Bi(OTf)3 no matter the reaction time (0.5
or 24 h; Entries 9 and 10). Entries 11 and 12 show that
Bi2O3 has some activity for the conversion, but it took 24 h
to reach a yield of 49%. Using AcOAc/Bi2O3 resulted in
no reaction (Entry 13); here the Bi2O3 remained suspended
during the course of the reaction. Next, we conducted an
experiment with Er(OTf)3, which does not hydrolyze readily
to TfOH[33] (Entry 14). The reaction was quite slow, and
after 24 h only 22% of 3b was obtained. Using instead
Sm(OTf)3 only gave 11% of 3b after 24 h. Taken together,
the experiments show that both BiIII and TfOH have an
influence on the acetylation reaction and the high yield ob-
tained after 0.5 h using Bi(OTf)3 is probably a result of the
individual action of both these two species.
Acetylation of the triazole-containing substrate 10a was
also studied in further detail (Table 2, Entries 16–19).
Again, we found that treatment with AcCl only, with no
additive, did not give any of the desired product, 10b (Entry
16). In this case, when using TfOH (Entry 17) instead of
Scheme 7. CuAAC reaction between 6b and the acetylenic fullerene
derivative 22.
4680
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4675–4688

Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates
Table 2. Acetylation of 3a and 10a under different conditions in CH3CN/toluene (2:1).
Entry
Substrate
Reagents
Time [h]
Product(s) [%]
1
2
3
4
5
6
7
8
3a
3a
AcCl/Bi(OTf)3 (0.2 equiv.)
AcCl
0.5
24
0.5
0.5
0.5
0.5
24
24
0.5
24
0.5
24
24
24
24
3b (78)
no reaction
3a
AcCl/TfOH (0.2 equiv.)
AcCl/TfOH (0.6 equiv.)
AcCl/TfOH (1.0 equiv.)
AcCl/BiCl3 (0.25 equiv.)
AcCl/BiCl3 (0.23 equiv.)
AcOAc/BiCl3 (0.25 equiv.)
AcOAc/Bi(OTf)3 (0.2 equiv.)
AcOAc/Bi(OTf)3 (0.2 equiv.)
AcCl/Bi2O3 (0.15 equiv.)
AcCl/Bi2O3 (0.1 equiv.)
AcOAc/Bi2O3 (0.1 equiv.)
AcCl/Er(OTf)3 (0.2 equiv.)
AcCl/Sm(OTf)3 (0.2 equiv.)
AcCl
3a (64) 3b (25)
3a (37) 3b (46)
3a (18) 3b (58)
3a (79) 3b (15)
3a (26) 3b (68)
no reaction
3a (72) 3b (28)
3a (65) 3b (34)
3a (94) 3b (3)
3a (44) 3b (49)
no reaction
3a (64) 3b (22)
3a (68) 3b (11)
no reaction
3a
3a
3a
3a
3a
9
3a
10
11
12
13
14
15
16
17
18
19
3a
3a
3a
3a
3a
3a
10a
10a
10a
10a
24
0.5
24
AcCl/TfOH (0.4 equiv.)
AcCl/BiCl3 (0.3 equiv.)
AcCl/BiCl3 (0.5 equiv.)
10b (trace) 27a/27b (trace)
10a (41) 10b (18) 27a/27b (36)
10a (3) 10b (62) 27a/27b (26)
24
Bi(OTf)3, the product 10b was only formed in trace amount,
signaling, as proposed above, that the triazole acts as a base
towards TfOH. Using AcCl in combination with BiCl3 and
a reaction time of 24 h turned out more successful. With
0.3 equiv. of BiCl3, 10b was obtained in 18% (Entry 18),
while using 0.5 equiv. of BiCl3, the yield increased to 62%
(Entry 19). The intermediates 27a/27b were also isolated.
Experimental Section
General Methods: Chemicals were used as purchased from commer-
cial sources. Purification of products was carried out by flash
chromatography on silica gel (40–63 μm, 60 Å). Thin-layer
chromatography (TLC) was carried out using aluminum sheets pre-
coated with silica gel. 1H NMR (500 MHz) and 13C NMR
(125 MHz) spectra were recorded on an instrument with a nonin-
verse cryoprobe using the residual solvent as the internal standard
1
(CDCl3, H 7.26 ppm and 13C 77.16 ppm). All chemical shifts are
Conclusions
quoted on the δ scale (ppm), and all coupling constants (J) are
expressed in Hz. In APT spectra, CH and CH3 correspond to nega-
tive signals and C and CH2 correspond to positive signals. 19F
NMR (282 MHz) spectra were recorded on an instrument using
locktube containing trifluoroacetic acid which was referenced to
–71.55 ppm. High resolution mass spectra (HRMS) were acquired
either using an electrospray method of ionization or using MALDI.
IR spectra were recorded of neat samples using the attenuated total
reflectance (ATR) sampling technique. Melting points are uncor-
rected. Compounds 4a,[14] 5a,[15] 12a,[15] 13,[3a] 14,[3a] 15,[16] 16,[18]
18,[23] and 21[24] were made by their respective literature methods.
For experiments pertaining to Table 2, see SI.
A new methodology using the weak Lewis acid Bi-
(OTf)3 in combination with acetyl chloride has been shown
to be capable of converting a large selection of aryl tert-
butyl thioethers to corresponding aryl thioacetates. In some
instances, undesired side reactions did occur due to some
functional group sensitivity under the conditions employed,
but it was possible to prepare derivatives containing both
redox-active DTF groups, electron-withdrawing dicyano-
ethylene units, and light-sensitive dihydroazulene photo-
switches. In the latter case, the mild conditions prevented
isomerization reactions to occur in the seven-membered
{[4-(tert-Butylthio)phenyl]ethynyl}triisopropylsilane (3a):[4] To a de-
ring of DHA. Mechanistically, it seems that both BiIII and gassed solution of 13 (4.00 g, 16.3 mmol) and triisopropylsilyl-
acetylene (5.0 mL, 22.3 mmol) in diisopropylamine (50 mL) and
THF (50 mL) was added CuI (124 mg, 0.65 mmol) and Pd(PPh3)2-
Cl2 (533 mg, 0.759 mmol) and the resulting mixture heated to re-
flux point for 1 h. The solvent was removed in vacuo and the crude
residue purified by flash column chromatography (5% CH2Cl2/pe-
troleum spirit) to afford 3a (4.27 g, 76%) as a colorless oil. Rf =
TfOH are effecting the conversions, and both species are
likely present under the reaction conditions. In addition, it
was found that BiIII was superior as a promoter in compari-
son to ErIII and SmIII. Using high loadings of the bismuth
salt, C60-containing substrates could also be employed in
this protocol. The methodology had, however, some limita-
tions for molecules incorporating the triazole unit, which in
some cases could be simply overcome by using more Bi-
(OTf)3. Gratifyingly, the reaction tolerated the azide func-
0.27 (petroleum spirit). IR: ν = 2157 cm–1. 1H NMR (500 MHz,
˜
CDCl3): δ = 7.46 (d, J = 8.2 Hz, 2 H), 7.43 (d, J = 8.2 Hz, 2 H),
1.28 (s, 9 H), 1.13 (s, 21 H) ppm. 13C NMR (125 MHz, CDCl3): δ
= 137.3, 133.4, 132.1, 124.0, 106.6, 92.5, 46.6, 31.1, 18.8, 11.5 ppm.
tionality, and 4-azidophenyl(tert-butyl)sulfane was readily GC–MS: m/z = 346 [M·+], 303, 247, 57.
converted to its thioacetate that could subsequently be em-
tert-Butyl(4-ethynylphenyl)sulfane (4a): To a solution of 3a (1.92 g,
ployed in the CuAAC reaction with a terminal alkyne sub-
strate to form a triazole. In all, the protocol provides access
to a wide variety of molecular wires with suitable electrode
anchoring groups, of importance for molecular electronics,
and an important azide building block.
5.54 mmol) in THF (50 mL) was added a solution of TBAF
(6.0 mL, 1 m in THF, 6.0 mmol) and the resulting solution stirred
for 1 h at rT. The reaction mixture was partitioned between ether
and water and the phases separated. The organic phase was dried
with Na2SO4, filtered and the solvent removed under reduced pres-
Eur. J. Org. Chem. 2015, 4675–4688
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4681

M. Jevric, A. U. Petersen, M. Mansø, A. Ø. Madsen, M. B. Nielsen
FULL PAPER
sure. The crude oil was purified by flash column chromatography
1
heptane). IR: ν = 2151, 1585 cm–1. H NMR (500 MHz, CDCl ):
˜
3
(5% CH2Cl2/petroleum spirit) to give 4a as a colorless oil (1.00 g,
δ = 7.50 (d, J = 8.5 Hz, 4 H), 7.47 (d, J = 8.5 Hz, 4 H), 1.30 (s, 18
95%). R = 0.17 (petroleum spirit). IR: ν = 3292, 2110, 1591 cm–1. H) ppm. 13C NMR (125 MHz, CDCl3): δ = 137.3, 135.0, 132.5,
˜
f
1H NMR (500 MHz, CDCl3): δ = 7.48 (d, J = 8.2 Hz, 2 H), 7.44
122.1, 81.8, 75.3, 46.9, 31.2 ppm. HRMS (MALDI +ve) calcd. for
378.1470, found 378.1469. C24H26S2
(d, J = 8.2 Hz, 2 H), 3.14 (s, 1 H), 1.29 (s, 9 H) ppm. 13C NMR C24H26S2 [M·+]: m/z
=
(125 MHz, CDCl3): δ = 137.3, 134.1, 132.2, 122.6, 83.3, 78.7, 46.6,
31.3 ppm. GC–MS: m/z = 190 [M·+], 134, 57.
(378.59): calcd. C 76.14, H 6.92; found C 76.11, H 6.95.
