Reactivity of Functionalized Ynamides with Tetracyanoethylene: Scope, Limitations and Optoelectronic Properties of the Adducts

Article abstract of DOI:10.1002/asia.201700353

The reactivity of functionalized ynamides and arylynamines with tetracyanoethylene at room temperature was evaluated. In most cases, the corresponding 1,1,4,4-tetracyanobutadienes (TCBDs) were obtained in good to excellent yields through a [2+2]-cycloaddition/[2+2]-retro-electrocyclization sequence. The influence of diverse functional groups on the yield of the reaction was investigated, in particular concerning multiple ynamides. These TCBDs were characterized by various spectroscopic techniques and electrochemistry and X-ray diffraction in some cases.

Full text of DOI:10.1002/asia.201700353

CHEMISTRY
AN ASIAN JOURNAL
www.chemasianj.org
Accepted Article
Title: Reactivity of functionalized ynamides with tetracyanoethylene:
scope, limitations and optoelectronic properties of the adducts
Authors: Marie Betou, Raphaël J. Durand, Antoine Sallustrau, Claire
Gousset, Erwann Le Coz, Yann R. Leroux, Loïc Toupet,
Elzbieta Trzop, Thierry Roisnel, and Yann Trolez
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To be cited as: Chem. Asian J. 10.1002/asia.201700353
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10.1002/asia.201700353
Chemistry - An Asian Journal
Reactivity of functionalized ynamides with
tetracyanoethylene: scope, limitations and optoelectronic
properties of the adducts
Marie Betou,a Raphaël J. Durand,a Antoine Sallustrau,a Claire Gousset,a Erwann Le Coz,a Yann
R. Leroux,a Loïc Toupet,b Elzbieta Trzop,b Thierry Roisnel,a Yann Trolez* a
[a] Institut des Sciences Chimiques de Rennes, UMR 6226, CNRS, Ecole Nationale Supérieure
de Chimie de Rennes, Université de Rennes 1, 35708 Rennes Cedex (France)
[b] Institut de Physique de Rennes, CNRS, UMR 6251, Université de Rennes 1, 263 avenue du
Général Leclerc, 35042 Rennes Cedex (France)
Supporting information for this article is available on the WWW under http://dx.doi.org./xxx
45000"
NC
NC
NC
Ts
40000"
35000"
30000"
25000"
20000"
15000"
10000"
5000"
0"
CN
Ts
Ts
CN
N
S
N
Bn
N
Bn
NC
CN
CN
230"
330"
430"
530"
630"
730"
Wavelength"(nm)"
10
0
NC
Ts
CN
NC
CN
NC
Ts
CN
N
N
N
Bn
Bn
NC
CN
N
NC
CN
-10
-20
NC
CN
-1.5
-1.0
-0.5
0.0
E (V vs Fc)
Abstract: The reactivity of functionalized ynamides and arylynamines with
tetracyanoethylene at room temperature has been evaluated. In most cases, the
corresponding 1,1,4,4-tetracyanobutadienes (TCBDs) have been obtained in good to
excellent yields, following a sequence of [2+2]cycloaddition and [2+2]retroelectrocyclization.
The influence of diverse functional groups on the yield of the reaction has been investigated,
in particular concerning multiple ynamides. These TCBDs have been characterized by various
spectroscopic techniques, electrochemistry and X-Ray diffraction for some of them.
Introduction
The synthesis of 1,1,4,4-tetracyanobutadienes (TCBDs) has met an increasing interest over
the last years.[1] Actually, the properties of such molecules could be of particular interest
given their exceptional electron-accepting ability and their intense non-linear absorption in
some cases.[2] Moreover, their ease of synthesis could also explain their recent rise. Indeed, a
certain number of research groups have shown that some organic alkynes activated by an
electron-donating group (EDG) could readily react with tetracyanoethylene (TCNE) according
to a sequence of [2+2]cycloaddition-retroelectrocyclization (CA-RE) to afford the
corresponding TCBDs in variable yields.[ 3 , 4 ] In some examples (p-aniline, azulene,
heteroazulene and rich porphyrin substituted alkynes), there is no need for heating the
reaction or using an excess of TCNE to reach yields over 90%.[4] Therefore, this type of
1
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10.1002/asia.201700353
Chemistry - An Asian Journal
reaction seems to meet the requirements of the “click” reactions as defined by Sharpless and
coworkers in 2001.[5]
However, this reaction is very dependent on the nature of the EDG. There is a right balance
to find between using an EDG which is rich enough to make the CC triple bond react with
TCNE, and an EDG which is too rich and induces an over-reaction of the alkyne with the TCBD
itself, producing thus a complex mixture with the formation of multiple oligomers and / or
the desired TCBD in bad yield. Following this idea, we recently reported that ynamides[6]
could be incorporated in the list of compounds which readily react with TCNE in generally
high yields, the nitrogen playing the role of the EDG (scheme 1).[7]
We now report on the extension of the scope of the reaction with differently
functionalized ynamides, including unsaturated groups that could potentially also react with
TCNE or the formed TCBD.[8] Moreover, systems bearing two ynamide functions conjugated
to each other were investigated. This study also conducted us to investigate the reactivity of
aromatic ynamines.
NC
NC
CN
CN
NC
EWG
CN
EWG
R'
R
N
R
N
TCNE
R'
NC
CN
TCBD
NC
NC
CN
CN
EWG
N
R
R'
Scheme 1. Reaction between an ynamide and TCNE.
Results and discussion
We first evaluated the influence of the different three groups of an ynamide (EWG, R1 and
R2 in Table 1). All the experiments used 1 equivalent of TCNE and were carried out in
dichloromethane at room temperature during 16 hours (unless otherwise stated).
We started by evaluating the influence of aromatic and heteroaromatic moieties
conjugated to the triple bond (R1 in table 1). When the phenyl was used, ynamide 1,[9] which
can be considered in this study as a model compound, allowed for the formation of the
corresponding TCBD 2 in 98% yield (table 1, entry 1) as already reported. The phenyl can be
substituted by a naphtyl (ynamide 3) or a p-fluorophenyl group (ynamide 23)[10] without any
dramatic effect on the yield of the reaction (entries 2 and 12). Heteroaromatic substituents
can also be used since furanyl (ynamide 5) and thiophene (ynamide 19)[10] gave the
corresponding TCBDs 6 and 20 in 97% and 87% yields respectively (entries 3 and 10).
Surprisingly, when an anthracenyl substituted in 9-position (ynamide 7) was reacted, no
TCBD could be obtained (entry 4). Only the starting material was recovered. No other side-
reaction (such as a Diels-Alder cycloaddition) was observed. The rational for such a poor
reactivity might come from steric hindrance of protons located in 1 and 8-positions that
"protect" the triple bond.
