Synthesis of 3-Amino-1-benzothiophene-1,1-diones by Alkyne Directed Hydroarylation and 1/N→3/C-Sulfonyl Migration

Article abstract of DOI:10.1002/ejoc.201801062

A completely regioselective and highly stereoselective palladium-catalyzed intramolecular hydroarylation of arenesulfonyl ynamines to benzothiazoles was developed. The presence of an electron-withdrawing group on the triple bond of the sulfonyl ynamine was crucial for the success of the reaction and our mechanistic studies suggest an alkyne-directed 5-exo-dig cyclization pathway. The products easily underwent photoinduced rearrangement to 3-amino-1-benzothiophene-1,1-diones (up to 35 % yields after two steps).

Full text of DOI:10.1002/ejoc.201801062

A Journal of
Accepted Article
Title: Synthesis of 3-Amino-1-benzothiophene-1,1-diones by Alkyne
Directed Hydroarylation and 1/N→3/C-Sulfonyl Migration
Authors: Ivan Bernar, Dani Blanco-Ania, Sophie Stok, Lia Sotorrios,
Enrique Gomez-Bengoa, and Floris P. J. T. Rutjes
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201801062
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European Journal of Organic Chemistry
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FULL PAPER
Synthesis of 3-Amino-1-benzothiophene-1,1-diones by Alkyne
Directed Hydroarylation and 1/N→3/C-Sulfonyl Migration
Ivan Bernar, Daniel Blanco-Ania, Sophie J. Stok, Lia Sotorríos, Enrique Gómez-Bengoa* and
[a]
[a]
[a]
[b]
[b]
Floris P. J. T. Rutjes*[a]
Abstract: A completely regioselective and highly stereoselective
palladium-catalyzed intramolecular hydroarylation of arenesulfonyl
ynamines to benzothiazoles was developed. The presence of an
electron-withdrawing group on the triple bond of the sulfonyl
ynamine was crucial for the success of the reaction and our
mechanistic studies suggest an alkyne-directed 5-exo-dig cyclization
Considering that compounds 1 react in the presence of
alkynophilic transition metals usually through -activation of the
triple bond, we anticipated that initial alkyne coordination might
direct an aromatic ortho-C–H activation followed by
a
stereocontrolled intramolecular hydroarylation (pathway A,
Scheme 1), similar to that of N-alkynyl indoles developed by
Park et al.[8] or alkynyl aryl ethers developed by Hiyama et al.[9]
Moreover, excitation of the obtained benzothiazolediones 2 with
light could trigger a [1,3]sigmatropic rearrangement of the
sulfonyl group by S–N bond cleavage[10] followed by colligation
to 3-amino-1-benzothiophene-1,1-diones 3 (pathway B, Scheme
pathway.
The
products
easily
underwent
photoinduced
rearrangement to 3-amino-1-benzothiophene-1,1-diones (up to 35%
yields after two steps).
[
11]
1).
In particular, our interest in these compounds was
Introduction
awakened because they are potential crop protecting agents,
and therefore beneficial for the ECHONET program we are part
of.[12] To the best of our knowledge, alkyne-directed 5-exo-dig
cyclizations of arenesulfonyl ynamines to 1,2-benzothiazole-1,1-
diones and its following rearrangement to 3-amino-1-benzothiophene-
Sulfonyl ynamines have recently emerged as a privileged class
of ynamides.[1] They are stable compounds, readily prepared[2]
and easy to handle. In addition, the polarized alkyne system of
sulfonyl ynamines shows excellent reactivity in a wide variety of
1,1-diones have not been yet explored.
3]
reactions
featuring
4]
-acid
catalysis,[
metal-catalyzed
cyclizations,[ cycloadditions and rearrangements[6] for the
synthesis of complex nitrogen-containing heterocycles and
natural products. With the idea of extending the chemistry of
these ynamines, we envisioned that arenesulfonyl ynamines 1
could be used as simple precursors for a single step, atom-
efficient synthesis of 1,2-benzothiazole-1,1-diones, key elements
of diverse biologically active compounds and useful reagents in
organic synthesis (Scheme 1).[7]
[5]
Results and Discussion
We initially investigated the behavior of sulfonyl ynamine 1a in
the presence of alkynophilic transition metals and Brønsted
acids (Table 1; for detailed information on the reaction
optimization, see the Supporting Information). The reaction took
place only with palladium-based catalysts. Thus, sulfonyl
ynamine 1a was converted to products (E/Z)-2a, 3, 4 and 5 in
the presence of Pd(OAc)
2
(5 mol %) in toluene at 100 °C for 18 h
(
Table 1, entry 1). The (E)-exocyclic alkylidene product 2a was
isolated in 21% yield after purification of the crude mixture by
neutral silica-gel column chromatography.
The structure of (E)-2a was unambiguously determined by NMR
spectroscopy and X-ray crystallography. This reaction also
showed degradation of sulfonyl ynamine 1a under the reaction
conditions forming N-phenyl sulfonamide 3, which was the main
byproduct of the ynamide cyclization. Compound 3 reacted
further with 1a to form Michael adduct 4, which was successfully
isolated after purification. Furthermore, sulfonyl ynamine 1a
underwent partial hydrogenation of the triple bond to yield
sulfonyl enamine 5 in a trace ammount.[13] The reaction also took
place in the presence of palladium(0), albeit in a much lower
Scheme 1. Syntheses and Applications of 1,2-Benzothiazole-1,1-diones and
3-Amino-1-benzothiophene-1,1-diones.
2
conversion compared to Pd(OAc) (entries 2 and 3). The use of
Pd(OAc)
2
and Zn, a catalytic system developed by Hiyama et al.
[
[
a]
Ivan Bernar, Daniel Blanco-Ania, Sophie J. Stok and Floris P. J. T.
Rutjes*
Institute for Molecules and Materials
for the cyclization of alkynyl aryl ethers,[ had no influence on
the yield of 2a (entry 4). These initial studies showed that
formation of benzothiazoledione 2a took place without any
further additives (e.g., NaOAc, entry 5). Finally, addition of
phosphine ligands promoted the cyclization. Bulky ligands led in
general to higher yields and better ratios of the stereoisomers
(entries 6 and 7).
9]
Radboud University
Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
E-mail: floris.rutjes@ru.nl (experimental part)
Lia Sotorríos and Enrique Gómez-Bengoa*
Department of Organic Chemistry I
University of the Basque Country (UPV/EHU)
P.O. Box 1072, 20080 Donostia-San Sebastián, Spain
E-mail: enrique.gomez@ehu.es (computational part)
b]
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European Journal of Organic Chemistry
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Table 1. Reaction Optimization.
ratio of products (%)[a]
entry
catalyst
additive
1a
27
30
43
23
28
13
10
2a
35
10
23
37
14
48
51
3
4
3
2
3
2
0
0
0
5
2
E/Z-ratio[a]
yield (E)-2a (%)[b]
1
2
3
4
5
6
7
Pd(OAc)
2
33
58
17
38
58
36
35
82:18
90:10
92:8
21
7
Pd(PPh
3
)
4
0
Pd(PPh
3
)
4
HOAc
Zn
14
0
14
20
8
Pd(OAc)
2
85:15
85:15
90:10
98:2
Pd(OAc)
2
NaOAc[c]
0
2
Pd(OAc) /PCy
3
3
27
37
Pd(OAc) /P(p-tol)
2
3
4
Reaction conditions: 1a (1.0 mmol), Pd catalyst (5 mol %), phosphine ligand (10 mol %), additive (10 mol %), PhMe (10.0 mL), 100 °C for 18 h. [a] Based on the
1
H NMR spectrum of the crude. [b] Isolated yield. [c] NaOAc (2.0 equiv).
Although the yields are relatively low, this unprecedented
intramolecular
hydroarylation
reaction
is
completely
regioselective and highly stereoselective: (E)-exocyclic 1,2-
benzothiazole-1,1-dione 2a is the major isomer with an E/Z-ratio
of up to 98:2, confirmed by NOE studies in all cases.
With these results in hand, we focused our attention on the
scope and limitations of the reaction varying the substituents on
1
the alkyne terminus (R ), on the aromatic ring of the sulfonamide
2
3
group (R ) and on the nitrogen (R ) for the hydroarylation of
sulfonyl ynamines 1a−k (Scheme 2). Notably, the presence of
an electron-withdrawing group on the triple bond, e.g., ester or
ketone, was essential for the success of the hydroarylation.
Thus, sulfonyl ynamines with a ketone showed similar reactivity
to sulfonyl ynamine 1a proceeding with exclusive regioselectivity
and excellent stereoselectivity (2b−2c). In stark contrast, when
the reaction was performed with sulfonyl ynamines 1d−1f (R = H,
SiMe
to
3
, Ph) no cyclization was detected and only decomposition
was observed. Changing the conditions (solvent,
3
temperature, Pd catalyst, addition of base) did not lead to
products 2d−2f either.
Next, a series of electronically different sulfonyl ynamines were
employed for this transformation. To our delight, we observed no
significant difference in the reaction efficiency when changing
the substituents at the aryl group of the sulfonamide. 1,2-
Benzothiazole-1,1-diones (2g−i) were obtained in comparable
yields and also with complete regioselectivity and with excellent
stereoselectivity. Finally, sulfonyl ynamines 1j and 1k were
subjected to the reaction conditions to compare the reactivity of
compounds with different substitution on the nitrogen.
Compound 1j formed product 2j in 31% yield and compound 1k
resulted in the formation of a mixture of 2k (>99:1 E/Z ratio) and
6
in 26 and 10% yield, respectively.[14]
Scheme 2. Scope of sulfonyl ynamines for intramolecular hydroarylation.
