Copper-Catalyzed Aerobic Oxidative Regioselective Thiocyanation of Aromatics and Heteroaromatics

Article abstract of DOI:10.1021/acs.joc.7b01122

A copper-catalyzed aerobic oxidative reaction between aromatics or heteroaromatics with KSCN is developed by using O₂ as the oxidant. The combination of Cu(OTf)₂, N,N,N′,N′-tetramethylethylenediamine (TMEDA) and BF₃·Et₂O provides an efficient catalytic system, affording substituted thiocyanation products and 2-aminobenzothiazoles in excellent yields. The reaction also possesses a good functional group tolerance for both strong electron-withdrawing and electron-donating groups.

Full text of DOI:10.1021/acs.joc.7b01122

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Article
Copper-Catalyzed Aerobic Oxidative Regioselective
Thiocyanation of Aromatics and Heteroaromatics
Huanfeng Jiang, Wentao Yu, Xiaodong Tang, Jianxiao Li, and Wanqing Wu
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.7b01122 • Publication Date (Web): 16 Aug 2017
Downloaded from http://pubs.acs.org on August 16, 2017
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CopperꢀCatalyzed Aerobic Oxidative Regioselective
Thiocyanation of Aromatics and Heteroaromatics
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Huanfeng Jiang*, Wentao Yu, Xiaodong Tang, Jianxiao Li, and Wanqing Wu*
Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of
Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640,
China
Fax: (+86) 20ꢀ8711ꢀ2906; Eꢀmail: cewuwq@scut.edu.cn, jianghf@scut.edu.cn
Abstract: A copperꢀcatalyzed aerobic oxidative reaction between aromatics or
heteroaromatics with KSCN is developed by using O2 as the oxidant. The
combination of Cu(OTf)2, N,N,N’,N’ꢀtetramethylethylene diamine (TMEDA) and
BF3·Et2O provides an efficient catalytic system, affording substituted thiocyanation
products and 2ꢀamino benzothiazoles in excellent yields. It also possesses a good
functional group tolerance for both strong electronꢀwithdrawing and electronꢀdonating
groups.
INTRODUCTION
Organosulfur compounds have been found in numbers of drug molecules due to their
high biological activities. Hence, much effort has been devoted to the introduction of
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sulfur moieties into organic carbon skeletons. Thiocyanation is one of the direct
methods for the introduction of sulphur atom on the aromatic rings.1 In addition, the
thiocyanate group is a useful intermediate since it can be readily converted into other
sulphur functionalities.2 In the past few years, many efficient methods for
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constructing this class of compounds by using thiocyanate salts, including visible
8
light3 electrolysis4, DDQ,5 hypervalent iodine reagents,6 oxone,7 Mn(OAc)3, or
,
others9 have been successfully reported (Scheme 1). Despite the significance, many of
these approaches still have some drawbacks and limitations, such as strong acidic or
oxidation conditions, the employment of stoichiometric metal salts and narrow
substrate scope.
Scheme 1. Synthetic Strategies for thiocyanation of aromatics and heteroaromatics
Substituted 2ꢀamino benzothiazoles represent a major class of heterocycles.10 Most
of them have been extensively studied for their biological activities and medicinal
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value (Figure 1, AꢀD) including the antiꢀHIV agent A,11a the antifungal compound
B,11c the H3ꢀreceptor ligand C11b and riluzole D11d (which is used to treat amyotrophic
lateral sclerosis (ALS), a lethal neurodegenerative disease). Therefore, their synthesis
has also attracted a broad attention from the organic chemistry community in the past
decades.12 Despite the significant advances, some of these developments suffer from
certain limitations, such as prefunctionalized reactants or harsh reaction conditions
which lower the synthetic efficiency and generality. Hence, the development of
efficient and practical synthetic methods for the straightforward construction of this
scaffold is still desirable.
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Figure 1. Several bioactive 2ꢀNꢀsubstituted benzothiazole derivatives
Compared to noble metal species, copper catalysts have received great attention
owing to low cost and abundance in organic synthesis.13,14 On the other hand,
molecular oxygen (O2) is a preferred ideal oxidant since it is atomꢀeconomical,
environmentally benign, and abundant.15 Therefore, combining Cu and O2 in catalytic
systems is notable due to the broad substrate suitability under mild conditions, which
is known as inherently “green” processes.16 As part of our continuous efforts on
copperꢀcatalyzed aerobic oxidative reactions,17 herein, we report a Cuꢀcatalyzed
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aerobic oxidative regioselective thiocyanation of aromatics and heteroaromatics with
O2 as the sole oxidant.
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RESULTS AND DISCUSSION
Indole 1a and KSCN 2a were initially chosen as model substrates to optimize the
reaction conditions (Table 1). Treatment of 1a with 2a using Cu(OTf)2 as catalyst in
DMSO under O2 atmosphere only gave the desired 3a in 12% yield (entry 1).
Significantly, the use of ligand (TMEDA) and additive (BF3·Et2O) improved the
catalytic efficiency and the target product 3a was afforded in 83% yield (entry 2).
However, in the absence of TMEDA or BF3·Et2O, the yield of 3a was decreased
dramatically (entries 3ꢀ4). Other copper catalysts, such as CuO, CuBr2, Cu(OAc)2,
CuCl, CuI were also examined (entries 5ꢀ9). Excitingly, Cu(OTf)2 proved to be an
ideal choice among the tested catalysts. Subsequently, different solvents were
investigated, and DMSO gave the best results (entries 10ꢀ12). Furthermore, various
ligands and Lewis acid additives were also examined (entries 13ꢀ19). It is found that
the combination of N,N,N’,N’ꢀtetramethylethylene diamine (TMEDA) and BF3·Et2O
gave the superior results than others. Control experiments revealed that copper and O2
atmosphere are critical to this transformation (entries 20ꢀ21). Thus, the optimal
reaction conditions were as follows: 1a (0.3 mmol), 2a (0.4 mmol), Cu(OTf)2 (20
mol %), TMEDA (20 mol %) and BF3·Et2O (0.6 mmol) in DMSO at 80 oC with O2 as
the oxidant.
Table 1. Optimization of Reaction Conditionsa
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Entry
1
Catalyst
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
CuO
Ligandb
ꢀ
Additive
ꢀ
Solvent
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
Toluene
MeCN
Yield (%)c
12
2
TMEDA
TMEDA
ꢀ
BF3·Et2O
ꢀ
90 (83)
45
3
4
BF3·Et2O
BF3·Et2O
BF3·Et2O
BF3·Et2O
BF3·Et2O
BF3·Et2O
BF3·Et2O
BF3·Et2O
BF3·Et2O
BF3.Et2O
BF3·Et2O
BF3·Et2O
Eu(OTf)3·XH2O
AgOTf
43
5
TMEDA
TMEDA
TMEDA
TMEDA
TMEDA
TMEDA
TMEDA
TMEDA
acetylacetone
Bpy
70
6
CuBr2
62
7
Cu(OAc)2
CuCl
10
8
15
9
CuI
12
10
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12
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20
21d
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
Cu(OTf)2
ꢀ
ND
NR
Trace
ND
ND
ND
16
1,4ꢀdioxane
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
DMSO
Phen
TMEDA
TMEDA
TMEDA
TMEDA
TMEDA
TMEDA
Trace
18
FeCl3
ZnCl2
Trace
NR
8
BF3·Et2O
BF3·Et2O
Cu(OTf)2
a The reactions were carried out with 1a (0.3mmol) , 2a (0.4mmol) , [Cu] (20 mol %), ligand (20
o
b
mol %), and additives (0.6 mmol), in 2 mL of solvent at 80 C under O2 balloon for 12 h.
