Synthesis of isothiosemicarbazones of potential antitumoral activity through a multicomponent reaction involving allylic bromides, carbonyl compounds and thiosemicarbazide

Article abstract of DOI:10.1016/j.tet.2020.131231

A convenient route for the synthesis of isothiosemicarbazones and 2-hydrazono-1,3-thiazin-4-ones through a multicomponent reaction featuring allylic bromides, carbonyl compounds and thiosemicarbazides is described. The transformations proceed under mild a

Full text of DOI:10.1016/j.tet.2020.131231

Journal Pre-proof
Synthesis of isothiosemicarbazones of potential antitumoral activity through a
multicomponent reaction involving allylic bromides, carbonyl compounds and
thiosemicarbazide
Laiéli S. Munaretto, Misael Ferreira, Daniela P. Gouvêa, Adailton J. Bortoluzzi, Laura
S. Assunção, Juliana Inaba, Tânia B. Creczynski-Pasa, Marcus M. Sá
PII:
S0040-4020(20)30366-5
https://doi.org/10.1016/j.tet.2020.131231
TET 131231
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 18 March 2020
Revised Date: 18 April 2020
Accepted Date: 20 April 2020
Please cite this article as: Munaretto LaiéS, Ferreira M, Gouvêa DP, Bortoluzzi AJ, Assunção LS,
Inaba J, Creczynski-Pasa TâB, Sá MM, Synthesis of isothiosemicarbazones of potential antitumoral
activity through a multicomponent reaction involving allylic bromides, carbonyl compounds and
thiosemicarbazide, Tetrahedron (2020), doi: https://doi.org/10.1016/j.tet.2020.131231.
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Synthesis of isothiosemicarbazones of potential
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antitumoral activity through a multicomponent
reaction involving allylic bromides, carbonyl
compounds and thiosemicarbazide
Laiéli S. Munaretto, Misael Ferreira, Daniela P. Gouvêa, Adailton J. Bortoluzzi, Laura S. Assunção, Juliana Inaba,
Tânia B. Creczynski-Pasa, Marcus M. Sá
Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil
Departamento de Ciências Farmacêuticas, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil

1
Tetrahedron
journal homepage: www.elsevier.com
Synthesis of isothiosemicarbazones of potential antitumoral activity through a
multicomponent reaction involving allylic bromides, carbonyl compounds and
thiosemicarbazide
Laiéli S. Munarettoa, Misael Ferreiraa, Daniela P. Gouvêaa, Adailton J. Bortoluzzia, Laura S. Assunçãob,
Juliana Inabab, Tânia B. Creczynski-Pasab, Marcus M. Sáa,
a Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil
b Departamento de Ciências Farmacêuticas, Universidade Federal de Santa Catarina, Florianópolis, SC 88040-900, Brazil
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
A convenient route for the synthesis of isothiosemicarbazones and 2-hydrazono-1,3-thiazin-4-
ones through a multicomponent reaction featuring allylic bromides, carbonyl compounds and
thiosemicarbazides is described. The transformations proceed under mild and environmentally
benign conditions with high yields and stereoselectivity. All novel compounds were obtained in
high purity without the need for chromatography stages. Different functional groups are well
tolerated, including halogen, alkoxy, nitro and unsaturated groups. This simple protocol offers
Available online
Keywords:
straightforward access to
a wide range of highly functionalized substances with
Allylic bromide
pharmacologically privileged structures. All compounds were fully characterized and the
structural assignment of key products was unequivocally confirmed by X-ray diffraction
analysis. Selected isothiosemicarbazones were screened against a triple-negative breast cancer
cell line and some compounds were shown to reduce the number of live tumoral cells (41-54%).
Multicomponent reaction
Isothiosemicarbazone
Green chemistry
Antitumoral activity
2020 Elsevier Ltd. All rights reserved
.
1. Introduction
have been successfully applied in programs devoted to drug
discovery conducted by pharmaceutical companies.
The growing concern with regard to environmental protection
has brought about the paradigm of green chemistry. This
approach favors the development of new methodologies that are
not only high yielding but also environmentally benign and
highly efficient. In principle, these goals can be achieved with the
appropriate selection of starting materials and reaction
conditions, as well as a re-evaluation of the work-up, separation
and purification procedures [1].
Functionalized allylic bromides derived from the Morita-
Baylis-Hillman (MBH) reaction [3] are versatile building blocks
widely used in modern synthetic organic chemistry. Due to the
highly electrophilic nature of allylic bromides, combined with
straightforward methods for their preparation [4], these
molecules are extremely useful substrates for nucleophilic
displacement with a range of C-, O-, N-, P-, S-, and Se-
nucleophiles [5,6]. In the particular case of reactions involving
allylic bromides and 1,3-bidentate nucleophiles, such as thioureas
and thiosemicarbazides, the resulting products are isothiou-
ronium salts A, isothiosemicarbazides B and cyclic analogues C,
which display pronounced antitumor activity in leukemia and
melanoma models [7] (Fig. 1).
The use of environmentally acceptable reagents and solvents
coupled with a reduction in the number of synthetic steps are
requirements to develop more sustainable synthetic methods. In
this context, multicomponent reactions (MCRs) and domino
processes have become popular tools among synthetic chemists,
in which several steps of bond formation are performed in a
single reaction flask without the need for the separation or
isolation of intermediates to give complex molecular structures
from simple and readily available substrates [2]. Besides saving
time, energy and resources by avoiding purification stages
between individual steps within a multistep synthesis, MCRs are
generally atom-economic transformations that can be carried out
at room temperature in non-toxic solvents with reduced
generation of waste, in accordance with the principles of green
chemistry. Due to the advantages of MCRs over traditional multi-
step synthesis in creating structural diversity efficiently, they
O
O
O
R'
OMe
S Br
R'
OMe
R'
NH
A
B
C
S
S
O
R
N
H
H2N
N
NH2
NH2
Fig. 1. Structures of isothiouronium salts A, isothiosemicarbazides B and 1,3-
thiazines C of biological importance.
In fact, thiosemicarbazones [8] (I) as well as
isothiosemicarbazones [9] (II and III) have attracted the attention
of medicinal chemists due to their wide variety of biological
activity, including anticancer, antimicrobial, and antioxidant
* Corresponding Author: Prof. Dr. Marcus Mandolesi Sá
MESOLab (Laboratory of Methodology and Organic Synthesis)
Departamento de Química - UFSC, Florianópolis, SC 88040-900, Brazil
Tel.: +55-48-37219967; e-mail: marcus.sa@ufsc.br

2
Tetrahedron
2.2. MCR with aldehydes
properties, among others (Fig. 2). However, the preparation of
isothiosemicarbazones usually involves high temperatures [9],
acid catalysts [9b] and/or multistep synthesis [9b-e], eventually
requiring the isolation and purification of products through
tedious work-up or chromatography [9c-e]. Therefore, milder and
greener methods to build up large collections of
isothiosemicarbazones and analogues for biological screenings
are in high demand.
To expand the structural diversity to other carbonyl
compounds, a representative series of aldehydes was employed in
this novel MCR involving allylic bromides
1
and
thiosemicarbazide (Scheme 1). Ethanol was chosen as the
solvent, rather than 2-propanol or acetonitrile, due to its wide
availability, low cost and environmental considerations [10].
However, in most of the reactions, the expected
isothiosemicarbazone salts 4 were obtained as a mixture of
isomers (varying from 2:1 to 10:1), which are possibly related to
the pair of E/Z diastereoisomers around the NC=NN double
R2
R2
S
S
S
4
4
R
R
R
N
1
R1
N
NH
N
N
N 2
N 1
N
N
2
H
bond.
It
is
well
known
that
N4-unsubstituted
H
H
I
II
III
R1
R1
isothiosemicarbazones predominantly have the configuration in
which the nitrogen atoms at the extremities (N1 and N4) lie cis to
each other about the C=N2 bond (i.e., E-configuration), due to the
presence of intramolecular hydrogen bonding (see structure II in
Fig. 2). Conversely, the isomer of Z-configuration (structure III
in Fig. 2) may coexist in solution if the solvent is sufficiently
polar to break down the intramolecular N-H---N interaction
[9a,11].
Fig. 2. Representation of thiosemicarbazones (I) and isothiosemicarbazones
(II, III).
Herein, we present a straightforward method for the synthesis
of functionalized isothiosemicarbazones through
multicomponent reaction (MCR), involving an allylic bromide 1,
a carbonyl compound and thiosemicarbazide, which is carried out
in alcoholic medium at room temperature with no need for a
catalyst or additive.
a
novel
O
S
O
OMe
OMe
MCR
2. Results and discussion
Br
1a
O
+
2.1. MCR with acetone
H2N
N
N
S
Ar
H
H
NH2
5
Initially, the synthesis of isothiosemicarbazone salts 2 was
performed in a single reaction step, employing the MCR from
allylic bromides 1, thiosemicarbazide and acetone (used in excess
to act simultaneously as the carbonyl reagent and the solvent) at
room temperature and in the absence of any catalyst or additive
(Table 1). Isothiosemicarbazone salts 2a-c were cleanly obtained
in high yields (97-78%) and short reaction times regardless of the
substitution pattern (R) at the aromatic ring. The use of an
equivalent amount of acetone combined with ethanol, 2-propanol
or acetonitrile as the solvent led to similar results. Salts 2 are
stable crystalline solids that can be stored for months without
significant decomposition. However, basic treatment with
aqueous bicarbonate readily converted salts 2 into the neutral
isothiosemicarbazones 3, with good overall yields (84-73% from
bromides 1) and high purity without any further purification.