1,4-Bis[4-(tert-butylthio)phenyl]-1H-1,2,3-triazole (10a): To a solu-
tion of 4a (201 mg, 1.06 mmol) and 6a (201 mg, 0.970 mmol) in
degassed diisopropylamine (0.20 mL) and tetrahydrofuran (15 mL)
was added CuI (24 mg, 0.126 mmol) and the resulting solution
stirred for 16 h at ambient temperature. The solution was dry
loaded onto celite and purified by silica gel column chromatog-
raphy (gradient elution of CH2Cl2 to 5% ethyl acetate/CH2Cl2) and
the solvent removed in vacuo. The material was then triturated
from CH2Cl2/toluene (50:10 mL) giving 10a (253 mg, 66%) as a
white fluffy solid, m.p. Ͼ 230 °C. Rf = 0.43 (1% ethyl acetate/
(4-Azidophenyl)(tert-butyl)sulfane (6a): This compound was made
using a previously reported procedure.[19] A solution of 16 (934 mg,
4.45 mmol), NaN3 (488 mg, 7.51 mmol) and Cu(OAc)2 (57 mg,
0.46 mmol) in methanol (25 mL) was heated to 60 °C for 3 h. The
solvent was carefully removed using rotary evaporation at room
temperature and the residue was extracted with diethyl ether (3ϫ
50 mL) and filtered. Volatiles were removed under reduced pressure
and the residue purified by flash column chromatography (20%
CH2Cl2/petroleum spirit) to give 6a (882 mg, 96%) as a pale yellow
f
2
2
CHCl ). IR: ν = 1594, 1550, 1501 cm–1. 1H NMR (500 MHz,
oil. R = 0.41 (20% CH Cl /petroleum spirit). IR: ν = 2126, 2092,
˜
˜
3
1589 cm–1. H NMR (500 MHz, CDCl3): δ = 7.51 (d, J = 8.5 Hz,
2 H), 6.99 (d, J = 8.5 Hz, 2 H), 1.27 (s, 9 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 140.9, 139.0, 129.1, 119.2, 46.2, 31.0 ppm.
GC–MS: m/z = 207 [M·+], 57. HRMS (MALDI +ve) calcd. for
C10H14N3S [[M + H]+]: m/z = 208.0903, found 208.0905.
1
CDCl3): δ = 8.23 (s, 1 H), 7.88 (d, J = 8.1 Hz, 2 H), 7.78 (d, J =
8.5 Hz, 2 H), 7.71 (d, J = 8.5 Hz, 2 H), 7.63 (d, J = 8.1 Hz, 2 H),
1.33 (s, 9 H), 1.32 (s, 9 H) ppm. 13C NMR (125 MHz, CDCl3): δ
= 148.1, 138.9, 138.1, 137.2, 134.1, 133.3, 130.5, 125.9, 120.4, 117.8,
46.8, 46.4, 31.1, 31.1 ppm. HRMS (MALDI +ve) calcd. for
C22H28N3S2 [[M
+ = 398.1719, found 398.1730.
H]+]: m/z
2-[4-(tert-Butylthio)benzylidene]malononitrile (7a): To a solution of
14 (217 mg, 1.12 mmol) and malononitrile (89 mg, 1.35 mmol) in
CH2Cl2 (10 mL) was added basic Al2O3 Brockmann I (381 mg) and
the resulting suspension stirred for 30 min. The alumina was re-
moved by filtration and the solvent removed in vacuo. The crude
residue was purified by flash column chromatography (80%
CH2Cl2/pentane) to afford 7a (253 mg, 93%) as a yellow solid, m.p.
C22H27N3S2 (397.60): calcd. C 66.46, H 6.85, N 10.57; found C
66.52, H 6.80, N 10.56.
1,2-Bis[4,5-bis(butylthio)-1,3-dithiol-2-ylidene]-1,2-bis[4-(tert-but-
ylthio)phenyl]ethane (11a): To a degassed solution of 8a (487 mg,
1.07 mmol) in CH2Cl2 (100 mL) was added I2 (785 mg, 3.09 mmol)
and the resulting solution stirred 12 h at room temp. A saturated
aqueous solution of Na2S2O3 (25 mL) was added and the contents
stirred a further 3 h. The phases were separated and the organic
phase was dried with Na2SO4. Filtration and removal of the solvent
under reduced pressure gave a crude oil, which was purified by
flash column chromatography (25% CH2Cl2/heptane) gave pure
11a (330 mg, 68%) as an orange oil. Rf = 0.49 (30% CH2Cl2/petro-
103–104.5 °C. Rf = 0.49 (toluene). IR: ν = 2229, 1593, 1581,
˜
1
1544 cm–1. H NMR (500 MHz, CDCl3): δ = 7.84 (d, J = 8.3 Hz,
2 H), 7.75 (s, 1 H), 7.65 (d, J = 8.3 Hz, 2 H), 1.37 (s, 9 H) ppm.
13C NMR (125 MHz, CDCl3): δ = 159.0, 143.0, 136.6, 130.5, 130.3,
113.8, 112.7, 83.0, 48.0, 31.3 ppm. GC–MS: m/z = 242 [M·+], 186,
57. HRMS (MALDI +ve) calcd. for C14H15N2S [[M + H]+]: m/z =
243.0951, found 243.0950. C14H14N2S (242.34): calcd. C 69.39, H
5.82, N 11.56; found C 69.48, H 5.90, N 11.51.
leum spirit). IR: ν = 1681, 1586, 1549, 1523 cm–1. 1H NMR
˜
(500 MHz, CDCl3): δ = 7.45 (d, J = 8.2 Hz, 4 H), 7.35 (d, J =
8.2 Hz, 4 H), 2.83 (t, J = 7.3 Hz, 4 H), 2.77 (t, J = 7.3 Hz, 4 H),
1.28 (s, 18 H), 1.66–1.55 (m, 8 H), 1.49–1.36 (m, 8 H), 0.93 (t, J =
7.3 Hz, 6 H), 0.88 (t, J = 7.3 Hz, 6 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 138.0, 137.7, 137.4, 131.0, 129.2, 126.6, 125.4, 123.7,
46.4, 36.0, 35.7, 319, 31.2, 21.8, 21.8, 13.8, 13.8 ppm, 1C masked.
HRMS (MALDI +ve) calcd. for C44H62S10 [M·+]: m/z = 910.2053,
found 910.2066. C44H62S10 (911.58): calcd. C 57.97, H 6.86; found
C 58.40, H 6.92.
4,5-Bis(butylthio)-2-[4-(tert-butylthio)benzylidene]-1,3-dithiole (8a):
A thoroughly degassed solution of 14 (491 mg, 2.53 mmol) and
thione 15 (1.21 g, 3.90 mmol) in dry triethyl phosphite (5 mL) was
heated to 100 °C for 2 h. The phosphite was removed under high
vacuum and the residue subjected to flash column chromatography
(30% CH2Cl2/petroleum spirit) to afford 8a (1.06 g, 92%) as an
orange paste, m.p. 32–33 °C. Rf = 0.49 (30% CH2Cl2/petroleum
spirit). IR: ν = 1587, 1570, 1541 cm–1. 1H NMR (500 MHz,
˜
CDCl3): δ = 7.50 (d, J = 7.9 Hz, 2 H), 7.16 (d, J = 7.9 Hz, 2 H),
6.46 (s, 1 H), 2.84 (t, J = 6.7 Hz, 2 H), 2.83 (t, J = 6.7 Hz, 2 H),
1.67–1.60 (m, 4 H), 1.49–1.41 (m, 4 H), 1.28 (s, 9 H), 0.93 (t, J =
7.1 Hz, 3 H), 0.92 (t, J = 7.1 Hz, 3 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 137.7, 136.7, 134.0, 129.9, 127.9, 126.7, 125.0, 113.5,
46.4, 36.0, 35.9, 32.0, 31.9, 31.1, 21.8, 21.8, 13.8, 13.8 ppm. HRMS
(MALDI +ve) calcd. for C22H32S5 [M·+]: m/z = 456.1102, found
456.1119. C22H32S5 (457.80): calcd. C 57.85, H 7.06; found C 57.94,
H 7.09.
Compound 19a: A mixture consisting of C60 (148 mg, 0.205 mmol),
14 (47 mg, 0.242 mmol) and amino acid 17 (116 mg, 1.12 mmol) in
toluene (75 mL) was heated to reflux point for 16 h. The solvent
was removed in vacuo and the residue purified by flash column
chromatography (gradient elution of CS2 to 20% toluene/CS2) to
afford 19a (63 mg, 32%) as a dark brown solid. Rf = 0.63 (10%
1
toluene/CS ). IR: ν = 1596 cm–1. H NMR (500 MHz, CDCl ): δ
˜
2
3
= 7.79 (br. s, 2 H), 7.56 (d, J = 8.0 Hz, 2 H), 5.13 (d, J = 9.3 Hz,
1 H), 5.11 (s, 1 H), 4.18 (d, J = 9.3 Hz, 1 H), 3.38 (dq, J = 14.3,
7.2 Hz, 1 H), 2.67 (dq, J = 14.3, 7.2 Hz, 1 H), 1.52 (t, J = 7.2 Hz,
3 H), 1.20 (s, 9 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 156.6,
154.4, 153.4, 147.5, 146.8, 146.6, 146.5, 146.4, 146.4, 146.3, 146.3,
146.3, 146.2, 146.1, 145.9, 145.7, 145.7, 145.6, 145.5, 145.5, 145.4,
145.4, 145.3, 145.3, 144.9, 144.8, 144.6, 144.5, 143.3, 143.1, 142.8,
142.7, 142.7, 142.4, 142.4, 142.3, 142.2, 142.2, 142.2, 142.1, 142.1,
1,4-Bis[4-(tert-butylthio)phenyl]buta-1,3-diyne (9a): To a solution of
4a (319 mg, 1.68 mmol) in toluene (10 mL) and triethylamine
(0.20 mL) under an aerial atmosphere was added CuI (32 mg,
0.168 mmol) and Pd(PPh3)2Cl2 (33 mg, 0.047 mmol) and the re-
sulting solution stirred, whilst open to air for 4 h. The solvent was
removed under reduced pressure and the residue purified by col-
umn chromatography (20% CH2Cl2/heptane) to give 9a (300 mg, 141.9, 141.8, 141.7, 140.3, 140.3, 140.0, 139.4, 138.4, 137.7, 136.9,
95%) as a white solid, m.p. 161–164 °C. Rf = 0.35 (20% CH2Cl2/ 136.7, 136.0, 135.9, 133.1, 129.5, 81.9, 69.0, 66.6, 47.3, 46.2, 31.1,
4682
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4675–4688

Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates
13.6 ppm, 1 sp3 C masked. HRMS (MALDI -ve) calcd. for
= 13.2 Hz, 1 H), 2.39 (s, 6 H), 1.87–1.82 (m, 2 H), 1.40–1.37 (m, 6
C74H21NS [M·–]: m/z = 955.1400, found 955.1406. C74H21NS H), 0.93 (t, J = 6.9 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
(956.05): calcd. C 92.97, H 2.21, N 1.47; found C 92.99, H 2.37, N
1.51.