As already observed, the nature of the EWG does not seem to have an influence since
replacing the tosyl group by a Boc group (ynamide 21)[11] led to TCBD 22 quantitatively (entry
11).
2
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10.1002/asia.201700353
Chemistry - An Asian Journal
We also evaluated the influence of the group linked to the nitrogen (R2 in table 1). When
using a phenyl group (compound 9)[12] instead of benzyl group, the reaction was completely
inhibited and the corresponding TCBD 10 was not obtained (entry 5). This observation could
be explained by a partial delocalization of the electron doublet of the nitrogen over this
phenyl ring, which makes it less available to enrich the CC triple bond. In this case, we thus
deduced that the triple bond was not electron-rich enough to react with TCNE. This group
could also be replaced by an allyl function (ynamide 11)[10] without any detrimental effect
(formation of TCBD 12 in 94% yield, entry 6). It is noteworthy that there was no further
cycloaddition involving the allylic double bond and the TCBD group. One might have
anticipated that a Diels-Alder reaction was possible as observed in other similar
compounds.[8,13] This system is probably too strained to allow for any further reactions,[14] at
least at room temperature. This reaction is also compatible with a propargylic group
(ynamide 13)[15] since the corresponding TCBD 14 was obtained in 64% yield (entry 7).
Contrary to what was observed with the allylic group, a significant decrease of the yield was
observed. Nevertheless, the conversion could be improved to 91% by stirring the reaction
mixture during 58 hours instead of the standard 16 hours. Therefore, a propargylic group
does not inhibit the reaction but only slows it down. No further reaction with the terminal
triple bond was observed, and as one could have anticipated, the selectivity between the
two CC triple bonds present in ynamide 13 is total.
Then, we tested the influence of a non-aromatic system linked to the triple bond on the
CA-RE sequence (R1 in table 1). After observing that a propargylic group could slow down the
reaction, we wanted to evaluate the influence of a CC triple bond conjugated to the CC triple
bond of an ynamide. Surprisingly, when a phenylacetylene unit was conjugated (ynamide 15),
the reaction was completely inhibited and the corresponding TCBD 16 has never been
obtained: 95% of the starting material was recovered after purification (entry 8). Heating the
reaction mixture did not change the result. A possible reason for this non-reactivity could be
that electron density of the CC triple bond linked to the nitrogen might be decreased
because of the conjugation with the second triple bond. On the contrary, when a vinyl group
was conjugated (ynamide 17),[10] the reaction worked perfectly and gave the expected TCBD
18 in 94% yield (entry 9). Once again, the presence of the double bond did not induce the
formation of by-products or over-reactions. These figures show that the presence of CC
double bonds is not detrimental to the formation of TCBDs, contrary to conjugated CC triple
bonds. A cyclopropyl group (ynamide 25)[16] could also be used to lead to the corresponding
TCBD 26 in 86% yield (entry 13).
Table 1. Influence of the different substituents on the reaction of ynamides with TCNE.
NC
EWG
EWG
CN
R1
TCNE
N
N
R1
CH2Cl2
r.t.
R2
R2
NC
CN
entry ynamide EWG
R1
R2
TCBD
yield
(%)
1
2
3
1
3
5
Ts
Ts
Ts
Ph
Bn
Bn
Bn
2
4
6
98
99
97
naphtalen-2-yl
furan-2-yl
3
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10.1002/asia.201700353
Chemistry - An Asian Journal
4
5
6
7
8
7
Ts
Ts
Ts
Ts
Ts
anthracen-9-yl
Bn
Ph
8
0a
0a
9
Ph
Ph
Ph
10
12
14
16
11
13
15
allyl
94
64b
0a
propargyl
Bn
9
17
Ts
Bn
18
94
10
11
12
13
19
21
23
25
Ts
Boc
Ts
thiophen-2-yl
Ph
Bn
Bn
Bn
Bn
20
22
24
26
87
99
99
86
p-fluorophenyl
cyclopropyl
Ts
aNo conversion, the starting material was recovered. bWhen the solution was stirred during 58 h instead of 16 h,
the yield was increased to 91%.
Taking into account that a phenyl group directly linked to the nitrogen of an ynamide
completely inhibits the reaction with TCNE, we wondered whether similar compounds
without EWG but only aromatic groups could react. For this purpose, three compounds were
investigated (Scheme 2). The first one was the acridinone derivative 27.[17] No reaction was
observed in this case. The electronic doublet of the nitrogen is probably too delocalized over
the aromatic rings rather than the CC triple bond so that it is not reactive enough. The
presence of the ketone in addition to aromatic systems conjugated with the nitrogen is
probably detrimental to the reaction. This is the reason why another similar compound was
tested without this ketone, namely the carbazole ynamine 29.[18] The corresponding TCBD 30
was obtained in a very good yield of 83%. This experiment completes the observation
recently made by Kato and collaborators that carbazole is also a good activating group for
initiating CA-RE with TCNE.[3f] Similarly the indole ynamine 31[19] was also reacted and
provided TCBD 32 in 59% yield. Concerning the formation of both TCBDs 30 and 32, no by-
products were isolated. The yield is therefore significantly lower than with ynamides, even
though it is important to note that no optimisation of these reactions was attempted.
Nevertheless, these last two experiments confirm that arylated ynamines can also provide
TCBDs in good yields,[20] contrary to alkylated ynamines that probably over-react with TCNE
to lead to a mixture of numerous products in low yields.[7] This observation opens new
prospects in the field of optoelectronics for this reaction since compounds 30 and 32 both
absorb light in the visible range (Figure 2).
4
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10.1002/asia.201700353
Chemistry - An Asian Journal
NC
CN
TCNE
O
N
O
N
X
CH2Cl2
r.t.
27
28
NC
NC
CN
CN
TCNE
N
N
CH2Cl2
r.t.
NC
29
CN
83%
30
NC
TCNE
CN
N
N
CH2Cl2
r.t.
31
NC
59%
CN
32
Scheme 2. Evaluation of the reactivity of arylated ynamines.
It is noteworthy to notice that 7,7,8,8-tetracyanoquinodimethane (TCNQ) can also be a
good reactant for CA-RE with some activated alkynes, although not as reactive as
TCNE.[ 3c,4d ,21] We tested the reactivity of this compound with some ynamides or ynamines
described in this paper, but we never observed the expected reactivity, neither at room
temperature nor at higher temperature. The majority of the starting material was recovered.
Consequently, we conclude that ynamides are able to react with TCNE but not TCNQ.