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TMEDA
=
N,N,N’,N’ꢀtetramethylethylene diamine; Bpy
=
2,2’ꢀbipyridine; Phen
=
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c
1,10ꢀphenanthroline. Determined by GC using dodecane as the internal standard. The value in
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parentheses is the isolated yield. d Under N2 atmosphere.
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With these optimized conditions in hand, we next explored the generality of the
process, and the results are summarized in Table 2. For Nꢀsubstituted indoles, such as
Nꢀmethylꢀ, Nꢀphenylꢀ, and Nꢀbenzyl indoles, the corresponding 3ꢀthiocyano products
were afforded in 78%, 94% and 92% yields respectively. For the indoles with a
phenyl or methyl group at the Cꢀ2 position, the corresponding products were formed
in excellent yields under identical conditions, indicating that the reaction was not
affected by Cꢀ2 steric hindrance. The reactions with substituted indoles bearing
electronꢀdonating or electronꢀwithdrawing groups at the phenyl ring proceeded
smoothly to provide the desired products in moderate to good yields, even strong
electronꢀwithdrawing substituents, such as 4ꢀCN, 6ꢀNO2, gave the corresponding
3ꢀthiocyano indoles (3j, 3r) in excellent yields. Halogen groups substituted including
fluoro, chloro, and bromo, at the phenyl ring of the indoles, were well tolerated under
the optimized reaction conditions. Moreover, pyrrole and 1ꢀmethyꢀ3ꢀaminopyrazols
also transferred to the corresponding products in moderate yields (3x, 3y).
Table 2. Scope of the thiocyanation reaction of substituted indoles a
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a Standard reaction conditions: 1a (0.3 mmol), 2a (0.4 mmol), Cu(OTf)2 (20 mol %), TMEDA (20
mol %), BF3·Et2O (0.6 mmol), DMSO (2 mL), O2 (1 balloon), 80 oC, 12 h.
In the past decade, few examples in the para aromatic CꢀH functionalization have
been reported, in which it has remained extremely difficult.18 Herein, we reported the
paraꢀthiocycnation of anilines under the optimized conditions. With increasing of
KSCN from 0.4 to 0.6 mmol, various anilines were converted into the respective
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4ꢀthiocyanatoanilines 5aꢀ5n in moderate to excellent yields in Table 3.
metaꢀSubstitution relative to the newly formed CꢀS bond was well tolerated bearing
electronꢀwithdrawing (5d, 5e, 5f) or electronꢀdonating substituents (5b). Interestingly,
for the metaꢀsubstituted anilines, the reaction could afford the corresponding products
regiospecifically in excellent yields (5gꢀ5j). As for Nꢀmethylaniline and
N,Nꢀdimethylaniline, they were also well tolerated under the optimized reaction
conditions (5m, 5n).
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Table 3. Scope of the thiocyanation of 4ꢀthiocyanation of anilines a
a Standard reaction conditions: 4a (0.3 mmol), 2a (0.6 mmol), Cu(OTf)2 (20 mol %), TMEDA (20
mol %), BF3·Et2O (0.6 mmol), DMSO (2 mL), O2 balloon, 80 oC, 12 h.
When the 4ꢀsubstituted anlinines were chosen for the reactant, various
1,3ꢀbenzothiazolꢀ2ꢀamines were produced (Table 4). The reaction conditions were
compatible with alkyl, fluoro, chloro, bromo, and trifluoromethyl groups (6aꢀ6c,
6fꢀ6i). However, the product yields decreased when the substituents were ꢀOMe,
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ꢀOBn, ꢀCN and ꢀSO2Me (6d, 6e, 6j, 6k). Obviously, the electronic effect plays an
important role, and both strong electronꢀrich and electronꢀpoor substituents on the
benzene ring disfavored the transformation. Noteworthily, the generation of
6ꢀthiocyanatoꢀ1,3ꢀbenzothiazolꢀ2ꢀamine from aniline requires the stronger reaction
conditions (6l).
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Table 4. Scope of the thiocyanation reaction of 4ꢀsubstituted anilines a
a Standard reaction conditions: 4a(0.3 mmol), 2a(0.6 mmol), Cu(OTf)2 (20 mol %), TMEDA (20
mol %), BF3·Et2O (0.6 mmol), DMSO (2 mL), O2 balloon, 100 oC, 12 h. b 80 oC. c 2a (0.9 mmol),
110 oC.
As the success of these methods in indoles and anilines, we next applied the
optimized conditions to other Nꢀheterocyclic compounds. Unfortunately, it is failed
when we tried to use other Nꢀheterocyclic substrates to produce the thiocyanation
products (Table 5).
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Table 5. Scope of the thiocyanation reaction of Nꢀheterocyclic substrates a
5
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Cu(OTf)2 (20 mol %)
TMEDA (20 mol %)
BF3.Et2O (2 equiv)
H
SCN
Het
7a
KSCN
Het
8a
SCN
+
DMSO, 80 oC, O2
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2a
N
N
HN
SCN
N
N
SCN
N
8a, 0%
8c, 0%
8b, 0%
HN
N
N
N
N
SCN
SCN
SCN
8e, 0%
8d, 0%
8f, 0%
a Standard reaction conditions: 7a (0.3 mmol), 2a (0.4 mmol), Cu(OTf)2 (20 mol %), TMEDA (20
mol %), BF3·Et2O (0.6 mmol), DMSO (2 mL), O2 (1 balloon), 80 oC, 12 h.
To understand more insight into the reaction mechanism, we conducted several
experiments (Scheme 2). First, by addition of radical inhibitor TEMPO to the process,
no thiocyanation product was detected. However, when
4
equiv of
1,1ꢀdiphenylethylene was added to the standard conditions, the 3ꢀthiocyanation
product 3a was obtained in 75% isolated yield and only a trace amount of
4ꢀthiocyanatoaniline 5a was obtained. These results suggested that free radical might
be involved in the reaction of anilines instead of indoles.19
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Scheme 2. Control Experiments
According to the above results, plausible mechanisms are proposed. For indoles
case, we suspect that an organometallic pathway should be involved in this
transformation (Scheme 3). The catalytic cycle would start with the activation of the
CuII species. CuII gains the ability to associate with the indole through πꢀcoordination
to form copper complex A.21a Then, a molecule of HX is lost to generate copper
complex B.21b Next, interchange of the anion between copper complex B and the
potassium thiocyanate occurs to form copper complex C.21b,c The complex C would
be oxidized to CuIII complex D and the product 3a is produced followed by the
reductive elimination.21b,d As for BF3·Et2O, we suggested that it may played as a
Lewis acid in the formation of the iodolium intermediate to activate C3 position of
indole.22
For aniline case, the above experiments imply the generation of SCN radical
(Scheme 4). The reaction is initiated by the copperꢀmediated single electron transfer
(SET) in CuIIꢀSCN E generates the SCN radical F.8,23 Then, the radical F reacts with
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the electronꢀrich site of aniline 4a to deliver intermediate G which is further oxidized
to the aromatic cation H.23e Finally, the desired product is afforded by proton
elimination of H.23f Meanwhile, the CuI can be oxidized by DMSO or O2 to generate
the CuII species.20 As for 4ꢀsubstituted aniline, when the oꢀanline was generated, it
could be cyclized immediately to form 2ꢀamino benzothiazoles via Nꢀattack.12
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Scheme 3. Possible mechanism
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Scheme 4. Possible mechanism
CONCLUSION
In conclusion, we have developed a Cuꢀcatalyzed aerobic oxidative thiocyanation
of aromatics and heteroaromatics, which are ubiquitous structural units in a number of
biologically active compounds. This method exhibits a good functional group
tolerance even with strong electronꢀwithdrawing groups. Moreover, this reaction
provides an attractive practical synthetic strategy for the direct CꢀS bond formation
and a new method for the synthesis of 2ꢀamino benzothiazoles. Meanwhile, the use of
molecular oxygen as the oxidant makes the overall chemical transformation
sustainable and practical.