H2N
N
H
Ar
O
S
CH2Cl2
NaHCO3(aq)
25 °C, 0.5 h
OMe
EtOH, 25 °C
1.5-4.5 h
E/Z isomers
H2N
Br
NH
N
4
H
Ar
Scheme 1. Optimization of the conditions for the MCR.
Attempts to obtain a single diastereoisomer 4 by varying the
reaction time (2-72 h), the solvent (2-propanol, acetonitrile) or
the order of addition of the reagents did not lead to any
improvement in the isomeric ratio. In addition, we were not able
to achieve a satisfactory separation of isomers by applying
chromatography or recrystallization techniques.
Table 1
Tricomponent reaction of allylic bromides 1, isothiosemicarbazide
and acetone.
Since the salt 4 could not be obtained as a sole isomer in pure
form, attention was turned to the preparation of the
corresponding isothiosemicarbazones 5 (Scheme 1). The direct
neutralization of an aqueous (or ethanolic) solution of the salt 4
with sodium bicarbonate or hydroxide gave the expected
isothiosemicarbazone 5 contaminated with non-characterized side
products. However, the use of a less polar solvent, such as
dichloromethane, in an aqueous biphasic system was found to be
crucial for the neutralization. Thus, the addition of saturated
bicarbonate to a stirred suspension of 4 in CH2Cl2 followed by an
aqueous work-up led to the isothiosemicarbazones 5 in good to
excellent yields (95-50%), as a sole isomer in each case (Scheme
2). Ethyl acetate was able to replace CH2Cl2 as a more
environmentally benign solvent, although with less satisfactory
results relating to yield and selectivity. A wide range of allylic
bromides 1 was employed, including aryl-substituted precursors
as well as an alkenyl [R = (E)-styryl, 5p] analogue.
O
O
1. 25 °C, 1.5 h
OMe
O
OMe
2. NaHCO3(aq)
25 °C, 0.5 h
R
Br
+
R
S
1
S
H2N
N
N
3
NH2
H2N
N
H
O
S
OMe
NaHCO3(aq)
25 °C, 0.5 h
25 °C, 1.5 h
R
H2N
Br
NH
N
2
#
Compound
R
H
CH3O
NO2
Yield 2 (%)a
Yield 3 (%)a
1
2
3
a
b
c
78
97
88
94
75
95
a Yields of isolated products.

3
O
S
O
S
R
OMe
R
OMe
O
S
O
CH2Cl2, NaHCO3(aq)
25 °C , 0.5 h
EtOH, 25 °C
2.5-4.5 h
+
+
R
OMe
NH2
H2N
N
R1
R2
H2N
Br
NH
N
H2N
N
N
H
Br
R2
R2
1
4
5
R1
R1
O
O
S
O
S
O
O
OMe
OMe
OMe
OMe
OMe
S
S
S
H2N
N
N
H2N
N
N
H2N
N
N
H2N
N
N
H2N
N
N
Br
5b
50% (2.5 h)
5d
90% (4.5 h)
5a
95% (2.5 h)
5c
50% (4.5 h)
5e
95% (4.5 h)
Cl
F
Br
O
O
S
O
S
O
O
S
OMe
OMe
OMe
OMe
OMe
MeO
S
MeO
MeO
Cl
S
Cl
H2N
N
N
H2N
N
N
H2N
N
N
H2N
N
N
H2N
N
N
5h
5i
90% (2.5 h)
5f
95% (2.5 h)
5g
5j
60% (2.5 h)
75% (4.5 h)
93% (2.5 h)
Cl
MeO
NO2
Cl
O
S
Cl
O
S
O
O
S
Br
OMe
OMe
OMe
OMe
Cl
S
O2N
H2N
N
N
H2N
N
N
H2N
N
N
H2N
N
N
5k
5n
5l
94% (2.5 h)
5m
85% (2.5 h)
94% (2.5 h)
95% (2.5 h)
MeO
O
MeO
O
Cl
MeO
O
O
OMe
OMe
OMe
OMe
MeO
S
MeO
S
S
S
H2N
N
N
H2N
N
N
H2N
N
N
H2N
N
N
5o
5p
5q
5r
90% (2.5 h)
60% (2.5 h)
80% (4.5 h)
90% (2.5 h)
Br
Cl
Scheme 2. Scope of the MCR involving allylic bromides 1, carbonyl compounds and thiosemicarbazide (yields were not optimized).
5h
5n
5l
Fig. 3. ORTEP plots of isothiosemicarbazones 5h, 5l, and 5n; ellipsoids are drawn at the 50% probability level. Hydrogen atoms were omitted for clarity.

4
Tetrahedron
The carbonyl counterpart was also shown to be versatile, since
These results indicate that pathway A is preferable to B
aldehyde (aromatic and aliphatic) and ketone react equally well
(Scheme 2). The effect of the substitution pattern on the aromatic
ring (R, R1) was also explored and no significant difference in the
reactivity was found for substrates bearing electron-releasing or
electron-withdrawing groups. Remarkably, this one-pot
transformation tolerates a variety of functional groups, including
halogen (fluorine, chlorine, bromine), alkoxy, nitro and
conjugated unsaturated groups, thus evidencing the potential
synthetic applicability and the mildness of the reaction conditions
involved in the process. The complete diastereoselectivity
observed for the two C=N unsaturated bonds formed during the
MCR should also be noted.
because the first step in pathway A (formation of salt 7) is more
favorable than that in pathway
B
(formation of
thiosemicarbazone 8), while the second step is equally efficient
in the two pathways. Nonetheless, due to the comparable facility
that these pathways take place, it is reasonable to expect that they
are equally important in terms of the outcome of the MCR.
O
R
OMe
S
1
Br
ArCHO
NH2
H2N
N
EtOH, 25 °C
EtOH, 25 °C
H
Isothiosemicarbazones 5h,l,n were slowly crystallized in
ethanol/ethyl acetate (1:1 v/v), which allowed for unequivocal
structural elucidation by single crystal X-ray crystallographic
analysis (Fig. 3 and Supporting Information).
Pathway
Pathway
O
S
S
O
A
B
R
OMe
H2N
N
N
R
OMe
H
1
ArCHO
Base
7
S
8
5
Base
H2N
Br
NH
H2N
N
N
2.3. Reaction profile and synthetic applications
NH2
H
X
Encouraged by the significant results achieved with the MCR
featuring thiosemicarbazide, we moved our attention to a
substituted dinucleophile, 4-methylthiosemicarbazide (Scheme
3). In this case, the reaction proceeded well and the expected
tricomponent product 6 was obtained in 70% yield, although the
diastereoselectivity was not as high as those observed for the
5e R = 4-MePh; X = Br
5h R = 4-MeOPh; X = Cl
5n R = 4-NO2Ph; X = MeO
X
Scheme 4. Proposed mechanistic pathways for the MCR.
isothiosemicarbazones
5
originating from the parent
Despite the presence of multiple functionalities in
thiosemicarbazide. This distinct behavior is not entirely
unexpected considering the known tendency of N4-substituted
isothiosemicarbazones to coexist in solution as mixtures of E/Z
diastereoisomers [9c,11], but attempts to separate them were
unsuccessful.
isothiosemicarbazones 2 and 5, it is possible to develop
chemoselective transformations providing that the reaction
conditions are correctly modulated. Thus, the selective N4-
acetylation of isothiosemicarbazone salt 2c was readily achieved
in
a
mild basic medium using Ac2O in
a
biphasic
organic/aqueous system [12] to furnish 9 in high yield (Scheme
5). On the other hand, alkaline conditions did not work well for
the acetylation of isothiosemicarbazone 5l and led to a complex
mixture of acetylated products. In this case, selective acetylation
of 5l was successfully performed in the absence of base to give
10 cleanly.
Cl
O
S
Cl
O
OMe
OMe
+
E/Z
isomers
(2.5:1)
Cl
Cl
Br
1g
a, b
H3C
N
N
N
S
H
70%
H
H3C
NH2
N
N
O
S
O
S
H
H
6
O
H
Ac2O
NaHCO3(aq)
OMe
OMe
CH2Cl2
25 °C, 20 min
92%
O2N
O2N
O
MeO
MeO
Conditions:
H2N
Br
NH
N
N
H
N
N
a. EtOH, 25 °C, 2.5 h; b. CH2Cl2, NaHCO3(aq), 25 °C, 0.5 h
2c
9
Scheme 3. MCR with 4-methylthiosemicarbazide.