TCBDs 4, 6, 14, 18, 20, 24, 26 and 30 were characterized by X-ray diffraction (Figure 1),
additionally to NMR spectroscopy and high-resolution mass spectrometry. As already
observed for other TCBDs, the two dicyanovinyls are not in the same plane. The torsion
angle measured for the first seven TCBDs is below 90° (between 60° and 86°) as usually
observed for TCBDs whereas for compound 30 it is over 90° (136°). This is probably due to
steric hindrance that precludes the TCBD moiety to stand in s-cis conformation. The
orientation of the unsaturated group (R1 in Table 1) linked to the TCBD group differs from
one another, depending on their nature. In the case of naphtyl, phenyl fluorophenyl and
carbazole groups (compounds 4, 14, 24 and 30 respectively), the torsion angle between the
dicyanovinyl and the aromatic group is comprised between 43 and 63°. In these cases, this
observation means that the aromatic groups are fairly conjugated to the TCBD, which can be
explained by steric hindrance. On the contrary, in the case of the furanyl, vinyl and
thiophenyl groups (compounds 6, 18 and 20), the torsion angle is comprised between 10°
and 20°, meaning that these groups are much more conjugated to the TCBD. This can be
explained by their geometrical nature that allows for a less congested conformation.
Moreover, an intramolecular π-stacking is observed between the tosyl group and the
aromatic group for naphtyl 4 and for thiophenyl 20. The distance between the tosyl and the
aromatic group is 3.4 and 3.5 Å respectively. Intermolecularly, some recurrent interactions
can be observed. Numerous N-H bond between nitriles and aromatic or benzylic protons are
at stake. Tosyl groups also participate to interactions with O-H bonds between oxygens of
the sulfonamide function and aromatic protons. In only two cases dipole-dipole interactions
can be observed between TCBDs in compounds 4 and 20. Intermolecular π-stacking could
not been evidenced, probably because of a too important steric congestion.
5
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10.1002/asia.201700353
Chemistry - An Asian Journal
4
14
6
18
24
20
26
30
Figure 1. X-ray structure of TCBDs 4, 6, 14, 18, 20, 24, 26 and 30; protons and solvent molecules have
been omitted for clarity.
In order to evaluate the possibility to perform multiple TCNE additions on the same
molecule, we reacted conjugated bis-ynamides[22] with two equivalents of TCNE in the same
conditions as previously described (Scheme 3). We started with mono-phenyl bis-ynamide
33 which was reacted overnight at room temperature with two equivalents of TCNE. The
major product obtained was the mono-adduct 34 in 79% yield. Trace amount of the bis-
1
adduct was observed by H NMR spectroscopy. The first addition of TCNE probably
deactivates the second CC triple bond because of the strong electron-withdrawing
properties of the TCBD moiety. Therefore, the second ynamide function was much less
reactive. The same reaction was tested with bis-ynamide 35 containing a thiophene unit
instead of the phenyl group. In that case, the mono-adduct 36 was exclusively formed in 97%
yield, despite the presence of two equivalents of TCNE. The same phenomenon as with bis-
ynamide 33 is at stake and is even reinforced by the fact that a thiophene is a better
conducting unit than a phenyl so that the effect of the presence of one TCBD on the second
triple bond is much stronger. This deactivation of the second conjugated triple bond is in
major contrast with what has been observed with other good activating groups,[4b,4c,23]
except with porphyrins where such a behavior has also been observed.[4d] On the contrary,
when using bis-ynamide 37 containing a triphenylamine spacer, the only isolated product
was bis-adduct 38 (92% yield). It can be explained by the fact that this unit itself is a strong
activating unit[21c,24] and that the distance between the two triple bonds (two phenyls and
one nitrogen atom) is longer than in the previous cases. The fact that multiple additions of
TCNE are possible on the same molecule offers interesting opportunities for the synthesis of
larger molecular systems, such as dendrimers[25] or polymers[26] in the future.
6
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10.1002/asia.201700353
Chemistry - An Asian Journal
NC
Ts
CN
Ts
N
Ts
N
Ts
TCNE (2 eq.)
N
N
CH2Cl2
r.t.
34
NC
33
CN
79%
Ts
Ts
NC
TCNE (2 eq.)
Ts
CN
Ts
N
N
S
Bn
N
Bn
S
CH2Cl2
r.t.
Bn
N
Bn
36
35
97%
NC
CN
Ts
Ts
NC
CN
NC
CN
Ts
N
Ts
N
Bn
Bn
N
N
Bn
TCNE (2 eq.)
Bn
NC
CN
38
N
N
NC
CN
CH2Cl2
r.t.
37
92%
Scheme 3. Evaluation of the reactivity of conjugated bis-ynamides with two equivalents of TCNE.
Most of the new TCBDs were characterized by cyclic voltammetry (figure S1). In general,
they exhibit two reversible reduction waves around -0.5 and -1.0 V vs ferrocene, which are
reminiscent to their electron super-accepting properties (Table 2). Both dicyanovinyl
moieties are subsequently reduced with one electron each time. Particularly noteworthy is
the case of compound 38 where two distinct waves were observed around -0.5 V vs
ferrocene, indicating a significant electronic coupling concerning the first reduction of the
two TCBD moieties. The second reduction wave around -1.0 V vs ferrocene does not exhibit
such a coupling since this reduction appears as one reversible two-electron wave.
Table 2. Reduction potentials of TCBDs 4, 6, 14, 18, 22, 24, 26, 30, 32, 34, 36 and 38. They
were measured from cyclic voltammograms presented in figure S3.
TCBD
4
E1/21 (V vs Fc)
-0.584
E1/22 (V vs Fc)
-1.015
-1.028
-1.065
-0.962
-1.172
-1.027
-1.134
-1.044
-1.021
-1.053
-0.905
-1.039
6
-0.611
-0.541
-0.623
-0.611
-0.570
-0.702
-0.483
-0.522
14
18
22
24
26
30
32
34
36
38
-0.542
-0.521
-0.520/-0.630
The UV-vis absorption properties of these new compounds are very dependent on the
nature of the group linked to the TCBD moieties. As indicated in figure 3, compounds 34, 36
and 38 exhibit very different absorption spectra in the visible range, with respective
7
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10.1002/asia.201700353
Chemistry - An Asian Journal
absorption maxima at 417, 468 and 604 nm. In particular, compound 38 absorbs in the
whole visible range, which allow to envisage different applications in opto-electronic devices.
The maximum absorption coefficients of these three species are comprised between 1.2 x
104 and 1.8 x 104 mol-1.L.cm-1 in this region.
Figure 2. UV-vis spectra of compounds 4 (in purple), 6 (in red), 30 (in green) and 32 (in blue)
in dichloromethane.
Figure 3. UV-vis spectra of compounds 34 (in blue), 36 (in red) and 38 (in black) in
dichloromethane.
