Visible Light-Induced Thiocyanation of Enaminone C-H Bond to Access Polyfunctionalized Alkenes and Thiocyano Chromones

Article abstract of DOI:10.1021/acs.joc.8b02981

The visible light induced C-H bond thiocyanation on the α-site of tertiary enaminones has been realized under metal-free, photocatalytic conditions in the presence of Rose Bengal, which enables the synthesis of thiocyanated alkene derivatives and chromones using NH₄SCN as the thiocyano source under an aerobic atmosphere. In addition, employing Ru(bpy)₃Cl₂·6H₂O as the photocatalyst switches the reaction pathway to provide NH₂-functionalized thiocyanated enamines via the difunctionalization process consisting of C-H bond thiocyanation and vinyl C-N bond transamination.

Full text of DOI:10.1021/acs.joc.8b02981

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Article
Visible Light-Induced Thiocyanation of Enaminone C-H Bond to
Access Polyfunctionalized Alkenes and Thiocyano Chromones
Yong Gao, Yunyun Liu, and Jie-Ping Wan
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.8b02981 • Publication Date (Web): 16 Jan 2019
Downloaded from http://pubs.acs.org on January 16, 2019
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Visible Light-Induced Thiocyanation of Enaminone C-H Bond to
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Yong Gao, Yunyun Liu, Jie-Ping Wan*
College of Chemistry and Chemical Engineering, Jiangxi Normal University, Nanchang 330022, P.R. China.
ABSTRACT: The visible light induced C-H bond thiocyanation on the α-site of tertiary enaminones has been realized under metal-
free, photocatalytic conditions in the presence of Rose Bengal, which enables the synthesis of thiocyanated alkene derivatives and
chromones using NH
photocatalyst switches the reaction pathway to provide NH
4
SCN as the thiocyano source under an aerobic atmosphere. In addition, employing Ru(bpy)
3 2 2
Cl ·6H O as
2
-functionalized thiocyanated enamines via the difunctionalization process
consisting of C-H bond thiocyanation and vinyl C-N bond transamination.
INTRODUCTION
well as the elemental sulfur-based double C-H thiolation14 have
been consequently reported. Amazingly, as a valuable functional
structure, the SCN group has not yet been successfully installed to
enaminones. Based on our longstanding interest in enaminone-
based organic synthesis, we report herein the first transition
metal-free synthesis of α-thiocyano enaminones through visible
light induced thiocyanation of the enaminone C-H bond, wherein
Rose Bengal (RB) is employed as a low cost and nonmetal
Organic thiocyanates are moieties possessing enriched
biological and pharmaceutical activities in both synthesized and
naturally occurring molecules. Moreover, the enriched reactivity
of the thiocyano group also endows organic thiocyanates with
widespread application as building blocks in organic synthesis.
Although different strategies on organic thiocyanate synthesis
have been known with efficiency, the thiocyanation reaction
3 4
employing low cost reagents such as Fe(SCN) , KSCN, NH SCN,
1
2
3
1
5
photocatalyst.
TMSCNS, etc as the thiocyano sources constitutes one major
option for the atom economical C-S bond formation. Inarguably,
RESULTS AND DISCUSSION
4
We started the investigation on the reaction of enaminone 1a
with ammonium thiocyanate 2. At first, several non-metal
photocatalysts, including Eosin Y, Eosin B and RB were
tentatively employed with the visible light irradiation of 14W
compact fluorescent lamp (CFL). We observed that RB could
catalyze the C-H thiocyanation of 1a to provide product 3a with
excellent yield in only 1% loading (entries 1-3, Table 1). Control
experiments revealed that the photocatalyst and visible light
irradiation were both mandatory (Table 1, entry 4-5). Later on, a
series of organic solvents with different polarities, such as
dioxane, acetone, MeCN and DMF were utilized as the reaction
medium, respectively (entries 6-9, Table 1), and THF was found
as the most favorable medium. At last, the decrease on the loading
of ammonium thiocyanate 2 was not favored, as lower yield of 3a
was provided (entry 10, Table 1).
the direct thiocyanation of the stable C-H bond is among the most
favorable route because such method allows the synthesis of
organic thiocyanates using those prevalently available C-H bond
donors. During the past decade, a plethora of catalytic methods
have been successfully developed for the direct thiocyanation of
2
5
3
6
both stable C(sp )-H and C(sp )-H bonds, which provides rapid
access to divergent thiocyanated molecules. Despite these notable
2
advances, most of the successful examples on the C(sp )-H bond
thiocyanation takes place on aromatic system. On the other hand,
much less transformations of such type on the equally pivotal
2
alkenyl C(sp )-H bond are known. In this regard, devising
2
catalytic methods enabling alkene C(sp )-H bond thiocyanation is
highly urgent for the sake of providing facile methods
synthesizing structurally diverse alkenyl thiocyanates.
Enaminones are a class of functionalized alkenes derivative
featured with easy access, ideal stability and highly versatile
reactivity. Among the various reported reaction pathways in
Table 1 Optimization on the reaction conditiona
7
O
O
photocatalyst (1 mol %)
14 W CFL
enaminones, the direct cross coupling of the alkenyl C-H bond has
in recent years gained extensive attention. For example, the
intramolecular C-H arylation of enaminones is a reliable method
N
N
+
4
NH SCN
solvent, rt, air, 12 h
SCN
1a
2
3a
8
for indole synthesis under different catalytic conditions. In
addition, the intermolecular arylations on the enaminone C-H
bond have been also realized via noble metal catalysis.
yield (%)b
entry
catalyst
Eosin Y
Eosin B
solvent
THF
9
1
2
21
17
Noteworthy, the functionalization on the same C-H bond under
transition metal-free has been recently found to be applicable in
forging new C-heteroatom bonds. Specifically, the enaminone C-
THF
3
Rose Bengal
-
THF
THF
THF
87
1
0
11
H acyloxyation and oxygenation, amination, sulfenylation/aryl
4
trace
0
1
2
13
selenylation and annulative alkyl thiolation, sulfonylation, as
5c
Rose Bengal
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Rose Bengal
Rose Bengal
Rose Bengal
Rose Bengal
Rose Bengal
dioxane
acetone
MeCN
DMF
52
37
45
0
Inspired by the satisfactory results acquired from the direct C-H
thiocyanation of tertiary enaminones 1, we assumed that this
transformation could be employed in designing cascade reaction
to synthesis thiocyanated molecules of higher structural
divergence. Consequently, the N,N-dimethyl enaminones 4 with
o-hydroxylphenyl substructure were selected to react with 2,
expecting that the 3-thiocyanated chromones of type 5 would be
synthesized by combing this newly developed C-H thiocyanation
and the chromone annulation featured with enaminones 4. To our
delight, under the standard conditions of visible light irradiation,
the thiocyanated chromones 5 were afforded with generally
excellent yield regardless the electronic property of the substituent
in the phenyl ring of 4 (5a-5g, Scheme 2). In addition, when (E)-
1
0d
THF
74
aGeneral Conditions: 1a (0.2 mmol), 2 (0.4 mmol), catalyst (1
mol %), and 2 mL solvent, stirred for 12 h at rt under air with 14
W CFL irradiation. Yield of isolated product based on 1a.
Reaction in dark atmosphere. Reaction with 1.1 equiv of 2.
b
c
d
0
1
2
3
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0
1
2
3
4
5
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8
9
0
Later, the generality of this photocatalytic thiocyanation
reaction was investigated, and the results are summarized in
Scheme 1. It was observed that this reaction tolerated a broad
array of functional groups of different features in the phenyl ring
of 1. The enaminone substrates containing electron donating and
electron withdrawing groups participated in the synthesis of
corresponding products 3 with good to excellent yields (3a-3i,
Scheme 1). The reactions employing enaminone 1a indicated that
the electron withdrawing effect in the phenyl ring was negative to
the reaction by affording thiocyanated products with slightly
lower yield (3f-3i, Scheme 1). On the other hand, the reactions
employing morpholine (3l and 3m, Scheme 1) piperidine (3n,
Scheme 1) and acylic alkyl (3o-3t, Scheme 1) functionalized
enaminones were found to give related products with lower yield
than those using 1a. Besides the reactions employing phenyl-
based aryl enaminones, a notable point was that the naphthyl and
heteroaryl functionalized enaminones also smoothly reacted with
1-(2-hydroxyphenyl)-3-morpholinoprop-2-en-1-one,
an
enaminone with different N,N-disubstitution was employed with
NH SCN under the catalytic conditions, the product 5a was
4
provided with 80% yield.