EXPERIMENTAL SECTION
General Information. All reactions were carried out in 10 mL tubes under O2 balloon.
TLC was performed by using commercially prepared 100−400 mesh silica gel plates
(GF254) and visualization was effected at 254 nm. Unless otherwise noted, all reagents
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were purchased as reagent grade and used without further purification. Melting points
were measured with a micromelting point apparatus. NMR spectra were recorded in
CDCl3, acetoneꢀd6 or DMSOꢀd6 on a 400 MHz spectrometer. Chemical shifts were
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1
reported in parts per million (δ) relative to TMS (0.00 ppm) for H NMR data and
13
CDCl3 (77.00 ppm), Acetone (206.68, 29.92) or DMSOꢀd6 (39.52 ppm) for C NMR
data. IR spectra were obtained either as potassium bromide pellets or as liquid films
between two potassium bromide pellets with an infrared Fourier spectrometer.
Highꢀresolution mass spectra (ESI) were obtained with a LCMSꢀITꢀTOF mass
spectrometer.
General Procedure for Thiocyanation of Indoles: Indole (0.3 mmol), potassium
thiocyanate (0.4 mmol), Cu(OTf)2 (20 mol %), TMEDA (20 mol %) and BF3·Et2O
(0.6 mmol) were mixed in DMSO to stir under O2 balloon at 80 oC. Upon completion,
the reaction mixture was washed by saturated NaCl aqueous solution (2×10 mL) and
then extracted with ethyl acetate (2×10 mL), and the organic layers were combined,
dried over anhydrous MgSO4, filtered, and concentrated under reduced pressure. The
residue was separated by column chromatography (petroleum ether/ethyl acetatet, 8/1
to 5/1) give the pure products.
3ꢀThiocyanatoꢀ1Hꢀindole (3a):3 Red solid (43 mg, 83 %), m.p. = 70 ꢀ 71 C; H
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NMR (400 MHz, CDCl3) δ 8.85 (s, 1H), 7.89 ꢀ 7.71 (m, 1H), 7.41 (m, 2H), 7.31 (m,
13
2H); C NMR (101 MHz, CDCl3) δ 136.0, 131.0, 127.6, 123.8, 121.9, 118.7, 112.0,
111.9, 92.2 ppm; vmax(KBr)/cmꢀ1 3315, 3116, 2154, 1714, 1504, 1466, 1234, 745; MS
(EI, 70 eV): m/z (%) = 174 [M]+, 142, 120, 87, 77.
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1ꢀMethylꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3b):3 Yellow solid (44 mg, 78 %), m.p. = 95 ꢀ
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96 C; H NMR (400 MHz, CDCl3) δ 7.81 (d, J = 7.6 Hz, 1H), 7.41ꢀ7.30 (m, 4H),
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3.79 (d, J = 1.1 Hz, 3H); C NMR (100 MHz, CDCl3) δ 137.1, 135.0, 128.4, 123.4,
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121.5, 118.9, 111.8, 110.2, 89.8, 33.3 ppm; vmax(KBr)/cmꢀ1 3112, 3055, 2942, 2152,
1510, 1459, 1330, 1242, 745; MS (EI, 70 eV): m/z (%) = 188 [M]+, 173, 155, 120, 94,
77.
1ꢀPhenylꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3c):3 Red solid (71 mg, 94 %), m.p. = 54 ꢀ 55 oC;
1H NMR (400 MHz, CDCl3) δ 7.90 (d, J = 7.5 Hz, 1H), 7.65 (s, 1H), 7.56 (m, 3H),
13
7.47 (d, J = 7.8 Hz, 3H), 7.42 ꢀ 7.34 (m, 2H); C NMR (100 MHz, CDCl3) δ 138.0,
136.5, 133.8, 129.8, 128.6, 127.9, 124.6, 124.1, 122.3, 119.1, 111.3, 111.2, 93.1 ppm;
vmax(KBr)/cmꢀ1 3157, 3056, 2154, 1595, 1507, 1458, 1318, 1225, 749; MS (EI, 70 eV):
m/z (%) = 250 [M]+, 249, 218, 146, 111, 77.
1ꢀBenzylꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3d):3 Yellow solid (73 mg, 92 %), m.p. = 102 ꢀ
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103 C; H NMR (400 MHz, CDCl3) δ 7.89 ꢀ 7.83 (m, 1H), 7.43 (s, 1H), 7.40 ꢀ 7.32
(m, 6H), 7.20 ꢀ 7.15 (m, 2H), 5.29 (s, 2H); 13C NMR (100 MHz, CDCl3) δ 136.7,
135.6, 134.2, 128.9, 128.5, 128.1, 127.0, 123.5, 121.7, 119.0, 111.6, 110.6, 90.7, 50.6
ppm; vmax(KBr)/cmꢀ1 3109, 3047, 2930, 2151, 1504, 1462, 1161, 738; MS (EI, 70 eV):
m/z (%) = 264 [M]+, 204, 173, 91, 63.
2ꢀMethylꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3e):9i Yellow solid (49 mg, 87 %), m.p. = 87 ꢀ
o
88 C; 1H NMR (400 MHz, CDCl3) δ 8.57 (s, 1H), 7.65 (d, J = 7.2 Hz, 1H), 7.22 (m,
13
3H), 2.44 (s, 3H); C NMR (100 MHz, CDCl3) δ 142.0, 135.1, 128.6, 122.9, 121.5,
117.9, 112.1, 111.2, 88.6, 11.9 ppm; vmax(KBr)/cmꢀ1 3391, 3324, 3056, 2922, 2148,
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1716, 1544, 1404, 1226, 740; MS (EI, 70 eV): m/z (%) = 188 [M]+, 173, 161, 155,
118, 77.
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2ꢀPhenylꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3f): Yellow solid (66 mg, 88 %), m.p. = 70ꢀ71
oC; 1H NMR (400 MHz, DMSO) δ 12.40 (s, 1H), 7.87 (d, J = 7.4 Hz, 2H), 7.73 (d, J
= 7.1 Hz, 1H), 7.63 (m, 2H), 7.55 (m, 2H), 7.35 ꢀ 7.27 (m, 2H); 13C NMR (100 MHz,
DMSO) δ 143.6, 136.3, 130.5, 129.8 129.7, 129.4, 129.3, 123.9, 121.9, 118.5, 113.0,
112.8, 87.6 ppm; vmax(KBr)/cmꢀ1 3336, 3063, 2151, 1718, 1549, 1403, 1222, 741;
HRMSꢀESI (m/z): calcd for C15H10N2NaS, [M+Na]+ : 273.0465, found 273.0457.
4ꢀMethoxyꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3g): Brown solid (54 mg, 89 %), m.p. = 143 ꢀ
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144 C; 1H NMR (400 MHz, CDCl3) δ 8.59 (s, 1H), 7.32 (d, J = 2.7 Hz, 1H), 7.18 (t,
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J = 8.1 Hz, 1H), 7.00 (d, J = 8.2 Hz, 1H), 6.62 (d, J = 7.9 Hz, 1H), 3.99 (s, 3H); C
NMR (100 MHz, CDCl3) δ 154.0, 137.9, 128.7, 124.9, 117.0, 113.0, 105.0, 101.7,
92.4, 55.6 ppm; vmax(KBr)/cmꢀ1 3309, 3108, 2928, 2842, 2154, 1587, 1510, 1252,
1084, 731; HRMSꢀESI (m/z): calcd for C10H8N2NaOS, [M+Na]+ : 227.0259, found
227.0250.
4ꢀ(Benzyloxy)ꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3h):3 Brown solid (70 mg, 83 %), m.p. =
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107 ꢀ 109 C; H NMR (400 MHz, CDCl3) δ 8.63 (s, 1H), 7.58 (d, J = 7.5 Hz, 2H),
7.39 (t, J = 7.5 Hz, 2H), 7.31 (t, J = 7.3 Hz, 1H), 7.22 (d, J = 2.1 Hz, 1H), 7.10 (t, J =
8.1 Hz, 1H), 6.93 (d, J = 8.2 Hz, 1H), 6.64 (d, J = 7.9 Hz, 1H), 5.22 (s, 2H); 13C NMR
(100 MHz, CDCl3) δ 152.8, 137.9, 136.9, 129.3, 128.5, 127.8, 127.3, 124.7, 117.1,
113.2, 105.3, 102.9, 91.9, 70.2 ppm; vmax(KBr)/cmꢀ1 3404, 3118, 3039, 2922, 2154,
1584, 1506, 1243, 1076, 731; MS (EI, 70 eV): m/z (%) = 280 [M]+, 149, 132, 91, 71.
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4ꢀAcetoxyꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3i): Black solid (66 mg, 94 %), m.p. = 117 ꢀ
118 oC; 1H NMR (400 MHz, CDCl3) δ 9.08 (s, 1H), 7.11 (t, J = 7.9 Hz, 1H), 7.03 (m,
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2H), 6.89 (d, J = 7.6 Hz, 1H), 2.52 (s, 3H); C NMR (100 MHz, CDCl3) δ 171.0,
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142.9, 138.0, 132.9, 123.6, 119.4, 114.5, 112.4, 110.7, 88.5, 21.1 ppm; vmax(KBr)/cmꢀ1
3353, 3123, 2924, 2156, 1752, 1207, 1045, 738; HRMSꢀESI (m/z): calcd for
C11H8N2NaO2S, [M+Na]+ : 255.0200, found 255.0199.
4ꢀCyanoꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3j): Yellow solid (55 mg, 92 %), m.p. = 177 ꢀ
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178 C; H NMR (400 MHz, Acetone) δ 11.45 (s, 1H), 7.99 (s, 1H), 7.75 (d, J = 8.3
Hz, 1H), 7.53 (d, J = 7.4 Hz, 1H), 7.26 (m, 1H); 13C NMR (100 MHz, Acetone) δ
138.0, 137.3, 129.0, 127.6, 124.0, 118.9, 118.0, 112.5, 102.8, 92.1 ppm;
vmax(KBr)/cmꢀ1 3299, 3114, 2912, 2221, 1715, 1541, 1346, 745; HRMSꢀESI (m/z):
calcd for C10H5N3NaS, [M+Na]+: 222.0103, found 222.0096.
5ꢀMethylꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3k):3 Yellow solid (51 mg, 91 %), m.p. = 94 ꢀ
95 oC; 1H NMR (400 MHz, CDCl3) δ 8.65 (s, 1H), 7.46 (s, 1H), 7.25 (s, 1H), 7.17 (d,
J = 8.3 Hz, 1H), 7.00 (d, J = 8.3 Hz, 1H), 2.39 (s, 3H); 13C NMR (100 MHz, CDCl3)
δ 134.3, 131.4, 131.1, 127.8, 125.4, 118.0, 112.4, 111.8, 90.8, 21.4 ppm;
v
max(KBr)/cmꢀ1 3327, 3120, 3036, 2920, 2154, 1480, 1414, 1235, 794; MS (EI, 70 eV):
m/z (%) = 188 [M]+, 155, 128, 130, 91, 80.
5ꢀMethoxyꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3l):3 Yellow solid (52 mg, 85 %), m.p. = 128 ꢀ
129 oC; 1H NMR (400 MHz, CDCl3) δ 8.76 (s, 1H), 7.31 (s, 1H), 7.18 (d, J = 9.0 Hz,
1H), 7.08 (s, 1H), 6.83 (d, J = 8.8 Hz, 1H), 3.81 (s, 3H); 13C NMR (100 MHz, CDCl3)
δ 155.6, 131.5, 130.8, 128.4, 114.3, 113.1, 112.2, 99.7, 91.0, 55.8 ppm;
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vmax(KBr)/cmꢀ1 3327, 3120, 2938, 2154, 1625, 1582, 1434, 1292, 1209, 806; MS (EI,
70 eV): m/z (%) = 204 [M]+, 188, 178, 161, 134, 76.
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5ꢀChloroꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3m): Black solid (57 mg, 90 %), m.p. = 123 ꢀ
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124 C; 1H NMR (400 MHz, Acetone) δ 11.10 (s, 1H), 7.82 (d, J = 2.8 Hz, 1H), 7.60
(d, J = 1.8 Hz, 1H), 7.44 (d, J = 8.7 Hz, 1H), 7.14 (m, 1H); 13C NMR (100 MHz,
Acetone) δ 135.2, 134.2, 129.1, 126.9, 123.5, 117.4, 114.3, 111.0, 90.8 ppm;
vmax(KBr)/cmꢀ1 3319, 3316, 2923, 2150, 1691, 1567, 1467, 792; HRMSꢀESI (m/z):
calcd for C9H5ClN2NaS, [M+Na]+ : 230.9744, found 230.9754.
5ꢀBromoꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3n):3 Red solid (63 mg, 83 %), m.p. = 175 ꢀ 176
oC; 1H NMR (400 MHz, Acetone) δ 11.24 (s, 1H), 7.95 (m, 1H), 7.91 (s, 1H), 7.54 (m,
1H), 7.45 ꢀ 7.38 (m, 1H); 13C NMR (100 MHz, Acetone) δ 135.5, 134.0, 129.6, 126.1,
120.5, 114.6, 114.4, 111.1, 90.7 ppm; vmax(KBr)/cmꢀ1 3328, 3111, 2149, 1696, 1563,
1453, 868, 792; MS (EI, 70 eV): m/z (%) = 253 [M]+, 251, 173, 146, 129.
6ꢀMethoxyꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3o):3 Red solid (49 mg, 80 %), m.p. = 113 ꢀ
114 oC; 1H NMR (400 MHz, CDCl3) δ 8.61 (s, 1H), 7.65 (d, J = 8.6 Hz, 1H), 7.37 (s,
13
1H), 6.99 ꢀ 6.82 (m, 2H), 3.84 (s, 3H); C NMR (100 MHz, CDCl3) δ 157.5, 137.0,
129.9, 121.7, 119.2, 112.2, 112.0, 95.3, 91.8, 55.6 ppm; vmax(KBr)/cmꢀ1 3323, 3129,
2918, 2160, 1627, 1511, 1243, 809; MS (EI, 70 eV): m/z (%) = 204 [M]+, 189, 178,
161, 134, 76.