Reaction conditions: 1 (1.0 mmol), Pd(OAc)
PhMe (10.0 mL), 100 °C for 18 h. [a] Isolated yield. [b] Based on the H NMR
2
(5 mol %), P(p-tol)
3
(10 mol %),
1
spectrum of the crude mixture.
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European Journal of Organic Chemistry
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Figure 1. Computed pathway for cyclization of 1l. Free energies (298 K) with respect to starting materials are shown in kcal/mol.
For a better understanding of the reaction mechanism, we
investigated the reaction pathway with DFT calculations (Figure
stereoselective manner (as proposed in Scheme 2), however the
major product further undergoes partial isomerization under the
reaction conditions.
1). The most logical mechanistic scenario for the reaction of
sulfonyl ynamine 1l and Pd(OAc) would involve coordination of
2
the Pd(II) species to the substrate, as in 7, followed by an
alkyne-directed concerted deprotonation-metalation sequence
(
CDM).[15] Thus, calculations indicate transition state TS1 in
2
which one of the acetate groups is acting both as a  ligand and
as
a base. The proton abstraction presents the highest
activation barrier within the catalytic cycle (22.6 kcal/mol), and
therefore should be considered as the rate-determining step of
the reaction. Additionally, ortho-C–H activation in TS1 proceeds
Scheme 3. Equilibration between (E)- and (Z)-isomers of 2a. Free energies
(298 K) are shown in kcal/mol.
much slower for the alkyne–H and alkyne–SiMe
3
substructures
(
24.5 and 24.6 kcal/mol, for 1d and 1e, respectively) compared
to the corresponding alkyne–CO
difference between these barrier values is >2.5 kcal/mol
corresponding to more than 100 times slower reaction rate,
2
Me substructure 1l. The
Finally, 1,2-benzothiazole-1,1-diones 2 underwent a previously
unexplored photoinduced rearrangement to 3-amino-1-
benzothiophene-1,1-diones 12 while being irradiated with UV
which is in agreement with the experimental results. Consequently, light (300 nm; Scheme 4).
the intermediate 8 performs a carbopalladation to the CC triple
bond through TS2, leading to intermediate 9. Also this step was
predicted to be a few kcal/mol higher for sulfonyl ynamines 1d
and 1e (16.0 and 14.2 kcal/mol respectively) than for sulfonyl
ynamine 1l (11.2 kcal/mol). Further protonation of the "push-pull"
alkenyl–Pd(II) species
9 with acetic acid forms an enol
intermediate 10, with almost free rotation around the exocyclic
C–C bond. We found that the enol structure 10 lies 12.9 kcal/mol
higher in energy than palladium species 9, confirming the
feasibility of this or related isomerization processes. The final
protodemetalation with acetic acid renders the major product
(
E)-2a and recovers the active Pd(II)-acetate species.
Our DFT calculations further reveal that the (E)-isomer is the
most stable isomer (2.5 kcal/mol lower in energy than the (Z)-
isomer, Scheme 3). To validate this result, (E)-2a and (Z)-2a
were subjected independently to the same experimental
conditions. We observed the formation of an 85:15 E/Z mixture
of isomers after 18 h of reaction time. These results suggest that
the cyclization of 1a might proceed in an exceptional
Scheme 4. Photochemical rearrangement of 1,2-benzothiazole-1,1-diones 2
to 3-amino-1-benzothiophene-1,1-diones 12. Reaction conditions: 2 (0.1 mmol),
CH CN (10.0 mL), h (300 nm), 24 h. [a] Isolated yield.
3
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European Journal of Organic Chemistry
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Thus, when either stereoisomer of 2a or the mixture of both was
detection by UV absorption (254 nm) where applicable, and by dipping
into a solution of aqueous KMnO /Na CO /NaOH solution followed by
4 2 3
charring at ca. 150 °C. IR spectra were recorded on a Bruker Tensor 27
FTIR spectrometer.
exposed to irradiation at 50 °C for 24 h,
a complete
photochemical conversion to 3-amino-1-benzothiophene-1,1-
dione 12a was observed. Furthermore, to show the scope of this
transformation, several 1,2-benzothiazoledione derivatives were
subjected to the same reaction conditions. The corresponding
products 12b−12d were obtained in excellent yields in all cases.
The structure of the products was confirmed by selNOE
spectroscopy and X-ray crystallography of 12a and 12d. We
General Procedure for the Synthesis of Sulfonamides. Sulfonamides
3
and S1–S5 were prepared by the literature procedure reported by
[16]
Murphy et al. The sulfonyl chloride (11 mmol, 1.1 equiv) was added to
a solution of the amine (10 mmol, 1 equiv) and pyridine (950 mg, 12
mmol, 1.2 equiv) in CH Cl (30 mL) portion-wise with stirring. The
2
2
also propose a plausible mechanism on the basis of previously
reported photoinduced cleavage of sulfonamides.[7] This
reaction mixture was then stirred at 23 ° for 12 h before evaporation of
CH Cl and quenching with an aqueous NaOH solution (2 N, 100 mL).
2
2
The aqueous solution was rinsed with diethyl ether (2 × 50 mL) then
acidified with concentrated HCl and extracted with CH Cl (3 × 50 mL).
[
1,3]sigmatropic rearrangement entails a homolytic cleavage of
2
2
the sulfonamide S–N bond of 1,2-benzothiazoledione 2, followed
by recombination of the resulting sulfinate radical with the C-
terminus of the enaminyl radical (13). Subsequent
tautomerization of the formed imine 14 results in 3-amino-1-
benzothiophene-1,1-dione 12.
The combined organic washings were dried over sodium sulfate and
concentrated in vacuo. The obtained crude product was used directly in
the next step without further purification.
N-Phenylbenzenesulfonamide (S1). Sulfonamide S1 was prepared from
aniline (0.9 g, 10 mmol) and benzenesulfonyl chloride (1.9 g, 11 mmol)
according to the general procedure and obtained in 90% yield as a white
1
solid. H NMR [400 MHz, δ (ppm), CDCl
3
]: 6.58 (br s, 1 H), 7.02–7.09 (m,
Conclusions
2
7
1
H), 7.09–7.18 (m, 1 H), 7.20–7.29 (m, 2 H), 7.40–7.48 (m, 2 H), 7.50–
.58 (m, 1 H), 7.72–7.79 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
21.6, 125.4, 127.3, 129.3, 129.7, 133.0, 136.5, 139.0. These data were
in accordance to those reported in the literature.
3
]:
In summary, we have demonstrated a completely regioselective
and highly stereoselective intramolecular hydroarylation of
sulfonyl ynamines. This method opens an easy access to
benzothiazole heterocycles, valuable scaffolds in medicinal and
organic synthesis. Our mechanistic studies suggest an alkyne-
directed 5-exo-dig intramolecular cyclization pathway, where the
presence of an electron-withdrawing group at the triple bond
was key for the success of the reaction. Moreover, we have
discovered the first example of photoinduced rearrangement of
[17]
4
-Methyl-N-phenylbenzenesulfonamide (3). Sulfonamide 3 was prepared
from aniline (0.9 g, 10 mmol) and 4-methylbenzenesulfonyl chloride (2.1
g, 11 mmol) according to the general procedure and obtained in 92%
yield as a white solid. H NMR [400 MHz, δ (ppm), CDCl
.61 (br s, 1 H), 7.02–7.10 (m, 2 H), 7.12–7.25 (m, 5 H), 7.62–7.68 (m, 2
H). 13C NMR [101 MHz, δ (ppm), CDCl
29.2, 129.6, 136.0, 136.4, 143.9. These data were in accordance to
those reported in the literature.[
1
3
]: 2.35 (s, 3 H),
6
3
]: 21.6, 121.5, 125.1, 127.5,
1
1,2-benzothiazole-1,1-diones
to
form
3-amino-1-
17]
benzothiophene-1,1-dione derivatives in excellent yields.
Optimization studies that broaden the synthetic scope and
applications of the reaction are currently under investigation.
4
-Methoxy-N-phenylbenzenesulfonamide (S2). Sulfonamide S2 was
prepared from aniline (0.9 g, 10 mmol) and 4-methoxybenzenesulfonyl
chloride (2.3 g, 11 mmol) according to the general procedure and
obtained in 81% yield as a white solid. 1H NMR [400 MHz, δ (ppm),
Experimental Section
CDCl
H), 7.18–7.31 (m, 2 H), 7.59–7.78 (m, 2 H). 13C NMR [101 MHz, δ
ppm), CDCl ]: 55.7, 114.3, 121.6, 125.2, 129.4, 129.5, 130.7, 136.9,
3
]: 3.82 (s, 3 H), 6.70 (br s, 1 H), 6.81–6.96 (m, 2 H), 7.03–7.15 (m,
3
(
3
General Information. Reagents were obtained from commercial
suppliers and were used without purification. Standard syringe
techniques were applied for the transfer of dry solvents and air- or
moisture-sensitive reagents. All inert reactions were carried out under a
nitrogen atmosphere using flame-dried flasks. If stated, reactions were
1
63.2. These data were in accordance to those reported in the
literature.[
17]
4-Nitro-N-phenylbenzenesulfonamide (S3). Sulfonamide S3 was
prepared from aniline (0.9 g, 10 mmol) and 4-nitrobenzenesulfonyl
chloride (2.4 g, 11 mmol) according to the general procedure and
performed in Biotage Initiator+ Microwave Synthesizer under a nitrogen
atmosphere. 1H and 13C NMR spectra were recorded at 298 K on a
1
Varian Inova 400 MHz or Bruker 500 MHz spectrometer in the solvent
indicated. Chemical shifts are given in parts per million (ppm) with
respect to tetramethylsilane (0.00 ppm) as internal standard for 1H NMR;
obtained in 94% yield as a light yellow solid. H NMR [400 MHz, δ (ppm),
CDCl
8.30 (m, 2 H).