δ = 156.6, 155.8, 154.3, 153.5, 153.5, 148.4, 147.4, 146.9, 146.6,
146.4, 146.4, 146.4, 146.3, 146.3, 146.2, 146.1, 146.1, 145.9, 145.7,
145.7, 145.7, 145.7, 145.5, 145.4, 145.4, 145.4, 145.3, 144.8, 144.7,
144.5, 144.5, 143.3, 143.1, 142.8, 142.7, 142.7, 142.7, 142.5, 142.4,
142.3, 142.2, 142.2, 142.2, 142.2, 142.1, 142.0, 141.8, 141.7, 140.3,
140.2, 140.1, 139.7, 138.8, 137.8, 137.3, 137.1, 136.6, 136.1, 135.8,
134.1, 132.3, 131.2, 130.4, 129.7, 126.4, 120.4, 117.8, 81.2, 76.8,
72.6, 68.9, 66.8, 56.6, 46.8, 31.9, 31.1, 30.6, 26.0, 22.8, 16.7, 14.2
ppm. HRMS (MALDI -ve) calcd. for C95H44N4OS [M·–]: m/z =
1288.3241, found 1288.3238. C95H44N4OS (1288.48): calcd. C
88.49, H 3.44, N 4.34; found C 88.35, H 3.36, N 4.46.
Compound 20a: A mixture consisting of C60 (142 mg, 0.197 mmol),
14 (50 mg, 0.26 mmol) and amino acid 18 (190 mg, 0.648 mmol) in
toluene (75 mL) was heated to reflux point for 16 h. The solvent
was removed in vacuo and the residue purified by flash column
chromatography (gradient elution of CS2 to 20% toluene/CS2) to
afford 20a (69 mg, 31%) as a dark brown solid. Rf = 0.33 (20%
1
toluene/CS ). IR: ν = 1596 cm–1. H NMR (500 MHz, CDCl ): δ
˜
2
3
= 7.90 (br. s, 2 H), 7.61 (d, J = 7.8 Hz, 2 H), 7.26 (s, 2 H), 5.17 (s,
1 H), 4.87 (d, J = 9.5 Hz, 1 H), 4.48 (d, J = 13.1 Hz, 1 H), 4.16 (d,
J = 9.5 Hz, 1 H), 3.84 (t, J = 6.6 Hz, 2 H), 3.60 (d, J = 13.1 Hz, 1
H), 2.39 (s, 6 H), 1.87–1.82 (m, 2 H), 1.57–1.51 (m, 2 H), 1.40–1.36
(m, 4 H), 1.21 (s, 9 H), 0.93 (t, J = 7.0 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 156.5, 155.8, 154.3, 153.4, 153.3, 147.5,
147.4, 146.8, 146.6, 146.4, 146.4, 146.4, 146.3, 146.3, 146.2, 146.1,
146.1, 145.9, 145.7, 145.7, 145.5, 145.4, 145.4, 145.3, 145.3, 144.8,
144.8, 144.5, 144.5, 143.3, 143.1, 142.8, 142.7, 142.7, 142.7, 142.5,
142.4, 142.3, 142.2, 142.2, 142.2, 142.2, 142.1, 142.1, 141.9, 141.8,
141.7, 140.3, 140.2, 140.0, 139.4, 138.1, 137.8, 137.0, 136.6, 136.1,
135.8, 133.2, 132.5, 131.3, 129.5, 81.0, 76.8, 72.6, 68.8, 66.8, 56.6,
46.2, 31.9, 31.1, 30.6, 26.0, 22.8, 16.7, 14.3 ppm. HRMS (MALDI
Acetylation Reactions (see Table 1)
Entry 1: To a solution of 3a (55 mg, 0.159 mmol) and acetyl chlor-
ide (0.25 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (23 mg, 0.035 mmol) and the contents of the vessel
stirred for 30 min at ambient temperature. The reaction mixture
was added to ice water (20 mL) and extracted with small portions
of CH2Cl2 (20 mL in total). The combined organics were passed
through a pad of cotton and the solvent removed under reduced
pressure. The residue was purified by flash column chromatography
(30% CH2Cl2/petroleum spirit) to afford 3b (41 mg, 78%) as a col-
orless oil.
-ve) calcd. for C87H39NOS [M·–]: m/z
= 1145.2758, found
Entry 2: To a solution of 3a (57 mg, 0.164 mmol) and acetyl chlor-
ide (0.25 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (11 mg, 0.017 mmol) and the contents of the vessel
stirred for 30 min at ambient temperature. The reaction mixture
was added to ice water (20 mL) and extracted with small portions
of CH2Cl2 (20 mL in total). The combined organics were filtered
through a pad of cotton and the solvent removed under reduced
pressure. The residue was purified by flash column chromatography
(30% CH2Cl2/petroleum spirit) to afford 3b (30 mg, 55%) as a col-
orless oil in addition to 3a (20 mg, 35%).
1145.2839. C87H39NOS (1146.34): calcd. C 91.16, H 3.43, N 1.22;
found C 91.04, H 3.52, N 1.27.
Compound 22: A mixture consisting of C60 (365 mg, 0.506 mmol),
21 (76 mg, 0.58 mmol) and amino acid 18 (718 mg, 2.45 mmol) in
toluene (170 mL) was heated to reflux point for 16 h. The solvent
was removed in vacuo and the residue purified by column
chromatography (gradient elution of CS2 to 20% toluene/CS2) to
afford 22 (150 mg, 27%) as a dark brown solid. Rf = 0.48 (20%
1
toluene/CS ). IR: ν = 3295 cm–1. H NMR (500 MHz, CDCl ): δ
˜
2
3
= 7.88 (br. s, 2 H), 7.59 (d, J = 8.0 Hz, 2 H), 7.22 (s, 2 H), 5.14 (s,
1 H), 4.86 (d, J = 9.6 Hz, 1 H), 4.39 (d, J = 13.1 Hz, 1 H), 4.15 (d,
J = 9.6 Hz, 1 H), 3.83 (t, J = 6.7 Hz, 2 H), 3.57 (d, J = 13.1 Hz, 1
H), 3.10 (s, 1 H), 2.38 (s, 6 H), 1.87–1.81 (m, 2 H), 1.40–1.37 (m,
6 H), 0.93 (t, J = 6.9 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 156.5, 155.8, 154.2, 153.3, 153.2, 147.5, 146.8, 146.5, 146.4,
146.4, 146.3, 146.3, 146.3, 146.2, 146.1, 146.1, 146.1, 145.9, 145.7,
145.7, 145.6, 145.5, 145.5, 145.4, 145.4, 145.4, 145.3, 144.8, 144.8,
144.5, 144.5, 143.3, 143.1, 142.8, 142.7, 142.7, 142.7, 142.5, 142.4,
142.3, 142.2, 142.2, 142.2, 142.1, 142.0, 142.0, 141.8, 141.7, 140.3,
140.2, 140.0, 139.7, 138.3, 137.1, 136.6, 136.1, 135.8, 132.7, 132.2,
131.2, 129.6, 122.3, 83.6, 81.1, 78.0, 76.7, 72.6, 68.8, 66.8, 56.6,
31.9, 30.6, 26.0, 22.8, 16.7, 14.3 ppm. HRMS (MALDI -ve) calcd.
for C85H31NO [M·–]: m/z = 1081.2411, found 1081.2381. C85H31NO
(1081.19): calcd. C 94.34, H 2.89, N 1.29; found C 94.17, H 3.02,
N 1.25.
Entry 3: To a solution of 3a (58 mg, 0.167 mmol) and acetyl chlor-
ide (0.25 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (12 mg, 0.018 mmol) and the contents of the vessel
stirred for 3 h at ambient temperature. The reaction mixture was
added to ice water (20 mL) and extracted with small portions of
CH2Cl2 (20 mL in total). The combined organics were passed
through a pad of cotton and the solvent removed under reduced
pressure. The residue was purified by flash column chromatography
(30% CH2Cl2/petroleum spirit) to afford 3b (32 mg, 58%) as a col-
orless oil in addition to recovered 3a (12 mg, 21%).
Entry 4: To a solution of 3a (98 mg, 0.283 mmol) in CH2Cl2
(3 mL), toluene (1.5 mL), acetyl chloride (0.5 mL) and acetic acid
(2 drops) was added Bi(OTf)3 (21 mg, 0.032 mmol) and the con-
tents of the vessel stirred for 24 h. The reaction mixture was added
to ice water (20 mL) and extracted with small portions of CH2Cl2
(20 mL in total). The combined organics were passed through a
pad of cotton and the solvent removed under reduced pressure.
The residue was purified by flash column chromatography (40%
CH2Cl2/petroleum spirit) to afford 3b (10 mg, 10%) as a colorless
oil and 24a (20 mg, 30%), a pungent smelling colorless oil.