6ꢀ(Trifluoromethoxy)ꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3p): Yellow solid (70 mg, 90 %),
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m.p. = 51 ꢀ 52 C; H NMR (400 MHz, CDCl3) δ 8.97 (s, 1H), 7.77 (d, J = 8.7 Hz,
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1H), 7.54 (d, J = 2.2 Hz, 1H), 7.31 (s, 1H), 7.19 (d, J = 8.7 Hz, 1H); C NMR (100
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MHz, CDCl3) δ 146.2, 135.7, 132.3, 126.2, 120.6 (q, J = 255.3 Hz), 119.6, 116.0,
111.7 (q, J = 7.6 Hz), 105.2, 92.6 (q, J =10.6 Hz) ppm; vmax(KBr)/cmꢀ1 3108, 2927,
1716, 1515, 1258, 1159, 961, 888; HRMSꢀESI (m/z): calcd for C10H5F3N2NaOS,
[M+Na]+ : 280.9967, found 280.9974.
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6ꢀFluoroꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3q):3 Red solid (52 mg, 90 %), m.p. = 106 ꢀ 107
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oC; H NMR (400 MHz, DMSO) δ 12.07 (s, 1H), 8.00 (s, 1H), 7.70 ꢀ 7.65 (m, 1H),
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7.36 (d, J = 9.7 Hz, 1H), 7.13 (t, J = 9.2 Hz, 1H); C NMR (100 MHz, DMSO) δ
159.5 (d, J = 235.5 Hz), 136.3 (d, J = 12.9 Hz), 133.9, 124.1, 119.0 (d, J = 10.2 Hz),
112.1, 109.7 (d, J = 24.8 Hz), 98.9 (d, J = 25.9 Hz), 89.9 ppm; vmax(KBr)/cmꢀ1 3313,
3121, 2923, 2154, 1727, 1506, 1231, 801; MS (EI, 70 eV): m/z (%) = 192 [M]+, 172,
166, 138, 107, 95.
6ꢀNitroꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3r): Yellow solid (60 mg, 91 %), m.p. = 179 ꢀ
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180 C; 1H NMR (400 MHz, Acetone) δ 11.52 (s, 1H), 8.37 (d, J = 1.8 Hz, 1H), 8.11
(d, J = 2.8 Hz, 1H), 8.01 (m, 1H), 7.75 (d, J = 8.8 Hz, 1H); 13C NMR (100 MHz,
Acetone) δ 149.5, 143.1, 140.5, 137.5, 123.7, 121.5, 116.0, 114.7, 97.9 ppm;
vmax(KBr)/cmꢀ1 3355, 3110, 2920, 2154, 1722, 1508, 1328, 665; HRMSꢀESI (m/z):
calcd for C9H5N3NaO2S, [M+Na]+ : 241.9996, found 241.9995.
7ꢀFluoroꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3s): Red solid (46 mg, 80 %), m.p. = 113 ꢀ 114
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oC; H NMR (400 MHz, Acetone) δ 7.93 (s, 1H), 7.52 (d, J = 8.0 Hz, 1H), 7.22 (m,
1H), 7.07 ꢀ 7.01 (m, 1H); 13C NMR (100 MHz, Acetone) δ 150.9 (d, J = 244 Hz),
134.5, 132.6 (d, J = 4.9 Hz), 125.9 (d, J = 14.3 Hz), 123.0 (d, J = 7.8 Hz), 115.3,
112.0, 109.2 (d, J = 16.2 Hz), 93.5 (d, J = 3.4 Hz) ppm; vmax(KBr)/cmꢀ1 3272, 3124,
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2159, 1578, 1423, 1232, 784, 685; HRMSꢀESI (m/z): calcd for C9H5FN2NaS,
[M+Na]+ : 215.0055, found 215.0050.
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7ꢀBromoꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3t): Yellow solid (62 mg, 82 %), m.p. = 155 ꢀ
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157 C; H NMR (400 MHz, Acetone) δ 11.14 (s, 1H), 7.84 (s, 1H), 7.62 (m, 1H),
7.38 (d, J = 7.6 Hz, 1H), 7.10 (m, 1H); 13C NMR (100 MHz, Acetone) δ 136.2, 134.5,
130.4, 127.0, 123.8, 118.8, 111.9, 106.3, 93.8 ppm; vmax(KBr)/cmꢀ1 3264, 2155, 1708,
1567, 1194, 774; HRMSꢀESI (m/z): calcd for C9H5BrN2NaS, [M+Na]+ : 274.9249,
found 274.9245.
2ꢀMethylꢀ5ꢀchloroꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3u): Yellow solid (62 mg, 93 %), m.p.
= 170 ꢀ 171 oC; 1H NMR (400 MHz, Acetone) δ 10.94 (s, 1H), 7.43 (s, 1H), 7.27 (d, J
= 8.6 Hz, 1H), 7.02 (d, J = 8.6 Hz, 1H), 2.44 (s, 3H); 13C NMR (100 MHz, Acetone) δ
144.7, 134.2, 130.0, 126.5, 122.6, 116.8, 113.2, 110.9, 87.9, 11.2 ppm; vmax(KBr)/cmꢀ1
3296, 2925, 2852, 2156,1717, 1549, 1454, 938, 860, 798; HRMSꢀESI (m/z): calcd for
C10H7ClN2NaS, [M+Na]+ : 244.9912, found 244.9911.
5,6ꢀDimethoxyꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3v): Red solid (53 mg, 75 %), m.p. = 142
ꢀ 143 oC; 1H NMR (400 MHz, CDCl3) δ 8.89 (s, 1H), 7.33 (d, J = 2.8 Hz, 1H), 7.15 (s,
13
1H), 6.87 (s, 1H), 3.98 (s, 3H), 3.86 (s, 3H); C NMR (100 MHz, CDCl3) δ 148.2,
146.6, 130.2, 129.3, 120.8, 112.1, 99.7, 95.1, 91.2, 56.3, 56.1 ppm; vmax(KBr)/cmꢀ1
3328, 3122, 2939, 2154, 1484, 1318, 1211,1157, 1020, 842; HRMSꢀESI (m/z): calcd
for C11H10N2NaO2S, [M+Na]+ : 257.0355, found 257.0359.
2,5ꢀDimethylꢀ3ꢀthiocyanatoꢀ1Hꢀindole (3w): Yellow solid (57 mg, 94 %), m.p. =
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135 ꢀ 136 C; H NMR (400 MHz, CDCl3) δ 8.45 (s, 1H), 7.47 (s, 1H), 7.19 (d, J =
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8.2 Hz, 1H), 7.08 ꢀ 7.02 (m, 1H), 2.49 (d, J = 2.9 Hz, 6H); 13C NMR (100 MHz,
CDCl3) δ 141.9, 133.3, 131.1, 128.9, 124.4, 117.7, 112.2, 110.8, 88.2, 21.4, 12.0 pm;
vmax(KBr)/cmꢀ1 3285, 3031, 2921, 2152, 1722, 1542, 1459, 1408, 1298, 1222, 798;
HRMSꢀESI (m/z): calcd for C11H10N2NaS, [M+Na]+ : 225.0457, found 225.0457.