3
]: 6.02 (br s, 1 H), 7.07–7.32 (m, 5 H), 7.89–7.93 (m, 2 H), 8.22–
13C NMR [101 MHz, δ (ppm), CDCl ]: 122.4, 124.3, 126.6,
3
(77.16 ppm) as internal standard for 13C NMR. Coupling
128.7, 129.9, 135.2, 144.5, 150.3. These data were in accordance to
those reported in the literature.[18]
and CDCl
3
constants are reported as J values in hertz (Hz). 1H NMR data are
reported as follows: chemical shift (ppm), multiplicity (s = singlet, d =
doublet, quint = quintet, t = triplet and combination of them), coupling
constants (Hz) and integration. All NMR signals were assigned on the
basis of 1H NMR, 13C NMR, gCOSY, gHSQC, gHMBS and NOESY
experiments. Mass spectra were recorded on a JEOL AccuTOF CS
JMST100CS (ESI) mass spectrometer. Automatic flash column
chromatography was performed using Biotage Isolera Spektra One,
using SNAP cartridges (Biotage, 30–100 µm, 60 Å), 10–50 g. Analysis by
TLC was conducted on Silica gel F254 (Merck KGaA) plates with
N-Benzyl-4-methylbenzenesulfonamide (S4). Sulfonamide S4 was
prepared from benzylamine (1.07 g, 10 mmol) and 4-
methylbenzenesulfonyl chloride (2.1 g, 11 mmol) according to the
1
general procedure and obtained in 91% yield as a white solid. H NMR
[400 MHz, δ (ppm), CDCl
(br t, J = 6.5 Hz, 1 H), 7.05–7.21 (m, 5 H), 7.27–7.31 (m, 2 H), 7.64–7.71
(m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 21.7, 48.3, 128.3, 128.4,
3
]: 2.32 (s, 3 H), 4.02 (d, J = 6.5 Hz, 2 H), 6.74
3
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European Journal of Organic Chemistry
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1
29.1, 129.5, 130.9, 139.1, 139.2, 144.3. These data were in accordance
129.83, 129.84, 137.0, 144.1, 150.6. FTIR [ν
1171, 1348, 1530, 3082, 3102. HRMS (ESI-TOF) m/z: [M + H] calcd. for
̅
(cm−1)]: 685, 738, 1094,
to those reported in the literature.[19]
+
14 2 2 4
C H12Cl N O S 372.9817, found 372.9834.
N,4-Dimethylbenzenesulfonamide (S5). Sulfonamide S5 was prepared
from methylamine hydrochloride (0.68 g, 10 mmol) and 4-
methylbenzenesulfonyl chloride (2.1 g, 11 mmol) according to the
N-Benzyl-N-[(E)-1,2-dichlorovinyl]-4-methylbenzenesulfonamide (S10).
Column chromatography (heptane/AcOEt 40:1 → 4:1) afforded the
1
general procedure and obtained in 89% yield as brown oil. H NMR [400
product S10 as a white solid (73%). R
F
(silica gel, heptane/AcOEt 10:1):
]: 2.47 (s,
1
MHz, δ (ppm), CDCl
H), 7.29–7.33 (m, 2 H), 7.70–7.76 (m, 2 H). 13C NMR [101 MHz, δ
ppm), CDCl ]: 21.2, 29.5, 127.3, 129.8, 135.7, 143.3. These data were
in accordance to those reported in the literature.
3
]: 2.42 (s, 3 H), 2.62 (d, J = 5.5 Hz, 3 H), 4.45 (br s,
0.23 (UV, KMnO
4
solution). H NMR [400 MHz, δ (ppm), CDCl
3
1
3 H), 3.72–4.81 (br s, 2 H), 6.27 (s, 1 H), 7.28–7.34 (m, 5 H), 7.32–7.37
(m, 2 H), 7.80–7.86 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 21.7,
(
3
3
[
20]
52.0, 121.7, 128.23, 128.28, 129.3, 129.4, 129.8, 133.5, 135.3, 144.7.
These data were in accordance to those reported in the literature.[21]
General Procedure for the Synthesis of 1,2-Dichlorovinyl
Sulfonamides. 1,2-Dichlorovinyl sulfonamides S6–S11 were prepared
by the literature procedure reported by Anderson et al.[21] The
sulfonamide (8 mmol, 1.0 equiv) was added dropwise at 0 °C to a
suspension of sodium hydride (670 mg, 60% dispersion in mineral oil,
N-[(E)-1,2-Dichlorovinyl]-N,4-dimethylbenzenesulfonamide
Column chromatography (heptane/ AcOEt 40:1 → 10:1) afforded the
(S11).
product S11 as brown oil (64%). R
F
(silica gel, heptane/AcOEt 10:1): 0.13
]: 2.45 (s, 3 H),
1
(UV, KMnO
4
solution). H NMR [400 MHz, δ (ppm), CDCl
3
16.8 mmol, 2.1 equiv) in DMF (30 mL) and the reaction mixture was
2.94 (s, 3 H), 6.39 (s, 1 H), 7.31–7.37 (m, 2 H), 7.79–7.85 (m, 2 H). 13C
NMR [101 MHz, δ (ppm), CDCl ]: 21.7, 37.9, 121.4, 127.8, 129.2, 129.5,
132.4, 143.2. FTIR [ν
(cm−1)]: 693, 722, 1084, 1160, 1333, 1498, 2986,
allowed to warm to 23 ° in 2 h. Trichloroethene (800 µL, 8.8 mmol, 1.1
equiv) was slowly added to this solution, which was after stirred at 50 °C
for 16 h. After cooling to 23 °, the reaction mixture was quenched with
water (300 mL) and extracted with AcOEt (3 × 50 mL). The combined
organic washings were dried over sodium sulfate, concentrated in vacuo
and the crude residue was purified by column chromatography as
indicated. The E-configuration of the obtained products including the new
compounds was assigned based on the 1H NMR spectra and X-ray
crystallography data known from the literature.[21]
3
̅
10 2 2
+ C H13Cl NO S
H]+ calcd. for
3012. HRMS (ESI-TOF) m/z: [M
279.9966, found 279.9983.
General Procedure A for the Syntheses of Sulfonyl Ynamines.
Sulfonyl Ynamines 1a, 1d, 1e, 1g, 1h, 1i, 1j and 1k were prepared by the
literature procedure reported by Davies et al.[23] nButyllithium (3.8 mL, 1.6
M in THF, 6 mmol, 2.1 equiv) was slowly added to a stirred solution of
1,2-dichlorovinyl sulfonamide (5 mmol, 1.0 equiv) in THF (30 mL) under
N-[(E)-1,2-Dichlorovinyl]-N-phenylbenzenesulfonamide (S6). Column
chromatography (heptane/AcOEt 40:1 → 10:1) afforded product S6 as a
an argon atmosphere at −78 °C. After stirring for 1 h, the lithium acetylide
was treated with the corresponding electrophile and stirred for 1 h at
−78 °C. The mixture was allowed to warm to 23 °C and stirred for 2–3 h.
The reaction mixture was quenched with brine (100 mL) and extracted
with Et O (2 × 50 mL). The combined organic washings were dried over
2
sodium sulfate, concentrated in vacuo and the crude residue was purified
by column chromatography as indicated.
yellow oil (72%). R
solution). 1H NMR [400 MHz, δ (ppm), CDCl
m, 5 H), 7.43–7.50 (m, 2 H), 7.58–7.63 (m, 1 H), 7.75–7.80 (m, 2 H). 13C
NMR [101 MHz, δ (ppm), CDCl ]: 120.7, 128.6, 128.78, 128.79, 129.2,
29.4, 130.6, 133.6, 137.6, 138.5. FTIR [ν
(cm−1)]: 811, 1089, 1169, 1363,
489, 2934, 3086. HRMS (ESI-TOF) m/z: [M
H]+ calcd. for
NO S 327.9966, found 327.9954.
F
(silica gel, heptane/AcOEt 10:1): 0.34 (UV, KMnO
4
3
]: 6.46 (s, 1 H), 7.30–7.39
(
3
1
1
̅
+
14
C H13Cl
2
2
General Procedure B for the Syntheses of Sulfonyl Ynamines.
Sulfonyl Ynamines 1b and 1c were prepared by the literature procedure
reported by Wolf et al.[24] Sulfonyl ynamine 1d (1.0 g, 3.7 mmol, 1.0
equiv), CuI (70 mg, 0.37 mmol, 0.1 equiv) and N,N-diisopropylethylamine
(1.5 mL, 7.4 mmol, 2.0 equiv) were dissolved in chloroform (20 mL)
under a nitrogen atmosphere. After 30 min, the acyl chloride (5.6 mmol,
1.5 equiv) was added, and the mixture was stirred until completion as
determined by TLC. Solvent was removed in vacuo and the crude
residue was purified by column chromatography as indicated.
N-[(E)-1,2-Dichlorovinyl]-4-methyl-N-phenylbenzenesulfonamide
(S7).
Column chromatography (heptane/AcOEt 40:1 → 10:1) afforded the
product S7 as a white solid (91%). R
F
(silica gel, heptane/AcOEt 1:1):
]: 2.41 (s,
1
0
3
2
1
.70 (UV, KMnO
4
solution). H NMR [400 MHz, δ (ppm), CDCl
3
H), 6.46 (s, 1 H), 7.19–7.27 (m, 2 H), 7.30–7.39 (m, 5 H), 7.61–7.69 (m,
H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 21.7, 120.5, 128.6, 128.8,
29.1, 129.3, 129.4, 130.7, 135.6, 137.7, 144.6. These data were in
accordance to those reported in the literature.[22]
3
General Procedure C for the Syntheses of Sulfonyl Ynamines.