Scheme 2 Synthesis of thiocyano chromones by C-H
a,b
thiocyanation
O
Rose Bengal
(1 mol %)
14 W CFL
O
SCN
SCN
N
R
+
NH SCN
4
R
THF, rt, air, 12 h
OH
O
4
2
5
O
O
O
SCN
SCN
O
O
O
O
NH
4
SCN to provide products 3j and 3k with excellent yields.
functionalized enaminones were not able to
5a, 89%
5b, 92%
5c, 94%
However, NH or NH
2
undergo this transformation under the present conditions. In
addition, the (E)-4-(dimethylamino)but-3-en-2-one, an alkyl-
based enaminone was not thiocyanated with the present catalytic
method.
O
O
O
F
SCN Cl
SCN Br
SCN
O
O
O
5d, 80%
5e, 86%
5f, 82%
Scheme 1 Scope of the thiocyanation reaction of tertiary
enaminones
O
a,b
SCN
Rose Bengal
Cl
O
O
O
O
(
1
1 mol %)
4 W CFL
THF, rt, air, 12 h
5g
, 84%
R1
R1
N
N
R
Ar
+
NH4SCN
R
Ar
R1
SCN R1
aGeneral Conditions: enaminone 4 (0.2 mmol), NH
SCN 2 (0.4
4
1
2
3
mmol), Rose Bengal (0.002 mmol) in THF (2 mL), stirred with 14
b
R = H, 3a, 87%
R = 4-Me, 3b, 85%
R = 3-OMe,
R = 2-Me, 3d, 81%
R = 3,4-(OCH2O), , 86%
R = 4-Br, 3f, 79%
R = 4-CN, 3g, 80%
R = 3-NO2, 3h, 76%
R = 3,4-Cl2, 3i, 81%
W CFL irradiation at room temperature for 12 h. Yield of
N
isolated product based on 4.
3c, 82%
O
SCN
3
j, 84%
Interestingly, the analogous C-H selenocyanation on enaminone
1a was found also highly practical by utilizing the commercially
available KSeCN as coupling reagent under the standard reaction
conditions (Eq 1). Another entry employing enaminone 1s,
however, did not provide the expected selenocyanated product.
N
3e
O
SCN
R
N
S
SCN
3
k, 83%
O
O
O
O
N
standard
N
conditions
N
SCN
O
N
(1)
+
KSeCN
R
SCN
SeCN
, 64%
R = H, 3l, 73%, R = Cl, 3m, 70%
1a
6
3
n, 68%
O
O
R1
N
SCN R1
During further investigation on the reaction, we also noticed an
interesting difunctionization reaction forming thiocyano and NH
functionalized alkenes 7 by using Ru(bpy) Cl ·6H O as the
N
2
-
SCN
R
R1 = Me, 3o, 71%, R1 = Et, 3p, 79%
R1 = n-Pr, 3q, 78%, R1 = benzyl, 3r, 74%
3
2
2
R = Me, 3s, 75%
R = Cl, 3t, 71%
16
photoredox catalyst (See Scheme 3).
Therefore, brief
optimization on the reaction employing different media was
conducted on the reaction providing 7a. While the entries
employing MeCN, dioxane and DMF did not provide this product,
the entry employing ethyl lactate (EL) gave 7a with 76% yield in
aGeneral Conditions: enominone 1 (0.2 mmol), NH
SCN 2 (0.4
4
mmol), RB (0.002 mmol) in THF (2 mL), stirred with 14 W CFL
irradiation at room temperature for 12h. Yield of isolated product
based on 1.
b
the presence of 1 mol% Ru(bpy)
3 2 2
Cl ·6H O, while the same
reaction in MeCN, DMF, EtOH or dioxane did not take place.
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Thus, the scope on this enaminone difunctionalization involving
fluorescence emission intensity occurred following the increased
concentration of NH SCN (Fig. 1). This tendency was also visual
in the corresponding Stern-Volmer plots (Fig. 2). On the contrary,
such quenching effect was not observed in corresponding
the C-H bond thiocyanation and the C-N bond amination was
examined. As outlined in Scheme 3, the polyfunctionalized
alkenes 7 were practically synthesized with moderate to good
yield under the irradiation of visible light in the presence of
4
1
experiments using enaminone 1o (R = H, R = Me, see SI).
3 2 2
Ru(bpy) Cl ·6H O. The selectivity in providing only Z-alkene
derivatives could be attributed to the stabilization effect resulting
from the presence of intramolecular hydrogen bond in 7. The
good results using the bio-mass feedstock EL as reaction medium
constituted additional advantage of this synthetic method.
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
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0
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Scheme 3 Photocatalytic difunctionalization of enaminonesa,b
O
Ru(bpy)3Cl2•6H O
2
O
NH2
(1 mol %)
N
14 W CFL
R
Ar
+
4
NH SCN
R
Ar
EL, rt, air, 12 h
SCN
1
2
7
O
NH2
O
NH2
O
NH2
NH2
SCN
a, 76%
SCN
SCN
Cl
7
7b, 69%
7c, 44%
O
NH2
O
NH2
O
Figure 1 Quenching of RB fluorescence emission with NH SCN
4
Cl
Cl
SCN
SCN
7e, 42%
SCN
7f, 63%
Br
7d, 41%
aGeneral conditions: enominone 1 (0.2 mmol), NH
mmol), Ru(bpy) Cl ·6H
4 W CFL irradiation at room temperature for 12h. Yield of
SCN (0.4
4
3
2
2
O (0.002 mmol) in 2 mL EL, stirred with
b
1
isolated product based on 1 was reported.
To gain possible information on the reaction process, several
control entries on the model reaction were executed. First, the
inhibition of TEMPO to the reaction supported that the reaction
took place via a free radical process (Eq 2). In addition, the very
2
low yield of product 3a in the reaction under N confirmed the
indispensable role of molecular oxygen (Eq 3). Finally, the yield
of 3a was not evidently undermined in the reaction conducted in
the presence of DABCO, indicating against the involvement of
singlet oxygen (Eq 4).17
Figure 2 Stern-Volmer plot. I0 is the inherent fluorescence
intensity of RB. I Is the fluorescence intensity of RB in the
presence of NH SCN.
4
O
standard
conditions
N
3a
According to the product structures as well as the results
obtained from control experiments, the mechanism for the C-H
thiocyanation reaction was proposed. As shown in Scheme 4, the
+
NH SCN
4
(2)
(3)
TEMPO (5 equiv) 19%
1
a
2
O
reactions may start from the quenching of NH SCN to the excited
standard
conditions
4
3
14%
a
RB* species generated from the visible light irradiation to RB
N
+
NH SCN
4
5j
under N2
catalyst, which gives rise to ˙SCN free radical. The
-
1a
2
simultaneously formed RB˙ can be regenerated to RB by the
oxidation of molecular oxidation. Subsequently, the addition of
the ˙SCN to the C=C double bond in 1 gives rise to free radical
intermediate A. The site selectivity of the addition transformation
is determined by the better stability of free radical A with the
adjacent electron donating amino group. By means of oxidation
from the superoxide radical ion generated during the RB
regeneration, free radical A is transformed into the carbon cation
intermediate B. The deprotonation on B then yields thiocyanated
product 3. When o-hydroxylphenyl functionalized enaminones are
used as substrates, the featured intramolecular annulation
successively takes place to give thiocyanated chromones 5. In
addition, when Ru-catalyst is employed, a transamination between
the tertiary enaminones and the ammonium is promoted to form
products 7, wherein the Ru-catalyst may act also as Lewis acid
(LA) catalyst. In fact, although the transamination of ammonium
with tertiary enaminone was hard, we carried out the typical
O
standard
conditions
3
a
N
+
NH SCN
(4)
(5)
4
DABCO (1 equiv) 76%
1a
2
.
O
Ru(bpy) Cl 6H O
Ph
3
2
2
O
HN
Ph
1
mol%
Ph
N
NH2
EL, rt, 12h
Ph
9
1o
8
60%
To further explore the interaction of RB with substrates, the
fluorescence quenching experiments of of RB with enaminone 1a
and NH
indicated that NH
emission of excited RB because the regularly diminished
4
SCN 2 were investigated, respectively. The results
4
SCN evidently quenching the fluorescence
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Lewis acid-catalyzed transamination between tertiary enaminone
MHz, CDCl3): δ 188.1, 159.6, 150.1, 142.2, 129.0, 120.0, 117.1,
1
8
+
and aniline in the presence of the Ru(bpy)
3
Cl
2
·6H
2
O without
112.3, 93.2, 55.4, 52.4, 47.0, 25.2; HRMS Calcd for C14
[M + H] 232.1332, found 232.1333.
H
18NO
2
+
CFL irradiation, which provided the expected NH-enaminone
with good yield (Eq 5), supporting the function of this catalyst as
Lewis acid.
(
E)-3-(Pyrrolidin-1-yl)-1-(o-tolyl)prop-2-en-1-one
(1d).