1ꢀMethylꢀ3ꢀamineꢀ5ꢀthiocyanatoꢀ1Hꢀpyrazol (3x): Yellow solid (35 mg, 75 %),
m.p. = 103 ꢀ 104 oC; 1H NMR (400 MHz, CDCl3) δ 7.39 (s, 1H), 3.93 (s, 2H), 3.70 (s,
3H); 13C NMR (100 MHz, CDCl3) δ 156.1, 135.6, 110.9, 81.3, 39.2 ppm;
vmax(KBr)/cmꢀ1 3302, 3120, 2929, 2154, 1725, 1607, 1541; HRMSꢀESI (m/z): calcd
for C5H6N4NaS, [M+Na]+ : 177.0205, found 177.0203.
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2ꢀThiocyanatoꢀ1Hꢀpyrrol (3y):9d black liquid (23mg, 62%); H NMR (400 MHz,
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CDCl3) δ 8.89 (s, 1H), 6.99 (s, 1H), 6.65 (s, 1H), 6.28 (s, 1H); C NMR (100 MHz,
CDCl3) δ 124.3, 120.1, 111.2, 110.7, 103.0 ppm; vmax(KBr)/cmꢀ1 3309, 3121, 2159,
1713, 1535, 1024, 740; MS (EI, 70 eV): m/z (%) = 124 [M]+, 98, 71, 70, 79.
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4ꢀThiocyanatoaniline (5a):9d Brown solid (35 mg, 78 %), m.p. = 75 ꢀ 76 C; H
NMR (400 MHz, CDCl3) δ 7.35 (d, J = 7.8 Hz, 2H), 6.66 (d, J = 7.8 Hz, 2H), 3.97 (s,
2H); 13C NMR (100 MHz, CDCl3) δ 148.8, 134.4, 116.0, 112.4, 109.4 ppm;
v
max(KBr)/cmꢀ1 3372, 3218, 3045, 2150, 1721, 1582, 1493, 1294, 822; MS (EI, 70 eV):
m/z (%) = 150[M]+, 123, 118, 106, 96, 80, 65.
2ꢀMethylꢀ4ꢀthiocyanatoaniline (5b):8 Yellow solid (34 mg, 69 %), m.p. = 69 ꢀ 70 oC;
1H NMR (400 MHz, CDCl3) δ 7.23 (m, 2H), 6.64 (d, J = 8.3 Hz, 1H), 3.75 (s, 2H),
2.14 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 147.1, 135.0, 132.0, 123.8, 115.7, 112.5,
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882, 813; MS (EI, 70 eV): m/z (%) = 164 [M]+, 138, 131, 104, 77.
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2ꢀFluoroꢀ4ꢀthiocyanatoaniline (5c): Brown solid (36 mg, 72 %), m.p. = 33 ꢀ 34 C;
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1H NMR (400 MHz, CDCl3) δ 7.23 (m, 1H), 7.16 (m, 1H), 6.77 (t, J = 8.7 Hz, 1H),
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3.83 (s, 2H); C NMR (100 MHz, CDCl3) δ 150.9 (d, J = 242.8 Hz), 137.4 (d, J =
12.6 Hz), 129.7 (d, J = 3.3 Hz), 119.7 (d, J = 20.7 Hz), 111.6, 109.4 (d, J = 7.3 Hz)
ppm; vmax(KBr)/cmꢀ1 3376, 3061, 2926, 2153, 1623, 1502, 1302, 1206, 877, 811;
HRMSꢀESI (m/z): calcd for C7H5FN2NaS, [M+Na]+ : 191.0050, found, 191.0041.
2ꢀChloroꢀ4ꢀthiocyanatoaniline (5d):8 Yellow solid (50 mg, 91 %), m.p. = 51 ꢀ 52 oC;
1H NMR (400 MHz, CDCl3) δ 7.47 (d, J = 2.0 Hz, 1H), 7.28 ꢀ 7.24 (m, 1H), 6.75 (d, J
= 8.5 Hz, 1H), 4.34 (s, 2H); 13C NMR (100 MHz, CDCl3) δ 145.3, 133.7, 132.5, 119.5,
116.3, 111.7, 109.7 ppm; vmax(KBr)/cmꢀ1 3480, 3072, 3065, 2152, 1614, 1487, 1309,
872, 813; MS (EI, 70 eV): m/z (%) = 184 [M]+, 152, 149, 122, 105, 90, 63.
2ꢀBromoꢀ4ꢀthiocyanatoaniline (5e): Yellow solid (62 mg, 90 %), m.p. = 57 ꢀ 59 oC;
1H NMR (400 MHz, CDCl3) δ 7.65 ꢀ 7.59 (m, 1H), 7.32 ꢀ 7.27 (m, 1H), 6.74 (m, 1H),
4.33 (s, 2H); 13C NMR (100 MHz, CDCl3) δ 146.5, 136.8, 133.2, 116.1, 111.7, 110.0,
109.1 ppm; vmax(KBr)/cmꢀ1 3476, 3370, 3063, 2152, 1614, 1483, 1308, 875, 812;
HRMSꢀESI (m/z): calcd for C7H5BrN2NaS, [M+Na]+ : 250.9249, found, 250.9246.
2ꢀCyanoꢀ4ꢀthiocyanatoaniline (5f): Brown solid (49 mg, 95 %), m.p. = 126 ꢀ 127 oC;
1H NMR (400 MHz, DMSO) δ 7.82 (d, J = 2.2 Hz, 1H), 7.58 (m, 1H), 6.89 (d, J = 8.9
Hz, 1H), 6.72 (s, 2H); 13C NMR (100 MHz, DMSO) δ 153.7, 139.0, 138.6, 117.5,
117.1, 112.9, 107.4, 95.0 ppm; vmax(KBr)/cmꢀ1 3441, 3362, 2216, 2151, 1729, 1636,
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1583, 1486, 896, 824; HRMSꢀESI (m/z): calcd for C8H5N3NaS, [M+Na]+ : 198.0096,
found, 198.0100.
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3ꢀMethylꢀ4ꢀthiocyanatoaniline (5g):8 Brown solid (39 mg, 80 %), m.p. = 56ꢀ58 C;
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1H NMR (400 MHz, CDCl3) δ 7.35 (d, J = 8.4 Hz, 1H), 6.58 (d, J = 2.5 Hz, 1H), 6.49
(m, 1H), 3.93 (s, 2H), 2.44 (s, 3H); 13C NMR (100 MHz, CDCl3) δ 149.4, 142.9,
136.2, 117.2, 113.6, 112.0, 108.9, 20.8 ppm; vmax(KBr)/cmꢀ1 3373, 3225, 2928, 2149,
1590, 1480, 1319, 1254, 858, 812; MS (EI, 70 eV): m/z (%) = 164 [M]+, 149, 131, 94,
77.
3ꢀBromoꢀ4ꢀthiocyanatoaniline (5h):8 Brown solid (57 mg, 83 %), m.p. = 63 ꢀ 65 oC;
1H NMR (400 MHz, CDCl3) δ 7.43 (m, 1H), 6.97 ꢀ 6.91 (m, 1H), 6.61 (m, 1H), 4.01
(s, 2H); 13C NMR (100 MHz, CDCl3) δ 149.7, 134.9, 127.5, 119.3, 115.0, 111.2,
110.8 ppm; vmax(KBr)/cmꢀ1 3371, 3064, 2152, 1712, 1580, 1107, 856; MS (EI, 70 eV):
m/z (%) = 228 [M]+, 198, 149, 123, 105, 90, 63.