Sulfonyl Ynamine 1f was prepared by the literature procedure reported
by Hsung et al.[25] Sulfonyl ynamine 1d (1.0 g, 3.7 mmol, 1.0 equiv),
N-[(E)-1,2-Dichlorovinyl]-4-methoxy-N-phenylbenzenesulfonamide (S8).
Column chromatography (heptane/AcOEt 40:1 → 10:1) afforded the
product S8 as a yellow oil (87%). R
F
(silica gel, heptane/AcOEt 7:1): 0.23
]: 3.86 (s, 3 H),
iodobenzene (830 mg, 4.1 mmol, 1.1 equiv) and Pd(PPh
3 4
) (214 mg,
1
(UV, KMnO
4
solution). H NMR [400 MHz, δ (ppm), CDCl
3
0.185 mmol, 0.05 equiv) were dissolved in Et N/toluene mixture (2:1, 36
3
6
.45 (s, 1 H), 6.86–6.98 (m, 2 H), 7.29–7.41 (m, 5 H), 7.65–7.73 (m, 2 H).
]: 55.6, 113.9, 120.4, 128.7, 129.0,
29.3, 130.0, 130.7, 130.9, 137.8, 163.6. FTIR [ν
(cm−1)]: 809, 1089,
mL) under a nitrogen atmosphere. The solution was stirred at 23 °C for
10 min, and CuI (11 mg, 0.06 mmol, 0.015 equiv) was then added. After
heating the reaction mixture at 60 °C for 12 h, the mixture was diluted
with AcOEt, filtered through a diatomaceous earth pad, and concentrated
in vacuo. The resulting crude residue was purified by silica gel flash
column chromatography as indicated.
1
3C NMR [101 MHz, δ (ppm), CDCl
3
1
1
̅
160, 1261, 1361, 1489, 1594, 2945, 3085. HRMS (ESI-TOF) m/z: [M +
+
H] calcd. for C15
H15Cl
2 3
NO S 358.0071, found 358.0092.
N-[(E)-1,2-Dichlorovinyl]-4-nitro-N-phenylbenzenesulfonamide
(S9).
Column chromatography (heptane/AcOEt 20:1 → 2:1) afforded the
Ethyl
3-(4-methyl-N-phenylbenzenesulfonamido]propanoate
(1a).
product S9 as a white solid (82%). R
F
(silica gel, heptane/AcOEt 10:1):
]: 6.51 (s,
Sulfonyl ynamine 1a was prepared according to general procedure A
using 1,2-dichlorovinyl sulfonamide S7 (1.7 g, 5.0 mmol). The lithium
acetylide was treated with freshly distilled ethyl chloroformate (714 µL,
7.5 mmol) at −78 °C for 15 min and at 23 °C for 2 h. Column
1
0
.11 (UV, KMnO
4
solution). H NMR [400 MHz, δ (ppm), CDCl
3
1
H), 7.31–7.49 (m, 5 H), 7.81–7.99 (m, 2 H), 8.21–8.40 (m, 2 H). 13C
]: 121.3, 124.0, 128.7, 129.72, 129.77,
NMR [101 MHz, δ (ppm), CDCl
3
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European Journal of Organic Chemistry
10.1002/ejoc.201801062
FULL PAPER
chromatography (heptane/AcOEt 40:1 → 10:1; silica gel was washed
2887, 3034. HRMS (ESI-TOF) m/z: [M + H]+ calcd. for C18
H23NO SSi
2
with 1% Et
3
N in heptane before being used for column chromatography)
344.1141, found 344.1134.
afforded the product 1a as
a
white solid (82%).
R
F
(silica gel,
1
heptane/AcOEt 10:1): 0.11 (UV, KMnO
ppm), CDCl
4
solution). H NMR [400 MHz, δ
4-Methyl-N-phenyl-N-(phenylethynyl)benzenesulfonamide (1f). Sulfonyl
(
3
]: 1.31 (t, J = 7.1 Hz, 3 H), 2.46 (s, 3 H), 4.24 (q, J = 7.1 Hz,
H), 7.16–7.23 (m, 2 H), 7.29–7.34 (m, 2 H), 7.34–7.38 (m, 3 H), 7.58–
.67 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.2, 21.8, 61.7,
ynamine 1f was prepared according to general procedure C. Column
chromatography (heptane/AcOEt 20:1 → 10:1; silica gel was washed
2
7
6
3
with 1% Et
afforded the product 1f as a light yellow solid (80%). R
solution). 1H NMR [400 MHz, δ
heptane/AcOEt 10:1): 0.27 (UV, KMnO
ppm), CDCl ]: 2.45 (s, 3 H), 7.27–7.36 (m, 9 H), 7.36–7.42 (m, 3 H),
7.61–7.65 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 21.7, 70.6,
83.2, 122.7, 126.5, 126.3, 128.1, 128.32, 128.34, 129.0, 129.5, 131.4,
132.9, 139.0, 145.1. These data were in accordance to those reported in
the literature.[27]
3
N in heptane before being used for column chromatography)
6.6, 82.2, 126.5, 128.4, 129.3, 129.6, 130.0, 133.1, 137.5, 145.9, 154.8.
F
(silica gel,
These data were in accordance to those reported in the literature.[23]
4
(
3
N-(4,4-Dimethyl-3-oxopent-1-yn-1-yl)-4-methyl-N-phenylbenzenesulfon-
amide (1b). Sulfonyl ynamine 1b was prepared according to general
procedure B. The reaction with pivaloyl chloride (690 µL, 6.6 mmol) was
performed at 30 °C for 18 h. Column chromatography (toluene; silica gel
3
was washed with 1% Et
3
N in heptane before being used for column
chromatography) afforded the product 1b as a light yellow oil (79%). R
F
Ethyl
3-(N-phenylbenzenesulfonamido)propanoate
(1g).
Sulfonyl
(
(
(
(
silica gel, toluene): 0.32 (UV, KMnO
ppm), CDCl ]: 1.20 (s, 9 H), 2.40 (s, 3 H), 7.16–7.20 (m, 2 H), 7.24–7.28
m, 2 H), 7.30–7.34 (m, 3 H), 7.53–7.59 (m, 2 H). 13C NMR [101 MHz, δ
ppm), CDCl ]: 21.6, 26.3, 44.5, 73.6, 89.1, 126.3, 128.3, 129.1, 129.3,
29.7, 133.2, 127.4, 145.6, 193.2. These data were in accordance to
those reported in the literature.[24]
solution). 1H NMR [400 MHz, δ
4
ynamine 1g was prepared according to general procedure A using 1,2-
dichlorovinyl sulfonamide S6 (1.6 g, 5.0 mmol). The lithium acetylide was
treated with freshly distilled ethyl chloroformate (714 µL, 7.5 mmol) at
3
3
−
78 °C for 15 min and at 23 °C for 2 h. Column chromatography (toluene;
1
silica gel was washed with 1% Et N in heptane before being used for
column chromatography) afforded the product 1g as a white solid (74%).
3
1
R
F
(silica gel, toluene): 0.35 (UV, KMnO
(ppm), CDCl
7.22 (m, 2 H), 7.30–7.41 (m, 3 H), 7.49–7.58 (m, 2 H), 7.64–7.73 (m, 1
H), 7.74–7.80 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.2, 61.8,
66.5, 81.9, 126.6, 128.3, 129.27, 129.29, 129.5, 134.6, 135.8, 137.0,
4
solution). H NMR [400 MHz, δ
4-Methyl-N-(3-oxo-3-phenylprop-1-yn-1-yl)-N-phenylbenzenesulfonamide
3
]: 1.31 (t, J = 7.1 Hz, 3 H), 4.24 (q, J = 7.1 Hz, 2 H), 7.14–
(
1c). Sulfonyl ynamine 1c was prepared according to general procedure
B. The reaction with benzoyl chloride (767 µL, 6.6 mmol) was performed
at 30 °C for 24 h. Column chromatography (heptane/AcOEt 20:1 → 10:1;
3
silica gel was washed with 1% Et
column chromatography) afforded the product 1c as a light yellow oil
86%). R (silica gel, heptane/AcOEt 10:1): 0.33 (UV, KMnO solution).
H NMR [400 MHz, δ (ppm), CDCl ]: 2.42 (s, 3 H), 7.25–7.29 (m, 4 H),
.36–7.41 (m, 3 H), 7.47–7.55 (m, 2 H), 7.60–7.65 (m, 3 H), 8.14–8.26
m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 21.7, 74.9, 90.2, 126.4,
28.2, 128.7, 129.2, 129.2, 129.5, 129.9, 132.9, 133.5, 136.9, 137.1,
45.9, 176.8. These data were in accordance to those reported in the
3
N in heptane before being used for
154.0. FTIR [ν̅
(cm−1)]: 685, 726, 1088, 1123, 1204, 1372, 1702, 2218,
2982. HRMS (ESI-TOF) m/z: [M + H]+ calcd. for C17
H17NO S 330.0800,
4
(
1
F
4
found 330.0812.
3
7
Ethyl
3-(4-methoxy-N-phenylbenzenesulfonamido)propanoate
(1h).
(
3
Sulfonyl ynamine 1h was prepared according to general procedure A
using 1,2-dichlorovinyl sulfonamide S8 (1.8 g, 5.0 mmol). The lithium
acetylide was treated with freshly distilled ethyl chloroformate (714 µL,
1
1
[
24]
literature.
7
.5 mmol) at −78 °C for 15 min and at 23 °C for 2 h. Column
chromatography (toluene; silica gel was washed with 1% Et N in heptane
before being used for column chromatography) afforded the product 1h
3
N-Ethynyl-4-methyl-N-phenylbenzenesulfonamide (1d). Sulfonyl ynamine
was prepared according to general procedure using 1,2-
1d
A
as colorless oil (84%). R
F
(silica gel, toluene): 0.25 (UV, KMnO
4
solution).