3
1
Yield 57%, 245 mg; yellow liquid; H NMR (400 MHz, CDCl ):
δ 7.50-6.99 (m, 5 H), 5.32 (d, J = 12.0 Hz, 1 H), 3.22 (brs, 4 H),
2
.41 (s, 3 H), 2.06-1.88 (m, 4 H); 13C{ H} NMR (100 MHz,
1
Scheme 4 The postulated reaction mechanism
3
CDCl ): δ 194.1, 150.9, 142.1, 135.3, 130.6, 128.5, 127.1, 125.2,
99.0, 52.3, 46.9, 25.2, 25.1, 19.8; HRMS Calcd for C14
+
NH /LA
R = 2-OH
H
18NO [M
3
7
3
+
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
5
+ H] 216.1383, found 216.1384.
-H+
(
E)-1-(Benzo[d][1,3]dioxol-5-yl)-3-(pyrrolidin-1-yl)prop-2-
hv
HNR'R'
O2
HNR'R'
o
1
en-1-one (1e). Yield 53%, 260 mg; mp 144-145 C; H NMR (400
MHz, CDCl ): δ 8.03-7.93 (m, 1 H), 7.54-7.41 (m, 2 H), 6.88-6.74
RB
Photoredox
O
3
RB
R'
(
m, 1 H), 6.00 (s, 2 H), 5.61 (d, J = 12.0 Hz, 1 H), 3.26 (brs, 4 H),
N
2.08-1.89 (m, 4 H). 13C{ H} NMR (100 MHz, CDCl ): δ 186.7,
1
Catalysis
R
3
SCN R'
B
149.6, 147.6, 135.2, 122.5, 107.9, 107.6, 101.4, 92.5, 52.3, 47.0,
2
2
+
+
5.2; HRMS Calcd for C14
46.1121.
3
H16NO [M + H] 246.1125, found
SCN
RB
O2
R
O
O
SCN
R'
N
(E)-1-(4-Bromophenyl)-3-(pyrrolidin-1-yl)prop-2-en-1-one
R'
N
o
1
(1f). Yield 64%, 357 mg; mp 122-123 C; H NMR (400 MHz,
CDCl ): δ 8.08-7.97 (m, 1 H), 7.78 (d, J = 8.2 Hz, 2 H), 7.54 (d, J
8.4 Hz, 2 H), 5.62 (d, J = 12.0 Hz, 1 H), 3.28 (brs, 4 H), 2.08-
R
SCN R'
R'
1
A
3
=
1
.90 (m, 4 H); 13C{ H} NMR (100 MHz, CDCl
1
3
): δ187.0, 150.3,
CONCLUSION
139.4, 131.3, 129.2, 125.3, 92.5, 52.5, 47.1, 25.2; HRMS Cald for
C
In conclusion, we have realized herein the first vinyl C-H bond
thiocyanation reaction of tertiary enaminones by metal-free
photocatalysis. Besides providing a simple and efficient approach
toward the synthesis of thiocyanated alkene derivatives, the
switchable synthesis of even more divergent organic thiocyanates,
including thiocyanated chromones and the polyfunctionalized
alkenes containing primary amino and thiocyano groups has been
achieved by simply modifying the substrate structure or the
photocatalyst species.
+
+
13
H
15BrNO [M + H] 280.0332, found 280.0335.
(E)-4-(3-(Pyrrolidin-1-yl)acryloyl)benzonitrile (1g). Yield
o
1
61%, 276 mg; mp 128-129 C; H NMR (400 MHz, CDCl
3
): δ
8.08-7.88 (m, 3 H), 7.67 (d, J = 7.8 Hz, 2 H), 5.59 (d, J = 11.6 Hz,
1
3
1
1 H), 3.27 (brs, 4 H), 2.10-1.90 (m, 4 H). C{ H} NMR (100
MHz, CDCl ): δ 186.1, 150.8, 144.4, 132.0, 128.0, 118.7, 113.8,
3
+
92.6, 52.6, 47.2, 25.2, 25.1; HRMS Cald for C H N O [M +
H] 227.1179, found 227.1178.
1
4
15
2
+
EXPERIMENTAL SECTION
(E)-1-(3-Nitrophenyl)-3-(pyrrolidin-1-yl)prop-2-en-1-one
o
1
(
1h). Yield 70%, 344 mg; mp 95-96 C; H NMR (400 MHz,
General experimental information. All experiments were
carried out under air atmosphere with the irradiation of 14W CFL
lamp (OSRAM Ltd., MUN-DULCOM20WSIN01BK, Bulb
shape- Standard). The enaminones 1 and 4 were synthesized
CDCl ): δ 8.70 (s, 1 H), 8.34-8.23 (m, 2 H), 8.14-8.05 (m, 1 H),
3
7.60 (t, J = 7.8 Hz, 1H), 5.68 (d, J = 12.0 Hz, 1 H), 3.35 (brs, 4
H), 2.12-1.96 (m, 4H); 13C{ H} NMR (100 MHz, CDCl
1
): δ
3
1
8b,19
following literature procedure in 2 mmol scale.
Known
185.1, 150.9, 148.1, 142.1, 133.4, 129.2, 125.2, 122.3, 92.1, 52.7,
47.3, 25.2, 25.2; HRMS Cald for C13
found 247.1079.
+
+
compounds synthesized by the literature methods have been
confirmed by comparing reported characterization data.
Characterization data for those newly synthesized substrates by
these methods were shown below (see SI for their chemical
structures). Other chemicals and solvents used in our experiments
were obtained from commercial sources and used directly without
15 2 3
H N O [M + H] 247.1077,
(
E)-1-(3,4-Dichlorophenyl)-3-(pyrrolidin-1-yl)prop-2-en-1-
o
1
one (1i). Yield 63%, 339 mg; mp 85-86 C; H NMR (400 MHz,
CDCl ): δ 8.12-7.88 (m, 2 H), 7.79-7.67 (m, 1 H), 7.53-7.41 (m, 1
H), 5.59 (d, J = 12.0 Hz, 1 H), 3.30 (brs, 4 H), 2.11-1.92 (m, 4 H);
C{ H} NMR (100 MHz, CDCl
32.4, 130.1, 129.5, 126.7, 92.2, 52.6, 47.2, 25.2, 25.2; HRMS
3
1
13
further treatment. The H and C NMR spectra were recorded in
13
1
3
): δ 185.3, 150.6, 140.4, 134.8,
1
4
00 MHz apparatus in CDCl
C NMR test were 400 MHz and 100 MHz, respectively. The
3
. The frequencies for H NMR and
1
1
3
+
+
2
Cald for C13H14Cl NO [M + H] 270.0447, found 270.0449.
chemical shifts were reported in ppm with TMS as internal
standard. Melting points were tested in X-4A instrument without
correcting the temperature. The HRMS data for all new products
were obtained under ESI model in a mass spectrometer equipped
with TOF analyzer.
(
E)-1-(Naphthalen-2-yl)-3-(pyrrolidin-1-yl)prop-2-en-1-one
o
1
(1j). Yield 72%, 361 mg; mp 106-107 C; H NMR (400 MHz,
CDCl ): δ 8.42 (s, 1 H), 8.15-7.82 (m, 5 H), 7.61-7.43 (m, 2 H),
.85 (d, J = 12.0 Hz, 1 H), 3.33 (brs, 4 H), 2.10-1.87 (m, 4 H);
C{ H} NMR (100 MHz, CDCl
32.8, 129.2, 127.8, 127.7, 127.6, 127.1, 126.2, 124.7, 93.2, 52.4,
3
5
1
3
1
3
): δ 188.2, 150.0, 137.9, 134.7,
(1b).20
(
E)-3-(Pyrrolidin-1-yl)-1-(p-tolyl)prop-2-en-1-one
1
4
2
1
3
Yield 71%, 305 mg; H NMR (400 MHz, CDCl ): δ 8.07-7.96 (m,
+
+
7.1, 25.2; HRMS Cald for C17
52.1382.
H18NO [M + H] 252.1383, found
1
H), 7.81 (d, J = 7.8 Hz, 2 H), 7.21 (d, J = 7.8 Hz, 2 H), 5.68 (d,
J = 12.2 Hz, 1 H), 3.27 (brs, 4 H), 2.38 (s, 3 H), 2.06-1.88 (m, 4
H).