To conclude, we have explored the scope and limitations of the reaction between
functionalized ynamides or arylynamines and TCNE. In most cases, TCBDs were obtained in
good to excellent yields. Only steric hindrance and conjugated triple bonds inhibit the
reaction. This study was crucial to evaluate the compatibility of this reactivity with the
elaboration of diversely functionalized structures. The possibility to run the reaction several
times on the same substrate allows us to potentially build more complex systems for diverse
8
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10.1002/asia.201700353
Chemistry - An Asian Journal
applications in different fields such as photovoltaic devices[27] or non-linear absorbers[28] to
exploit the exceptional electron-accepting properties of such TCBD moieties.
CCDC 1004149 (4), CCDC 1010768 (6), CCDC 1021633 (14), CCDC 1480922 (18), CCDC 960489
(20), CCDC 1406171 (24), CCDC 1429182 (26) and CCDC 1429183 (30) contain the
supplementary crystallographic data for this paper. These data can be obtained free of
charge
from
the
Cambridge
Crystallographic
Data
Centre
via
www.ccdc.cam.ac.uk/data_request/cif.
Experimental Section
General information
Reactions were monitored by thin layer chromatography (Merck TLC silica gel 60 F254 on
aluminum sheets) and visualized under UV irradiation at 254 nm or KMnO4 staining solution.
Compounds were purified by column chromatography using Geduran® silica gel 60 (0.040 –
0.063 nm). NMR spectra were recorded on Bruker Avance 400 MHz spectrometer. Spectra
were recorded in deuterochloroform referenced to residual CHCl3 (1H, 7.26 ppm) or CDCl3
(13C, 77.2 ppm). Chemical shifts (δ) are reported in ppm and coupling constants (J) are
reported in Hz. The following abbreviations are used to describe multiplicity: s-singlet, d-
doublet, t-triplet, dt-doublet of triplet, td-triplet of doublet, tt-triplet of triplet, ddd-doublet
of doublet of doublet, ddt-doublet of doublet of triplet and m-multiplet. HRMS experiments
were carried out on a Waters Q-Tof 2 (ESI) spectrometer.
Electrochemical experiments
Electrochemical Setup and Procedure
All electrochemical measurements were performed with an Autolab PGSTAT 12 (Metrohm)
and a conventional three-electrode system, comprising a glassy carbon (GC) electrode as
working electrode, a platinum wire as the auxiliary electrode, and SCE electrode (Metrohm)
as reference electrode. Ferrocene/ferrocenium redox couple was used as an internal
reference and all potential are indicated versus this redox couple for clarity. The GC
electrodes were purchased from CH Instrument, Inc. (Tx, USA) as 2-mm-diameter rods. The
electrodes were polished with grit. 4000 SiC paper (Struers) wetted with Milli-Q water. The
electrodes were thoroughly rinsed with Milli-Q water and acetone. The electrodes were
dried with an argon gas stream, before measurements.
Crystallography
All measurements were made in the x-scan technique on a CCD Saphire 3 Xcalibur (Oxford
Diffraction) or an APEXII Bruker-AXS diffractometer with graphite monochromatized Mo Kα
radiation. The structure was solved by direct methods.[29] The non-hydrogen atoms were
refined anisotropically by the full-matrix least-square techniques using the program
9
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10.1002/asia.201700353
Chemistry - An Asian Journal
SHELXL97.[30] All the hydrogen atoms bonded to C atoms were located geometrically and
treated using a riding model, with C–H = 0.95–1.00 Å and Uiso(H) = 1.2 or 1.5Ueq(C).
Synthesis
Compound 4
A solution of ynamide 3 (200 mg, 0.486 mmol) and TCNE (62.0 mg, 0.486 mmol) in CH2Cl2 (5
mL) was stirred at r.t. for 16 h. The mixture was concentrated under reduced pressure and
purified by column chromatography (pentane:EtOAc 8:2) to give TCBD 4 (260 mg, 0.482
mmol, 99%) as an orange solid. 1H NMR (400 MHz, CDCl3) δ 7.92 (d, J = 8.1 Hz, 1H), 7.87 (dt, J
= 8.7, 2.5 Hz, 3H), 7.73 – 7.59 (m, 3H), 7.47 (d, J = 1.8 Hz, 1H), 7.42 (d, J = 8.3 Hz, 2H), 7.33 –
7.25 (m, 2H), 7.09 (t, J = 7.8 Hz, 2H), 6.99 (dd, J = 8.2, 1.1 Hz, 2H), 4.74 (s, 2H), 2.49 (s, 3H).
13C NMR (100 MHz, CDCl3) δ 166.2, 158.7, 147.4, 135.2, 133.3, 132.4, 131.1, 130.9, 130.2,
129.9, 129.8, 129.6, 129.5, 129.3, 129.2, 128.4, 128.1, 127.6, 127.0, 124.3, 111.7, 111.6,
111.3, 111.2, 93.7, 81.9, 52.8, 21.9. HRMS (ESI) calculated for C32H21N5NaO2S [M+Na]+
562.13137, found 562.1315. UV-visible spectroscopy (CH2Cl2): λmax (log ε) = 263 (4.47), 349
(3.93) nm. Crystal data: Crystallogenesis: liquid diffusion from a CH2Cl2 solution into
cyclohexane; Formula: C32H21N5O2S, Temperature: 130(2) K, Wavelength: 0.71073 Å, Crystal
system: Monoclinic, space group, P21/c, Unit cell dimensions: a = 13.4821(2) Å, b =
16.6381(3) Å, c = 13.6268(2) Å, α = 90°, β = 119.292(2)°, γ = 90°, Volume: 2665.88(9) Å3, Z = 4,
Calculated density: 1.344 Mg/m3, Absorption coefficient 0.161 mm-1, F(000): 1120, Crystal
size: 0.224 x 0.169 x 0.109 mm3, Theta range for data collection: 2.99 to 27.00°, Limiting
indices: -17<=h<=16, -21<=k<=12, -17<=l<=17, Reflections collected / unique: 23487 / 5821
[R(int) = 0.0856], Completeness to theta = 27.00°, 99.9%, Absorption correction: None,
Refinement method: Full-matrix least-squares on F2, Data / restraints / parameters: 5821 / 0
/ 362, Goodness-of-fit on F2: 1.020, Final R indices [I>2sigma(I)]: R1 = 0.0641, wR2 = 0.1492,
R indices (all data) : R1 = 0.1092, wR2 = 0.1799, Largest diff. peak and hole : 0.615 and -0.460
e.A-3.