1
dichlorovinyl sulfonamide S7 (1.7 g, 5.0 mmol). The lithium acetylide was
treated with water (10 mL) and the resulting mixture was stirred at 23 °C
for 2 h. Column chromatography (heptane/AcOEt 20:1 → 10:1; silica gel
H NMR [400 MHz, δ (ppm), CDCl ]: 1.30 (t, J = 7.1 Hz, 3 H), 3.88 (s, 3
3
H), 4.23 (q, J = 7.1 Hz, 2 H), 6.91–7.03 (m, 2 H), 7.15–7.24 (m, 2 H),
7.3–7.40 (m, 3 H), 7.64–7.73 (m, 2 H). 13C NMR [101 MHz, δ (ppm),
was washed with 1% Et
chromatography) afforded the product 1d as a light yellow oil (81%). R
silica gel, heptane/AcOEt 10:1): 0.18 (UV, KMnO
solution). 1H NMR
400 MHz, δ (ppm), CDCl ]: 2.44 (s, 3 H), 2.83 (s, 1 H), 7.23–7.34 (m, 7
H), 7.56–7.61 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 21.7, 59.1,
5.8, 126.2, 128.2, 128.3, 129.0, 129.4, 132.7, 138.4, 145.0. These data
were in accordance to those reported in the literature.[26]
3
N in heptane before being used for column
CDCl
130.6, 137.2, 154.1, 164.4. FTIR [ν
1593, 1702, 2216, 2981. HRMS (ESI-TOF) m/z: [M + H]+ calcd. for
18 5
C H19NO S 360.0906, found 360.0922.
3
]: 14.2, 55.8, 61.7, 66.6, 82.5, 114.4, 126.4, 127.2, 129.2, 129.5,
̅
(cm−1)]: 689, 1087, 1123, 1371, 1496,
F
(
[
4
3
3
7
Ethyl 3-(4-nitro-N-phenylbenzenesulfonamido)propanoate (1i) and ethyl
,3-bis(4-nitro-N-phenyl-benzenesulfonamido)acrylate (15). Sulfonyl
3
ynamine 1i and compound 15 were prepared according to general
procedure A using 1,2-dichlorovinyl sulfonamide S9 (1.9 g, 5.0 mmol).
The lithium acetylide was treated with freshly distilled ethyl chloroformate
(714 µL, 7.5 mmol) at −78 °C for 15 min and at 23 °C for 3 h. Column
4
-Methyl-N-phenyl-N-[(trimethylsilyl)ethynyl]benzenesulfonamide
(1e).
Sulfonyl ynamine 1e was prepared according to general procedure A
using 1,2-dichlorovinyl sulfonamide S7 (1.7 g, 5.0 mmol). The lithium
acetylide was treated with trimethylsilyl chloride (952 µL, 7.5 mmol) at
3
chromatography (toluene; silica gel was washed with 1% Et N in heptane
−
(
78 °C for 15 min and at 23 °C for 2 h. Column chromatography
heptane/AcOEt 20:1; silica gel was washed with 1% Et N in heptane
before being used for column chromatography) afforded the product 1e
as a white solid (52%). R (silica gel, heptane/AcOEt 10:1): 0.27 (UV,
solution). H NMR [400 MHz, δ (ppm), CDCl ]: 0.17 (s, 9 H), 2.45
s, 3 H), 7.21–7.25 (m, 2 H), 7.26–7.30 (m, 2 H), 7.30–7.36 (m, 3 H),
before being used for column chromatography) afforded the product 1i
(42%) and product 15 (41%) as white solids. Product 15 was a common
3
side product during the course of the reaction.[28] Compound 1i: R
gel, toluene): 0.33 (UV, KMnO
CDCl ]: 1.32 (t, J = 7.1 Hz, 3 H), 4.25 (q, J = 7.1 Hz, 2 H), 7.17–7.23 (m,
2 H), 7.36–7.46 (m, 3 H), 7.92–8.00 (m, 2 H), 8.33–8.42 (m, 2 H). 13C
NMR [101 MHz, δ (ppm), CDCl ]: 14.1, 62.0, 66.7, 80.4, 124.5, 126.5,
129.7, 129.81, 129.84, 136.5, 140.9, 150.7, 153.6. FTIR [ν
(cm−1)]: 690,
740, 854, 1086, 1126, 1184, 1206, 1348, 1533, 1593, 1706, 2223, 2925,
107. HRMS (ESI-TOF) m/z: [M + H]+ calcd. for C17
S 375.0651,
(silica
solution). 1H NMR [400 MHz, δ (ppm),
4
F
F
1
KMnO
4
3
3
(
7
7
.54–7.60 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
3.4, 93.2, 126.3, 128.3, 128.6, 129.2, 129.5, 133.0, 138.7, 145.1. FTIR
(cm−1)]: 752, 834, 902, 1056, 1168, 1372, 1476, 1592, 2137, 2161,
3
]: 0.16, 21.9,
3
̅
[ν
̅
3
16 2 6
H N O
This article is protected by copyright. All rights reserved.

European Journal of Organic Chemistry
10.1002/ejoc.201801062
FULL PAPER
found 375.0659. Compound 15: R
F
(silica gel, toluene): 0.07 (UV, KMnO
4
HRMS (ESI-TOF) m/z: [M + H]+ calcd. for C18
H19NO S 344.0957, found
4
344.0966.
solution). 1H NMR [400 MHz, δ (ppm), CDCl
3
]: 1.41 (t, J = 7.1 Hz, 3 H),
4
2
7
.33 (q, J = 7.1 Hz, 2 H), 6.14 (s, 1 H), 7.11–7.16 (m, 2 H), 7.20–7.23 (m,
H), 7.24–7.27 (m, 2 H), 7.33–7.38 (m, 2 H), 7.40–7.45 (m, 2 H), 7.45–
.50 (m, 3 H), 7.52–7.57 (m, 1 H), 7.93–8.00 (m, 2 H), 8.09–8.18 (m, 2
Ethyl
ylidene)acetate [(Z)-2a].
solution). 1H NMR [400 MHz, δ (ppm), CDCl
(Z)-2-(5-methyl-1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-
(silica gel, toluene): 0.28 (UV, KMnO
]: 1.01 (t, J = 7.1 Hz, 3 H),
R
F
4
H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.1, 61.6, 110.0, 117.5, 123.4,
24.1, 129.4, 129.6, 129.7, 129.93, 129.97, 129.99, 130.0, 136.0, 136.3,
39.9, 143.4, 144.2, 149.9, 150.4, 163.9. FTIR [ν
(cm−1)]: 694, 740, 855,
3
3
1
1
1
2
7
=
9
1
.54 (s, 3 H), 3.66 (q, J = 7.1 Hz, 2 H), 5.83 (s, 1 H), 7.36–7.49 (m, 5 H),
.55 (m, J = 8.0, 1.2, 0.6 Hz, 1 H), 7.62 (quint, J = 0.6 Hz, 1 H), 7.79 (d, J
8.0 Hz, 1 H). 13C NMR [101 MHz, δ (ppm), CDCl
3
]: 13.9, 22.0, 60.4,
̅
086, 1139, 1172, 1202, 1350, 1531, 1720, 3106. HRMS (ESI-TOF) m/z:
+
[M + H] calcd. for C29
H N O S
26 4 10 2
653.1012, found 653.1034.
3.0, 121.5, 122.0, 126.9, 128.6, 128.9, 129.5, 130.2, 133.1, 134.9,
40.2, 144.9, 164.0. FTIR [ν
̅
(cm−1)]: 693, 907, 1082, 1145, 1266, 1327,
+
Ethyl 3-(N,4-dimethylbenzenesulfonamido)propanoate (1j). Sulfonyl
ynamine 1j was prepared according to general procedure A using 1,2-
dichlorovinyl sulfonamide S11 (1.4 g, 5.0 mmol). The lithium acetylide
was treated with freshly distilled ethyl chloroformate (714 µL, 7.5 mmol)
at −78 °C for 15 min and at 23 °C for 2 h. Column chromatography
1494, 1635, 1708, 3029. HRMS (ESI-TOF) m/z: [M + H] calcd. for
18 4
C H19NO S 344.0957, found 344.0943.
4-Methyl-N-phenylbenzenesulfonamide (3). The spectroscopic data were
identical to those reported above.
(
heptane/AcOEt 20:1 → 10:1; silica gel was washed with 1% Et
heptane before being used for column chromatography) afforded the
product 1j as a white solid (71%). R (silica gel, heptane/AcOEt 1:1): 0.6
UV, KMnO ]: 1.31 (t, J =
solution). 1H NMR [400 MHz, δ (ppm), CDCl
.1 Hz, 3 H), 2.47 (s, 3 H), 3.17 (s, 3 H), 4.23 (q, J = 7.1 Hz, 2 H), 7.35–
.44 (m, 2 H), 7.78–7.92 (m, 2 H). 13C NMR [101 MHz, δ (ppm), CDCl
]:
4.2, 21.8, 38.5, 61.6, 66.0, 83.5, 128.0, 130.2, 133.0, 145.8, 154.1.
3
N in
Ethyl 3,3-bis(4-methyl-N-phenylbenzenesulfonamido)acrylate (4).