(
E)-3-(Pyrrolidin-1-yl)-1-(thiophen-2-yl)prop-2-en-1-one
o
1
(
1k). Yield 59%, 244 mg; mp 114-115 C; H NMR (400 MHz,
(
E)-1-(3-Methoxyphenyl)-3-(pyrrolidin-1-yl)prop-2-en-1-
CDCl ): δ 8.01 (d, J = 12.0 Hz, 1 H), 7.68-7.44 (m, 2 H), 7.14-
3
o
1
one (1c). Yield 67%, 309 mg; mp 82-83 C; H NMR (400 MHz,
CDCl ): δ 8.12-7.98 (m, 1 H), 7.47 (d, J = 7.0 Hz, 2 H), 7.55-7.42
m, 2 H), 7.08-6.93 (m, 1 H), 5.67 (d, J = 12.0 Hz, 1 H), 3.87 (s, 3
7.02 (m, 1 H), 5.60 (d, J = 12.0 Hz, 1 H), 3.28 (brs, 4 H), 2.08-
3
1.90 (m, 4 H); 13C{ H} NMR (100 MHz, CDCl
1
): δ 180.6, 149.3,
3
(
1
H), 3.29 (brs, 4 H), 2.12-1.88 (m, 4H); 13C{ H} NMR (100
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1
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2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
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5
5
5
5
5
5
5
5
5
6
147.6, 130.1, 128.3, 127.5, 92.5, 52.4, 47.0, 25.2; HRMS Cald for
C
3
CDCl ): δ 13.97 (s, 1 H), 7.97–7.85 (m, 1 H), 7.78 (s, 1 H), 7.43
(d, J = 8.4 Hz, 1 H), 6.85 (d, J = 8.4 Hz, 1 H), 5.68 (d, J = 13.6
+
+
11
H
14NOS [M + H] 208.0791, found 208.0790.
(1n).10b
Hz, 1 H), 3.22 (s, 3 H), 3.01 (s, 3 H).
(E)-1-Phenyl-3-(piperidin-1-yl)prop-2-en-1-one
1
Yield 70%, 299 mg; H NMR (400 MHz, CDCl
3
): δ 7.94-7.76 (m,
(E)-1-(4-Chloro-2-hydroxyphenyl)-3-(dimethylamino)prop-
2
3
1
3
4
H), 7.42 (d, J = 7.0 Hz, 3 H), 5.84 (d, J = 11.0 Hz, 1 H), 3.37 (s,
H), 1.67 (s, 6 H).
2-en-1-one (4g). Yield 58%, 260 mg; H NMR (400 MHz,
CDCl ): δ 14.30 (s, 1 H), 7.95–7.82 (m, 1 H), 7.61 (d, J = 8.8 Hz,
3
(1s).21
1 H), 6.94 (s, 1 H), 6.79 (d, J = 7.2 Hz, 1 H), 5.69 (d, J = 12.0 Hz,
1 H), 3.20 (s, 3 H), 2.98 (s, 3 H).
(
E)-3-(Dimethylamino)-1-phenylprop-2-en-1-one
1
Yield 62%, 218 mg; H NMR (400 MHz, CDCl
3
): δ 7.91 (d, J =
8
(
.0 Hz, 2 H), 7.86-7.76 (m, 1 H), 7.43 (d, J = 8.0 Hz, 3 H), 5.73
d, J = 13.2 Hz, 1 H), 3.14 (s, 3 H), 2.93 (s, 3 H).
E)-3-(Dimethylamino)-1-(p-tolyl)prop-2-en-1-one
General procedure for the synthesis of products 3 and 6. To
a 25 mL round-bottom flask were added enaminone 1 (0.2 mmol),
NH SCN or KSeCN (0.4 mmol), RB (0.002 mmol) and THF (2
4
mL). The mixture was then stirred at room temperature for 12h
with the irradiation of 14 W CFL (distance bulb−vessel
approximately 5 cm) under air atmosphere (TLC). Upon on
completion, 5 mL water was added to the flask, and the resulting
mixture was extracted with ethyl acetate (3 × 8 mL). The organic
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
(1t).21
(
1
Yield 52%, 196 mg; H NMR (400 MHz, CDCl
3
): δ 7.93–7.75
(m, 3 H), 7.22 (d, J = 8.0 Hz, 2 H), 5.73 (d, J = 12.0 Hz, 1 H),
3.12 (s, 3 H), 2.93 (s, 3 H), 2.40 (s, 3 H).
(E)-1-(4-chlorophenyl)-3-(dimethylamino)prop-2-en-1-one
2
1
1
(1u). Yield 65%, 272 mg; H NMR (400 MHz, CDCl
.71 (m, 3 H), 7.38 (d, J = 8.4 Hz, 2 H), 5.67 (d, J = 12.8 Hz, 1
H), 3.16 (s, 3 H), 2.93 (s, 3 H).
E)-1-(4-Bromophenyl)-3-(dimethylamino)prop-2-en-1-one
3
): δ 7.99–
2 4
phases were collected and dried with anhydrous Na SO . After
7
filtration, the resulting solution was employed under reduced
pressure to remove the solvent. The acquired residue was
subjected to flash silica gel column chromatography to provide
pure products by the elution with mixed petroleum ether/ethyl
acetate (v/v = 3 : 1).
(
1
0b
1
(
7
1v). Yield 65%, 329 mg; H NMR (400 MHz, CDCl
.72 (m, 3 H), 7.55 (d, J = 7.4 Hz, 2 H), 5.67 (d, J = 12.0 Hz, 1
H), 3.17 (s, 3 H), 2.94 (s, 3 H).
E)-1-(3,4-Dichlorophenyl)-3-(dimethylamino)prop-2-en-1-
3
): δ 7.89-
(Z)-1-Phenyl-3-(pyrrolidin-1-yl)-2-thiocyanatoprop-2-en-1-
(
one (3a). Yield 87%, 45.0 mg; R = 0.2; yellow solid; mp 90-91
f
o
1
o
1
one (1w). Yield 73%, 354 mg; mp 92-93 C; H NMR (400 MHz,
CDCl ): δ 7.99 (s, 1 H), 7.88-7.80 (m, 1 H), 7.74 (d, J = 8.0 Hz, 1
C; H NMR (400 MHz, CDCl ): δ 7.83 (s, 1 H), 7.48-7.41 (m, 5
3
H), 4.09 (brs, 2 H), 3.57 (brs, 2 H), 2.08-1.94 (m, 4 H); 13C{ H}
1
3
H), 7.49 (d, J = 8.4 Hz, 1 H), 5.63 (d, J = 12.8 Hz, 1 H), 3.19 (s, 3
NMR (100 MHz, CDCl
3
): 192.5, 155.3, 140.0, 130.3, 128.3,
H), 2.96 (s, 3 H); 13C{ H} NMR (100 MHz, CDCl
1
): δ 185.6,
3
1
28.0, 113.7, 87.8, 56.3, 49.5, 26.2, 24.0; ESI-HRMS Calcd for
154.9, 140.3, 134.9, 132.4, 130.1, 129.5, 126.7, 91.3, 45.2, 37.4;
C H N NaOS [M + Na]
+
281.0719, found 281.0731.
1
4
14
2
+
+
HRMS Calcd for C11
44.0293.
E)-3-(dimethylamino)-1-(naphthalen-2-yl)prop-2-en-1-one
2
H12Cl NO [M + H] 244.0290, found
(
Z)-3-(Pyrrolidin-1-yl)-2-thiocyanato-1-(p-tolyl)prop-2-en-1-
= 0.3; yellow solid; mp 118-119
H NMR (400 MHz, CDCl ): δ 7.85 (s, 1 H), 7.42 (d, J = 7.5
2
one (3b). Yield 85%, 46.2 mg; R
C;
f
(
o
1
3
2
1
1
(
(
1x). Yield 61%, 274 mg; H NMR (400 MHz, CDCl
3
): δ 8.42
Hz, 2 H), 7.22 (d, J = 7.7 Hz, 2 H), 4.10 (brs, 2 H), 3.59 (brs, 2
s, 1 H), 8.08–7.81 (m, 5 H), 7.53 (s, 2 H), 5.89 (d, J = 12.4 Hz, 1
H), 2.40 (s, 3 H), 2.00 (brs, 4 H); 13C{ H} NMR (100 MHz,
1
H), 3.14 (s, 3 H), 2.97 (s, 3 H).
E)-3-(Dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-
3
CDCl ): 192.4, 155.1, 140.7, 137.0, 128.9, 128.3, 113.9, 87.7,
(
56.3, 49.4, 26.1, 23.9, 21.5; ESI-HRMS Calcd for C15
H
16
N
2
NaOS
22
1
+
one (4a). Yield 75%, 286 mg; H NMR (400 MHz, CDCl
3
): δ
[M + Na] 295.0876, found 295.0866.
1
3.98 (s, 1H), 7.95-7.84 (m, 1 H), 7.71 (d, J = 8.0 Hz, 1 H), 7.45–
7.32 (m, 1 H), 6.95 (d, J = 8.0 Hz, 1 H), 6.87–6.79 (m, 1 H), 5.79
(d, J = 12.0 Hz, 1 H), 3.20 (s, 3 H), 2.98 (s, 3 H).