3ꢀEthoxyformylꢀ4ꢀthiocyanatoaniline (5i): Yellow solid (56 mg, 83 %), m.p. = 143
ꢀ 144 oC; 1H NMR (400 MHz, CDCl3) δ 7.61 (d, J = 8.6 Hz, 1H), 7.39 (d, J = 2.7 Hz,
1H), 6.91 (m, 1H), 4.38 (q, J = 7.1 Hz, 2H), 3.89 (s, 2H), 1.40 (t, J = 7.1 Hz, 3H); 13C
NMR (100 MHz, CDCl3) δ 165.9, 146.3, 129.4, 127.9, 120.3, 117.3, 116.3, 112.6,
62.0, 14.1 ppm; vmax(KBr)/cmꢀ1 3461, 3369, 3237, 2921, 2146, 1683, 1273, 813, 773;
HRMSꢀESI (m/z): calcd for C10H10N2NaO2S, [M+Na]+ : 245.0355, found, 245.0358.
3ꢀTrifluoromethylꢀ4ꢀthiocyanatoꢀaniline (5j): Yellow solid (58 mg, 88 %), m.p. =
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58 ꢀ 59 C; H NMR (400 MHz, CDCl3) δ 7.57 (d, J = 8.5 Hz, 1H), 6.99 (d, J = 2.6
Hz, 1H), 6.78 (m, 1H), 4.26 (s, 2H); 13C NMR (100 MHz, CDCl3) δ 149.2, 138.2,
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133.6 (q, J = 30.8 Hz), 122.8 (q, J = 272.3 Hz), 117.9, 113.7 (q, J = 5.5 Hz), 111.5,
106.5 ppm; vmax(KBr)/cmꢀ1 3378, 3070, 2156, 1732, 1596, 1329, 1263, 1126, 877, 824;
HRMSꢀESI (m/z): calcd for C8H6F3N2S, [M+H]+ : 219.0198, found, 219.0200.
2,6ꢀDimethylꢀ4ꢀthiocyanatoaniline (5k): Yellow solid (48 mg, 89 %), m.p. = 82 ꢀ 83
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oC; H NMR (400 MHz, CDCl3) δ 7.16 (s, 2H), 3.77 (s, 2H), 2.16 (s, 6H); C NMR
(100 MHz, CDCl3) δ 145.2, 132.8, 123.1, 112.6, 108.4, 17.3 ppm; vmax(KBr)/cmꢀ1
3419, 3344, 3246, 2962, 2151, 1638, 1456, 871; HRMSꢀESI (m/z): calcd for
C9H10N2NaS, [M+Na]+ : 201.0457, found, 201.0459.
3,5ꢀDimethylꢀ4ꢀthiocyanatoaniline (5l): Black solid (43 mg, 77 %), m.p. = 123 ꢀ 124
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oC; H NMR (400 MHz, CDCl3) δ 6.46 (s, 2H), 3.82 (s, 2H), 2.48 (s, 6H); C NMR
(100 MHz, CDCl3) δ 149.0, 144.5, 115.1, 111.8, 109.1, 22.0 ppm; vmax(KBr)/cmꢀ1
3480, 3387, 3216, 2930, 2141, 1588, 1463, 1336, 851; HRMSꢀESI (m/z): calcd for
C9H10N2NaS, [M+Na]+ : 201.0457, found, 201.0460.
4ꢀThiocyanatoꢀNꢀmethylaniline (5m):8 Black liquid (37 mg, 76 %), H NMR (400
1
MHz, CDCl3) δ 7.37 (d, J = 7.8 Hz, 2H), 6.57 (d, J = 7.9 Hz, 2H), 4.02 (s, 1H), 2.83
13
(s, 3H); C NMR (100 MHz, CDCl3) δ 151.0, 134.6, 113.3, 112.6, 107.3, 30.1 ppm;
v
max(KBr)/cmꢀ1 3410, 2927, 2149, 1594, 1510, 1327, 814; MS (EI, 70 eV): m/z (%) =
164 [M]+, 149, 131, 105, 81, 63.
4ꢀThiocyanatoꢀN,Nꢀdimethylaniline (5n):9d Brown solid (43 mg, 80 %), m.p. = 67 ꢀ
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68 C; H NMR (400 MHz, CDCl3) δ 7.42 (d, J = 8.5 Hz, 2H), 6.67 (d, J = 8.6 Hz,
13
2H), 2.99 (s, 6H); C NMR (100 MHz, CDCl3) δ 151.6, 134.4, 129.4, 113.1, 112.5,
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106.4, 40.0 ppm; vmax(KBr)/cmꢀ1 3338, 3061, 2925, 2152, 1447, 742, 683; MS (EI, 70
eV): m/z (%) = 178 [M]+, 145, 118, 104, 89, 81.
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6ꢀMethylꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6a):11f Yellow solid (34 mg, 70 %), m.p. =
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129ꢀ130 C; H NMR (400 MHz, CDCl3) δ 7.44 ꢀ 7.38 (m, 2H), 7.11 (d, J = 8.0 Hz,
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1H), 5.53 (s, 2H), 2.39 (s, 3H); C NMR (100 MHz, CDCl3) δ 165.6, 149.7, 131.9,
131.4, 127.1, 120.9, 118.5, 21.2 ppm; vmax(KBr)/cmꢀ1 3392, 3288, 3045, 2932, 1636,
1535, 1460, 1113, 813; MS (EI, 70 eV): m/z (%) = 164 [M]+, 136, 110, 77, 69.
6ꢀIsopropylꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6b): Green solid (35 mg, 60 %), m.p. = 121
ꢀ 122 oC; 1H NMR (400 MHz, CDCl3) δ 7.45 (d, J = 8.5 Hz, 2H), 7.17 (d, J = 8.3 Hz,
1H), 5.78 (s, 2H), 2.95 (m, 1H), 1.27 (d, J = 6.9 Hz, 6H); 13C NMR (100 MHz, CDCl3)
δ 165.8, 150.0, 143.2, 131.7, 124.6, 118.7, 118.3, 33.9, 24.2 ppm; vmax(KBr)/cmꢀ1
3436, 3088, 2955, 1632, 1531, 1462, 822; HRMSꢀESI (m/z): calcd for C10H13N2S,
[M+H]+ : 193.0794, found, 193.0796.
6ꢀTertꢀbutylꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6c): Black solid (46 mg, 69 %), m.p. = 141
ꢀ 142 oC; 1H NMR (400 MHz, CDCl3) δ 7.59 (d, J = 1.5 Hz, 1H), 7.46 (d, J = 8.5 Hz,
13
1H), 7.34 (m, 1H), 5.74 (s, 2H), 1.35 (s, 9H). C NMR (100 MHz, CDCl3) δ 166.0,
149.6, 145.5, 131.5, 123.6, 118.4, 117.3, 34.7, 31.6 ppm. vmax(KBr)/cmꢀ1 3434, 3279,
3082, 2957, 1634, 1527, 1464, 1309, 1109, 822 cm−1; HRMSꢀESI (m/z): calcd for
C11H15N2S, [M+H]+ : 207.0950; found, 207.0955.
6ꢀMethoxyꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6d):11f Black solid (19 mg, 36 %), m.p. = 158
ꢀ 159 oC; 1H NMR (400 MHz, CDCl3) δ 7.44 (d, J = 8.8 Hz, 1H), 7.12 (d, J = 2.5 Hz,
13
1H), 6.90 (m, 1H), 5.15 (s, 2H), 3.82 (s, 3H); C NMR (100 MHz, CDCl3) δ 164.1,
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155.7, 146.0, 132.5, 119.6, 113.7, 105.4, 55.9 ppm; vmax(KBr)/cmꢀ1 3383, 3295, 3095,
2925, 1543, 1461, 1269, 1205, 807; MS (EI, 70 eV): m/z (%) = 180 [M]+, 165, 137,
110, 80 ,69.
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6ꢀPhenoxyꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6e):11f Green solid (52 mg, 71 %), m.p. = 168
ꢀ 169 oC; 1H NMR (400 MHz, Acetone) δ 7.41 (d, J = 8.7 Hz, 1H), 7.34 (dt, J = 10.6,
5.1 Hz, 3H), 7.06 (t, J = 7.4 Hz, 1H), 6.96 (d, J = 8.5 Hz, 3H), 6.89 (s, 2H); 13C NMR
(100 MHz, Acetone) δ 167.5, 159.9, 152.6, 150.9, 134.0, 131.0, 123.9, 120.3, 119.0,
118.9, 113.3 ppm; vmax(KBr)/cmꢀ1 3429, 3069, 1536, 1466, 1221, 867, 854, 726; MS
(EI, 70 eV): m/z (%) = 242 [M]+, 165, 137, 110, 77.
6ꢀFluoroꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6f):11f Green solid (38 mg, 75 %), m.p. = 183 ꢀ
184 oC; 1H NMR (400 MHz, DMSO) δ 7.59 (m, 1H), 7.47 (s, 2H), 7.32 (m, 1H), 7.09
ꢀ 7.01 (m, 1H); 13C NMR (100 MHz, DMSO) δ 166.8, 157.6 (d, J = 234.7 Hz), 149.9,
132.4 (d, J = 11.1 Hz), 118.6 (d, J = 8.8 Hz), 113.2 (d, J = 23.5 Hz), 108.2 (d, J =
26.9 Hz) ppm; vmax(KBr)/cmꢀ1 3299, 2086, 2923, 1719, 1539, 1480, 917, 846, 805;
MS (EI, 70 eV): m/z (%) = 167 [M]+, 141, 114, 84, 70.
6ꢀChloroꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6g):11f Yellow solid (50 mg, 90 %),m.p. = 200
ꢀ 201 oC; 1H NMR (400 MHz, Acetone) δ 7.56 (s, 1H), 7.23 (d, J = 8.6 Hz, 1H), 7.10
(d, J = 8.5 Hz, 1H), 6.88 (s, 2H); 13C NMR (100 MHz, Acetone) δ 168.1, 153.1, 134.3,
126.7, 126.7, 121.3, 120.2 ppm; vmax(KBr)/cmꢀ1 3456, 3282, 3100, 1714, 1529, 1443,
852, 798; MS (EI, 70 eV): m/z (%) = 184 [M]+, 156, 149, 122, 93, 62.
6ꢀBromoꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6h):12f Yellow solid (44 mg, 65 %), m.p. = 214
ꢀ 215 oC; 1H NMR (400 MHz, Acetone) δ 7.82 (d, J = 1.9 Hz, 1H), 7.37 (m, 1H), 7.31
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(d, J = 8.5 Hz, 1H), 6.99 (s, 2H); 13C NMR (100 MHz, Acetone) δ 168.0, 153.3, 134.7,
129.5, 124.1, 120.7, 113.9 ppm; vmax(KBr)/cmꢀ1 3452, 3287, 3099, 2923, 1712, 1628,
1526, 1442; MS (EI, 70 eV): m/z (%) = 227[M]+, 200, 149, 122, 95, 63.
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6ꢀTrifluoromethylꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6i): Yellow solid (52 mg, 80 %), m.p.
= 109 ꢀ 110 oC; 1H NMR (400 MHz, CDCl3) δ 7.83 (s, 1H), 7.53 (s, 2H), 6.30 (s, 2H).
13C NMR (100 MHz, CDCl3) δ 168.6, 154.4, 131.4, 124.4 (q, J = 270.1 Hz), 124.3 (q,
J = 32.5 Hz), 123.2 (q, J = 3.6 Hz), 118.6, 118.4 (q, J =4.0 Hz) ppm; vmax(KBr)/cmꢀ1
3297, 3112, 1526, 1320, 1117, 884, 822; HRMSꢀESI (m/z): calcd for C8H6F3N2S,
[M+H]+ : 219.0198, found, 219.0198.
6ꢀCyanoꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6j): Yellow solid (34 mg, 58 %), m.p. = 204 ꢀ
206 oC; 1H NMR (400 MHz, Acetone) δ 7.96 (s, 1H), 7.46 (d, J = 8.4 Hz, 1H), 7.35 (d,
13
J = 8.3 Hz, 1H), 7.23 (s, 2H); C NMR (100 MHz, Acetone) δ 170.9, 157.6, 130.5,
125.9, 120.0, 119.5, 104.6 ppm; vmax(KBr)/cmꢀ1 3360, 3076, 2918, 2215, 1520, 1465,
1303, 814; HRMSꢀESI (m/z): calcd for C8H6N3S, [M+H]+ : 176.0277, found,
176.0275.
6ꢀMethylsulfonylꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6k): Yellow solid (35 mg, 51 %), m.p.
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= 224 ꢀ 225 C; H NMR (400 MHz, Acetone) δ 8.23 (d, J = 1.8 Hz, 1H), 7.79 (m,
1H), 7.53 (d, J = 8.5 Hz, 1H), 7.34 (s, 2H), 3.10 (s, 3H); 13C NMR (100 MHz,
Acetone) δ 171.4, 158.4, 135.0, 133.5, 126.4, 122.1, 119.4, 45.4 ppm; vmax(KBr)/cmꢀ1
3360, 3114, 2922, 1717, 1520, 1288, 1142, 956; HRMSꢀESI (m/z): calcd for
C8H9N2O2S2, [M+H]+ : 229.0100, found, 229.0095.
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6ꢀThiocyanatoꢀ1,3ꢀbenzothiazolꢀ2ꢀamine (6l): Yellow solid (43 mg, 72 %), m.p. =
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214 ꢀ 217 C; H NMR (400 MHz, DMSO) δ 8.06 (s, 1H), 7.84 (s, 2H), 7.50 (d, J =
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8.4 Hz, 1H), 7.42 (d, J = 8.4 Hz, 1H); C NMR (100 MHz, DMSO) δ 168.7, 154.6,
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132.9, 129.9, 125.2, 118.8, 113.3, 112.5 ppm; vmax(KBr)/cmꢀ1 3304, 3100, 1720, 1532,
958; HRMSꢀESI (m/z): calcd for C8H6N3S2, [M+H]+ : 207.9998, found, 207.9999.
Acknowledgments
The authors thank the National Natural Science Foundation of China (21672072 and
21420102003), the China Postdoctoral Science Foundation (2016T90779 and
2015M572303), and the Fundamental Research Funds for the Central Universities
(2015ZY001 and 2015ZM150) for financial support.
Supporting Information
Copies of 1H and 13C NMR spectra data for all compounds. This material is available
free of charge via the Internet at http://pubs.acs.org.
REFERENCES
(1) For selected examples, see: (a) Castanheiro, T.; Suffert, J.; Donnard, M.; Gulea,
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