R
F
F
solution). 1H NMR [400 MHz, δ
(
(
(
7
(
silica gel, toluene): 0.06 (UV, KMnO
ppm), CDCl ]: 1.39 (t, J = 7.1 Hz, 3 H), 2.30 (s, 3 H), 2.38 (s, 3 H), 4.33
q, J = 7.1 Hz, 2 H), 6.09 (s, 1 H), 6.86–6.94 (m, 4 H), 7.06–7.12 (m, 2 H),
.12–7.19 (m, 6 H), 7.26–7.33 (m, 2 H), 7.33–7.40 (m, 3 H), 7.42–7.48
m, 1 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.1, 21.5, 21.6, 61.1,
15.5, 127.3, 128.18, 128.23, 128.93, 128.97, 129.0, 129.4, 129.5, 130.0,
4
(
4
3
3
7
7
1
3
3
These data were in accordance to those reported in the literature.[29]
1
1
(
30.2, 135.1, 136.0, 136.8, 137.1, 140.6, 143.5, 144.3, 164.7. FTIR [ν
̅
Ethyl 3-(N-benzyl-4-methylbenzenesulfonamido)propanoate
(1k).
cm−1)]: 695, 814, 1087, 1139, 1167, 1362, 1489, 1531, 1719, 2981.
Sulfonyl ynamine 1k was prepared according to general procedure A
using 1,2-dichlorovinyl sulfonamide S10 (1.8 g, 5.0 mmol). The lithium
acetylide was treated with freshly distilled ethyl chloroformate (714 µL,
+
HRMS (ESI-TOF) m/z: [M + H] calcd. for C31
H N O S
32 2 6 2
591.1624, found
591.1638.
7
.5 mmol) at −78 °C for 15 min and at 23 °C for 2 h. Column
chromatography (heptane/AcOEt 40:1 → 10:1; silica gel was washed
with 1% Et N in heptane before being used for column chromatography)
afforded the product 1k as
Ethyl (E)-3-(4-methyl-N-phenylbenzenesulfonamido)acrylate (5).
R
F
(
silica gel, toluene): 0.12 (UV, KMnO
ppm), CDCl ]: 1.24 (t, J = 7.1 Hz, 3 H), 2.44 (s, 3 H), 4.14 (q, J = 7.1 Hz,
H), 4.62 (d, J = 13.8 Hz, 1 H), 6.88–6.97 (m, 2 H), 7.27–7.32 (m, 2 H),
.35–7.45 (m, 3 H), 7.53–7.60 (m, 2 H), 8.37 (d, J = 13.7 Hz, 1 H). 13C
]: 14.3, 21.7, 60.1, 100.0, 121.7, 127.8,
29.7, 129.86, 129.89, 134.8, 135.1, 143.9, 144.9, 167.1. FTIR [ν
27, 906, 1089, 1170, 1368, 1624, 1737, 2245, 2981. HRMS (ESI-TOF)
S 346.1113, found 346.1131.
solution). 1H NMR [400 MHz, δ
4
3
(
3
a
white solid (87%).
R
F
(silica gel,
2
7
1
heptane/AcOEt 10:1): 0.17 (UV, KMnO
ppm), CDCl
H), 4.62 (s, 2 H), 7.24–7.33 (m, 7 H), 7.68–7.75 (m, 2 H). 13C NMR
101 MHz, δ (ppm), CDCl ]: 14.2, 21.6, 55.3, 61.4, 68.1, 82.5, 127.6,
4
solution). H NMR [400 MHz, δ
(
2
[
3
]: 1.28 (t, J = 7.1 Hz, 3 H), 2.44 (s, 3 H), 4.18 (q, J = 7.1 Hz,
NMR [101 MHz, δ (ppm), CDCl
3
(cm−1)]:
̅
1
7
3
1
28.5, 128.6, 129.3, 129.7, 133.5, 134.1, 145.4, 153.9. These data were
m/z: [M + H]+ calcd. for C18
H21NO
4
in accordance to those reported in the literature.[22]
General Procedure for the Intramolecular Hydroarylation of Sulfonyl
Ynamines 1a–c and 1g–k. Sulfonyl ynamine 1 (1.0 mmol, 1.0 equiv)
was dissolved in toluene (10 mL) under a nitrogen atmosphere in a
Biotage microwave vial (10.0–20.0 mL) equipped with a magnetic stirring
Products of Palladium-Catalyzed Intramolecular Hydroarylation of
Sulfonyl Ynamine 1a. Sulfonyl ynamine 1a (343 mg, 1.0 mmol, 1.0
equiv) was dissolved in toluene (10 mL) under a nitrogen atmosphere in
a Biotage microwave vial (10.0–20.0 mL) equipped with a magnetic
bar. Pd(OAc)
2
(11 mg, 0.05 mmol, 0.05 equiv) and tri(p-tolyl)phosphine
stirring bar. Pd(OAc)
2
(11 mg, 0.05 mmol, 0.05 equiv) and tri(p-
(30 mg, 0.1 mmol, 0.1 equiv) were added at 23 °C. The vial was covered
tolyl)phosphine (30 mg, 0.1 mmol, 0.1 equiv) were added at 23 °C. The
vial was covered with a Teflon septum and secured via a crimped
with a Teflon septum and secured via a crimped aluminum cap. The
reaction was irradiated in a Biotage Initiator microwave at 100 °C for 18 h
aluminum cap. The reaction was irradiated in
a Biotage Initiator
(30 second pre-stir, Fixed Hold Time On, Low absorbance level). The
microwave at 100 °C for 18 h (30 second pre-stir, Fixed Hold Time On,
Low absorbance level). The reaction mixture was quenched with brine
reaction mixture was quenched with brine (50 mL) and extracted with
AcOEt (2 × 20 mL). The resulting organic washings were dried over
sodium sulfate, concentrated in vacuo and the crude residue was purified
by column chromatography as indicated.
(50 mL) and extracted with AcOEt (2 × 20 mL). The resulting organic
washings were dried over sodium sulfate, concentrated in vacuo and the
crude residue was purified by column chromatography (toluene; silica gel
was washed with 1% Et
chromatography).
3
N in heptane before being used for column
Ethyl
(E)-2-(5-methyl-1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-
ylidene)acetate [(E)-2a]. (E)-1,2-Benzothiazoledione 2a was prepared
according to general procedure using sulfonyl ynamine 1a (343 mg, 1.0
mmol). Ratio E/Z = 98:2 was determined by 1H NMR spectroscopy.
Ethyl
ylidene)acetate [(E)-2a].
solution). 1H NMR [400 MHz, δ (ppm), CDCl
(E)-2-(5-methyl-1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-
(silica gel, toluene): 0.33 (UV, KMnO
]: 1.26 (t, J = 7.1 Hz, 3 H),
R
F
4
Column chromatography (toluene; silica gel was washed with 1% Et
heptane before being used for column chromatography) afforded product
E)-2a as a white solid (127 mg, 37%). The spectroscopic data were
identical to those reported above.
3
N in
3
2
.57 (s, 3 H), 4.18 (q, J = 7.1 Hz, 2 H), 5.11 (s, 1 H), 7.47–7.51 (m, 2 H),
.54–7.62 (m, 4 H), 7.82 (d, J = 7.9 Hz, 1 H), 9.23 (quint, J = 0.8 Hz, 1 H).
(
7
1
3C NMR [101 MHz, δ (ppm), CDCl
3
]: 14.2, 22.2, 60.5, 97.0, 120.9, 127.4,
29.8, 130.36, 130.39, 130.43, 130.5, 131.0, 133.1, 144.8, 146.2, 166.1.
1
FTIR [ν
̅
(cm−1)]: 714, 902, 1089, 1174, 1302, 1512, 1635, 1737, 2992.
This article is protected by copyright. All rights reserved.

European Journal of Organic Chemistry
10.1002/ejoc.201801062
FULL PAPER
(E)-3,3-Dimethyl-1-(5-methyl-1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-
Ethyl
(E)-2-(5-nitro-1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-
ylidene)butan-2-one [(E)-2b]. (E)-1,2-Benzothiazoledione 2b was
prepared according to general procedure using sulfonyl ynamine 1b (355
ylidene)acetate [(E)-2i]. (E)-1,2-Benzothiazoledione 2i was prepared
according to general procedure using sulfonyl ynamine 1i (375 mg, 1.0
mmol). Ratio E/Z > 99:1 was determined by 1H NMR spectroscopy.
mg, 1.0 mmol). Ratio E/Z
spectroscopy. Column chromatography (toluene; silica gel was washed
with 1% Et N in heptane before being used for column chromatography)
afforded the product (E)-2b as a white solid (121 mg, 34%). R (silica gel,
solution). H NMR [400 MHz, δ (ppm),
]: 1.05 (s, 9 H), 2.57 (s, 3 H), 5.71 (s, 1 H), 7.48–7.53 (m, 2 H),
.54–7.65 (m, 4 H), 7.82 (d, J = 7.9 Hz, 1 H), 9.10 (quint, J = 0.6 Hz, 1 H).
]: 22.3, 26.8, 44.7, 101.5, 121.0,
>
99:1 was determined by 1H NMR
Column chromato-graphy (toluene; silica gel was washed with 1% Et
heptane before being used for column chromatography) afforded the
product (E)-2i as a white solid (113 mg, 30%). R (silica gel, toluene):
0.28 (UV, KMnO ]: 1.28 (t,
solution). 1H NMR [400 MHz, δ (ppm), CDCl
3
N in
3
F
F
1
toluene): 0.28 (UV, KMnO
CDCl
4
4
3
3
J = 7.1 Hz, 3 H), 4.24 (q, J = 7.1 Hz, 2 H), 5.27 (s, 1 H), 7.46–7.56 (m, 2
H), 7.58–7.69 (m, 3 H), 8.12 (d, J = 8.5 Hz, 1 H), 8.61 (dd, J = 8.5, 1.9 Hz,
7
1
3C NMR [101 MHz, δ (ppm), CDCl
1 H), 10.43 (d, J = 1.9 Hz, 1 H). 13C NMR [101 MHz, δ (ppm), CDCl
3
3
]:
1
27.8, 129.4, 130.4, 130.5, 130.6, 130.8, 130.9, 133.4, 145.1, 145.6,
14.2, 61.2, 99.9, 122.5, 125.6, 127.3, 129.1, 129.6, 130.7, 130.9, 131.1,
204.3. FTIR [ν
̅
(cm−1)]: 695, 966, 1078, 1183, 1322, 1566, 1673, 2965.