Compound 23a: To a stirring degassed solution of 22 (49 mg,
0.0453 mmol) and 6a (26 mg, 0.125 mmol) in triethylamine
(0.10 mL) and toluene (10 mL) was added CuI (3 mg, 0.016 mmol)
and the resulting solution stirred 24 h at ambient temperature. The
solvent was removed in vacuo and the residue purified by column
chromatography (0.25% ethyl acetate/toluene) to give 23a (42 mg,
72%) as a dark brown solid. Rf = 0.20 (0.25% ethyl acetate/tolu-
S-{4-[(Triisopropylsilyl)ethynyl]phenyl} Ethanethioate (3b): Rf
=
1
0.33 (30% CH Cl /petroleum spirit). IR: ν = 2156, 1715 cm–1. H
˜
2
2
ene). IR: ν = 1593, 1503 (shoulder) cm–1. 1H NMR (500 MHz, NMR (500 MHz, CDCl3): δ = 7.50 (d, J = 8.1 Hz, 2 H), 7.35 (d,
˜
CDCl3): δ = 8.22 (s, 1 H), 8.01 (br. d, includes br. s, J = 7.4 Hz, 4 J = 8.1 Hz, 2 H), 2.42 (s, 3 H), 1.13 (s, 21 H) ppm. 13C NMR
H), 7.76 (d, J = 8.7 Hz, 2 H), 7.70 (d, J = 8.7 Hz, 2 H), 7.26 (s, 2
H), 5.20 (s, 1 H), 4.88 (d, J = 9.5 Hz, 1 H), 4.47 (d, J = 13.2 Hz, 1
H), 4.18 (d, J = 9.5 Hz, 1 H), 3.84 (t, J = 6.6 Hz, 2 H), 3.62 (d, J
(125 MHz, CDCl3): δ = 193.6, 134.3, 132.8, 128.2, 124.9, 106.3,
92.9, 30.4, 18.8, 11.4 ppm. GC–MS: m/z = 332 [M·+], 289, 247,
207.
Eur. J. Org. Chem. 2015, 4675–4688
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4683

M. Jevric, A. U. Petersen, M. Mansø, A. Ø. Madsen, M. B. Nielsen
FULL PAPER
S-[4-(1-Chlorovinyl)phenyl] Ethanethioate (24a): Rf = 0.26 (40%
CDCl3): δ = 194.1, 141.6, 136.1, 124.0, 120.0, 30.2 ppm. HRMS
(MALDI +ve) calcd. for C8H8N3OS [[M + H]+]: m/z = 194.0383,
found 194.0386.
CH Cl /petroleum spirit). IR: ν = 1709, 1608 cm–1. 1H NMR
˜
2
2
(500 MHz, CDCl3): δ = 7.67 (d, J = 8.4 Hz, 2 H), 7.41 (d, J =
8.4 Hz, 2 H), 5.82 (d, J = 2.0 Hz, 1 H), 5.58 (d, J = 2.0 Hz, 1 H),
2.44 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 193.7, 139.2,
138.0, 134.4, 129.1, 127.2, 114.0, 30.5 ppm. HRMS (MALDI +ve)
calcd. for C10H10ClOS [[M + H]+]: m/z = 213.0135, found 213.0137.
Entry 8: To a solution of 7a (72 mg, 0.297 mmol) and acetyl chlor-
ide (0.50 mL) in toluene (1.0 mL) and CH3CN (2.0 mL) was added
Bi(OTf)3 (43 mg, 0.066 mmol) and the contents of the vessel stirred
for 3 h. The reaction mixture was added to ice water (20 mL) and
extracted with small portions of CH2Cl2 (20 mL in total). The com-
bined organics were passed through a pad of cotton and the solvent
removed under reduced pressure. The residue was purified by flash
column chromatography (CH2Cl2) to afford 7b (58 mg, 86%) as an
off-yellow crystalline solid.
Entry 5: To a solution of 4a (62 mg, 0.326 mmol) and acetyl chlor-
ide (0.50 mL) in toluene (1.0 mL) and CH3CN (2.0 mL) was added
Bi(OTf)3 (39 mg, 0.594 mmol) and the contents of the vessel stirred
for 30 min at ambient temperature. The reaction mixture was added
to ice water (20 mL) and extracted with small portions of CH2Cl2
(20 mL in total). The combined organics were passed through a
pad of cotton and the solvent removed under reduced pressure.
The residue was purified by flash column chromatography (50%
CH2Cl2/petroleum spirit) to afford a mixture of 4b/24b (33 mg,
40:9%) as a colorless oil, which was unstable neat.
S-[4-(2,2-Dicyanovinyl)phenyl] Ethanethioate (7b): M.p. 108–109 °C.
R = 0.56 (CH Cl ). IR: ν = 2229, 1706, 1586, 1550 cm–1. 1H NMR
˜
f
2
2
(500 MHz, CDCl3): δ = 7.92 (d, J = 8.3 Hz, 2 H), 7.77 (s, 1 H),
7.59 (d, J = 8.3 Hz, 2 H), 2.48 (s, 3 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 191.9, 158.8, 136.2, 134.8, 131.3, 131.0, 113.6, 112.4,
Mixture of S-(4-Ethynylphenyl) Ethanethioate (4b) and S-(4-{1- 84.1, 30.8 ppm. HRMS (MALDI +ve) calcd. for C12H9N2OS [[M
[(Trifluoromethanesulfonyl)oxy]vinyl}phenyl) Ethanethioate (24b):
R = 0.46 (50% CH Cl /petroleum spirit). IR: ν = 3283, 1704, 1651,
+ H]+]: m/z = 229.0430, found 229.0431. C12H8N2OS (228.27):
calcd. C 63.14, H 3.53, N 12.27; found C 63.11, H 3.49, N 12.20.
˜
f
2
2
1589 cm–1. 4b: 1H NMR (500 MHz, CDCl3): δ = 7.52 (d, J =
8.4 Hz, 2 H), 7.37 (d, J = 8.4 Hz, 2 H), 3.15 (s, 1 H), 2.43 (s, 3 H)
ppm. 13C NMR (125 MHz, CDCl3): δ = 193.4, 134.3, 132.9, 128.9,
123.5, 83.0, 79.0, 30.4 ppm. HRMS (MALDI +ve) calcd. for
C10H9OS [[M + H]+]: m/z = 177.0369, found 177.0373. 24b: 1H
NMR (500 MHz, CDCl3): δ = 7.58 (d, J = 8.6 Hz, 2 H), 7.47 (d,
J = 8.6 Hz, 2 H), 5.67 (d, J = 4.1 Hz, 1 H), 5.45 (d, J = 4.1 Hz, 1
H), 2.45 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 193.1,
152.7, 134.8, 133.0, 130.8, 126.0, 118.6 (q, CFJ = 320 Hz), 105.5,
30.5 ppm. 19F NMR (282 MHz, CDCl3): δ = –67.5 ppm. HRMS
(MALDI +ve) calcd. for C11H10F3O4S2 [[M + H]+]: m/z =
326.9971, found 326.9974.
Entry 9: To a solution of 8a (69 mg, 0.151 mmol) and acetyl chlor-
ide (0.25 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (24 mg, 0.037 mmol) and the contents of the vessel
stirred for 3 h. The reaction mixture was added to ice water (20 mL)
and extracted with small portions of CH2Cl2 (20 mL in total). The
combined organics were passed through a pad of cotton and the
solvent removed under reduced pressure. The residue was purified
by flash column chromatography (gradient elution 30% CH2Cl2/
heptane to 2% ethyl acetate/CH2Cl2) to afford 8b (5 mg, 7%) as an
orange oil, 25 (14 mg, 19%) and 26 (3 mg, 4%), both yellow oils.
In addition, starting material 8a (25 mg) was isolated.
Entry 10: To a solution of 8a (68 mg, 0.149 mmol) and acetyl chlor-
ide (0.25 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (50 mg, 0.076 mmol) and the contents of the vessel
stirred for 30 min. The reaction mixture was added to ice water
(20 mL) and extracted with small portions of CH2Cl2 (20 mL in
total). The combined organics were passed through a pad of cotton
and the solvent removed under reduced pressure. The residue was
purified by flash column chromatography (gradient elution 30%
CH2Cl2/heptane to CH2Cl2) to afford 8b (36 mg, 55%) as an
orange oil. In addition, 8a (12 mg) was recovered.
Entry 6: To a solution of 5a (34 mg, 0.163 mmol) and acetyl chlor-
ide (0.25 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (24 mg, 0.035 mmol) and the contents of the vessel
stirred for 1 h. The reaction mixture was added to ice water (20 mL)
and extracted with small portions of CH2Cl2 (20 mL in total). The
combined organics were passed through a pad of cotton and the
solvent removed under reduced pressure. The residue was purified
by flash column chromatography (1% ethyl acetate/CH2Cl2) to af-
ford 5b (15 mg, 47%) as a white solid.
S-(4-Acetylphenyl) Ethanethioate (5b): M.p. 62–63 °C (ref.[26b] 62.5–
S-(4-{[4,5-Bis(butylthio)-1,3-dithiol-2-ylidene]methyl}phenyl) Eth-
63.5 °C). R = 0.30 (CH Cl ). IR: ν = 1708, 1685, 1592 cm–1. 1H
˜
f
2
2
anethioate (8b): R = 0.59 (70% CH Cl /heptane). IR: ν = 1709,
˜
f
2
2
NMR (500 MHz, CDCl3): δ = 7.98 (d, J = 8.5 Hz, 2 H), 7.52 (d,
J = 8.5 Hz, 2 H), 2.62 (s, 3 H), 2.46 (s, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 197.5, 192.8, 137.5, 134.3, 133.9, 129.0,
30.6, 26.8 ppm. HRMS (MALDI +ve) calcd. for C10H11OS2 [[M
+ H]+]: m/z = 195.0474, found 195.0476.