(Z)-1-(3-Methoxyphenyl)-3-(pyrrolidin-1-yl)-2-
thiocyanatoprop-2-en-1-one (3c). Yield 82%, 47.1 mg; R
f
= 0.2;
1
3
yellow liquid; H NMR (400 MHz, CDCl ): δ 7.79 (s, 1 H), 7.26-
(E)-3-(Dimethylamino)-1-(2-hydroxy-5-methylphenyl)prop-
7.20 (m, 1 H), 6.97-6.91 (m, 3 H), 4.03 (brs, 2 H), 3.77 (s, 3 H),
2
2
1
3.52 (brs, 2 H), 2.02-1.88 (m, 4 H); 13C{ H} NMR (100 MHz,
1
2
-en-1-one (4b). Yield 69%, 282 mg; H NMR (400 MHz,
CDCl ): δ 13.77 (s, 1 H), 7.96-7.79 (m, 1 H), 7.49 (s, 1 H), 7.18
d, J = 7.2 Hz, 1 H), 6.85 (d, J = 8.4 Hz, 1 H), 5.78 (d, J = 12.0
Hz, 1 H), 3.19 (s, 3 H), 2.99 (s, 3 H), 2.31 (s, 3 H).
E)-3-(Dimethylamino)-1-(2-hydroxy-4-methoxyphenyl)
3
CDCl
): 192.4, 159.5, 155.3, 141.3, 129.3, 120.3, 116.5, 113.8,
3
(
1
C
13.0, 87.7, 56.3, 55.4, 49.8, 26.2, 24.2; ESI-HRMS Calcd for
+
15
H
16
N
2
NaO
2
S [M + Na] 311.0825, found 311.0836.
(
(
Z)-3-(Pyrrolidin-1-yl)-2-thiocyanato-1-(o-tolyl)prop-2-en-1-
= 0.3; yellow solid; mp 105-106
): δ 7.64 (s, 1 H), 7.28-7.10 (m, 4
H), 4.04 (brs, 2 H), 3.49 (brs, 2 H), 2.25 (s, 3 H), 2.05 (brs, 2 H),
2
2
1
prop-2-en-1-one (4c). Yield 63%, 278 mg; H NMR (400 MHz,
CDCl ): δ 14.50 (s, 1 H), 7.99-7.71 (m, 1 H), 7.62 (d, J = 8.8 Hz,
H), 6.55-6.23 (m, 2 H), 5.69 (d, J = 12.8 Hz, 1 H), 3.82 (s, 3 H),
3.17 (s, 3 H), 2.95 (s, 3 H).
one (3d). Yield 81%, 44.1 mg; R
f
o
1
3
C; H NMR (400 MHz, CDCl
3
1
.87 (brs, 2 H); 13C{ H} NMR (100 MHz, CDCl
1
1
3
): 193.4, 154.9,
(
E)-3-(Dimethylamino)-1-(5-fluoro-2-hydroxyphenyl)prop-
140.2, 134.9, 130.6, 128.9, 126.5, 125.5, 113.4, 89.0, 56.3, 49.5,
2
2
1
+
2-en-1-one (4d).
Yield 60%, 251 mg;
H
NMR (400
26.1, 23.9, 19.2; ESI-HRMS Calcd for C H N NaOS [M + Na]
295.0876, found 295.0882.
1
5
16
2
MHz,CDCl
.09 (s, 1 H), 6.90 (s, 1 H), 5.67 (d, J = 12.0 Hz, 1 H), 3.22 (s, 3
H), 2.99 (s, 3 H).
E)-1-(5-Chloro-2-hydroxyphenyl)-3-(dimethylamino)prop-
3
): δ 13.70 (s, 1 H), 8.07–7.77 (m, 1 H), 7.37 (s, 1 H),
7
(Z)-1-(Benzo[d][1,3]dioxol-5-yl)-3-(pyrrolidin-1-yl)-2-
thiocyanatoprop-2-en-1-one (3e). Yield 86%, 52.0 mg; R
f
= 0.8;
1
(
yellow liquid; H NMR (400 MHz, CDCl ): δ 7.85 (s, 1 H), 7.06-
3
2
2
1
2
-en-1-one (4e). Yield 63%, 283 mg; H NMR (400 MHz,
CDCl ): δ 13.94 (s, 1H), 7.98–7.83 (m, 1 H), 7.64 (s, 1 H), 7.30
d, J = 7.6 Hz, 1 H), 6.89 (d, J = 8.8 Hz, 1 H), 5.69 (d, J = 12.0
Hz, 1 H), 3.22 (s, 1 H), 3.00 (s, 1 H).
E)-1-(5-Bromo-2-hydroxyphenyl)-3-(dimethylamino)prop-
7.03 (m, 2 H), 6.82 (d, J = 7.8 Hz, 1 H), 6.02 (s, 2 H), 4.06 (brs, 2
H), 3.65 (brs, 2 H), 2.02 (s, 4 H); 13C{ H} NMR (100 MHz,
1
3
(
CDCl
3
): 191.2, 155.0, 149.7, 147.6, 133.7, 123.3, 113.8, 109.0,
1
C
07.8, 101.5, 87.4, 56.0, 49.7, 25.9, 24.4; ESI-HRMS Calcd for
+
(
15
H
14
N
2
NaO
3
S [M + Na] 325.0617, found 325.0629.
22
1
2
-en-1-one (4f). Yield 64%, 344 mg; H NMR (400 MHz,
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1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
(Z)-1-(4-Bromophenyl)-3-(pyrrolidin-1-yl)-2-
J = 8.3 Hz, 2 H), 7.40 (d, J = 8.3 Hz, 2 H), 3.93 (brs, 4 H), 3.85-
3.84 (m, 4 H); 13C{ H} NMR (100 MHz, CDCl ): 191.7, 156.0,
1
thiocyanatoprop-2-en-1-one (3f). Yield 79%, 53.1 mg; R
f
= 0.3;
): δ 7.82
s, 1 H), 7.54 (d, J = 8.3 Hz, 2 H), 7.37 (d, J = 8.3 Hz, 2 H), 4.08
3
o
1
yellow solid; mp 118-119 C; H NMR (400 MHz, CDCl
3
1
37.8, 136.8, 129.5, 128.6, 112.0, 87.0, 66.8, 52.0; ESI-HRMS
(
(
(
1
C
+
Calcd for C14
331.0277.
2 2
H13ClN NaO S [M + Na] 331.0278, found
brs, 2 H), 3.60 (brs, 2 H), 2.09-1.94 (m, 4 H); 13C{ H} NMR
100 MHz, CDCl ): 191.3, 155.1, 138.8, 131.5, 129.7, 124.7,
13.6, 87.3, 56.4, 49.6, 26.2, 24.0; ESI-HRMS Calcd for
1
3
(
Z)-1-Phenyl-3-(piperidin-1-yl)-2-thiocyanatoprop-2-en-1-
1
f
one (3n). Yield 68%, 37.0 mg; R = 0.5; yellow liquid; H NMR
+
14
H
13BrN
2
NaOS [M + Na] 358.9824, found 358.9810.
(
400 MHz, CDCl
3
): δ 7.71 (s, 1 H), 7.51-7.40 (m, 5 H), 3.85 (brs,
4 H), 1.76 (s, 6 H); 13C{ H} NMR (100 MHz, CDCl ): 193.2,
1
(Z)-4-(3-(Pyrrolidin-1-yl)-2-
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
thiocyanatoacryloyl)benzonitrile (3g). Yield 80%, 45.3 mg; R
f
1
56.3, 140.0, 130.3, 128.3, 128.0, 112.7, 85.9, 26.7, 23.9; ESI-
1
= 0.1; yellow liquid; H NMR (400 MHz, CDCl
3
): δ 7.83 (s, 1 H),
+
HRMS Calcd for C15
273.1059.
17 2
H N OS [M + H] 273.1056, found
7
.65 (d, J = 8.1 Hz, 2 H), 7.52 (d, J = 8.0 Hz, 2 H), 4.06 (brs, 2
H), 3.59 (brs, 2 H), 2.07-1.90 (m, 4 H); 13C{ H} NMR (100
1
(Z)-3-(Dimethylamino)-1-phenyl-2-thiocyanatoprop-2-en-1-
MHz, CDCl
3
): 191.1, 155.0, 144.4, 132.2, 128.3, 118.2, 113.7,
1
one (3o). Yield 71%, 33.0 mg; R
f
= 0.4; yellow liquid; H NMR
): δ 7.66 (s, 1 H), 7.50-7.40 (m, 5 H), 3.38 (brs,
): 192.9, 158.5, 139.8,
1
C
13.3, 86.7, 56.6, 49.7, 26.2, 24.0; ESI-HRMS Calcd for
(
6
1
400 MHz, CDCl
3
+
15
H
13
N
3
NaOS [M + Na] 306.0672, found 306.0672.