Compound 6
A solution of ynamide 5 (200 mg, 0.569 mmol) and TCNE (72.9 mg, 0.569 mmol) in CH2Cl2
(5.5 mL) was stirred at r.t. for 16 h. The mixture was concentrated under reduced pressure
and purified by column chromatography (pentane:EtOAc 7:3) to give TCBD 6 (266 mg, 0.555
mmol, 97%) as a yellow solid. 1H NMR (400 MHz, CDCl3) δ 7.93 (d, J = 8.5 Hz, 2H), 7.66 (dd, J
= 1.8, 0.5 Hz, 1H), 7.46 – 7.42 (m, 3H), 7.39 (dd, J = 5.0, 1.8 Hz, 3H), 7.27 (d, J = 3.9 Hz, 2H),
13
6.72 – 6.69 (m, 1H), 4.93 (s, 2H), 2.49 (s, 3H). C NMR (100 MHz, CDCl3) δ 157.1, 150.0,
148.2, 147.5, 145.2, 133.2, 132.5, 130.9, 129.6, 129.4, 128.9, 128.8, 123.5, 115.2, 111.9,
111.5, 111.5, 111.4, 83.3, 80.5, 53.7, 21.9. HRMS (ESI) calculated for C26H17N5NaO3S [M+Na]+
502.09498, found 502.0948. UV-visible spectroscopy (CH2Cl2): λmax (log ε) = 281 (4.31), 380
(4.25) nm. Crystal data: Crystallogenesis: liquid diffusion from a CH2Cl2 solution into
cyclohexane; Formula: C26H17N5O3S, Temperature: 250 K, Wavelength: 0.71073 Å, Crystal
system: Triclinic, space group: P-1, Unit cell dimensions: a = 8.0434(6) Å, b = 9.1866(8) Å, c =
17.657(10) Å, α = 92.121(7)°, β = 99.213(7)°, γ = 110.069(7)°, Volume: 1203.71(15) Å3, Z = 2,
Calculated density: 1.323 Mg/m3, Absorption coefficient 0.172 mm-1, F(000): 496, Crystal
size: 0.263 x 0.131 x 0.081 mm3, Theta range for data collection: 3.05 to 27.00°, Limiting
indices: -9<=h<=10, -11<=k<=11, -22<=l<=20, Reflections collected / unique: 9231 / 5247
10
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Chemistry - An Asian Journal
[R(int) = 0.0449], Completeness to theta = 27.00°, 99.8%, Absorption correction: None,
Refinement method: Full-matrix least-squares on F2, Data / restraints / parameters: 5247 / 0
/ 316, Goodness-of-fit on F2: 1.002, Final R indices [I>2sigma(I)]: R1 = 0.0634, wR2 = 0.1384,
R indices (all data) : R1 = 0.1216, wR2 = 0.1767, Largest diff. peak and hole : 0.317 and -0.238
e.A-3.
Compound 12
A solution of ynamide 11 (105 mg, 0.337 mmol) and TCNE (43.3 mg, 0.337 mmol) in CH2Cl2
(3.4 mL) was stirred at r.t. for 16 h. The mixture was concentrated under reduced pressure
and purified by column chromatography (pentane to pentane:EtOAc 8:2) to give TCBD 12
1
(140 mg, 0.318 mmol, 94%) as a yellow solid. H NMR (400 MHz, CDCl3) δ 7.76 (dt, J = 8.8,
1.6 Hz, 2H), 7.68 (tt, J = 7.2, 1.6 Hz, 1H), 7.58 – 7.63 (m, 2H), 7.53 – 7.56 (m, 2H), 7.43 (d, J =
8.0 Hz, 2H), 5.41 – 5.45 (m, 2H), 5.30 (ddt, J = 17.2, 9.6, 6.4 Hz, 1H), 4.28 (d, J = 6.4 Hz, 2H),
13
2.49 (s, 3H). C NMR (100 MHz, CDCl3) δ 166.2, 159.4, 147.4, 133.7, 133.0, 131.1, 130.9,
129.8, 129.4, 128.3, 128.1, 124.4, 111.8, 111.3, 111.2, 110.6, 93.0, 82.7, 53.2, 21.9. HRMS
(ESI) calculated for C24H17N5NaO2S [M+Na]+ 462.1001, found 462.1006; calculated for
C24H17KN5O2S [M+K]+ 478.0740, found 478.0766.
Compound 14
A solution of ynamide 13 (82.1 mg, 0.265 mmol) and TCNE (33.9 mg, 0.265 mmol) in CH2Cl2
(8 mL) was stirred overnight at r.t. for 16 h. The mixture was concentrated under reduced
pressure and purified by column chromatography (pentane:EtOAc 8:2) to give TCBD 12 (72.2
mg, 0.167 mmol, 64%) as a beige solid. 1H NMR (400 MHz, CDCl3) δ 7.75 – 7.71 (m, 2H), 7.68
– 7.64 (m, 3H), 7.60 – 7.55 (m, 2H), 7.43 (d, J = 8.0 Hz, 2H), 4.48 (d, J = 2.5 Hz, 2H), 2.70 (t, J =
2.5 Hz, 1H), 2.48 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 165.4, 158.2, 147.7, 133.9, 132.3, 131.2,
130.8, 129.9, 129.7, 128.1, 111.8, 111.6, 110.7, 110.1, 92.2, 85.1, 79.9, 73.7, 41.1, 21.9.
HRMS (ESI) calculated for C24H15N5NaO2S [M+Na]+ 460.0844, found 460.0844. Crystal data:
Crystallogenesis: liquid diffusion from a CH2Cl2 solution into cyclohexane; Formula:
C24H15N5O2S, Temperature: 140 K, Wavelength: 0.71073 Å, Crystal system: monoclinic, space
group: P 21/c, Unit cell dimensions: a = 8.6183(2) Å, b = 13.0256(3) Å, c = 20.2405(5) Å, α =
90°, β = 100.456(2)°, γ = 90°, Volume: 2234.44(9) Å3, Z = 4, Calculated density: 1.300 Mg/m3,
Absorption coefficient 0.176 mm-1, F(000): 904, Crystal size: 0.218 x 0.167 x 0.114 mm3,
Theta range for data collection: 3.188 to 26.999°, Limiting indices: -10<=h<=11, -16<=k<=16,
-25<=l<=25, Reflections collected / unique: 17112 / 4857 [R(int) = 0.0495], Completeness to
theta = 25.242°, 99.8%, Absorption correction: None, Refinement method: Full-matrix least-
squares on F2, Data / restraints / parameters: 4857 / 0 / 290, Goodness-of-fit on F2: 0.975,
Final R indices [I>2sigma(I)]: R1 = 0.0428, wR2 = 0.0920, R indices (all data) : R1 = 0.0709,
wR2 = 0.1079, Largest diff. peak and hole : 0.251 and -0.369 e.A-3.