To gain a more in-depth insight into the MCR profile, the two
possible two-step pathways (nucleophilic displacement and
condensation) available for generating the isothiosemicarbazones
5 were investigated in detail (Scheme 4). In pathway A, the
transformation commenced with the SN2-type reaction between
thiosemicarbazide and allylic bromides 1 in ethanol at rt for 0.5-1
h to give quantitatively (>90%) the isothiosemicarbazide salts 7,
which were subsequently treated with an aldehyde for 1 h to
furnish the multicomponent adducts 5 in high yields. In pathway
B, the steps were inverted: first, thiosemicarbazide condensed
with an aldehyde, under the same conditions employed for
pathway A. In this case, the formation of the expected
thiosemicarbazones 8 in reasonable amounts (>70% conversion)
was only achieved after 1-2 h. The second step involved the
subsequent SN2 reaction between 8 and allylic bromide 1 for 1 h
to deliver the tricomponent product 5.
Cl
O
S
Cl
O
S
Ac2O
CH2Cl2
OMe
OMe
Cl
Cl
O
25 °C, 1 h
87%
H2N
N
N
N
H
N
N
10
5l
H
H
MeO
MeO
Scheme 5. Chemoselective acetylation of isothiosemicarbazones.
During the studies to determine the scope of this novel MCR,
we observed that some isothiosemicarbazones 5 were prone to

5
spontaneous cyclization, generating the corresponding 2-
hydrazono-1,3-thiazin-4-ones 11 (Scheme 6). The synthesis and
reactivity of the 1,3-thiazin-4-one framework [12,13] has recently
been reviewed [14], highlighting the importance of this class of
S-heterocycles in medicinal chemistry [7d,14].
In the case of thiazinone 11c, it was isolated as a crystalline
solid in good yield (70%), although the NMR spectra (1H and
13C) indicated the presence of two isomers (11 and, possibly, 12
or 13) coexisting in solution (Scheme 6). On the other hand,
thiazinone 11h was obtained as a sole isomer, although in low
isolated yield (4%) due to difficulties associated with separating
the cyclic compound 11 from its precursor 5. Surprisingly,
thiazinone 11s was obtained directly from the MCR with allylic
bromide 1b, 4-nitrobenzaldehyde and isothiosemicarbazide in
excellent yield (96%), without isolating the elusive
isothiosemicarbazone intermediate. These results indicate that the
11c
propensity of isothiosemicarbazones
5 to cyclize to the
corresponding thiazinones 11 is dependent on the electronic
factors exerted by the substituents presented in the aryl rings.
The structural determination of 2-hydrazono-1,3-thiazin-4-
ones 11c and 11h was unequivocally assigned by X-ray
diffraction analysis (Fig. 4), thus confirming the proposed
stereochemistry (see the crystallographic data in the Supporting
Information).
11h
Fig. 4. ORTEP plots of 1,3-thiazin-4-ones 11c and 11h; ellipsoids are drawn
at the 50% probability level. Hydrogen atoms were omitted for clarity.
It is important to compare our results with those recently
described by Ablajan and cols [15], where the MCR involving
isothiosemicarbazide, carbonyl compounds and ethyl 2-
chloroacetoacetate catalyzed by anhydrous sodium acetate under
reflux in ethanol led to the formation of thiazoles in high yields
(Scheme 7). In our case, the MCR employing allylic bromides 1,
isothiosemicarbazide and carbonyl compounds in ethanol at rt
(with no catalyst or additive) gave rise to the
isothiosemicarbazones 5, which subsequently cyclized to a 6-
membered ring (i.e., 1,3-thiazinones 11) instead of a thiazole or
other isomeric 5-membered ring, as described elsewhere [15,16].
Therefore, the MCR described herein expands the scope of allylic
bromides 1 as building blocks for the synthesis of sulfur-
containing heterocycles as pharmacologically privileged
structures.
R1
Cl
CO2Et
, 80 o
CO2Et
N
HN
S
N
C
O
S
Thiazoles
Reference 15
NH2
H2N
N
H
O
O
+
R
NH
R
OMe
O
Br , 25 o
C
S
N
N
1
R1
H
This work
Thiazinones
R1
Scheme 7. Previous work on MCR involving isothiosemicarbazide.
O
S
O
O
S
2.4. Antitumor activity of isothiosemicarbazones
R
NH
R
N
R
NH
Due to the pronounced antitumor activity of related
thiosemicarbazides and analogues [7], it was important to verify
whether the novel isothiosemicarbazones 3 and 5 present
cytotoxicity toward a tumor cell line. Therefore, the cell viability
of triple-negative breast cancer cell line MDA-MB-231, which is
related to an aggressive type of cancer [17], was evaluated by the
MTT assay [18], after 24 h of exposure to isothiosemicarbazone
3 or 5 (50 µM).
N
R1
rt
N
S
NH
N
5
N
N
11
12
13
R1
R1
O
S
O
S
11h
MeO
NH
NH
N
N
As can be seen in Table 2, five out of the twenty
isothiosemicarbazones screened (5e,g,m,n,p; respectively, entries
7, 9, 15, 16, 18) led to significant reduction (41-54%) in the
number of live tumoral cells. On the other hand, all
isothiosemicarbazones presented low cytotoxicity for HUVEC, a
non-tumoral cell line. While these results are of a preliminary
11c
N
N
O
S
NH
MeO
N
11s
N
Cl
Cl
nature,
they
strongly
suggest
that
these
novel
isothiosemicarbazones 5 undergo distinct interactions with non-
tumoral and tumoral cell lines, which is a desirable property for
the future development of selective anticancer agents.
NO2
Scheme 6. Cyclization of isothiosemicarbazones 5 to thiazinones 11.

6
Tetrahedron
recorded at 400 MHz or at 200 MHz and 13C {1H} NMR spectra
(fully decoupled) were recorded at 100 MHz or at 50 MHz.
Splitting patterns are designated as s (singlet), bs (broad singlet),
d (doublet), dd (doublet of doublet), t (triplet), q (quartet), sx
(sextet), m (multiplet). Coupling constants (J) are measured in
Hertz (Hz). Chemical shifts were recorded in parts per million
(ppm, δ) relative to solvent (CDCl3 at 7.26 ppm or DMSO-d6 at
Table 2
Cellular viability (in %) of selected isothiosemicarbazones 3 and 5.a
Entry Compoundb MDA-MB-231c
HUVECd
98 ± 2.4
90 ± 2.1
95 ± 8.6
82 ± 6.1
72 ± 4.2
80 ± 3.7
82 ± 4.6
98 ± 4.4
84 ± 2.5
83 ± 4.2
87 ± 4.7
80 ± 2.0
77 ± 8.1
90 ± 8.0
80 ± 5.7
87 ± 3.2
107 ± 1.6
86 ± 3.3
88 ± 5.6
100 ± 5.4
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
102 ± 7.8
76 ± 10.8
58 ± 9.0
67 ± 3.2
59 ± 4.7
76 ± 10.4
43 ± 1.0
94 ± 17.4
54 ± 5.4
63 ± 9.3
55 ± 6.1
75 ± 3.9
60 ± 10.3
63 ± 10.0
47 ± 8.4
41 ± 7.5
85 ± 5.5
54 ± 8.9
82 ± 9.7
99 ± 15.2
3a
3b
3c
5a
5b
5d
5e
5f
5g
5h
5i
5j
5k
5l
5m
5n
5o
5p
5q
5r
1
2.48 ppm for H NMR, and CDCl3 at 77.16 ppm or DMSO-d6 at
39.52 ppm for 13C NMR) as the internal standard. Elemental
analyses were conducted in a CHNS microanalyzer and the
analytical results were within ± 0.4% of the theoretical values.
The ESI-QTOF mass spectrometer was operated in the positive
ion mode at 4.5 kV and at a desolvation temperature of 180 °C.
The standard electrospray ion (ESI) source was used to generate
the ions. The instrument was calibrated in the range m/z 50-3000
using a calibration standard (low concentration tuning mix
solution) and data were processed with the aid of computer
software.
Allylic bromides 1 were prepared from Morita-Baylis-Hillman
adducts according to the described methods [4a] and their
physical and spectral data were consistent with the expected
structures and the related literature [4a,d,19]. The allylic
bromides 1a (R = phenyl), 1d (R = 4-methylphenyl), 1e (R = 4-
chlorophenyl), and 1h (R = 3-bromophenyl) were obtained as
mixtures of diastereoisomers (Z:E 9-19:1) and were used as such.