1570, 1545 cm–1. 1H NMR (500 MHz, CDCl3): δ = 7.38 (d, J =
8.3 Hz, 2 H), 7.24 (d, J = 8.3 Hz, 2 H), 6.45 (s, 1 H), 2.83 (t, J =
7.4 Hz, 2 H), 2.83 (t, J = 7.4 Hz, 2 H), 2.41 (s, 3 H), 1.67–1.60 (m,
4 H), 1.49–1.41 (m, 4 H), 0.94 (t, J = 7.3 Hz, 3 H), 0.93 (t, J =
7.3 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 194.5, 137.6,
134.9, 134.7, 127.9, 127.4, 125.1, 124.6, 113.2, 36.0, 35.9, 32.0, 31.9,
30.3, 21.8, 21.8, 13.8, 13.7 ppm. HRMS (MALDI +ve) calcd. for
C20H26OS5 [M·+]: m/z = 442.0582, found 442.0584. C20H26OS5
(442.73): calcd. C 54.26, H 5.92; found C 54.31, H 5.96.
Entry 7: To a solution of 6a (69 mg, 0.333 mmol) and acetyl chlor-
ide (0.50 mL) in toluene (1.0 mL) and CH3CN (2.0 mL) was added
Bi(OTf)3 (46 mg, 0.070 mmol) and the contents of the vessel stirred
for 1 h. The reaction mixture was added to ice water (20 mL) and
extracted with small portions of CH2Cl2 (20 mL in total). The com-
bined organics were passed through a pad of cotton and the solvent
removed under reduced pressure. The residue was purified by flash
column chromatography (50% CH2Cl2/pentane) to afford 6b
(53 mg, 82%) as a white glassy solid.
1-[4,5-Bis(butylthio)-1,3-dithiol-2-ylidene]-1-[4-(tert-butylthio)phen-
yl]propan-2-one (25): R = 0.62 (CH Cl ). IR: ν = 1620, 1503 cm–1.
˜
f
2
2
1H NMR (500 MHz, CDCl3): δ = 7.63 (d, J = 8.1 Hz, 2 H), 7.23
(d, J = 8.1 Hz, 2 H), 2.95 (t, J = 7.4 Hz, 2 H), 2.74 (t, J = 7.4 Hz,
2 H), 2.02 (s, 3 H), 1.65 (p, J = 7.4 Hz, 2 H), 1.57–1.36 (m, 6 H),
1.33 (s, 9 H), 0.93 (t, J = 7.4 Hz, 3 H), 0.87 (t, J = 7.4 Hz, 3 H)
ppm. 13C NMR (125 MHz, CDCl3): δ = 191.0, 160.9, 139.1, 138.7,
134.3, 133.4, 130.0, 126.5, 122.4, 46.4, 36.3, 35.8, 32.0, 31.7, 31.2,
27.2, 21.9, 21.7, 13.8, 13.7 ppm. HRMS (MALDI +ve) calcd. for
S-(4-Azidophenyl) Ethanethioate (6b): M.p. 25–27 °C. Rf = 0.45
(50% CH Cl /pentane). IR: ν = 2130, 2094, 1710, 1590, 1571 cm–1.
˜
2
2
1H NMR (500 MHz, CDCl3): δ = 7.38 (d, J = 8.6 Hz, 2 H), 7.07
(d, J = 8.6 Hz, 2 H), 2.42 (s, 3 H) ppm. 13C NMR (125 MHz,
4684
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4675–4688

Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates
C24H34OS5 [[M + H]+]: m/z = 499.1286, found 499.1289.
137.6, 137.2, 136.0, 135.1, 134.2, 133.4, 131.3, 130.5, 128.9, 128.2,
C24H34OS5 (498.84): calcd. C 57.79, H 6.87; found C 57.86, H 6.76. 126.6, 126.0, 121.0, 120.4, 118.0, 117.7, 46.8, 46.4, 31.1, 31.1, 30.5,
30.4 ppm. HRMS (MALDI +ve) calcd. for C20H22N3OS2 [[M +
S-(4-{1-[4,5-Bis(butylthio)-1,3-dithiol-2-ylidene]-2-oxopropyl}-
H]+]: m/z = 384.1197, found 384.1199. C20H21N3OS2 (383.53):
phenyl) Ethanethioate (26): R = 0.22 (CH Cl ). IR: ν = 1713, 1685,
˜
f
2
2
calcd. C 62.63, H 5.52, N 10.96; found C 62.51, H 5.50, N 10.84.
1
1592 cm–1. H NMR (500 MHz, CDCl3): δ = 7.53 (d, J = 8.4 Hz,
2 H), 7.32 (d, J = 8.4 Hz, 2 H), 2.95 (t, J = 7.3 Hz, 2 H), 2.75 (t,
J = 7.3 Hz, 2 H), 2.46 (s, 3 H), 2.03 (s, 3 H), 1.66 (p, J = 7.3 Hz,
2 H), 1.54 (p, J = 7.3 Hz, 2 H), 1.46 (sextet, J = 7.3 Hz, 2 H), 1.39
(sextet, J = 7.3 Hz, 2 H), 0.93 (t, J = 7.3 Hz, 3 H), 0.88 (t, J =
7.3 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 193.6, 190.9,
161.3, 139.7, 135.6, 134.4, 130.7, 128.5, 126.6, 122.0, 36.3, 35.8,
32.0, 31.6, 30.5, 27.3, 21.9, 21.7, 13.8, 13.7 ppm. HRMS (MALDI
+ve) calcd. for C22H28O2S5 [[M + H]+]: m/z = 485.0766, found
485.0766.
S,SЈ-[(1H-1,2,3-Triazole-1,4-diyl)bis(4,1-phenylene)] Diethanethio-
ate (10b): M.p. 221–225 °C. Rf = 0.40 (10% ethyl acetate/toluene).
IR: ν = 1712 (shoulder), 1703, 1595, 1504 cm–1 1H NMR
.
˜
(500 MHz, CDCl3): δ = 8.24 (s, 1 H), 7.96 (d, J = 8.2 Hz, 2 H),
7.86 (d, J = 8.6 Hz, 2 H), 7.60 (d, J = 8.6 Hz, 2 H), 7.51 (d, J =
8.2 Hz, 2 H), 2.48 (s, 3 H), 2.45 (s, 3 H) ppm. 13C NMR (125 MHz,
CDCl3): δ = 194.0, 193.2, 147.9, 137.6, 136.0, 135.1, 131.3, 129.0,
128.3, 126.7, 121.0, 117.9, 30.5, 30.4 ppm. HRMS (MALDI +ve)
calcd. for C18H16N3O2S2 [[M + H]+]: m/z = 370.0678, found
370.0676. C18H15N3O2S2 (369.46): calcd. C 58.52, H 4.09, N 11.37;
found C 58.60, H 3.91, N 11.23.
Entry 11: To a suspension of 9a (60 mg, 0.158 mmol) and acetyl
chloride (0.30 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (49 mg, 0.075 mmol) and the contents of the vessel
stirred for 30 min. The precipitate was filtered and washed success-
ively with CH3CN, diethyl ether and pentane to give pure 9b
(35 mg, 63%) as a white solid.
Entry 15: To a suspension of 11a (88 mg, 0.0965 mmol) and acetyl
chloride (0.30 mL) in toluene (0.5 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (65 mg, 0.099 mmol) and the contents of the vessel
stirred for 30 min. The reaction mixture was added to ice water
(20 mL) and extracted with small portions of CH2Cl2 (20 mL in
total). The combined organics were passed through a pad of cotton
and the solvent removed under reduced pressure. The residue was
purified by flash column chromatography (gradient elution 50 to
70% CH2Cl2/heptane) to afford 11b (63 mg, 78%) as a pasty yellow
solid and 28 (8 mg, 9%) as a bright yellow oil.
Entry 12: To a suspension of 9a (59 mg, 0.156 mmol) and acetyl
chloride (0.30 mL) in CH3CN (1.0 mL) was added Bi(OTf)3
(48 mg, 0.073 mmol) and the contents of the vessel subjected to
ultra-sonication for 1 h. The precipitate was filtered and washed
with CH3CN to give pure 9b (52 mg, 95%) as a white solid.
S-(3-{[4-(Acetylthio)phenyl]buta-1,3-diyn-1-yl}phenyl) Ethanethioate
(9b): M.p. 195.5–197.5 °C (ref.[28] 279–280 °C). Rf = 0.70 (CH2Cl2).
S-(4-{1,2-Bis[4,5-bis(butylthio)-1,3-dithiol-2-ylidene]-2-[4-(tert-but-
1
IR: ν = 2155, 1701, 1586 cm–1. H NMR (500 MHz, CDCl ): δ =
˜
ylthio)phenyl]ethyl}phenyl) Ethanethioate (28): Rf = 0.43 (50 %
3
1
CH Cl /heptane). IR: ν = 1710, 1587, 1550, 1522 cm–1. H NMR
7.55 (d, J = 8.4 Hz, 4 H), 7.39 (d, J = 8.4 Hz, 4 H), 2.44 (s, 6 H)
ppm. 13C NMR (125 MHz, CDCl3): δ = 193.2, 134.3, 133.2, 129.7,
122.9, 81.6, 75.4, 30.5 ppm. HRMS (MALDI +ve) calcd. for
C20H14O2S2 [M·+]: m/z = 350.0430, found 350.0430.
˜
2
2
(500 MHz, CDCl3): δ = 7.46 (d, J = 8.5 Hz, 2 H), 7.44 (d, J =
8.6 Hz, 2 H), 7.35 (d, J = 8.5 Hz, 2 H), 7.34 (d, J = 8.6 Hz, 2 H),
2.83 (t, J = 7.3 Hz, 4 H), 2.77 (t, J = 7.3 Hz, 2 H), 2.76 (t, J =
7.3 Hz, 2 H), 2.41 (s, 3 H), 1.66–1.54 (m, 8 H), 1.49–1.36 (m, 8 H),
1.29 (s, 9 H), 0.93 (t, J = 7.3 Hz, 3 H), 0.93 (t, J = 7.3 Hz, 3 H),
0.88 (t, J = 7.3 Hz, 3 H), 0.88 (t, J = 7.3 Hz, 3 H) ppm. 13C NMR
(125 MHz, CDCl3): δ = 194.3, 139.0, 138.3, 138.2, 137.7, 137.2,
134.6, 131.0, 129.4, 129.0, 127.3, 126.5, 125.7, 125.6, 125.1, 123.5,
123.4, 46.4, 36.0, 36.0, 35.8, 35.7, 31.9, 31.2, 21.8, 21.8, 13.8, 13.8,
13.8, 13.8 ppm, 6 C masked. HRMS (MALDI +ve) calcd. for
C42H56OS10 [M·–]: m/z = 896.1483, found 896.1514. C42H56OS10
(897.51): calcd. C 56.21, H 6.29; found C 56.28, H 6.29.