H); 13C{ H} NMR (100 MHz, CDCl
1
3
(Z)-1-(3-Nitrophenyl)-3-(pyrrolidin-1-yl)-2-
30.4, 128.3, 128.1, 113.4, 87.5; ESI-HRMS Calcd for
thiocyanatoprop-2-en-1-one (3h). Yield 76%, 46.1 mg; R
f
= 0.2;
yellow solid; mp 125-126 C; H NMR (400 MHz, CDCl ): δ
.32-8.29 (m, 2 H), 7.93 (s, 1 H), 7.86 (d, J = 7.6 Hz, 1 H), 7.64
+
C
12
H
12
N
2
NaOS [M + Na] 255.0563, found 255.0562.
o
1
3
(
Z)-3-(Diethylamino)-1-phenyl-2-thiocyanatoprop-2-en-1-
8
1
f
one (3p). Yield 79%, 41.1 mg; R = 0.3; yellow liquid; H NMR
(t, J = 7.9 Hz, 1 H), 4.14 (brs, 2 H), 3.68 (brs, 2 H), 2.15-1.98 (m,
(
2
400 MHz, CDCl
3
): δ 7.65 (s, 1 H), 7.48-7.40 (m, 5 H), 3.82 (brs,
4 H); 13C{ H} NMR (100 MHz, CDCl
1
): 190.1, 155.1, 147.9,
3
H), 3,43 (brs, 2 H), 1.29 (s, 6 H); 13C{ H} NMR (100 MHz,
1
141.6, 133.7, 129.6, 124.8, 122.6, 113.2, 86.5, 56.6, 49.8, 26.2,
3
CDCl ): 192.8, 156.6, 140.1, 130.3, 128.3, 128.0, 112.8, 86.5,
+
2
4.0; ESI-HRMS Calcd for C14
found 326.0579.
Z)-1-(3,4-Dichlorophenyl)-3-(pyrrolidin-1-yl)-2-
thiocyanatoprop-2-en-1-one (3i). Yield 81%, 53.0 mg; R
13 3 3
H N NaO S [M + Na] 326.0570,
+
5
3.6, 44.1, 14.4; ESI-HRMS Calcd for C14
261.1056, found 261.1057.
(Z)-3-(Dipropylamino)-1-phenyl-2-thiocyanatoprop-2-en-1-
17 2
H N OS [M + H]
(
f
= 0.3;
): δ 7.83
s, 1 H), 7.58 (s, 1 H), 7.50 (d, J = 8.2 Hz, 1 H), 7.33 (d, J = 7.6
Hz, 1 H), 4.10 (brs, 2 H), 3.64 (brs, 2 H), 2.12-1.96 (m, 4 H);
1
f
one (3q). Yield 78%, 45.0 mg; R = 0.5; yellow liquid; H NMR
o
1
yellow solid; mp 111-112 C; H NMR (400 MHz, CDCl
3
(
2
400 MHz, CDCl
3
): δ 7.62 (s, 1 H), 7.48-7.39 (m, 5 H), 3.78 (brs,
(
H), 3.22 (brs, 2 H), 1.69 (s, 4 H), 0.95 (s, 6 H); 13C{ H} NMR
1
(100 MHz, CDCl
3
): 192.8, 157.1, 140.0, 130.3, 128.2, 128.0,
13
1
C{ H} NMR (100 MHz, CDCl
3
): 189.9, 155.2, 139.8, 134.5,
1
C
12.7, 86.5, 61.3, 50.8, 22.2, 10.8; ESI-HRMS Calcd for
132.7, 130.4, 129.9, 127.2, 113.3, 87.1, 56.5, 49.8, 26.2, 24.0;
+
16
H
21
N
2
OS [M + H] 289.1369, found 289.1383.
+
ESI-HRMS Calcd for C14
found 348.9947.
2 2
H12Cl N NaOS [M + Na] 348.9940,
(
Z)-3-(Ddibenzylamino)-1-phenyl-2-thiocyanatoprop-2-en-
1
1
(
-one (3r). Yield 74%, 57.0 mg; R
400 MHz, CDCl ): δ 7.95 (s, 1 H), 7.46-7.34 (m, 11 H), 7.17 (d,
J = 6.9 Hz, 4 H), 4.77 (brs, 4 H); 13C{ H} NMR (100 MHz,
CDCl ): 192.9, 157.8, 139.6, 134.5, 130.5, 129.3, 128.6, 128.4,
128.2, 127.6, 112.3, 88.8; ESI-HRMS Calcd for C24 NaOS
f
= 0.5; yellow liquid; H NMR
(Z)-1-(Naphthalen-2-yl)-3-(pyrrolidin-1-yl)-2-
3
thiocyanatoprop-2-en-1-one (3j). Yield 84%, 51.7 mg; R
f
= 0.3;
): δ 7.99
s, 1 H), 7.91-7.86 (m, 4 H), 7.62-7.52 (m, 3 H), 4.08 (brs, 2 H),
1
o
1
yellow solid; mp 125-126 C; H NMR (400 MHz, CDCl
3
3
(
3
20 2
H N
.53 (brs, 2 H), 2.05-1.91 (m, 4 H); 13C{ H} NMR (100 MHz,
): 192.4, 155.3, 137.3, 134.1, 132.5, 128.7, 128.2, 128.1,
27.8, 127.3, 126.7, 125.3, 113.8, 87.9, 55.9, 49.5, 26.1, 23.9;
1
+
[
M + Na] 407.1189, found 407.1170.
(Z)-3-(Dimethylamino)-2-thiocyanato-1-(p-tolyl)prop-2-en-
1-one (3s). Yield 75%, 36.9 mg; R = 0.7; yellow solid; mp 92-93
): δ 7.65 (s, 1 H), 7.41 (d, J = 7.9
Hz, 2 H), 7.22 (d, J = 7.8 Hz, 2 H), 3.37 (brs, 6 H), 2.39 (s, 3 H);
CDCl
3
1
+
f
ESI-HRMS Calcd for C18
331.0874.
16 2
H N NaOS [M + Na] 331.0876, found
o
1
C; H NMR (400 MHz, CDCl
3
(Z)-3-(Pyrrolidin-1-yl)-2-thiocyanato-1-(thiophen-2-yl)prop-
2-en-1-one (3k). Yield 83%, 43.7 mg; R = 0.3; yellow solid; mp
): δ 8.20 (s, 1 H), 7.68 (s,
H), 7.57-7.56 (m, 1 H), 7.10 (s, 1 H), 4.09 (brs, 2 H), 3.72 (brs,
1
3
1
C{ H} NMR (100 MHz, CDCl
128.9, 128.3, 113.4, 87.4, 21.5; ESI-HRMS Calcd for
3
): 192.8, 158.3, 140.9, 136.9,
f
o
1
1
1
2
1
2
23-124 C; H NMR (400 MHz, CDCl
3
+
C
13
H
14
N
2
NaOS [M + Na] 269.0719, found 269.0718.
(Z)-1-(4-Chlorophenyl)-3-(dimethylamino)-2-
thiocyanatoprop-2-en-1-one (3t). Yield 71%, 37.8 mg; R
H), 2.05 (brs, 4 H); 1 C{ H} NMR (100 MHz, CDCl
3
1
3
): 182.6,
54.9, 143.1, 131.5, 131.3, 127.2, 113.7, 85.7, 56.3, 49.7, 26.1,
f
= 0.2;
3
yellow solid; mp 85-86 C; H NMR (400 MHz, CDCl ): δ 7.63
o
1
+
12 2 2
4.1; ESI-HRMS Calcd for C12H N NaOS [M + Na] 287.0283,
found 287.0275.
(s, 1 H), 7.45 (d, J = 8.4 Hz, 2 H), 7.39 (d, J = 8.4 Hz, 2 H), 3.39
(brs, 6 H); 13C{ H} NMR (100 MHz, CDCl
1
): 191.6, 158.3,
3
(Z)-3-Morpholino-1-phenyl-2-thiocyanatoprop-2-en-1-one
o
138.2, 136.5, 129.5, 128.5, 113.2, 87.0; ESI-HRMS Calcd for
(
3l). Yield 73%, 40.0 mg; R
f
= 0.4; yellow solid; mp 122-123 C;
+
1
C
12
H
11ClN
2
NaOS [M + Na] 289.0173, found 289.0174.