Isothiosemicarbazide salts 7 were prepared and characterized as
previously described [7b,c]. Thiosemicarbazones 8 were prepared
as follows: To a stirred solution of thiosemicarbazide (1.0 mmol)
in 1.0 mL of ethanol at 25 °C was added the appropriate aldehyde
(1.0 mmol). After stirring for 1 h, the insoluble solid formed was
resolubilized by gently warming the reaction mixture and the
final solution was allowed to slowly crystallize at rt. The
crystalline thiosemicarbazone 8 formed was collected by
filtration and dried. Their physical and spectral data were
consistent with the expected structures and the related literature
[20].
a Results expressed as the mean ± SD, n = 3.
b Concentration tested = 50 µM.
c MDA-MB-231: triple-negative breast cancer cell line
d HUVEC: vascular endothelium cell line
3. Conclusion
In conclusion, isothiosemicarbazones 3 and 5 were readily
prepared using multicomponent synthesis from accessible
starting materials, such as aldehydes or ketones,
thiosemicarbazide and allylic bromides 1, through the use of
environmentally benign conditions (ethanol as the solvent at
room temperature) without extra additives. This one-pot
transformation tolerates a variety of functional groups, thus
evidencing its potential synthetic applicability. Besides the
twenty-two isothiosemicarbazones 3, 5 and 6 synthesized by this
method, the three isothiosemicarbazone salts 2 and the two
acetylated derivatives 9 and 10 are novel compounds that were
obtained in good to excellent yields (95-50%) and high
stereoselectivity without requiring further purification stages in
most cases. The somewhat unexpected cyclization of selected
isothiosemicarbazones 5 to give the 2-hydrazono-1,3-thiazin-4-
one framework 11 expanded the scope of this MCR, allowing
access to a class of S-heterocycles under mild conditions. Finally,
compounds 5e,g,m,n,p showed cytotoxic activity toward an
aggressive breast cancer cell line, thus highlighting the
anticipated pharmacological importance of this class of
compounds. Further studies on the chemical and biological
properties of these novel isothiosemicarbazones and thiazinones
are actively in progress and will be reported in due course.
4.2. Typical procedure for the preparation of isothiosemicar-
bazone salts 2
To a stirred solution of allylic bromide 1 (1.0 mmol) in 3.0
mL of acetone at 25 °C was added thiosemicarbazide (1.05
mmol). After stirring for 1.5 h, the final mixture was
concentrated under reduced pressure and the solid formed was
crushed with ethyl ether/CH2Cl2 (4:1) and filtered to obtain the
expected products 2 in pure form.
4.2.1. (4E,8Z)-5-Amino-3,4-diaza-8-methoxycarbonyl-2-methyl-
9-phenyl-6-thianona-2,4,8-triene hydrobromide (2a)
Yield: 78% (300 mg); white solid, mp 143.0-144.0 °C. IR
(KBr) νmax/cm-1: 3276, 3094, 2917, 1709, 1640, 1579, 1450,
1277, 1203. 1H NMR (400 MHz, CDCl3): δ 2.02 (s, 3H), 2.16 (s,
3H), 3.88 (s, 3H), 4.14 (s, 2H), 7.35-7.48 (m, 5H), 7.97 (s, 1H),
8.77 (bs, 1H), 9.80 (bs, 1H), 12.28 (bs, 1H). 13C NMR (100 MHz,
CDCl3): δ 20.2 (CH3), 25.1 (CH3), 28.0 (CH2), 53.5 (OCH3),
125.0 (C), 129.3 (2 × CH), 129.5 (2 × CH), 130.4 (CH), 133.5
(C), 145.7 (=CH), 160.8 (C), 168.5 (C), 171.3 (C). Anal. calcd
for C15H20BrN3O2S (%): C, 46.64; H, 5.22; N, 10.88; S, 8.30.
Found: C, 46.28; H, 5.10; N, 10.58; S, 8.47.
4. Experimental section
4.1. General information
4.2.2.
(4E,8Z)-5-Amino-3,4-diaza-8-methoxycarbonyl-9-(4-
methoxyphenyl)-2-methyl-6-thianona-2,4,8-triene hydrobromide
(2b)
All chemicals were of reagent grade and were used as
received. Melting points were determined using a hot plate
apparatus and are uncorrected. Infrared spectra were acquired
with a FT-IR spectrometer (range 4000 e 400 cm-1) using KBr for
solids and film for liquid samples. 1H NMR spectra were
Yield 97% (402 mg); white solid, mp 156.0-158.0 °C. IR
(KBr) νmax/cm-1: 3263, 3092, 2947, 2841, 1717, 1634, 1601,
1
1509, 1436, 1262, 1173. H NMR (400 MHz, CDCl3): δ 2.04 (s,

7
3H), 2.19 (s, 3H), 3.85 (s, 3H), 3.88 (s, 3H), 4.15 (s, 2H), 6.99 (d,
J = 9.0 Hz, 2H), 7.38 (d, J = 9.0 Hz, 2H), 7.90 (s, 1H), 8.91 (bs,
1H), 9.86 (bs, 1H), 12.37 (bs, 1H). 13C NMR (100 MHz, CDCl3):
δ 20.2 (CH3), 25.1 (CH3), 28.3 (CH2), 53.2 (OCH3), 55.5 (OCH3),
114.8 (2 × CH), 121.9 (C), 125.8 (C), 132.0 (2 × CH), 145.3
(=CH), 160.6 (C), 161.4 (C), 168.8 (C), 171.4 (C). Anal. calcd
for C16H22BrN3O3S (%): C, 46.16; H, 5.33; N, 10.09. Found: C,
46.08; H, 5.55; N, 10.10.
2H), 7.62 (d, J = 8.6 Hz, 2H), 7.80 (s, 1H), 8.23 (d, J = 8.6 Hz,
2H). 13C NMR (100 MHz, CDCl3): δ 18.0 (CH3), 25.1 (CH3),
27.1 (CH2), 52.8 (OCH3), 123.8 (2 × CH), 130.4 (2 × CH), 131.2
(C), 139.3 (=CH), 141.0 (C), 147.6 (C), 156.4 (C), 162.4 (C),
167.0 (C=O). HRMS (ESI+): m/z calcd for C15H19N4O4S
[M+H]+: 351.1122, found: 351.1124.
4.4.
Typical
procedure
for
the
preparation
of
isothiosemicarbazones 5 and 6
4.2.3. (4E,8Z)-5-Amino-3,4-diaza-8-methoxycarbonyl-2-methyl-
9-(4-nitrophenyl)-6-thianona-2,4,8-triene hydrobromide (2c)
To a stirred solution of allylic bromide 1 (1.0 mmol) in 3.0
mL of ethanol (or acetonitrile, for the alkyl-substituted product
5q) at 25 °C were added the carbonyl compound (aldehyde or
ketone, 1.0 mmol) and thiosemicarbazide (1.0 mmol) or 4-
methylthiosemicarbazide (for 6). After stirring for 1.5-4.5 h, the
final mixture was concentrated under reduced pressure and the
solid formed was crushed with ethyl ether and decanted to give
the isothiosemicarbazone salt 4. To this solid was added 2.0 mL
of dichloromethane followed by satd NaHCO3 (3.0 mL). After
stirring for 0.5 h, the final mixture was diluted with
dichloromethane, washed twice with water, dried over anhydrous
Na2SO4, filtered and concentrated under reduced pressure. The
resulting isothiosemicarbazones 5a-r and 6 were obtained in high
purity without any further purification step. The isothio-
semicarbazones 5a-e,i,j,m were obtained as mixtures of
diastereoisomers (7Z:7E = 9-20:1) with the same isomeric ratio
observed for the starting allylic bromides (1a,d,e,h).
Yield 88% (378 mg); yellowish solid, mp 177.5-179.0 °C. IR
(KBr) νmax/cm-1: 3274, 3167, 3065, 2955, 1721, 1638, 1577,
1
1507, 1434, 1344, 1252. H NMR (400 MHz, CDCl3): δ 2.06 (s,
3H), 2.19 (s, 3H), 3.94 (s, 3H), 4.15 (s, 2H), 7.60 (d, J = 8.6 Hz,
2H), 8.02 (s, 1H), 8.34 (d, J = 8.6 Hz, 2H), 12.27 (bs, 1H). 13C
NMR (100 MHz, CDCl3): δ 20.0 (CH3), 25.2 (CH3), 28.1 (CH2),
53.6 (OCH3), 124.5 (2 × CH), 128.0 (C), 130.2 (2 × CH), 139.9
(C), 143.1 (=CH), 148.3 (C), 161.0 (C), 167.1 (C), 171.0 (C).
Anal. calcd for C15H19BrN4O4S (%): C, 41.77; H, 4.44; N, 12.99;
S, 7.43. Found: C, 41.39; H, 4.49; N, 12.77; S, 7.33.
4.3.
Typical
procedure
for
the
preparation
of
isothiosemicarbazones 3
To a stirred solution of allylic bromide 1 (1.0 mmol) in 3.0
mL of acetone at 25 °C was added thiosemicarbazide (1.0 mmol).
After stirring for 1.5 h, satd NaHCO3 (3.0 mL) was added to the
mixture and the resulting suspension was allowed to stir for 0.5
h. The final mixture was diluted with dichloromethane, washed
twice with water, dried over anhydrous Na2SO4, filtered and
concentrated under reduced pressure. The resulting
isothiosemicarbazones 3a-c were obtained in high purity without
any further purification step.