Entry 13: To a suspension of 10a (62 mg, 0.156 mmol) and acetyl
chloride (0.30 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (49 mg, 0.0747 mmol) and the contents of the ves-
sel stirred for 3 h. The reaction mixture was added to ice water
(20 mL) and extracted with small portions of CH2Cl2 (20 mL in
total). The combined organics were passed through a pad of cotton
and the solvent removed under reduced pressure. The residue was
purified by flash column chromatography (5% ethyl acetate/tolu-
ene) to afford 10b (7 mg, 12 %) as a white crystalline solid, 27
(16 mg, 27%), a white solid, and recovered 10a (38 mg, 61%).
S,SЈ-({1,2-Bis[4,5-bis(butylthio)-1,3-dithiol-2-ylidene]ethane-1,2-
diyl}bis(4,1-phenylene)) Diethanethioate (11b): M.p. 76.5–79 °C. Rf
Entry 14: To a suspension of 10a (59 mg, 0.148 mmol) and acetyl
chloride (0.30 mL) in toluene (0.50 mL) and CH3CN (1.0 mL) was
added Bi(OTf)3 (96 mg, 0.146 mmol) and the contents of the vessel
stirred for 30 min. The reaction mixture was added to ice water
(20 mL) and extracted with small portions of CH2Cl2 (20 mL in
total). The combined organics were passed through a pad of cotton
and the solvent removed under reduced pressure. The residue was
purified by flash column chromatography (10% ethyl acetate/tolu-
ene) to afford 10b (53 mg, 97%) as a white crystalline solid.
= 0.18 (50 % CH Cl /heptane). IR: ν = 1709, 1587, 1554,
˜
2
2
1
1523 cm–1. H NMR (500 MHz, CDCl3): δ = 7.43 (d, J = 8.6 Hz,
4 H), 7.34 (d, J = 8.6 Hz, 4 H), 2.83 (t, J = 7.3 Hz, 4 H), 2.77 (t,
J = 7.3 Hz, 4 H), 2.41 (s, 6 H), 1.66–1.54 (m, 4 H), 1.49–1.35 (m,
4 H), 0.93 (t, J = 7.4 Hz, 6 H), 0.88 (t, J = 7.4 Hz, 6 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 194.2, 139.2, 138.1, 134.6, 129.2,
127.2, 125.8, 125.4, 123.1, 36.0, 35.8, 31.9, 30.4, 21.8, 21.8, 13.8,
13.8 ppm; 1 C masked. HRMS (MALDI +ve) calcd. for
C40H50O2S10 [M·–]: m/z = 882.0963, found 882.1000. C40H50O2S10
(883.44): calcd. C 54.38, H 5.70; found C 54.37, H 5.72.
Mixture of S-(4-{1-[4-(tert-Butylthio)phenyl]-1H-1,2,3-triazol-4-
yl}phenyl) Ethanethioate (27a) and S-(4-{4-[4-(tert-Butylthio)-
phenyl]-1H-1,2,3-triazol-1-yl}phenyl) Ethanethioate (27b): M.p. Entry 16: To a solution of 12a (39 mg, 0.0767 mmol) and acetyl
188–190 °C. R = 0.48 (5% ethyl acetate/toluene). IR: ν = 1699,
chloride (0.30 mL) in toluene (0.5 mL) and CH3CN (1.0 mL) was
˜
f
1596, 1503 cm–1. H NMR (500 MHz, CDCl3): δ = 8.24 (s, 1 H), added Bi(OTf)3 (46 mg, 0.070 mmol) and the contents of the vessel
1
8.24 (s, 1 H), 7.96 (d, J = 8.3 Hz, 2 H), 7.88–7.85 (m, 4 H), 7.77 stirred for 30 min. The reaction mixture was added to ice water
(d, J = 8.6 Hz, 2 H), 7.71 (d, J = 8.6 Hz, 2 H), 7.63 (d, J = 8.2 Hz,
2 H), 7.60 (d, J = 8.6 Hz, 2 H), 7.51 (d, J = 8.3 Hz, 2 H), 2.48 (s,
(20 mL) and extracted with small portions of CH2Cl2 (20 mL in
total). The combined organics were passed through a pad of cotton
3 H), 2.45 (s, 3 H), 1.33 (s, 9 H), 1.32 (s, 9 H) ppm. 13C NMR and the solvent removed under reduced pressure. The residue was
(125 MHz, CDCl3): δ = 194.0, 193.2, 148.2, 147.8, 138.8, 138.1, purified by flash column chromatography (2% ethyl acetate/tolu-
Eur. J. Org. Chem. 2015, 4675–4688
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4685

M. Jevric, A. U. Petersen, M. Mansø, A. Ø. Madsen, M. B. Nielsen
FULL PAPER
ene) to give an orange oil which was crystallized (CH2Cl2/heptane)
to afford 12b (31 mg, 84%) as a yellow solid.
(941.98): calcd. C 91.81, H 1.61, N 1.49; found C 91.70, H 1.72, N
1.54.
Entry 17: To a thick suspension of 12a (88 mg, 0.173 mmol) and
acetyl chloride (0.30 mL) in CH3CN (1.0 mL) was added Bi(OTf)3
(101 mg, 0.154 mmol), resulting in immediate dissolution and the
resulting solution stirred at rT for 30 min. The reaction mixture
was added to ice water (20 mL) and extracted with small portions
of CH2Cl2 (20 mL in total). The combined organics were passed
through a pad of cotton and the solvent removed under reduced
pressure. The residue was purified by flash column chromatography
(2% ethyl acetate/toluene) to give an orange oil, which was crys-
Entry 20: To a solution of 20a (40 mg, 0.0349 mmol) and acetyl
chloride (0.10 mL) in toluene (0.50 mL), CH3CN (1.0 mL) and 1,2-
dichlorobenzene (1.0 mL) was added Bi(OTf)3 (5 mg, 0.0076 mmol)
and the contents of the vessel stirred for 2 h at ambient tempera-
ture. The reaction mixture was added to ice water (20 mL) and
extracted with small portions of CH2Cl2 (20 mL in total). The com-
bined organics were dried with Na2SO4, filtered and the solvent
removed under reduced pressure. The residue was purified by flash
column chromatography (toluene) giving back 20a (39 mg) as a
tallized (CH2Cl2/heptane) to afford 12b (73 mg, 88%) as a yellow dark brown solid.
solid.
Entry 21: To a solution of 20a (40 mg, 0.0349 mmol) and acetyl
S,SЈ-[(3,3-Dicyano-3,3a-dihydroazulene-2,5-diyl)bis(4,1-phenylene)] chloride (0.10 mL) in toluene (0.50 mL), CH3CN (1.0 mL) and 1,2-
Diethanethioate (12b): M.p. 148–151 °C. Rf = 0.40 (2% ethyl acet-
dichlorobenzene (1.0 mL) was added Bi(OTf)3 (37 mg,
0.0564 mmol) and the contents of the vessel stirred for 2 h at ambi-
ent temperature. The reaction mixture was added to ice water
(20 mL) and extracted with small portions of CH2Cl2 (20 mL in
total). The combined organics were dried with Na2SO4, filtered and
the solvent removed under reduced pressure. The residue was puri-
ate/toluene). IR: ν = 2254, 1705 cm–1. 1H NMR (500 MHz,
˜
CDCl3): δ = 7.78 (d, J = 8.4 Hz, 2 H), 7.53 (d, J = 8.4 Hz, 2 H),
7.44 (d, J = 8.4 Hz, 2 H), 7.41 (d, J = 8.4 Hz, 2 H), 6.95 (s, 1 H),
6.84 (dd, J = 11.5, 5.5 Hz, 1 H), 6.77 (d, J = 11.5 Hz, 1 H), 6.41
(br. d, J = 5.5 Hz, 1 H), 6.01 (d, J = 4.6 Hz, 1 H), 3.85 (dd, J =
4.6, 1.5 Hz, 1 H), 2.46 (s, 3 H), 2.43 (s, 3 H) ppm. 13C NMR fied by flash column chromatography (toluene) to afford 20b
(125 MHz, CDCl3): δ = 194.0, 193.1, 141.1, 140.4, 140.4, 139.2, (35 mg, 89%) as a dark brown solid.
135.1, 134.7, 132.9, 132.8, 132.0, 131.3, 130.6, 128.6, 128.0, 126.9,
1
Compound 20b: R = 0.59 (toluene). IR: ν = 1712 cm–1. H NMR
˜
f
121.1, 117.1, 115.0, 112.9, 51.0, 45.0, 30.6, 30.4 ppm. HRMS (ESI
(500 MHz, CDCl3): δ = 7.97 (br. s, 2 H), 7.52 (br. d, J = 8.3 Hz, 1
H), 7.25 (s, 2 H), 5.18 (s, 1 H), 4.87 (d, J = 9.5 Hz, 1 H), 4.45 (d,
J = 13.1 Hz, 1 H), 4.15 (d, J = 9.5 Hz, 1 H), 3.83 (t, J = 6.6 Hz, 2
H), 3.55 (d, J = 13.1 Hz, 1 H), 2.41 (s, 3 H), 2.38 (s, 6 H), 1.87–
+ve) calcd. for C28H20N2O2S2Na [[M + Na]+]: m/z = 503.0858,
found 503.0871. C28H20N2O2S2 (480.60): calcd. C 69.97, H 4.19, N
5.83; found C 69.85, H 4.23, N 5.83.