Compound 18
A solution of ynamide 17 (88.3 mg, 0.228 mmol) and TCNE (29.2 mg, 0.228 mmol) in CH2Cl2
(2.3 mL) was stirred at r.t. for 16 h. The mixture was concentrated under reduced pressure
and purified by column chromatography (pentane to pentane:EtOAc 8:2) to give TCBD 12
(111 mg, 0.215 mmol, 94%) as an orange solid. 1H NMR (400 MHz, CDCl3) δ 8.02 (d, J = 8.5 Hz,
1H), 7.55 – 7.35 (m, 11H), 7.26 – 7.21 (m, 3H), 7.04 (d, J = 16.1 Hz, 1H), 4.88 (s, 2H), 2.48 (s,
3H). 13C NMR (100 MHz, CDCl3) δ 160.4, 157.7, 148.2, 147.7, 133.4, 132.9, 132.8, 132.7,
11
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130.9, 129.9, 129.7, 129.6, 129.5, 129.1, 128.4, 119.6, 111.6, 111.3, 111.0, 110.9, 88.6, 53.0,
52.9, 21.9. HRMS (ESI) calculated for C30H21N5NaO2S [M+Na]+ 538.1314, found 538.1321;
calculated for C30H21KN5O2S [M+K]+ 554.1053, found 554.1054. Crystal data:
Crystallogenesis: slow evaporation of a CH2Cl2 solution; Formula: C30H21N5O2S, Temperature:
295 K, Wavelength: 0.71073 Å, Crystal system: Monoclinic, space group, P 21/c, Unit cell
dimensions: a = 16.6788(6) Å, b = 17.3511(9) Å, c = 9.4234(5) Å, α = 90°, β = 94.829(2)°, γ =
90°, Volume: 2717.4(2) Å3, Z = 4, Calculated density: 1.260 g.cm3, Absorption coefficient
0.155 mm-1, F(000): 1072, Crystal size: 0.340 x 0.160 x 0.090 mm3, Theta range for data
collection: 3.197 to 27.483°, Limiting indices: -18≤h≤21, -13≤k≤22, -11≤l≤12, Reflections
collected / unique: 18561 / 6197 [R(int) = 0.0297], Completeness to theta = 99.5%,
Absorption correction: multi-scan, Refinement method: Full-matrix least-squares on F2, Data
/ restraints / parameters: 6197 / 0 / 248, Goodness-of-fit: 1.059, Final R indices [I>2sigma(I)]:
R1a = 0.0858, wR2b = 0.2778, R indices (all data) : R1a = 0.1445, wR2b = 0.3319, Largest diff.
peak and hole : 0.626 and -0.501 e.A-3.
Compound 20
The spectroscopic data are similar to those reported in the literature.[7] Crystal data:
Crystallogenesis: liquid diffusion from a CH2Cl2 solution into cyclohexane; Formula:
C26H17N5O2S2, Temperature: 100 K, Wavelength: 0.71073 Å, Crystal system: Monoclinic,
space group, P 21/n, Unit cell dimensions: a = 13.5158(3) Å, b = 10.2890(2) Å, c = 17.4575(3)
Å, α = 90°, β = 108.622(2)°, γ = 90°, Volume: 2300.61(8) Å3, Z = 4, Calculated density: 1.431
g.cm3, Absorption coefficient 0.267 mm-1, F(000): 1024, Crystal size: 0.268 x 0.154 x 0.147
mm, Theta range for data collection: 3.04 to 26.99°, Limiting indices: -14≤h≤17, -11≤k≤13, -
22≤l≤22, Reflections collected / unique: 17883 / 5013 [R(int) = 0.0246], Completeness to
theta = 99.8%, Absorption correction: none, Refinement method: Full-matrix least-squares
on F2, Data / restraints / parameters: 5013 / 0 / 316, Goodness-of-fit: 1.084, Final R indices
[I>2sigma(I)]: R1a = 0.0375, wR2b = 0.1057, R indices (all data) : R1a = 0.0494, wR2b = 0.1091,
Largest diff. peak and hole : 0.465 and -0.485 e.A-3.
Compound 22
A solution of ynamide 21 (200 mg, 0.651mmol) and TCNE (83 mg, 0.651 mmol) in CH2Cl2 (10
mL) was stirred at r.t. for 18 h. The mixture was concentrated under reduced pressure and
purified by column chromatography (petroleum ether:Et2O 1:0 to 1:1) to give TCBD 22 (285
mg, 0.650 mmol, 99%) as a brown solid. 1H NMR (400 MHz, CDCl3) δ 7.64 (t, J = 7.4 Hz, 1H),
7.49 (t, J = 7.9 Hz, 2H), 7.43 (dd, J = 8.5, 1.2 Hz, 2H), 7.38 – 7.34 (m, 3H), 7.10 – 7.13 (m, 2H),
4.87 (s, 2H), 1.45 (s, 9H). 13C NMR (100 MHz, CDCl3) 164.3, 161.4, 150.4, 134.5, 134.4, 130.3,
129.8, 129.6, 129.3, 128.8, 127.2, 111.6, 111.3, 111.0, 111.0, 90.3, 87.5, 82.3, 53.4, 27.7.
HRMS (ESI) calculated for C26H21N5NaO2 [M+Na]+ 458.15929, found 458.1591.
Compound 24
A solution of ynamide 23 (105 mg, 0.277 mmol) and TCNE (35 mg, 0.276 mmol) in CH2Cl2 (3
mL) was stirred at r.t. for 18 h. The mixture was concentrated under reduced pressure to
1
give TCBD 24 (140 mg, 0.276 mmol, 99%) as a bright yellow powder. H NMR (400 MHz,
CDCl3) δ 7.90 (d, J = 8.5 Hz, 2H), 7.49 (d, J = 8.1 Hz, 2H), 7.42 (t, J = 7.5 Hz, 1H), 7.31 (t, J = 7.7
12
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Chemistry - An Asian Journal
1
Hz, 2H), 7.10 (d, J = 7.1 Hz, 2H), 7.04 (d, J = 7.1 Hz, 4H), 4.79 (s, 2H), 2.52 (s, 3H). H NMR
{19F} (400 MHz, CDCl3) δ 7.89 (d, J = 8.1 Hz, 2H), 7.48 (d, J = 8.1 Hz, 2H), 7.42 (t, J = 7.6 Hz, 1H),
7.30 (t, J = 7.6 Hz, 2H), 7.09 (d, J = 7.6 Hz, 2H), 7.02 (s, 4H), 4.79 (s, 2H), 2.51 (s, 3H). 13C NMR
(100 MHz, CDCl3) δ 165.2 (t, JC-F = 128 Hz), 158.5, 147.5, 133.1, 131.5 (d, J = 9.4 Hz), 131.1,
131.0, 129.6, 129.5, 129.4, 128.2, 125.7 (d, J = 3.3 Hz), 117.2, 117.0, 111.5, 111.4, 111.0,
110.9, 93.6 (d, J = 1.3 Hz), 81.7, 52.6, 21.9. 19F NMR (376 MHz, CDCl3) δ -103.2. HRMS (ESI)
calculated for C28H18FKN5O2S [M+K]+ 546.08023, found 546.0801; calculated for
C28H18FN5NaO2S [M+Na]+ 530.10629, found 530.1058. Crystal data: Crystallogenesis: liquid
diffusion from a CH2Cl2 solution into cyclohexane; Formula: C31H24FN5O2S, Formula weight:
549.61, Temperature: 150 K, Wavelength: 1.54184 Å, Crystal system: Triclinic, space group:
P-1, Unit cell dimensions: a = 10.1604(3) Å, b = 11.6936(5) Å, c = 13.2402(5) Å, α =
115.472(4)°, β = 97.027(3)°, γ = 94.319(3)°, Volume: 1395.07(10) Å3, Z = 2, Calculated
density: 1.308 Mg/m3, Absorption coefficient: 1.397 mm-1, F(000): 572, Crystal size: 0.296 x
0.210 x 0.207 mm3, Theta range for data collection: 3.754 to 70.729°, Limiting indices: -
12<=h<=9, -14<=k<=14, -16<=l<=15, Reflections collected / unique: 13777 / 5330 [R(int) =
0.0230], Completeness to theta = 67.684°, 99.9 %, Absorption correction: Semi-empirical
from equivalents, Max. and min. transmission: 1.00000 and 0.90963, Refinement method:
Full-matrix least-squares on F2, Data / restraints / parameters: 5330 / 0 / 363, Goodness-of-
fit on F2: 1.054, Final R indices [I>2sigma(I)]: R1 = 0.0522, wR2 = 0.1413, R indices (all data) :
R1 = 0.0555, wR2 = 0.1473, Extinction coefficient: 0.0036(5), Largest diff. peak and hole:
1.888 and -0.387 e.A-3.