4.4.1. (1E,3E,7Z)-4-Amino-2,3-diaza-7-methoxycarbonyl-1-(4-
methylphenyl)-8-phenyl-5-thiaocta-1,3,7-triene (5a)
Time = 2.5 h; yield 95% (350 mg); 7Z:7E = 9:1; yellow oil. IR
(neat) νmax/cm-1: 3453, 3341, 3155, 3025, 2951, 1711, 1609,
1
1587, 1530, 1271, 816, 732. H NMR (200 MHz, CDCl3): δ 2.38
(s, 3H), 3.87 (s, 3H), 4.27 (s, 2H), 5.80 (bs, 2H), 7.19 (d, J = 7.6
Hz, 2H), 7.37-7.47 (m, 5H), 7.60 (d, J = 7.6 Hz, 2H), 7.83 (s,
1H), 8.12 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 21.6 (CH3),
27.7 (CH2), 52.5 (OCH3), 127.6 (C), 127.8 (2 × CH), 128.8 (2 ×
CH), 129.3 (CH), 129.4 (2 × CH), 129.8 (2 × CH), 132.4 (C),
134.6 (C), 140.3 (C), 142.5 (=CH), 155.0 (HC=N), 161.0 (C),
168.0 (C=O). HRMS (ESI+): m/z calcd for C20H22N3O2S
[M+H]+: 368.1427, found: 368.1430.
4.3.1. (4E,8Z)-5-Amino-3,4-diaza-8-methoxycarbonyl-2-methyl-
9-phenyl-6-thianona-2,4,8-triene (3a)
Yield 94% (287 mg); 7Z:7E 9:1; yellow oil. IR (neat) νmax/cm-
1: 3449, 3343, 3059, 2992, 2949, 1713, 1632, 1595, 1269, 761,
1
700. H NMR (400 MHz, CDCl3): δ 1.94 (s, 3H), 1.98 (s, 3H),
3.85 (s, 3H), 4.22 (s, 2H), 5.47 (bs, 2H), 7.35-7.50 (m, 5H), 7.82
(s, 1H). 13C NMR (100 MHz, CDCl3): δ 18.1 (CH3), 25.2 (CH3),
27.7 (CH2), 52.5 (OCH3), 127.3 (C), 128.8 (2 × CH), 129.3 (CH),
129.8 (2 × CH), 134.4 (C), 142.6 (=CH), 157.3 (C), 162.2 (C),
167.9 (C=0). HRMS (ESI+): m/z calcd for C15H20N3O2S [M+H]+:
306.1271, found: 306.1266.
4.4.2.
(1E,3E,7Z)-4-Amino-2,3-diaza-1-(2-bromophenyl)-7-
methoxycarbonyl-8-phenyl-5-thiaocta-1,3,7-triene (5b)
Time = 2.5 h; yield 50% (216 mg); 7Z:7E = 9:1; yellow solid,
mp 114.8-116.8 °C. IR (neat) νmax/cm-1: 3404, 3288, 3172, 2943,
1709, 1601, 1524, 1265, 1212, 751. 1H NMR (400 MHz, CDCl3):
δ 3.88 (s, 3H), 4.28 (s, 2H), 5.91 (bs, 2H), 7.18-7.50 (m, 8H),
7.56 (d, J = 8.0, 1H), 7.84 (s, 1H), 8.02 (d, J = 8.0, 1H), 8.60 (s,
1H). 13C NMR (100 MHz, CDCl3): δ 27.8 (CH2), 52.6 (OCH3),
124.9 (C), 127.4 (CH), 127.5 (C), 128.1 (CH), 128.9 (2 × CH),
129.5 (CH), 129.8 (2 × CH), 131.1 (CH), 133.3 (CH), 134.1 (C),
134.4 (C), 142.8 (=CH), 153.7 (HC=N), 162.5 (C), 168.0 (C=O).
HRMS (ESI+): m/z calcd for C19H19BrN3O2S [M+H]+: 434.0356,
found: 434.0355.
4.3.2.
(4E,8Z)-5-Amino-3,4-diaza-8-methoxycarbonyl-9-(4-
methoxyphenyl)-2-methyl-6-thianona-2,4,8-triene (3b)
Yield 75% (251 mg); yellow oil. IR (neat) νmax/cm-1: 3449,
1
3341, 3000, 2951, 1707, 1603, 1511, 1258, 1179, 836. H NMR
(200 MHz, CDCl3): δ 1.98 (s, 3H), 1.99 (s, 3H), 3.83 (s, 3H),
3.84 (s, 3H), 4.25 (s, 2H), 5.46 (bs, 2H), 6.92 (d, J = 8.9 Hz, 2H),
7.49 (d, J = 8.9 Hz, 2H), 7.77 (s, 1H). 13C NMR (100 MHz,
CDCl3): δ 18.2 (CH3), 25.3 (CH3), 28.0 (CH2), 52.5 (OCH3), 55.5
(OCH3), 114.4 (2 × CH), 124.8 (C), 127.1 (C), 132.0 (2 × CH),
142.6 (=CH), 157.6 (C), 160.7 (C), 162.3 (C), 168.3 (C=O).
HRMS (ESI+): m/z calcd for C16H22N3O3S [M+H]+: 336.1376,
found: 336.1373.
4.4.3
(1E,3E,7Z)-4-Amino-2,3-diaza-1-(4-chlorophenyl)-7-
methoxycarbonyl-8-phenyl-5-thiaocta-1,3,7-triene (5c)
Time = 4.5 h; yield 50% (424 mg); 7Z:7E = 9:1; yellow oil. IR
(neat) νmax/cm-1: 3451, 3357, 2949, 1709, 1611, 1524, 1269,
4.3.3. (4E,8Z)-5-Amino-3,4-diaza-8-methoxycarbonyl-2-methyl-
9-(4-nitrophenyl)-6-thianona-2,4,8-triene (3c)
1
1087, 826, 787. H NMR (400 MHz, CDCl3): δ 3.85 (s, 3H),
4.28 (s, 2H), 5.95 (bs, 2H), 7.32 (d, J = 8.4 Hz, 2H), 7.36-7.50
(m, 5H), 7.61 (d, J = 8.4 Hz, 2H), 7.83 (s, 1H), 8.07 (s, 1H). 13C
NMR (100 MHz, CDCl3): δ 27.8 (CH2), 52.6 (OCH3), 127.6 (C),
128.9 (2 × CH), 129.0 (4 × CH), 129.4 (CH), 129.8 (2 × CH),
133.7 (C), 134.6 (C), 135.9 (C), 142.6 (=CH), 153.6 (HC=N),
Yield 95% (333 mg); yellow solid, mp 115.0-117.0 °C. IR
(neat) νmax/cm-1: 3451, 3341, 3076, 2994, 2947, 1703, 1634,
1
1595, 1518, 1342, 1256, 848. H NMR (400 MHz, CDCl3): δ
1.86 (s, 3H), 1.98 (s, 3H), 3.88 (s, 3H), 4.19 (s, 2H), 5.33 (bs,

8
Tetrahedron
161.9 (C), 168.0 (C=O). HRMS (ESI+): m/z calcd for
4.4.8.
(1E,3E,7Z)-4-Amino-2,3-diaza-1-(4-chlorophenyl)-7-
C19H19ClN3O2 [M+H]+: 338.0881, found: 338.0887.
methoxycarbonyl-8-(4-methoxyphenyl)-5-thiaocta-1,3,7-triene
(5h)
4.4.4.
(1E,3E,7Z)-4-Amino-2,3-diaza-1-(4-fluorophenyl)-7-
methoxycarbonyl-8-phenyl-5-thiaocta-1,3,7-triene (5d)
Time = 2.5 h; yield 60% (250 mg); yellow solid, mp 116.4-
118.4 °C. IR (neat) νma1x/cm-1: 3447, 3327, 2947, 1701, 1607,
1528, 1301, 1256, 836. H NMR (200 MHz, CDCl3): δ 3.76 (s,
3H), 3.80 (s, 3H), 4.25 (s, 2H), 5.87 (bs, 2H), 6.88 (d, J = 8.8 Hz,
2H), 7.28 (d, J = 8.6 Hz, 2H), 7.42 (d, J = 8.8 Hz, 2H), 7.58 (d, J
= 8.6 Hz, 2H), 7.73 (s, 1H), 8.09 (s, 1H). 13C NMR (100 MHz,
CDCl3): δ 28.0 (CH2), 52.5 (OCH3), 55.4 (OCH3), 114.4 (2 ×
CH), 125.0 (C), 127.1 (C), 128.9 (4 × CH), 131.9 (2 × CH), 133.8
(C), 135.8 (C), 142.5 (=CH), 153.5 (HC=N), 160.7 (C), 162.1
(C), 168.3 (C=O). HRMS (ESI+): m/z calcd for C20H21ClN3O3S
[M+H]+: 418.09867, found: 418.09871.