Entry 18: To a solution of 19a (20 mg, 0.021 mmol) and acetyl
chloride (0.10 mL) in toluene (0.50 mL), CH3CN (1.0 mL) and 1,2-
1.82 (m, 2 H), 1.55–1.51 (m, 2 H), 1.40–1.36 (m, 4 H), 0.93 (t, J =
7.0 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 193.9, 156.5,
dichlorobenzene (1.0 mL) was added Bi(OTf)3 (4 mg, 0.0061 mmol) 155.8, 154.2, 153.3, 153.2, 147.5, 147.5, 146.8, 146.5, 146.4, 146.4,
and the contents of the vessel stirred for 30 min at ambient tem-
perature. The reaction mixture was added to ice water (20 mL) and
extracted with small portions of CS2 (20 mL in total). The com-
bined organics were dried with Na2SO4, filtered and the solvent
removed under reduced pressure. The residue was purified by flash
column chromatography (toluene) to afford 19b (2 mg, 10%) as a
dark brown solid in addition to recovered 19a (16 mg).
146.4, 146.3, 146.3, 146.1, 146.1, 146.1, 146.1, 145.7, 145.7, 145.7,
145.5, 145.5, 145.4, 145.4, 145.3, 144.8, 144.8, 144.6, 144.5, 143.3,
143.1, 142.8, 142.7, 142.7, 142.7, 142.5, 142.4, 142.3, 142.2, 142.2,
142.1, 142.0, 141.8, 141.7, 140.3, 140.2, 140.1, 139.6, 138.9, 137.1,
136.6, 136.1, 135.8, 134.8, 132.4, 131.2, 130.3, 129.5, 128.4, 81.1,
76.7, 72.6, 68.9, 66.9, 56.8, 31.9, 30.6, 30.4, 26.0, 22.8, 16.7, 14.3
ppm. HRMS (MALDI +ve) calcd. for C85H33NO2S [M·–]: m/z =
1131.2238, found 1131.2320. C85H33NO2S (1132.26): calcd. C
90.17, H 2.94, N 1.24; found C 90.11, H 3.03, N 1.28.
Entry 19: To a solution of 19a (45 mg, 0.0471 mmol) and acetyl
chloride (0.10 mL) in toluene (0.50 mL), CH3CN (1.0 mL) and 1,2-
dichlorobenzene (1.0 mL) was added Bi(OTf)3 (46 mg, Entry 22: To a solution of 23a (30 mg, 0.0233 mmol) and acetyl
0.0701 mmol) and the contents of the vessel stirred for 30 min at chloride (0.10 mL) in toluene (0.50 mL), CH3CN (1.0 mL) and 1,2-
ambient temperature. The reaction mixture was added to ice water dichlorobenzene (1.0 mL) was added Bi(OTf)3 (30 mg, 0.046 mmol)
(20 mL) and extracted with small portions of CS2 (20 mL in total).
The combined organics were dried with Na2SO4, filtered and the
solvent removed under reduced pressure. The residue was purified
by flash column chromatography (gradient elution of 75% toluene/
and the contents of the vessel stirred for 30 min at ambient tem-
perature. The reaction mixture was added to ice water (20 mL) and
extracted with small portions of CH2Cl2 (20 mL in total). The com-
bined organics were dried with Na2SO4, filtered and the solvent
CS2 to toluene) to afford 19b (34 mg, 77%) as a dark brown solid, removed under reduced pressure. The residue was purified by flash
in addition to recovered 19a (6 mg, 13%).
column chromatography (gradient elution 0.25%–0.5% ethyl acet-
ate/toluene) to afford 23b (7 mg, 24%) as a dark brown solid in
addition to recovered 23a (7 mg, 23%).
Compound 19b: R = 0.58 (toluene). IR: ν = 1727 cm–1. H NMR
1
˜
f
(500 MHz, CDCl3/CS2, 2:1): δ = 7.86 (br. s, 1 H), 7.46 (br. d, J =
7.7 Hz, 1 H), 5.13 (d, J = 9.3 Hz, 1 H), 5.12 (s, 1 H), 4.18 (d, J =
9.3 Hz, 1 H), 3.38 (dq, J = 14.3, 7.2 Hz, 1 H), 2.65 (dq, J = 14.3,
Compound 23b: R = 0.40 (2% ethyl acetate/toluene). IR: ν = 1726,
˜
f
1596 cm–1. 1H NMR (500 MHz, CDCl3): δ = 8.23 (s, 1 H), 8.01
7.2 Hz, 1 H), 2.41 (s, 3 H), 1.54 (t, J = 7.2 Hz, 3 H) ppm. 13C (br. d on top of br. s, J = 7.7 Hz, 4 H), 7.85 (d, J = 8.7 Hz, 2 H),
NMR (125 MHz, CDCl3/CS2, 2:1): δ = 193.1, 156.3, 154.1, 153.2, 7.59 (d, J = 8.7 Hz, 2 H), 7.26 (s, 2 H), 5.20 (s, 1 H), 4.88 (d, J =
152.9, 147.3, 146.6, 146.4, 146.3, 146.3, 146.2, 146.2, 146.2, 146.1,
146.0, 146.0, 145.9, 145.8, 145.6, 145.6, 145.5, 145.4, 145.4, 145.3,
145.3, 145.3, 145.2, 145.2, 144.7, 144.6, 144.4, 144.4, 143.2, 143.0,
142.7, 142.6, 142.6, 142.6, 142.3, 142.3, 142.2, 142.2, 142.1, 142.1,
142.1, 142.0, 141.9, 141.9, 141.7, 141.6, 140.3, 140.2, 140.0, 139.5,
138.8, 137.0, 136.6, 135.9, 135.7, 134.6, 130.0, 128.3, 81.8, 76.6,
68.8, 66.5, 47.4, 30.2, 13.6 ppm. HRMS (MALDI +ve) calcd. for
C72H15NOS [M·–]: m/z = 941.0907, found 941.0886. C72H15NOS
9.6 Hz, 1 H), 4.47 (d, J = 13.1 Hz, 1 H), 4.18 (d, J = 9.6 Hz, 1 H),
3.84 (t, J = 6.6 Hz, 2 H), 3.62 (d, J = 13.1 Hz, 1 H), 2.47 (s, 3 H),
2.39 (s, 6 H), 1.87–1.82 (m, 2 H), 1.57–1.51 (m, 2 H), 1.40–1.36 (m,
4 H), 0.93 (t, J = 7.0 Hz, 3 H) ppm. 13C NMR (125 MHz, CDCl3):
δ = 193.2, 156.6, 155.8, 154.3, 153.5, 153.5, 148.5, 147.5, 146.9,
146.6, 146.4, 146.4, 146.4, 146.3, 146.3, 146.2, 146.1, 146.1, 145.9,
145.7, 145.7, 145.7, 145.7, 145.5, 145.4, 145.4, 145.4, 145.3, 144.9,
144.8, 144.6, 144.5, 143.3, 143.1, 142.8, 142.7, 142.7, 142.7, 142.5,
4686
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4675–4688

Bismuth(III)-Promoted Acetylation of Thioethers into Thioacetates
K. Nørgaard, Langmuir 2012, 28, 4016–4023; b) J. Fock, M.
Leijnse, K. Jennum, A. S. Zyazin, J. Paaske, P. Hedegård, M. B.
Nielsen, H. S. J. van der Zant, Phys. Rev. B 2012, 86, 235403;
c) C. R. Parker, Z. Wei, C. R. Arroyo, K. Jennum, T. Li, M.
Santella, N. Bovet, G. Zhao, W. Hu, H. S. J. van der Zant, M.
Vanin, G. C. Solomon, B. W. Laursen, K. Nørgaard, M. B.
Nielsen, Adv. Mater. 2013, 25, 405–409; d) C. R. Parker, E.
Leary, R. Frisenda, Z. Wei, K. S. Jennum, E. Glibstrup, P. B.
Abrahamsen, M. Santella, M. A. Christensen, E. A. Della Pia,
T. Li, M. T. Gonzalez, B. W. Laursen, K. Nørgaard, H.
van der Zant, N. Agraït, M. B. Nielsen, J. Am. Chem. Soc.
2014, 136, 16497–16507.
142.4, 142.3, 142.3, 142.2, 142.2, 142.2, 142.1, 142.1, 142.0, 141.8,
141.7, 140.3, 140.2, 140.1, 139.7, 137.9, 137.7, 137.1, 136.7, 136.1,
136.0, 135.8, 132.3, 131.2, 130.3, 129.7, 128.9, 126.4, 121.0, 117.7,
81.2, 76.8, 72.6, 68.9, 66.8, 56.6, 31.9, 30.6, 30.5, 26.0, 22.8, 16.7,
14.3 ppm. HRMS (MALDI -ve) calcd. for C93H38N4O2S [M·–]: m/z
= 1274.2721, found 1274.2729. C93H38N4O2S (1273.49): calcd. C
87.58, H 3.00, N 4.39; found C 87.49, H 3.23, N 4.46.
CuAAC Reaction Between 22 and 6b: A solution of 22 (49 mg,
0.453 mmol), 6b (22 mg, 0.114 mmol) and copper(I) iodide (6 mg,
0.032 mmol) in toluene (10 mL) and triethylamine (0.10 mL) was
stirred at ambient temperature under an argon atmosphere 16 h.
The solvent was removed in vacuo and the resulting residue puri-
fied by column chromatography (2% ethyl acetate/toluene) to af-
ford pure 23b (41 mg, 71%) as a dark brown solid.
[12]
[13]
S. L. Broman, M. B. Nielsen, Phys. Chem. Chem. Phys. 2014,
16, 21172–21182.
a) S. L. Broman, S. Lara-Avila, C. L. Thisted, A. D. Bond,
A. V. Danilov, S. E. Kubatkin, M. B. Nielsen, Adv. Funct. Ma-
ter. 2012, 22, 4249–4258; b) T. Li, M. Jevric, J. R. Hauptmann,
R. Hviid, Z. Wei, R. Wang, N. E. A. Reeler, E. Thyrhaug, S. V.
Petersen, J. A. S. Meyer, N. E. Bovet, T. A. J. Vosch, J. Nygård,
X. Qiu, W. Hu, Y. Liu, G. C. Solomon, H. G. Kjaergaard, T.
Bjørnholm, M. B. Nielsen, B. W. Laursen, K. Nørgaard, Adv.