H NMR (400 MHz, CDCl
3
): δ 7.67 (s, 1 H), 7.52-7.41 (m, 5 H),
3.92 (brs, 4 H), 3.85-3.83 (m, 4 H); 1 C{ H} NMR (100 MHz,
3
1
(Z)-1-Phenyl-3-(pyrrolidin-1-yl)-2-selenocyanatoprop-2-en-
1
1
f
-one (6). Yield 64%, 39.1 mg; R = 0.3; yellow liquid; H NMR
CDCl ): 193.0, 156.1, 139.4, 130.7, 128.4, 128.1, 112.2, 87.5,
3
+
(400 MHz, CDCl
3
): δ 7.84 (s, 1 H), 7.52-7.41 (m, 5 H), 3.84 (brs,
6
2
7.1, 66.8, 52.1; ESI-HRMS Calcd for C14
75.0849, found 275.0860.
Z)-1-(4-Chlorophenyl)-3-morpholino-2-thiocyanatoprop-2-
en-1-one (3m). Yield 70%, 43.2 mg; R = 0.4; yellow solid; mp
): δ 7.66 (s, 1 H), 7.46 (d,
15 2 2
H N O S [M + H]
4 H), 2.03 (s, 4 H); 13C{ H} NMR (100 MHz, CDCl
1
): 192.7,
3
1
55.6, 140.1, 130.3, 128.3, 128.2, 104.2, 89.0, 25.1, 24.9; ESI-
(
+
HRMS Calcd for C14
307.0342.
15 2
H N OSe [M + H] 307.0344, found
f
o
1
1
34-135 C; H NMR (400 MHz, CDCl
3
ACS Paragon Plus Environment

Page 7 of 11
The Journal of Organic Chemistry
1
2
Synthesis of 3o in 1 mmol scale. To a 25 mL round bottom
flask were charged with enaminone 1o (1 mmol), NH SCN (2
mmol), RB (0.01 mmol) and THF (5 mL). The mixture was
stirred at room temperature with the irradiation of 14 W CFL
(400 MHz, CDCl
3
): δ 8.31 (s, 1 H), 8.19 (d, J = 8.2 Hz, 1 H), 7.57
(s, 1 H), 7.49 (d, J = 8.1 Hz, 1 H); 13C{ H} NMR (100 MHz,
1
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
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4
4
4
4
4
5
5
5
5
5
5
5
5
5
5
6
2
CDCl
13.3, 108.6.
General procedure for the enaminone difunctionalized
providing products 7. To a 25 mL round-bottom flask were
charged with enaminone 2 (0.2 mmol), NH SCN 2 (0.4 mmol),
Ru(bpy) Cl ·6H O (0.002 mmol) and EL (2 mL). The mixture
3
): 172.2, 156.4, 155.1, 141.3, 127.6, 127.5, 121.1, 118.5,
1
(distance bulb−vessel approximately 5 cm) for 12h under air
atmosphere. Successively, 10 mL water was added to the flask,
and the resulting mixture was extracted with ethyl acetate (3 × 10
mL). The subsequent operation following equivalent 0.2 mmol
scale experiment provided product 3o with 57% yield (133 mg).
4
3
2
2
was stirred with the irradiation of 14 W CFL for 12 h under air
atmosphere (TLC). Upon completion, 5 mL of water was added to
the flask, and the resulting mixture was extracted with ethyl
acetate (3 × 8 mL). The combined organic phases were collected
and washed with small amount of water for several times. After
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General procedure for the synthesis of 3-thiocyanated
chromenones 5. To a 25 mL round-bottom flask were added
o-hydroxyaryl enaminone 4 (0.2 mmol), NH SCN (0.4 mmol),
4
RB (0.002 mmol) and THF (2 mL). The mixture was then stirred
at room temperature for 12h with the irradiation of 14 W CFL
2 4
drying with anhydrous Na SO and filtration, the solvent was
(distance bulb−vessel approximately 5 cm) under air atmosphere
removed from the solution at reduced pressure. The resulting
residue was subjected to flash silica gel column chromatography
to provide pure products by employing mixed petroleum
ether/ethyl acetate (v/v = 3 : 1) as eluent.
(TLC). Upon on completion, 5 mL water was added to the flask,
and the resulting mixture was extracted with ethyl acetate (3 × 8
mL). The organic phases were collected dried with anhydrous
Na SO . After filtration, the resulting solution was employed to
2 4
reduced pressure to remove the solvent. The acquired residue was
subjected to flash silica gel column chromatography to provide
pure products by the elution with mixed petroleum ether/ethyl
acetate (v/v = 10 : 1).
(E)-3-Amino-1-phenyl-2-thiocyanatoprop-2-en-1-one (7a).
o
1
f
Yield 76%, 31 mg; R = 0.3; yellow solid; mp 160-161 C; H
NMR (400 MHz, DMSO-d
6
): δ 8.24-8.20 (m, 2 H), 7.69-7.63 (m,
H), 7.51-7.45 (m, 5 H); 13C{ H} NMR (100 MHz, DMSO-d
89.9, 159.0, 140.1, 130.8, 128.8, 128.3, 112.7, 90.0; ESI-HRMS
1
):
1
1
6
5c
3
-Thiocyanato-4H-chromen-4-one (5a). Yield 89%, 36.0
+
Calcd for C10
8 2
H N NaOS [M + Na] 227.0250, found 227.0244.
o
1
f
mg; R = 0.2; yellow solid; mp 150-151 C; H NMR (400 MHz,
(E)-3-Amino-2-thiocyanato-1-(p-tolyl)prop-2-en-1-one (7b).
CDCl
3
): δ 8.35 (s, 1 H), 8.25 (d, J = 7.9 Hz, 1 H), 7.79 (t, J = 7.8
o
1
Yield 69%, 30.2 mg; R
f
= 0.3; yellow solid; mp 142-143 C; H
): δ 8.20-8.16 (m, 2 H), 7.69-7.63 (m,
H), 7.36 (d, J = 8.0 Hz, 2 H), 7.27 (d, J = 7.9 Hz, 2 H), 2.36 (s,
Hz, 1 H), 7.56-7.51 (m, 2 H); 13C{ H} NMR (100 MHz, CDCl
1
):
3
NMR (400 MHz, DMSO-d
6
173.0, 156.3, 155.4, 135.0, 126.7, 126.1, 122.7, 118.4, 112.6,
1
3
1
1
08.9.
H); 13C{ H} NMR (100 MHz, DMSO-d
1
6
): 189.7, 158.7, 140.7,
5
c
6-Methyl-3-thiocyanato-4H-chromen-4-one (5b).
Yield
37.2, 129.3, 128.5, 112.7, 89.9, 21.4; ESI-HRMS Calcd for
o
1
9
2%, 39.8 mg; R
f
= 0.3; yellow solid; mp 134-135 C; H NMR
+
C
11
H
11
N
2
OS [M + H] 219.0587, found 219.0586.
E)-3-Amino-1-(4-chlorophenyl)-2-thiocyanatoprop-2-en-1-
= 0.2; yellow solid; mp 147-148
(
400 MHz, CDCl
3
): δ 8.32 (s, 1 H), 8.00 (s, 1 H), 7.59-7.57 (m, 1
(
H), 7.44 (d, J = 8.6 Hz, 1 H), 2.48 (s, 3 H); 13C{ H} NMR (100
1
one (7c). Yield 44%, 21.0 mg; R
f
MHz, CDCl
3
): 173.0, 155.5, 154.6, 137.0, 136.2, 125.3, 122.4,
o
1
C; H NMR (400 MHz, DMSO-d
6
): δ 8.31-8.27 (m, 2 H), 7.71-
1
18.2, 112.1, 109.1, 21.0.
.65 (m, 1 H), 7.50 (q, J = 8.6 Hz, 4 H); 13C{ H} NMR (100
1
7
7
-Methoxy-3-thiocyanato-4H-chromen-4-one (5c). Yield
6
MHz, DMSO-d ): 188.7, 159.1, 138.8, 135.5, 130.3, 128.9, 112.6,
o
1
9
4%, 43.8 mg; R
f
= 0.2; yellow solid; mp 159-160 C; H NMR
+
8
9.8; ESI-HRMS Calcd for C10
found 239.0038.
E)-3-Amino-1-(4-bromophenyl)-2-thiocyanatoprop-2-en-1-
one (7d). Yield 41%, 23.1 mg; R = 0.2; yellow solid; mp 158-
59 C; H NMR (400 MHz, DMSO-d ): δ 8.31-8.26 (m, 2 H),
.71-7.65 (m, 3 H), 7.41 (d, J = 8.4 Hz, 2 H); 13C{ H} NMR (100
): 188.8, 159.1, 139.2, 131.8, 130.5, 124.3, 112.6,
8 2
H ClN OS [M + H] 239.0040,
(
400 MHz, CDCl
3
): δ 8.25 (s, 1 H), 8.13 (d, J = 9.0 Hz, 1 H),
7.07-7.04 (m, 1 H), 6.90 (d, J = 2.2 Hz, 1 H), 3.94 (s, 3 H);
(
1
3
1
C{ H} NMR (100 MHz, CDCl
3
): 172.2, 165.0, 158.3, 154.5,
f
127.5, 116.4, 116.0, 112.7, 109.1, 100.5, 56.1; ESI-HRMS Calcd
for C11
o
1
1
7
6
+
H
8
NO
3
S [M + H] 234.0219, found 234.0219.