Time = 4.5 h; yield 90% (334 mg); 7Z:7E = 9:1; yellow oil. IR
(neat) νmax/cm-1: 3455, 3343, 2951, 1709, 1601, 1507, 1228, 836,
1
734. H NMR (200 MHz, CDCl3): δ 3.88 (s, 3H), 4.26 (s, 2H),
5.81 (bs, 2H), 7.07 (t, J = 8.6 Hz, 2H), 7.37-7.47 (m, 5H), 7.68
(dd, J = 8.6, 5.5 Hz, 2H), 7.83 (s, 1H), 8.09 (s, 1H). 13C NMR
(100 MHz, CDCl3): δ 27.7 (CH2), 52.6 (OCH3), 115.8 (d, J =
32.0 Hz, 2 × CH), 127.6 (C), 128.8 (2 × CH), 129.3 (CH), 129.6
(d, J = 9.0 Hz, 2 × CH), 129.8 (2 × CH), 131.4 (d, J = 2.0 Hz, C),
134.6 (C), 142.6 (=CH), 153.6 (HC=N), 161.5 (C), 163.9 (d, J =
248.0 Hz, CF), 168.0 (C=O). HRMS (ESI+): m/z calcd for
C19H19FN3O2S [M+H]+: 372.11765, found: 372.11768.
4.4.9.
(1E,3E,7Z)-4-Amino-2,3-diaza-8-(4-chlorophenyl)-7-
methoxycarbonyl-1-(4-methoxyphenyl)-5-thiaocta-1,3,7-triene
(5i)
4.4.5.
(1E,3E,7Z)-4-Amino-2,3-diaza-1-(4-bromophenyl)-7-
methoxycarbonyl-8-(4-methylphenyl)-5-thiaocta-1,3,7-triene (5e)
Time = 2.5 h; yield 90% (376 mg); 7Z:7E = 15:1; yellow
solid, mp 113.0-115.2 °C. IR (neat) νmax/cm-1: 3471, 3359, 3000,
2945, 1705, 1609, 1585, 1242, 1079, 828. H NMR (200 MHz,
Time = 4.5 h; yield 95% (424 mg); 7Z:7E = 9:1; yellow solid,
mp 62.6-65.6 °C. IR (neat) νmax/cm-1: 3437, 3288, 3027, 2949,
1703, 1640, 1607, 1528, 1269, 812, 728. H NMR (400 MHz,
1
1
CDCl3): δ 3.83 (s, 3H), 3.86 (s, 3H), 4.25 (s, 2H), 5.68 (bs, 2H),
6.90 (d, J = 9.1 Hz, 2H), 7.34-7.45 (m, 4H), 7.65 (d, J = 9.1 Hz,
2H), 7.74 (s, 1H), 8.02 (s, 1H). 13C NMR (100 MHz, CDCl3): δ
27.5 (CH2), 52.6 (OCH3), 55.5 (OCH3), 114.2 (2 × CH), 127.9
(C), 128.4 (C), 129.1 (2 × CH), 129.4 (2 × CH), 131.2 (2 × CH),
133.2 (C), 135.3 (C), 141.0 (=CH), 154.8 (HC=N), 160.1 (C),
161.4 (C), 167.8 (C=O). HRMS (ESI+): m/z calcd for
C20H21ClN3O3S [M+H]+: 418.0987, found: 418.0986.
CDCl3): δ 2.37 (s, 3H), 3.86 (s, 3H), 4.26 (s, 2H), 5.91 (bs, 2H),
7.22 (d, J = 7.8 Hz, 2H), 7.39 (d, J = 7.8 Hz, 2H), 7.50 (d, J = 8.4
Hz, 2H), 7.56 (d, J = 8.4 Hz, 2H), 7.81 (s, 1H), 8.10 (s, 1H). 13C
NMR (100 MHz, CDCl3): δ 21.6 (CH3), 27.9 (CH2), 52.6
(OCH3), 124.2 (C), 126.5 (C), 129.2 (2 × CH), 129.6 (2 × CH),
130.0 (2 × CH), 131.7 (C), 131.9 (2 × CH), 134.2 (C), 139.8 (C),
142.8 (=CH), 153.6 (HC=N), 162.2 (C), 168.2 (C=O). HRMS
(ESI+): m/z calcd for C20H21BrN3O2S [M+H]+: 448.0512, found:
448.0517.
4.4.10.
(1E,3E,7Z)-4-Amino-2,3-diaza-8-(4-chlorophenyl)-7-
methoxycarbonyl-1-(4-nitrophenyl)-5-thiaocta-1,3,7-triene (5j)
4.4.6. (1E,3E,7Z)-4-Amino-2,3-diaza-7-methoxycarbonyl-8-(4-
methoxyphenyl)-1-(2-naphthyl)-5-thiaocta-1,3,7-triene (5f)
Time = 4.5 h; yield 75% (325 mg); 7Z:7E = 15:1; yellow
solid, mp 126.0-128.0 °C. IR (neat) νmax/cm-1: 3492, 3365, 3064,
2951, 1709, 1658, 1591, 1507, 1336, 1285, 838. H NMR (400
Time = 2.5 h; yield 95% (411 mg); yellow solid, mp 138.0-
140.0 °C. IR (neat) νmax/cm-1: 3465, 3319, 3055, 2953, 1693,
1605, 1534, 1432, 1256, 1179, 820. 1H NMR (400 MHz, CDCl3):
δ 3.80 (s, 3H), 3.86 (s, 3H), 4.34 (s, 2H), 5.97 (bs, 2H), 6.94 (d, J
= 8.8 Hz, 2H), 7.48-7.51 (m, 4H), 7.80-7.87 (m, 4H), 7.96 (s,
1H), 8.00-8.03 (m, 1H), 8.36 (s, 1H). 13C NMR (100 MHz,
CDCl3): δ 28.0 (CH2), 52.5 (OCH3), 55.4 (OCH3), 114.4 (2 ×
CH), 123.5 (CH), 125.0 (C), 126.5 (CH), 126.9 (CH), 127.1
(CH), 127.9 (C), 128.36 (CH), 128.45 (CH), 129.5 (CH), 131.9
(2 × CH), 132.9 (C), 133.3 (C), 134.4 (C), 142.4 (=CH), 154.9
(HC=N), 160.6 (C), 161.8 (C), 168.3 (C=O). HRMS (ESI+): m/z
calcd for C24H24N3O3S [M+H]+: 434.1533, found: 434.1528.
1
MHz, CDCl3): δ 3.87 (s, 3H), 4.26 (s, 2H), 5.89 (bs, 2H), 7.39 (s,
4H), 7.76 (s, 1H), 7.83 (d, J = 8.6 Hz, 2H), 8.01 (s, 1H), 8.23 (d,
J = 8.6 Hz, 2H). 13C NMR (100 MHz, CDCl3): δ 27.4 (CH2), 52.7
(OCH3), 124.0 (2 × CH), 128.2 (2 × CH + C), 129.1 (2 × CH),
131.0 (2 × CH), 133.1 (C), 135.3 (C), 141.1 (C), 141.2 (=CH),
148.4 (C), 151.9 (HC=N), 163.3 (C), 167.6 (C=O). HRMS
(ESI+): m/z calcd for C19H18ClN4O4S [M+H]+: 433.0732, found:
433.0734.
4.4.11.
(1E,3E,7Z)-4-Amino-2,3-diaza-8-(2-chlorophenyl)-7-
methoxycarbonyl-1-(4-methoxyphenyl)-5-thiaocta-1,3,7-triene
(5k)
4.4.7. (1E,3E,7Z)-4-Amino-2,3-diaza-7-methoxycarbonyl-8-(4-
methoxyphenyl)-1-(4-methylphenyl)-5-thiaocta-1,3,7-triene (5g)
Time = 2.5 h; yield 94% (393 mg); yellow solid, mp 35.0-37.0
°C. IR (neat νmax/cm-1: 3449, 3335, 3053, 2953, 1695, 1605,
Time = 2.5 h; yield 93% (370 mg); yellow oil. IR (neat)
νmax/cm-1: 3461, 3347, 3045, 2947, 1701, 1605, 1589, 1520,
1267, 824, 749. 1H NMR (400 MHz, CDCl3): δ 2.36 (s, 3H), 3.80
(s, 3H), 3.84 (s, 3H), 4.29 (s, 2H), 5.91 (bs, 2H), 6.92 (d, J = 8.8
Hz, 2H), 7.17 (d, J = 7.8 Hz, 2H), 7.48 (d, J = 8.8 Hz, 2H), 7.60
(d, J = 7.8 Hz, 2H), 7.78 (s, 1H), 8.20 (s, 1H). 13C NMR (100
MHz, CDCl3): δ 21.5 (CH3), 27.9 (CH2), 52.4 (OCH3), 55.3
(OCH3), 114.3 (2 × CH), 124.9 (C), 127.0 (C), 127.7 (2 × CH),
129.3 (2 × CH), 131.8 (2 × CH), 132.4 (C), 140.3 (C), 142.4
(=CH), 154.8 (HC=N), 160.6 (C), 161.2 (C), 168.2 (C=O).