Mater. 2013, 25, 4164–4170.
Acknowledgments
The University of Copenhagen is acknowledged for support.
[14]
[15]
[16]
E. H. van Dijk, D. J. T. Myles, M. H. van der Veen, J. C. Hum-
melen, Org. Lett. 2006, 8, 2333–2336.
M. Jevric, S. L. Broman, M. B. Nielsen, J. Org. Chem. 2013,
78, 4348–4356.
N. Le Narvor, N. Robertson, E. Wallace, J. Kilburn, A. E. Un-
derhill, P. N. Bartlett, M. Webster, J. Chem. Soc., Dalton Trans.
1996, 823–828.
S. S. Schou, C. R. Parker, K. Lincke, K. Jennum, J. Vibenholt,
A. Kadziola, M. B. Nielsen, Synlett 2013, 24, 231–235.
X. Zeng, C. Wang, A. S. Batsanov, M. R. Bryce, J. Gigon, B.
Urasinska-Wojcik, G. J. Ashwell, J. Org. Chem. 2010, 75, 130–
136.
[1] a) N. Robertson, C. A. McGowan, Chem. Soc. Rev. 2003, 32,
96–103; b) A. C. Benniston, Chem. Soc. Rev. 2004, 33, 573–
578; c) K. Nørgaard, T. Bjørnholm, Chem. Commun. 2005,
1812–1823; d) N. Weibel, S. Grunder, M. Mayor, Org. Biomol.
Chem. 2007, 5, 2343–2353; e) R. Klajn, J. F. Stoddart, B. A.
Grzybowski, Chem. Soc. Rev. 2010, 39, 2203–2237; f) R. J.
Nichols, W. Haiss, S. J. Higgins, E. Leary, S. Martin, D. Bethell,
Phys. Chem. Chem. Phys. 2010, 12, 2801–2815; g) K. Jennum,
M. B. Nielsen, in: Organic Synthesis and Molecular Engineering
(Ed.: M. B. Nielsen), Wiley, Hoboken, 2014, p. 46–75.
[2] a) R. G. Nuzzo, D. L. Allara, J. Am. Chem. Soc. 1983, 105,
4481–4483; b) L. Strong, G. M. Whitesides, Langmuir 1988, 4,
546–558; c) J. C. Love, L. A. Estroff, J. K. Kriebel, R. G.
Nuzzo, G. M. Whitesides, Chem. Rev. 2005, 105, 1103–1169;
d) K. Nørgaard, M. B. Nielsen, T. Bjørnholm, in: Functional
Organic Materials (Eds.: T. J. J. Müller, U. H. F. Bunz), Wiley-
VCH, Weinheim, Germany, 2007, p. 353–392; e) K. Moth-
Poulsen, T. Bjørnholm, Nat. Nanotechnol. 2009, 4, 551–556; f)
J. S. Meisner, S. Ahn, S. V. Aradhya, M. Krikorian, R. Parame-
swaran, M. Steigerwald, K. Venkataraman, C. Nuckolls, J. Am.
Chem. Soc. 2012, 134, 20440–20445.
[17]
[18]
[19]
[20]
K. D. Grimes, A. Gupte, C. C. Aldrich, Synthesis 2010, 1441–
1448.
For an X-ray crystal structure of 9a, see: N. Seidel, S. Förster,
W. Seichter, E. Weber, Acta Crystallogr., Sect. E 2012, 68,
o1543.
a) C. W. Tornøe, C. Christensen, M. Meldal, J. Org. Chem.
2002, 67, 3057–3064; b) V. V. Rostovtsev, L. G. Green, V. V.
Fokin, K. B. Sharpless, Angew. Chem. Int. Ed. 2002, 41, 2596–
2599; Angew. Chem. 2002, 114, 2708.
a) M. Maggini, G. Scorrano, M. Prato, J. Am. Chem. Soc. 1993,
115, 9798–9799; b) M. Prato, M. Maggini, Acc. Chem. Res.
1998, 31, 519–526; c) N. Tagmatarchis, M. Prato, Synlett 2003,
768–779.
M. V. Solano, E. A. Della Pia, M. Jevric, C. Schubert, X.
Wang, C. van der Pol, A. Kadziola, K. Nørgaard, D. M. Guldi,
M. B. Nielsen, J. O. Jeppesen, Chem. Eur. J. 2014, 20, 9918–
9929.
[21]
[22]
[23]
[3] a) N. Stuhr-Hansen, Synth. Commun. 2003, 33, 641–646; b) N.
Stuhr-Hansen, J. K. Sørensen, K. Moth-Poulsen, J. B. Chris-
tensen, T. Bjørnholm, M. B. Nielsen, Tetrahedron 2005, 61,
12288–12295.
[4] A. Blaszczyk, M. Elbing, M. Mayor, Org. Biomol. Chem. 2004,
2, 2722–2724.
[5] C. Lai, B. J. Backes, Tetrahedron Lett. 2007, 48, 3033–3037.
[6] a) N. M. Leonard, L. C. Wieland, R. S. Mohan, Tetrahedron
2002, 58, 8373–8397; b) J. M. Bothwell, S. W. Krabbe, R. S.
Mohan, Chem. Soc. Rev. 2011, 40, 4649–4707; c) T. Ollevier,
Org. Biomol. Chem. 2013, 11, 2740–2755.
[7] A. Oussaid, P. Garrigues, B. Garrigues, C. R. Acad. Sci. Paris
Chimie/Chem. 2001, 4, 691–694.
[8] a) A. R. Hajipour, S. E. Mallakpour, I. Mohammadpoor-Bal-
tork, H. Adibi, Phosphorus Sulfur Silicon Relat. Elem. 2002,
177, 2805–2811; b) A. Kamal, P. S. M. M. Reddy, D. R. Reddy,
Tetrahedron Lett. 2003, 44, 2857–2860.
[9] For a deprotection of aryl tert-butyl ether using Er(OTf)3, see:
A. Procopio, P. Costanzo, M. Curini, M. Nardi, M. Oliverio,
R. Paonessa, Synthesis 2011, 73–78.
[24]
[25]
[26]
T. Sasaki, J.-F. Morin, M. Lu, J. M. Tour, Tetrahedron Lett.
2007, 48, 5817–5820.
Compound 4b has previously been reported, see: D. L. Pear-
son, J. M. Tour, J. Org. Chem. 1997, 62, 1376–1387.
Compound 5b has previously been reported, see: a) S. M. So-
ria-Castro, A. B. Penenory, Beilstein J. Org. Chem. 2013, 9,
467–475; b) C. G. Overberger, A. Lebovits, J. Am. Chem. Soc.
1956, 78, 4792–4797.
For comparison, conversion of alkynes to vinyl triflates has
been observed previously in the presence of trimethylsilyl trifl-
ate and a metal triflate catalyst, see: M. Al-huniti, S. D. Lepore,
Org. Lett. 2014, 16, 4154–4157.
[27]
[28]
[29]
Compound 9b has previously been reported: T. W. T. Mues-
mann, M. S. Wickleder, J. Christoffers, Synthesis 2011, 2775–
2780.
For reviews on triazoles acting as ligands, see: a) P. I. P. Elliott,
Organomet. Chem. 2014, 39, 1–25; b) H. van der Salm, A. B. S.
Elliott, K. C. Gordon, Coord. Chem. Rev. 2015, 282–283, 33–
49.
[10] a) C. A. Martin, D. Ding, J. K. Sørensen, T. Bjørnholm, J. M.
van Ruitenbeek, H. S. J. van der Zant, J. Am. Chem. Soc. 2008,
130, 13198–13199; b) E. Leary, M. T. González, C. van der Pol,
M. R. Bryce, S. Filippone, N. Martín, G. Rubio-Bollinger, N.
Agraït, Nano Lett. 2011, 11, 2236–2241.
[11] a) Z. Wei, T. Li, K. Jennum, M. Santella, N. Bovet, W. Hu,
M. B. Nielsen, T. Bjørnholm, G. C. Solomon, B. W. Laursen,
Eur. J. Org. Chem. 2015, 4675–4688
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4687

M. Jevric, A. U. Petersen, M. Mansø, A. Ø. Madsen, M. B. Nielsen
FULL PAPER
[30] a) R. D. Hancock, I. Cukrowski, J. Baloyi, J. Mashishi, J.
Chem. Soc., Dalton Trans. 1993, 2895–2899; b) R. Luckay, J. H.
Reibenspies, R. D. Hancock, J. Chem. Soc., Chem. Commun.
1995, 2365–2366; c) R. Luckay, I. Cukrowski, J. Mashishi, J. H.
Reibenspies, A. H. Bond, R. D. Rogers, R. D. Hancock, J.
Chem. Soc., Dalton Trans. 1997, 901–908; d) X.-W. Zhang, J.
Xia, H.-W. Yan, S.-L. Luo, S.-F. Yin, C.-T. Au, W.-Y. Wong, J.
Organomet. Chem. 1999, 694, 3019–3026; e) S. L. Benjamin, L.
Karagiannidis, W. Levason, G. Reid, M. C. Rogers, Organome-
tallics 2011, 30, 895–904.
[31]
C. R. Parker, C. G. Tortzen, S. L. Broman, M. Schau-Mag-
nussen, K. Kilså, M. B. Nielsen, Chem. Commun. 2011, 47,
6102–6104.
S. Répichet, A. Zwick, L. Vendier, C. Le Roux, J. Dubac, Tetra-
hedron Lett. 2002, 43, 993–995.
[32]
[33] R. Dalpozzo, A. De Nino, L. Maiuolo, M. Nardi, A. Procopio,
A. Tagarelli, Synthesis 2004, 496–498.
Received: May 31, 2015
Published Online: June 15, 2015
4688
www.eurjoc.org
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2015, 4675–4688