Compound 26
A solution of ynamide 25 (291 mg, 0.894 mmol) and TCNE (116 mg, 0.906 mmol) in CH2Cl2
(10 mL) was stirred at r.t. for 18 h. The mixture was first dark red and then turned orange
with white precipitate. The mixture was concentrated under reduced pressure and purified
by column chromatography (n-pentane:CH2Cl2 1:0 to 0:1) to give TCBD 26 (350 mg, 0.772
mmol, 86%) as a dark yellow solid. 1H NMR (400 MHz, CDCl3) δ 7.94 (dt, J = 8.4, 1.6 Hz, 2H),
7.48 (d, J = 8.0 Hz, 2H), 7.43 – 7.38 (m, 5H), 4.94 (s, 2H), 2.51 (s, 3H), 1.85 (tt, J = 8.5, 5.5 Hz,
13
1H), 1.14 – 1.08 (m, 2H), 0.99 – 0.94 (m, 2H). C NMR (100 MHz, CDCl3) δ 172.1, 159.5,
147.6, 133.2, 131.9, 131.1, 130.0, 129.6, 129.5, 128.5, 111.3, 111.3, 111.1, 110.4, 93.3, 79.7,
52.9, 22.0, 18.2, 11.8. HRMS (ESI) calculated for C25H19N5NaO2S [M+Na]+ 476.1157, found
476.1154. Crystal data: Crystallogenesis: liquid diffusion from a CH2Cl2 solution into
cyclohexane; Formula: C25H19N5O2S, Formula weight: 453.52, Temperature: 150 K,
Wavelength: 1.54184 Å, Crystal system: Triclinic, space group: P-1, Unit cell dimensions: a =
8.1626(4) Å, b = 8.7035(5) Å, c = 16.8844(8) Å, α = 91.953(4)°, β = 95.786(4)°, γ = 111.987(5)°,
Volume: 1103.25(11) Å3, Z = 2, Calculated density: 1.365 Mg/m3, Absorption coefficient:
1.578 mm-1, F(000): 472, Crystal size: 0.5653 x 0.0548 x 0.0418 mm3, Theta range for data
collection: 5.282 to 71.217°, Index ranges: -10<=h<=6, -10<=k<=10, -20<=l<=20, Reflections
collected: 8920, Independent reflections: 4217 [R(int) = 0.0274], Completeness to theta =
67.684°, 99.9 %, Absorption correction: Gaussian, Max. and min. transmission: 0.943 and
0.684, Refinement method: Full-matrix least-squares on F2, Data / restraints / parameters:
4217 / 0 / 299, Goodness-of-fit on F2: 1.031, Final R indices [I>2sigma(I)]: R1 = 0.0387, wR2 =
0.1037, R indices (all data) : R1 = 0.0452, wR2 = 0.1086, Extinction coefficient: n/a, Largest
diff. peak and hole: 0.641 and -0.407 e.A-3.
13
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Compound 30
A solution of ynamide 29 (43.0 mg, 0.161 mmol) and TCNE (23.0 mg, 0.178 mmol) in CH2Cl2
(10 mL) was stirred at r.t. for 18 h. The mixture was concentrated under reduced pressure
and purified by column chromatography (pentane:CH2Cl2 1:1 to CH2Cl2) to give TCBD 30
(53.0 mg, 0.134 mmol, 83%) as a purple solid. 1H NMR (400 MHz, CDCl3) δ 8.03 (ddd, J = 7.6,
1.4, 0.7 Hz, 2H), 7.75 – 7.71 (m, 2H), 7.69 – 7.64 (m, 1H), 7.54 (ddd, J = 8.3, 7.3, 1.3 Hz, 4H),
7.48 (td, J = 7.5, 1.0 Hz, 2H), 7.44 (dt, J = 8.2, 0.8 Hz, 2H). 13C NMR (100 MHz, CDCl3) δ 162.8,
156.3, 138.2, 135.1, 131.3, 130.4, 130.2, 127.6, 126.7, 125.6, 121.6, 112.7, 112.0, 111.2,
110.8, 110.7, 91.6, 83.3. HRMS (ESI) calculated for C26H14N5 [M+H]+ 396.12492, found
396.1249. UV-visible spectroscopy (CH2Cl2): λmax (log ε) = 279 (4.08), 315 (3.84), 511 (3.20)
nm. Crystal data: Crystallogenesis: liquid diffusion from a CH2Cl2 solution into cyclohexane,
Formula: C26H13N5, Temperature: 250 K, Wavelength: 1.54184 Å, Crystal system:
Orthorhombic, space group, P212121, Unit cell dimensions: a = 7.9516(3) Å, b = 12.0897(4) Å,
c = 21.5176(7) Å, α = 90°, β = 90°, γ = 90°, Volume: 2068.54(12) Å3, Z = 4, Calculated density:
1.270 Mg/m3, Absorption coefficient 0.621 mm-1, F(000): 816, Crystal size: 0.2708 x 0.0668 x
0.0367 mm3, Theta range for data collection: 4.194 to 72.112°, Limiting indices: -9<=h<=6, -
14<=k<=13, -26<=l<=25, Reflections collected / unique: 8409 / 4043 [R(int) = 0.0220],
Completeness to theta = 67.684°, 99.9 %, Absorption correction: Gaussian, Max. and min.
transmission: 0.979 and 0.910, Refinement method: Full-matrix least-squares on F2, Data /
restraints / parameters: 4043 / 0 / 280, Goodness-of-fit on F2: 1.052, Final R indices
[I>2sigma(I)]: R1 = 0.0339, wR2 = 0.0870, R indices (all data) : R1 = 0.0377, wR2 = 0.0870,
Absolute structure parameter: -0.1(2), Extinction coefficient: n/a, Largest diff. peak and hole:
0.089 and -0.176 e.A-3.