HRMS (ESI+): m/z calcd for C21H24N3O3S [M+H]+: 398.1533,
found: 398.1531.
1
1509, 1301, 1248, 834, 753. H NMR (400 MHz, CDCl3): δ 3.82
(s, 3H), 3.87 (s, 3H), 4.12 (s, 2H), 5.81 (bs, 2H), 6.89 (d, J = 8.8
Hz, 2H), 7.26-7.30 (m, 2H), 7.37-7.45 (m, 2H), 7.62 (d, J = 8.8
Hz, 2H), 7.88 (s, 1H), 8.02 (s, 1H). 13C NMR (100 MHz, CDCl3):
δ 27.6 (CH2), 52.6 (OCH3), 55.4 (OCH3), 114.1 (2 × CH), 127.0
(CH), 127.8 (C), 129.3 (2 × CH), 129.8 (CH), 130.0 (C), 130.2
(CH), 130.4 (CH), 133.3 (C), 134.2 (C), 139.2 (=CH), 154.5
(HC=N), 160.2 (C), 161.3 (C), 167.4 (C=O). HRMS (ESI+): m/z
calcd for C20H21ClN3O3S [M+H]+: 418.0987, found: 418.0989.
4.4.12. (1E,3E,7Z)-4-Amino-2,3-diaza-8-(2,4-dichlorophenyl)-7-
methoxycarbonyl-1-(4-methoxyphenyl)-5-thiaocta-1,3,7-triene
(5l)
Time = 2.5 h; yield 94% (425 mg); yellow solid, mp 122.7-
124.7 °C. IR (neat) νmax/cm-1: 3445, 3333, 3006, 2953, 1693,
1607, 1587, 1509, 1289, 1252, 834. 1H NMR (200 MHz, CDCl3):

9
δ 3.84 (s, 3H), 3.88 (s, 3H), 4.12 (s, 2H), 5.65 (bs, 2H), 6.91 (d, J
= 8.3 Hz, 2H), 7.26-7.42 (m, 3H), 7.65 (d, J = 8.3 Hz, 2H), 7.79
(s, 1H), 7.94 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 27.4 (CH2),
52.6 (OCH3), 55.4 (OCH3), 114.2 (2 × CH), 127.3 (CH), 127.8
(C), 129.4 (2 × CH), 129.6 (CH), 130.7 (C), 131.3 (CH), 132.1
(C), 135.0 (C), 135.3 (C), 137.7 (=CH), 154.5 (HC=N), 159.6
(C), 161.3 (C), 167.2 (C=O). HRMS (ESI+): m/z calcd for
C20H20Cl2N3O3S [M+H]+: 452.0597, found: 452.0593.
4.4.17. (3E,5E,9Z)-6-Amino-4,5-diaza-9-methoxycarbonyl-10-
(4-methoxyphenyl)-7-thiadeca-3,5,9-triene (5q)
Time = 2.5 h; yield 90% (302 mg); yellow oil. IR (neat)
νmax/cm-1: 3443, 3339, 3174, 2968, 1707, 1632, 1603, 1511,
1258, 1179, 836, 732. 1H NMR (200 MHz, CDCl3): δ 1.10 (t, J =
7.2 Hz, 3H), 2.23-2.38 (m, 2H), 3.84 (s, 6H), 4.21 (s, 2H), 5.66
(bs, 2H), 6.92 (d, J = 8.4 Hz, 2H), 7.47 (d, J = 8.4 Hz, 2H), 7.66
(t, J = 5.0 Hz, 1H), 7.76 (s, 1H). 13C NMR (100 MHz, CDCl3): δ
10.8 (CH3), 26.2 (CH2), 28.0 (CH2), 52.4 (OCH3), 55.4 (OCH3),
114.3 (2 × CH), 124.9 (C), 127.0 (C), 131.9 (2 × CH), 142.4
(=CH), 160.1 (C), 160.3 (HC=N), 160.7 (C), 168.2 (C=O).
HRMS (ESI+): m/z calcd for C16H22N3O3S [M+H]+: 336.1376,
found: 336.1374.
4.4.13. (1E,3E,7Z)-4-Amino-2,3-diaza-8-(3-bromophenyl)-1-(4-
chlorophenyl)-7-methoxycarbonyl-5-thiaocta-1,3,7-triene (5m)
Time = 2.5 h; yield 85% (397 mg); 7Z:7E = 20:1; yellow
solid, mp 40.0-42.0 °C. IR (neat) νmax/cm-1: 3451, 3339, 3059,
1
2949, 1709, 1611, 1587, 1524, 1289, 787. H NMR (200 MHz,
CDCl3): δ 3.82 (s, 3H), 4.21 (s, 2H), 5.69 (bs, 2H), 7.18-7.46 (m,
6H), 7.58 (d, J = 8.6 Hz, 2H), 7.67 (s, 1H), 7.99 (s, 1H). 13C
NMR (100 MHz, CDCl3): δ 27.2 (CH2), 52.6 (OCH3), 122.8 (C),
128.1 (C), 128.82 (2 × CH), 128.85 (2 × CH), 129.1 (CH), 130.2
(CH), 132.0 (CH), 132.4 (CH), 133.6 (C), 135.7 (C), 136.6 (C),
140.4 (=CH), 153.4 (HC=N), 161.2 (C), 167.5 (C=O). HRMS
(ESI+): m/z calcd for C19H18BrClN3O2S [M+H]+: 467.9965,
found: 467.9967.
4.4.18.
(2E,6Z)-3-Amino-1,2-diaza-1-(cyclohexylidene)-6-
methoxycarbonyl-7-(4-methoxyphenyl)-4-thiahepta-2,6-diene
(5r)
Time = 2.5 h; yield 90% (337 mg); yellow oil. IR (neat)
νmax/cm-1: 3449, 3341, 3000, 2933, 1707, 1603, 1511, 1258,
1
1179, 836, 732. H NMR (400 MHz, CDCl3): δ 1.58-1.61 (m,
4H), 1.67-1.71 (m, 2H), 2.28-2.32 (m, 2H), 2.61 (bs, 2H), 3.82 (s,
3H), 3.83 (s, 3H), 4.23 (s, 2H), 5.52 (bs, 2H), 6.91 (d, J = 8.6 Hz,
2H), 7.49 (d, J = 8.6 Hz, 2H), 7.76 (s, 1H). 13C NMR (100 MHz,
CDCl3): δ 26.2 (CH2), 26.6 (CH2), 27.7 (CH2), 27.9 (CH2), 28.1
(CH2), 36.0 (CH2), 52.4 (OCH3), 55.4 (OCH3), 114.3 (2 × CH),
124.7 (C), 127.0 (C), 132.0 (2 × CH), 142.4 (=CH), 158.0 (C),
160.6 (C), 167.7 (C), 168.2 (C=O). HRMS (ESI+): m/z calcd for
C19H26N3O3S [M+H]+: 376.1689, found: 376.1687.
4.4.14. (1E,3E,7Z)-4-Amino-2,3-diaza-7-methoxycarbonyl-1-(4-
methoxyphenyl)-8-(4-nitrophenyl)-5-thiaocta-1,3,7-triene (5n)
Time = 2.5 h; yield 95% (407 mg); yellow solid, mp 120.0-
122.0 °C. IR (neat) νmax/cm-1: 3463, 3347, 3074, 2955, 1705,
1
1605, 1511, 1350, 1250, 830. H NMR (200 MHz, CDCl3): δ
3.83 (s, 3H), 3.88 (s, 3H), 4.24 (s, 2H), 5.57 (bs, 2H), 6.89 (d, J =
8.9 Hz, 2H), 7.56-7.63 (m, 4H), 7.78 (s, 1H), 7.91 (s, 1H), 8.23
(d, J = 8.6 Hz, 2H). 13C NMR (100 MHz, CDCl3): δ 27.2 (CH2),
52.8 (OCH3), 55.5 (OCH3), 114.3 (2 × CH), 124.0 (2 × CH),
127.7 (C), 129.4 (2 × CH), 130.5 (2 × CH), 131.6 (C), 139.1
(=CH), 141.4 (C), 147.8 (C), 154.8 (HC=N), 159.3 (C), 161.6
(C), 167.2 (C=O). HRMS (ESI+): m/z calcd for C20H21N4O5S
[M+H]+: 429.1227, found: 429.1228.
4.4.19.
(1E,3E,7Z)-2,3-Diaza-8-(2,4-dichlorophenyl)-7-
methoxycarbonyl-1-(4-methoxyphenyl)-4-methylamino-5-
thiaocta-1,3,7-triene (6)
Obtained as a mixture of isomers (3E:3Z = 2.5:1). Time = 2.5
h; yield 70% (325 mg); yellow solid, mp 117.1-120.2 °C. IR
(neat) νmax/cm-1: 3368, 3009, 2939, 1707, 1605, 1552, 1265,
1
1089, 822. H NMR (400 MHz, CDCl3): Data for the major
4.4.15.