137.6, 143.8, 151.2, 165.6. FTIR [ν
̅
(cm−1)]: 694, 740, 1095, 1113, 1186,
+
+
HRMS (ESI-TOF) m/z: [M + H] calcd. for C20
3
H23NO S 356.1320, found
1341, 1537, 1706, 2926, 3111. HRMS (ESI-TOF) m/z: [M + H] calcd. for
356.1343.
17 16 2 6
C H N O S 375.0651, found 375.0667.
(
E)-2-(5-methyl-1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-ylidene)-1-
phenylethan-1-one [(E)-2c]. (E)-1,2-Benzothiazoledione 2c was
prepared according to general procedure using sulfonyl ynamine 1c (375
mg, 1.0 mmol). Ratio E/Z
98:2 was determined by 1H NMR
spectroscopy. Column chromatography (toluene; silica gel was washed
with 1% Et N in heptane before being used for column chromatography)
afforded the product (E)-2c as a white solid (116 mg, 31%). R (silica gel,
toluene): 0.31 (UV, KMnO
solution). 1H NMR [400 MHz, δ (ppm),
CDCl ]: 2.57 (s, 3 H), 6.09 (s, 1 H), 7.37–7.45 (m, 2 H), 7.48–7.55 (m, 1
H), 7.56–7.66 (m, 6 H), 7.72–7.79 (m, 2 H), 7.85 (d, J = 8.0 Hz, 1 H),
Ethyl
(E)-2-(2,5-dimethyl-1,1-dioxo-1,2-benzothiazol-3(2H)-
ylidene)acetate [(E)-2j]. (E)-1,2-Benzothiazoledione 2j was prepared
according to general procedure using sulfonyl ynamine 1j (281 mg, 1.0
mmol). Ratio E/Z = 95:5 was determined by 1H NMR spectroscopy.
Column chromato-graphy (toluene; silica gel was washed with 1% Et
heptane before being used for column chromatography) afforded the
product (E)-2j as colorless oil (87 mg, 31%). R (silica gel, toluene): 0.23
solution). 1H NMR [400 MHz, δ (ppm), CDCl
(UV, KMnO ]: 1.35 (t, J =
=
3
N in
3
F
F
4
4
3
3
7.1 Hz, 3 H), 2.54 (s, 3 H), 3.15 (s, 3 H), 4.25 (q, J = 7.1 Hz, 2 H), 5.33 (s,
1 H), 7.50 (d, J = 7.9 Hz, 1 H), 7.76 (d, J = 7.9 Hz, 1 H), 9.17 (s, 1 H). 13C
9
1
1
1
.00 (quint, J = 0.5 Hz, 1 H). 13C NMR [101 MHz, δ (ppm), CDCl
02.4, 121.1, 127.4, 127.7, 128.2, 128.6, 129.1, 130.5, 130.6, 130.7,
30.9, 132.8, 133.6, 139.4, 145.1, 146.4, 189.7. FTIR [ν
(cm−1)]: 696, 959,
3
]: 22.2,
NMR [101 MHz, δ (ppm), CDCl
127.9, 129.8, 130.5, 132.7, 144.8, 144.9, 166.0. FTIR [ν
3
]: 14.3, 22.2, 26.5, 60.5, 95.0, 120.8,
(cm−1)]: 701, 823,
̅
̅
1039, 1137, 1159, 1315, 1619, 1708, 2982. HRMS (ESI-TOF) m/z: [M +
+
185, 1323, 1565, 1653, 1724, 2922, 3064. HRMS (ESI-TOF) m/z: [M +
H] calcd. for C13
4
H17NO S 282.0800, found 282.0819.
+
H] calcd. for C22
3
H19NO S 376.1007, found 376.1015.
Ethyl
ylidene)acetate
methylbenzenesulfonyl)isoindolin-1-ylidene]acetate
Benzothiazoledione 2k and compound 6 were prepared according to
general procedure using sulfonyl ynamine 1k (357 mg, 1.0 mmol). Ratio
(E)-2-(2-benzyl-5-methyl-1,1-dioxo-1,2-benzothiazol-3(2H)-
Ethyl (E)-2-(1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-ylidene)acetate
(E)-2g]. (E)-1,2-Benzothiazoledione 2g was prepared according to
general procedure using sulfonyl ynamine 1g (330 mg, 1.0 mmol). Ratio
E/Z
98:2 was determined by 1H NMR spectroscopy. Column
chromatography (toluene; silica gel was washed with 1% Et N in heptane
before being used for column chromatography) afforded the product (E)-
[(E)-2k]
and
ethyl
(E)-2-[2-(4-
[
(6).
(E)-1,2-
=
99:1 was determined by 1H NMR spectroscopy. Column
N in heptane
3
E/Z
>
chromatography (toluene; silica gel was washed with 1% Et
3
2
g as a white solid (112 mg, 34%). R
F
(silica gel, toluene): 0.31 (UV,
before being used for column chromatography) afforded the product (E)-
2k as a white solid (93 mg, 26%) and product 6 as a colorless oil (36 mg,
1
KMnO
4
solution). H NMR [400 MHz, δ (ppm), CDCl ]: 1.28 (t, J = 7.1 Hz,
3
3
7
H), 4.20 (q, J = 7.1 Hz, 2 H), 5.16 (s, 1 H), 7.46–7.56 (m, 2 H), 7.57–
.67 (m, 3 H), 7.76–7.85 (m, 2 H), 7.92–8.02 (m, 1 H), 9.44 (m, 1 H). 13C
10%). Compound (E)-2k: R
F
(silica gel, toluene): 0.30 (UV, KMnO
4
solution). 1H NMR [400 MHz, δ (ppm), CDCl
3
]: 1.26 (t, J = 7.1 Hz, 3 H),
NMR [101 MHz, δ (ppm), CDCl
30.5, 130.6, 130.7, 131.2, 132.5, 133.3, 133.9, 146.2, 166.3. FTIR [ν
cm−1)]: 692, 910, 1045, 1099, 1157, 1186, 1324, 1619, 1708, 2925.
HRMS (ESI-TOF) m/z: [M + H]+ calcd. for C17
S 330.0800, found
30.0827.
3
]: 14.4, 60.7, 97.6, 121.3, 127.4, 129.9,
2.53 (s, 3 H), 4.15 (q, J = 7.1 Hz, 2 H), 4.84 (s, 2 H), 5.28 (s, 1 H), 7.27–
7.33 (m, 1 H), 7.34–7.40 (m, 2 H), 7.40–7.44 (m, 2 H), 7.52 (dd, J = 7.9,
1
(
̅
0.6 Hz, 1 H), 7.81 (d, J = 7.9 Hz, 1 H), 9.13 (quint, J = 0.6 Hz, 1 H). 13
C
H17NO
4
3
NMR [101 MHz, δ (ppm), CDCl ]: 14.4, 22.4, 44.5, 60.6, 96.5, 121.0,
127.2, 127.8, 128.1, 129.1, 130.1, 130.4, 132.9, 134.1, 143.7, 145.1,
3
1
2
3
66.0. FTIR [ν
̅
(cm−1)]: 670, 732, 831, 1136, 1168, 1311, 1626, 1706,
+
986, 3098. HRMS (ESI-TOF) m/z: [M + H] calcd. for C19
4
H21NO S
Ethyl
(E)-2-(5-methoxy-1,1-dioxo-2-phenyl-1,2-benzothiazol-3(2H)-
58.1113, found 358.1118. Compound 6: R
solution). 1H NMR [400 MHz, δ (ppm), CDCl
7.1 Hz, 3 H), 2.40 (s, 3 H), 4.19 (q, J = 7.1 Hz, 2 H), 5.02 (s, 2 H), 6.43 (s,
H), 7.28–7.39 (m, 4 H), 7.41–7.47 (m, 1 H), 7.76–7.83 (m, 2 H), 9.13 (d,
J = 8.1 Hz, 1 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.6, 21.8, 55.4,
0.1, 96.7, 121.9, 127.7, 128.4, 128.9, 130.1, 131.3, 133.0, 134.6, 138.1,
F
(silica gel, toluene): 0.21
ylidene)acetate [(E)-2h]. (E)-1,2-Benzothiazoledione 2h was prepared
according to general procedure using sulfonyl ynamine 1h (360 mg, 1.0
mmol). Ratio E/Z = 95:5 was determined by 1H NMR spectroscopy.
(UV, KMnO
4
3
]: 1.32 (t, J =
1
Column chromatography (toluene; silica gel was washed with 1% Et
heptane before being used for column chromatography) afforded the
product (E)-2h as a white solid (119 mg, 33%). R (silica gel, toluene):
solution). 1H NMR [400 MHz, δ (ppm), CDCl
.17 (UV, KMnO ]: 1.25 (t,
J = 7.1 Hz, 3 H), 3.98 (s, 3 H), 4.16 (q, J = 7.1 Hz, 2 H), 5.12 (s, 1 H),
3
N in
3
6
F
145.1, 152.0, 167.0. FTIR [ν̅
(cm−1)]: 667, 800, 1089, 1165, 1344, 1620,
0
4
3
1
3
705, 2922. HRMS (ESI-TOF) m/z: [M + H]+ calcd. for C19
H21NO S
4
58.1113, found 358.1132.