Compound 32
A solution of ynamide 31 (91.0 mg, 0.419 mmol) and TCNE (53.7 mg, 0.419 mmol) in CH2Cl2
(10 mL) was stirred at r.t. for 18 h. The mixture was concentrated under reduced pressure
and purified by column chromatography (pentane:CH2Cl2 1:1 to CH2Cl2) to give TCBD 32
(85.0 mg, 0.246 mmol, 59%) as a very slimy dark red liquid. 1H NMR (400 MHz, CDCl3) δ 7.82
(dt, J = 8.6, 1.8 Hz, 2H), 7.74 (ddd, J = 7.6, 2.0, 1.2 Hz, 1H), 7.68 – 7.60 (m, 4H), 7.40 – 7.32 (m,
2H), 7.32 – 7.28 (m, 1H), 7.00 (dd, J = 3.7, 0.8 Hz, 1H). 13C NMR (100 MHz, CDCl3): δ 162.2,
157.3, 135.4, 134.9, 131.2, 130.9, 130.4, 130.3, 127.6, 125.8, 125.7, 123.3, 114.0, 112.8,
111.7, 111.6, 111.0, 110.3, 90.4, 76.6. HRMS (ESI) calculated for C22H12N5 [M+H]+ 346.10927,
found 346.1096. UV-visible spectroscopy (CH2Cl2): λmax (log ε) = 258 (4.25), 336 (4.18), 443
(3.57) nm.
Compound 34
A solution of ynamide 33 (50 mg, 0.10 mmol) and TCNE (26 mg, 0.20 mmol) in CH2Cl2 (2 mL)
was stirred at r.t. for 16 h. The mixture was concentrated under reduced pressure and
purified by column chromatography (CH2Cl2:cyclohexane 9:1) to give TCBD 34 (49 mg, 0.080
mmol, 79%) as an orange-red solid. 1H NMR (400 MHz, CDCl3) δ 7.84 (d, J = 8.3 Hz, 2H), 7.74
(d, J = 8.4 Hz, 2H), 7.65 (d, J = 8.8 Hz, 2H), 7.51 (d, J = 8.8 Hz, 2H), 7.46 (d, J = 8.0 Hz, 2H), 7.41
13
(d, J = 8.0 Hz, 2H), 3.45 (s, 3H), 3.21 (s, 3H), 2.51 (s, 3H), 2.48 (s, 3H). C NMR (100 MHz,
CDCl3) δ 164.3, 163.6, 147.7, 145.5, 133.4, 132.3, 131.5, 131.1, 130.3, 130.2, 129.6, 128.3,
127.9, 111.9, 111.9, 110.8, 110.5, 90.7, 88.8, 80.2, 69.8, 41.2, 39.3, 27.1, 22.0, 21.9. HRMS
14
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10.1002/asia.201700353
Chemistry - An Asian Journal
(ESI) calculated for C32H24N6NaO4S2 [M+Na]+ 643.1198, found 643.1198. UV-visible
spectroscopy (CH2Cl2): λmax (log ε) = 276 (4.48), 313 (4.41), 416 (4.17) nm.
Compound 36
A solution of ynamide 35 (52 mg, 0.080 mmol) and TCNE (20 mg, 0.16 mmol) in CH2Cl2 (0.8
mL) was stirred at r.t. for 16 h. The reaction mixture was purified by column chromatography
1
(pentane:EtOAc 8:2 to 7:3) to give TCBD 36 (61 mg, 0.078 mmol, 98%) as a red solid. H
NMR (400 MHz, CDCl3) δ 7.75 (d, J = 8.3 Hz, 2H), 7.62 (d, J = 8.2 Hz, 2H), 7.31 – 7.03 (m, 14H),
6.73 – 6.64 (m, 2H), 4.74 (s, 2H), 4.46 (s, 2H), 2.31 (s, 6H). 13C NMR (100 MHz, CDCl3) δ 158.9,
154.4, 148.1, 146.1, 137.6, 136.2, 134.6, 134.0, 133.3, 132.4, 132.3, 131.9, 131.3, 130.6,
130.1, 130.0, 129.8, 129.3, 129.3, 129.2, 128.1, 126.4, 126.2, 112.8, 112.2, 111.7, 111.6,
95.4, 84.4, 65.5, 55.7, 53.2, 21.6, 21.5. HRMS (ESI) calculated for C42H30N6NaO4S3 [M+Na]+
801.1388, found 801.1376. UV-visible spectroscopy (CH2Cl2): λmax (log ε) = 285 (4.26), 337
(4.08), 468 (4.25) nm.
Compound 38
A solution of ynamide 37 (37 mg, 0.045 mmol) and TCNE (12 mg, 0.091 mmol) in CH2Cl2 (0.5
mL) was stirred at r.t. for 16 h. The reaction mixture was purified by column chromatography
1
(CH2Cl2 to CH2Cl2:Et2O 9:1) to give TCBD 38 (45 mg, 42 mmol, 92%) as a purple solid. H
NMR (400 MHz, CDCl3) δ 7.96 (d, J = 8.3 Hz, 4H), 7.55 (t, J = 7.6 Hz, 2H), 7.49 (d, J = 8.3 Hz,
4H), 7.43 (t, J = 7.6 Hz, 1H), 7.38 – 7.18 (m, 12H), 7.08 – 6.97 (m, 8H), 4.82 (s, 4H), 2.52 (s,
6H). 13C NMR (100 MHz, CDCl3) δ 164.0, 159.2, 150.8, 147.6, 144.5, 133.2, 131.4, 131.2,
131.1, 130.8, 130.0, 129.7, 129.4, 128.6, 127.8, 127.7, 123.9, 122.8, 112.2, 112.1, 111.6,
111.4, 90.0, 81.2, 52.7, 22.0. HRMS (ESI) calculated for C62H42N11NaO4S2 [M+H+Na]+
1090.26821, found 1090.26766. UV-visible spectroscopy (CH2Cl2): λmax (log ε) = 306 (5.05),
335 (4.98), 579 (4.49) nm.
Acknowledgments
M. Betou and A. Sallustrau thank the Région Bretagne for a post-doctoral grant. J.-C.
Guillemin is acknowledged for proofreading the manuscript.
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