1
5
c
6-Fluoro-3-thiocyanato-4H-chromen-4-one (5d). Yield 80%,
MHz, DMSO-d
6
o
1
3
5.4 mg; R
f
= 0.2; yellow solid; mp 164-165 C; H NMR (400
+
89.8; ESI-HRMS Calcd for C10
found 282.9530.
8 2
H BrN OS [M + H] 282.9535,
MHz, CDCl
3
): δ 8.38 (s, 1 H), 7.88-7.86 (m, 1 H), 7.61-7.49 (m, 2
H); 13C{ H} NMR (100 MHz, CDCl
1
): 172.3, 158.9 (d, J = 244
3
(E)-3-Amino-1-(3,4-dichlorophenyl)-2-thiocyanatoprop-2-
en-1-one (7e). Yield 42%, 23.0 mg; R = 0.2; yellow solid; mp
Hz), 155.8, 152.6, 123.9 (d, J = 8.5 Hz), 123.5 (d, J = 24.2 Hz),
f
1
20.8 (d, J = 7.7 Hz), 112.1, 111.2 (d, J = 24.2 Hz), 108.7.
o
1
1
58-159 C; H NMR (400 MHz, DMSO-d
6
): δ 8.43-8.36 (m, 2
5
c
6
-Chloro-3-thiocyanato-4H-chromen-4-one (5e).
Yield
H), 7.78-7.71 (m, 3 H), 7.44 (d, J = 9.8 Hz, 1 H); 13C{ H} NMR
1
o
1
8
6%, 40.8 mg; R
f
= 0.2; yellow solid; mp 185-186 C; H NMR
(100 MHz, DMSO-d
6
): 187.3, 159.5, 140.6, 133.4, 131.7, 131.1,
Cl OS
(
7
400 MHz, CDCl
3
): δ 8.35 (s, 1 H), 8.19 (d, J = 2.4 Hz, 1 H),
1
30.2, 128.6, 112.5, 89.7; ESI-HRMS Calcd for C10
H
7
2 2
N
.74-7.71 (m, 1 H), 7.53 (d, J = 9.0 Hz, 1 H); 13C{ H} NMR (100
1
+
[
M + H] 272.9651, found 272.9645.
E)-3-Amino-1-(naphthalen-2-yl)-2-thiocyanatoprop-2-en-1-
one (7f). Yield 63%, 32.0 mg; R = 0.1; yellow solid; mp 178-179
C; H NMR (400 MHz, DMSO-d ): δ 8.27-8.25 (m, 2 H), 8.06-
.97 (m, 4 H), 7.81-7.75 (m, 1 H), 7.63-7.56 (m, 3 H); 13C{ H}
NMR (100 MHz, DMSO-d ): 189.8, 159.2, 137.3, 134.1, 132.5,
129.1, 128.5, 128.2, 128.1, 127.8, 127.2, 125.7, 112.7, 90.2; ESI-
MHz, CDCl
120.2, 112.9, 108.6.
6-Bromo-3-thiocyanato-4H-chromen-4-one (5f). Yield 82%,
46.1 mg; R
MHz, CDCl
3
): 171.9, 155.4, 154.7, 135.3, 132.8,125.4, 123.5,
(
f
5
c
o
1
6
o
1
f
= 0.4; yellow solid; mp 189-190 C; H NMR (400
1
7
3
): δ 8.36-8.34 (m, 2 H), 7.87-7.85 (m, 1 H), 7.46 (d, J
6
1
=
1
8.9 Hz, 1 H); 13C{ H} NMR (100 MHz, CDCl
3
): 171.8, 155.3,
55.1, 138.0, 128.7, 123.8, 120.3, 120.2, 113.0, 108.5.
+
HRMS Calcd for C14
255.0583.
11 2
H N OS [M + H] 255.0587, found
5
c
7
-Chloro-3-thiocyanato-4H-chromen-4-one (5g).
Yield
o
1
8
4%, 39.8 mg; R
f
= 0.3; yellow solid; mp 178-179 C; H NMR
ACS Paragon Plus Environment

The Journal of Organic Chemistry
Page 8 of 11
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The transamination reaction between enaminone 1d and
aniline with Ru(bpy) Cl ·6H O. Enaminone 1d (0.2 mmol),
aniline 8 (0.2 mmol) and Ru(bpy) Cl ·6H O (0.002 mmol) were
3
pot reaction of propargyl amines, AgSCF , and di-tert-butyl peroxide:
access to allenyl thiocyanates and allenyl trifluoromethylthioethers.
Org. Lett. 2018, 20, 3109-3113.
3
2
2
3
2
2
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(a) Yu, J.-T.; Teng, F.; Cheng, J. The construction of X–CN
mixed with EL (2 mL) in the 25 mL round bottom flask, and the
mixture was stirred at room temperature for 12h without CFL
irradiation. After pouring water (10 mL) into the vessel to quench
the reaction, the resulting mixture was extracted with ethyl acetate
(3 × 8 mL). The subsequent treatment following known
(X=N, S, O) bonds. Adv. Synth. Catal. 2017, 359, 26-38. (b) Guo, W.;
Tan, W.; Zhao, M.; Zheng, L.; Tao, K.; Chen, D.; Fan, X. Direct
photocatalytic S–H bond cyanation with green “CN” source. J. Org.
Chem. 2018, 83, 6580-6588. (c) Zhu, D.; Chang, D.; Shi, L.
Transition-metal-free
cross-coupling
of
thioethers
with
1
8a
procedures gave pure product 9.
aryl(cyano)iodonium triflates: a facile and efficient method for the
one-pot synthesis of thiocyanates. Chem. Commun. 2015, 51, 7180-
7183. (d) Teng, F.; Yu, J.-T.; Yang, H.; Jiang, Y.; Cheng, J. Copper-
catalyzed cyanation of disulfides by azobisisobutyronitrile leading to
thiocyanates. Chem. Commun. 2014, 50, 12139-12141. (e) Frei, R.;
Courant, T.; Wodrich, M. D.; Waser, J. General and practical
formation of thiocyanates from thiols. Chem.-Eur. J. 2015, 21, 2662-
2668. (f) Liang, Z.; Wang, F.; Chen, P.; Liu, G. Copper-catalyzed
intermolecular trifluoromethylthiocyanation of alkenes: convenient
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ASSOCIATED CONTENT
Supporting Information.
The Supporting Information is available free of charge on the
ACS Pulicationss website at DOI:
Details on the fluorescent quenching experiments, H and 13C
1
NMR spectra of all products.
3
access to CF -containing alkyl thiocyanates. Org. Lett. 2015, 17,
2
438-2441. (g) Yang, X.; She, Y.; Chong, Y.; Zhai, H.; Zhu, H.;
AUTHOR INFORMATION
Corresponding Author
Chen, B.; Huang, G.; Yan, R. Iodothiocyanation/nitration of allenes
with potassium thiocyanate/silver nitrite and iodine. Adv. Synth.
Catal 2016, 358, 3130-3134.
*
E-mail for J.-P. Wan: wanjieping@jxnu.edu.cn.
4 For a review and selected examples, see: (a) Castanheiro, T.;
Suffert, J.; Donnard, M.; Gulea, M. Recent advances in the chemistry
of organic thiocyanates. Chem. Soc. Rev. 2016, 45, 494-505. (b) Jiang,
G.; Zhu, C.; Li, J.; Wu, W.; Jiang, H. Silver‐catalyzed regio‐ and
stereoselective thiocyanation of haloalkynes: access to (Z)‐vinyl
thiocyanates. Adv. Synth. Catal. 2017, 359, 1208-1212. (c) Dwivedi,
V.; Rajesh, M.; Kumar, R.; Kant, R.; Reddy, M. S. A stereoselective
thiocyanate conjugate addition to electron deficient alkynes and
concomitant cyclization to N,S-heterocycles. Chem. Commun. 2017,
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT
The work is supported by the National Natural Science
Foundation of China (21861019), the Natural Science Foundation
of Jiangxi Province (20161ACB21010) and the Science Fund for
Distinguished
Young
Scholars
in
Jiangxi
Province
5
3, 11060-11063. (d) Sun, N.; Che, L.; Mo, W.; Hu, B.; Shen, Z.; Hu,
(20162BCB23023).
X. A mild copper-catalyzed aerobic oxidative thiocyanation of
arylboronic acids with TMSNCS. Org. Biomol. Chem. 2015, 13, 691-
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> Visible-light catalysis
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> Metal-free, air as oxidant
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