7
7
.25 (dd, J = 8.7, 2.2 Hz, 1 H), 7.47–7.52 (m, 2 H), 7.53–7.64 (m, 3 H),
.83 (d, J = 8.6 Hz, 1 H), 9.14 (d, J = 2.3 Hz, 1 H). 13C NMR [101 MHz, δ
(
1
1
ppm), CDCl
3
]: 14.3, 56.1, 60.5, 97.2, 113.4, 119.7, 122.4, 125.1, 129.6,
Intramolecular Hydroarylation of 1d, 1e and 1f. Sulfonyl ynamines 1d,
1e or 1f were submitted to the reaction conditions according to general
procedure. 1H NMR spectroscopy of the crude product indicated partial
30.43, 130.49, 130.53, 131.0, 146.3, 164.0, 166.2. FTIR [ν
183, 1252, 1307, 1473, 1583, 1621, 1707, 2988, 3118. HRMS (ESI-
̅
(cm−1)]: 1103,
+
TOF) m/z: [M + H] calcd. for C18
5
H19NO S 360.0906, found 360.0919.
degradation
of
the
starting
material
to
4-methyl-N-
This article is protected by copyright. All rights reserved.

European Journal of Organic Chemistry
10.1002/ejoc.201801062
FULL PAPER
phenylbenzenesulfonamide 3 and additional unidentified products. The
formation of products 2d, 2e or 2f was not observed.
used for column chromatography) afforded the product 12c as a white
solid (31 mg, 87%). R
F
(silica gel, toluene): 0.20 (UV, KMnO
H NMR [400 MHz, δ (ppm), CDCl ]: 1.45 (t, J = 7.1 Hz, 3 H), 3.48 (s, 3
H), 4.43 (q, J = 7.1 Hz, 2 H), 6.13 (d, J = 2.2 Hz, 2 H), 7.04 (dd, J = 8.5,
4
solution).
1
3
Study of Equilibration between E- and Z-isomers of 2a. (E)-1,2-
Benzothiazole-1,1-dione 2a or (Z)-1,2-Benzothiazole-1,1-dione 2a (69
mg, 0.2 mmol, 1.0 equiv) were independently dissolved in toluene (2 mL)
under a nitrogen atmosphere in a Biotage microwave vial (2.0–5.0 mL)
2
1
6
1
1
.2 Hz, 1 H), 7.32–7.38 (m, 2 H), 7.44–7.53 (m, 3 H), 7.72 (d, J = 8.5 Hz,
H), 10.41 (bs, 1 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.4, 55.4,
1.2, 100.7, 111.6, 118.3, 122.8, 127.2, 127.8, 128.8, 130.0, 132.7,
37.4, 154.4, 162.3, 164.5. FTIR [ν
(cm−1)]: 703, 729, 910, 1021, 1162,
245, 1567, 1655, 2926. HRMS (ESI-TOF) m/z: [M + H]+ calcd. for
3
̅
2
equipped with a magnetic stirring bar. Pd(OAc) (2.2 mg, 0.01 mmol, 0.05
equiv) and tri(p-tolyl)phosphine (6.1 mg, 0.02 mmol, 0.1 equiv) were
added at 23 °C. The vial was covered with a Teflon septum and secured
via a crimped aluminum cap. The reaction was irradiated in a Biotage
Initiator microwave at 100 °C for 18 h (30 second pre-stir, Fixed Hold
Time On, Low absorbance level). The reaction mixture was quenched
with brine (50 mL) and extracted with AcOEt (2 × 20 mL). The combined
organic washings were dried over sodium sulfate, filtered off and
18 5
C H19NO S 360.0906, found 330.0927.
Ethyl
3-(benzylamino)-5-methyl-1,1-dioxo-1-benzothiophene-2-
carboxylate (12d). 3-Amino-1-benzothiophene-1,1-dione 12d was
prepared according to general procedure using 1,2-benzothiazole-1,1-
dione 2k (36 mg, 0.1 mmol). Column chromatography (toluene; silica gel
1
concentrated in vacuo. H NMR spectroscopy of the crude product
3
was washed with 1% Et N in heptane before being used for column
indicated a mixture of isomers with ratio E/Z = 85:15. Additionally, partial
decomposition of the starting material was observed.
chromatography) afforded the product 12d as a white solid (34 mg, 95%).
1
R
(
F
(silica gel, toluene): 0.25 (UV, KMnO
ppm), CDCl
H), 5.02 (d, J = 5.9 Hz, 2 H), 7.33–7.40 (m, 3 H), 7.40–7.46 (m, 2 H),
.49 (d, J = 7.8 Hz, 1 H), 7.59 (s, 1 H), 7.77 (d, J = 7.8 Hz, 1 H), 9.44 (bs,
H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.5, 22.2, 50.0, 61.0, 100.1,
4
solution). H NMR [400 MHz, δ
3
]: 1.40 (t, J = 7.1 Hz, 3 H), 2.40 (s, 3 H), 4.36 (q, J = 7.1 Hz,
2
7
1
1
1
1
3
General procedure for Photochemical Rearrangement of 1,2-
Benzothiazole-1,1-diones. To 25 mL quartz flask was added 1,2-
benzothiazole-1,1-dione 2a, 2g, 2h or 2k (0.1–1.0 mmol, 1.0 equiv) in 10
mL of deoxygenated MeCN with stirring. This flask was irradiated in a
Rayonet RMR-600 photochemical reactor, using eight lamps of 300 nm
of wavelength for 24 h with internal temperature of 50 °C. After cooling to
3
21.2, 125.9, 126.5, 127.0, 128.6, 129.8, 133.6, 137.4, 138.2, 142.8,
54.9, 164.5. FTIR [ν
738, 2925, 3254. HRMS (ESI-TOF) m/z: [M + H] calcd. for C19
̅
(cm−1)]: 735, 786, 1141, 1216, 1268, 1577, 1659,
+
4
H21NO S
58.1113, found 358.1133.
23 °C, the solvent was removed in vacuo and the crude residue was
purified by column chromatography as indicated.
CCDC 1828629, 1828630 and 1828631 {for (E)-2a, 12a and 12d} contain
the supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic Data
Centre.
Ethyl
5-methyl-1,1-dioxo-3-(phenylamino)-1-benzothiophene-2-
carboxylate (12a). 3-Amino-1-benzothiophene-1,1-dione 12a was
prepared according to general procedure using 1,2-benzothiazole-1,1-
dione 2a (343 mg, 1.0 mmol). Column chromatography (toluene; silica
gel was washed with 1% Et
chromatography) afforded the product 12a as a white solid (316 mg,
2%). R (silica gel, toluene): 0.22 (UV, KMnO
solution). 1H NMR [400
MHz, δ (ppm), CDCl ]: 1.45 (t, J = 7.1 Hz, 3 H), 2.12 (s, 3 H), 4.43 (q, J =
.1 Hz, 2 H), 6.40 (quint, J = 0.5 Hz, 1 H), 7.30–7.34 (m, 2 H), 7.39 (ddd,
J = 7.8, 1.3, 0.7 Hz, 1 H), 7.44–7.54 (m, 3 H), 7.71 (d, J = 7.8 Hz, 1 H),
3
N in heptane before being used for column
Acknowledgements
9
F
4
3
Financial support for this research was provided by the
FP7Marie Curie Actions of the European Commission via the
ITN ECHONET (MCITN-2012-316379). Enrique Gómez-Bengoa
and Lia Sotorríos thank MINECO (CTQ2016-78083-P) and IZO-
SGI SGIker of UPV-EHU for human and technical support. Huub
van Amerongen is kindly acknowledged for the preparation of
the starting materials..
7
1
1
1
1
0.43 (bs, 1 H). 13C NMR [101 MHz, δ (ppm), CDCl
]: 14.4, 21.7, 61.1,
3
00.1, 121.2, 125.9, 126.5, 127.0, 128.6, 129.8, 133.6, 137.4, 138.2,
42.8, 155.0, 164.5. FTIR [ν
̅
(cm−1)]: 704, 730, 1027, 1122, 1160, 1247,
+
285, 1569, 1657, 2854, 2925. HRMS (ESI-TOF) m/z: [M + H] calcd. for
18 4
C H19NO S 344.0957, found 344.0963.
Ethyl 1,1-dioxo-3-(phenylamino)-1-benzothiophene-2-carboxylate (12b).
-Amino-1-benzothiophene-1,1-dione 12b was prepared according to
general procedure using 1,2-benzothiazoledione 2g (33 mg, 0.1 mmol).
Column chromatography (toluene; silica gel was washed with 1% Et N in
heptane before being used for column chromatography) afforded the
product 12b as a white solid (31 mg, 96%). R (silica gel, toluene): 0.24
UV, KMnO ]: 1.45 (t, J =
solution). 1H NMR [400 MHz, δ (ppm), CDCl
.1 Hz, 3 H), 4.44 (q, J = 7.1 Hz, 2 H), 6.66 (d, J = 8.0 Hz, 1 H), 7.23–
.28 (m, 1 H), 7.29–7.36 (m, 2 H), 7.43–7.54 (m, 3 H), 7.58–7.62 (m, 1
3
Keywords: Ynamines • Palladium catalysis • C–H activation
3
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Entry for the Table of Contents
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C–H activation*
Ivan Bernar, Daniel Blanco-Ania, Sophie
J. Stok, Lia Sotorríos, Enrique Gómez-
Bengoa* and Floris P. J. T. Rutjes*
Page No. – Page No.
A
completely regioselective and highly stereoselective palladium-catalyzed
Synthesis of 3-Amino-1-
intramolecular hydroarylation of arenesulfonyl ynamines to benzothiazoles was
developed. Our mechanistic studies suggest an alkyne-directed 5-exo-dig
cyclization pathway of the process. The products easily underwent photoinduced
rearrangement to 3-amino-1-benzothiophene-1,1-diones (up to 35% yields after two
steps).
benzothiophene-1,1-diones by Alkyne
Directed Hydroarylation and
1/N→3/C-Sulfonyl Migration
*one or two words that highlight the emphasis of the paper or the field of the study
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