(1E,3E,7Z)-4-Amino-2,3-diaza-1-(4-bromophenyl)-7-
isomer: δ 2.94 (d, J = 5.2 Hz, 3H), 3.83 (s, 3H), 3.88 (s, 3H),
4.20 (s, 2H), 6.38 (d, J = 5.2 Hz, 1H), 6.90 (d, J = 8.6 Hz, 2H),
7.26-7.29 (m, 1H), 7.40-7.48 (m, 2H), 7.62 (d, J = 8.6 Hz, 2H),
7.82 (s, 1H), 8.22 (s, 1H). 13C NMR (100 MHz, CDCl3): Data for
the major isomer:δ 27.1 (CH2), 29.9 (CH3), 52.6 (OCH3), 55.4
(OCH3), 114.1 (2 × CH), 127.3-135.2 (CAr + CHAr), 137.7 (=CH),
152.7 (HC=N), 161.0 (C), 162.0 (C), 167.1 (C=O). HRMS
(ESI+): m/z calcd for C21H22Cl2N3O3S [M+H]+: 466.0753, found:
466.0754.
methoxycarbonyl-8-(2-naphthyl)-5-thiaocta-1,3,7-triene (5o)
Time = 2.5 h; yield 60% (289 mg); yellow solid, mp 133.3-
135.0 °C. IR (neat) νmax/cm-1: 3465, 3319, 3055, 2953, 1693,
1
1605, 1589, 1534, 1256, 820, 749. H NMR (400 MHz, CDCl3):
δ 3.90 (s, 3H), 4.38 (s, 2H), 5.80 (bs, 2H), 7.37 (d, J = 8.4 Hz,
2H), 7.45-7.57 (m, 5H), 7.74 (s, 1H), 7.82-7.87 (m, 3H), 7.96 (s,
1H), 7.98 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 27.7 (CH2),
52.6 (OCH3), 124.2 (C), 126.7 (CH), 126.9 (CH), 127.2 (CH),
127.7 (CH), 127.9 (C), 128.4 (CH), 128.8 (CH), 129.1 (2 × CH),
130.0 (CH), 131.8 (2 × CH), 132.2 (C), 133.2 (C), 133.4 (C),
134.0 (C), 142.4 (=CH), 153.6 (HC=N), 161.7 (C), 168.1 (C=O).
HRMS (ESI+): m/z calcd for C23H21BrN3O2S [M+H]+: 484.0513,
found: 484.0514.
4.5.
Preparation
of
(4E,8Z)-5-acetylamino-3,4-diaza-8-
methoxycarbonyl-2-methyl-9-(4-nitrophenyl)-6-thianona-2,4,8-
triene (9)
To a stirred suspension of the isothiosemicarbazone salt 2c
(1.0 mmol) in 3.0 mL of CH2Cl2 at 25 °C was added acetic
anhydride (3.0 mmol) followed by satd NaHCO3 (3.0 mL). After
stirring for 20 min, the final mixture was diluted with CH2Cl2 and
the organic extract was washed with H2O and brine, dried over
anhydrous Na2SO4, filtered and concentrated under reduced
pressure. The resulting residue was purified by column
chromatography (7:3 hexane/ethyl acetate) to give the
corresponding acetylated isothiosemicarbazone 9. Yield 92%
(360 mg); yellowish solid, mp 151.5-153.0 °C. IR (KBr) νmax/cm-
1: 3322, 3288, 3112, 2953, 1717, 1634, 1545, 1511, 1344, 1206.
1H NMR (200 MHz, CDCl3): δ 1.94 (s, 3H), 2.03 (s, 3H), 2.15 (s,
3H), 3.85 (s, 3H), 4.09 (s, 2H), 7.66 (d, J = 8.6 Hz, 2H), 7.85 (s,
1H), 8.22 (d, J = 8.6 Hz, 2H), 9.70 (bs, 1H). 13C NMR (100
MHz, CDCl3): δ 18.6 (CH3), 24.0 (CH3), 25.3 (CH3), 27.9 (CH2),
52.9 (OCH3), 124.0 (2 × CH), 130.49 (C), 130.54 (2 × CH),
4.4.16. (1E,3E,7Z,9E)-4-Amino-2,3-diaza-1-(4-chlorophenyl)-7-
methoxycarbonyl-10-phenyl-5-thiadeca-1,3,7,9-tetraene (5p)
Time = 4.5 h; yield 80% (331 mg); yellow solid, mp 141.7-
142.7 °C. IR (neat) νmax/cm-1: 3455, 3298, 2945, 1689, 1605,
1
1591, 1515, 1289, 834, 751. H NMR (200 MHz, CDCl3): δ 3.83
(s, 3H), 4.27 (s, 2H), 5.60 (bs, 2H), 6.84-6.99 (m, 1H), 7.26-7.51
(m, 11H), 8.26 (s, 1H). 13C NMR (100 MHz, CDCl3): δ 26.4
(CH2), 52.2 (OCH3), 124.6 (CH), 127.0 (C), 127.6 (2 × CH),
128.8 (4 × CH), 128.9 (2 × CH), 129.2 (CH), 133.6 (C), 135.8
(C), 136.4 (C), 141.0 (=CH), 141.3 (=CH), 153.3 (HC=N), 161.7
(C), 167.8 (C=O). HRMS (ESI+): m/z calcd for C21H21ClN3O2S
[M+H]+: 414.1038, found: 414.1040.

10
Tetrahedron
140.4 (=CH), 141.2 (C), 147.8 (C), 152.6 (C), 165.9 (C),
(s, 3H), 4.11 (s, 2H), 7.04 (d, J = 8.6 Hz, 2H), 7.48 (d, J = 8.6
Hz, 2H), 7.53 (s, 1H), 8.01 (d, J = 8.4 Hz, 2H), 8.31 (d, J = 8.4
Hz, 2H), 8.54 (s, 1H), 11.47 (bs, 1H). 13C NMR (100 MHz,
DMSO-d6): δ 24.1 (CH2), 55.2 (OCH3), 114.3 (2 × CH), 124.0 (2
× CH), 124.1 (C), 126.3 (C), 128.5 (2 × CH), 131.5 (2 × CH),
136.9 (C), 140.4 (=CH), 148.1 (C), 154.3 (HC=N), 160.0 (C),
161.8 (C), 165.8 (C). HRMS (ESI+): m/z calcd for C19H16N4O4S
[M+H]+: 397.0965, found: 397.0967.
166.9 (C), 167.6 (C). HRMS (ESI+): m/z calcd for
C17H20N4O5SNa [M+Na]+: 415.1047, found: 415.1044.
4.6. Preparation of (1E,3E,7Z)-4-acetylamino-2,3-diaza-8-(2,4-
dichlorophenyl)-7-methoxycarbonyl-1-(4-methoxyphenyl)-5-
thiaocta-1,3,7-triene (10)
To a stirred solution of isothiosemicarbazone 5l (1.0 mmol) in
3.0 mL of dichloromethane at 25 °C was added acetic anhydride
(1.5 mmol). After stirring for 1 h, the final mixture was
concentrated under reduced pressure and the solid formed was
crushed with ethyl ether and filtered to obtain the expected
acetylated isothiosemicarbazone 10 in pure form. Yield 87% (429
mg); yellow solid, mp 147.0-149.0 °C. IR (neat) νmax/cm-1: 3335,
4.8. Cytotoxicity assay
To evaluate the potential antitumoral activity of the
isothiosemicarbazones 3 and 5, the MTT [3-(4,5-dimethyl-2-
thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide] method was
used to determine the cell viability of MDA-MB-231(Human
Caucasian Breast Adenocarcinoma Cells) and HUVEC (Human
Umbilical Vein Endothelial Cells) lines. Therefore, cell lines (1 ×
104/well) were seeded in 96-well plates and incubated for 24 h
with 50 µM of the isothiosemicarbazone. After incubation, the
old culture medium was replaced with fresh culture medium with
5 mg/mL of MTT, followed by incubation for 2 h at 37 °C. MTT-
formazan crystals were dissolved in DMSO and the absorbance
was measured at 540 nm, using a micro-well system reader. As
control group of each cell line, cells were incubated without the
compounds and considered as 100% cell viability. Results where
expressed as the mean ± SD of three experiments.
1
3072, 2960, 1724, 1701, 1611, 1536, 1236, 832. H NMR (400
MHz, CDCl3): δ 2.19 (s, 3H), 3.86 (s, 6H), 4.10 (s, 2H), 6.94 (d,
J = 8.8 Hz, 2H), 7.28 (dd, J = 8.4, 2.0 Hz, 1H), 7.41 (d, J = 2.0
Hz, 1H), 7.52 (d, J = 8.4 Hz, 1H), 7.65 (d, J = 8.8 Hz, 2H), 7.84
(s, 1H), 7.91 (s, 1H), 9.76 (bs, 1H). 13C NMR (100 MHz, CDCl3):
δ 24.0 (CH3), 27.5 (CH2), 52.6 (OCH3), 55.5 (OCH3), 114.3 (2 ×
CH), 126.6 (C), 127.3 (CH), 129.6 (CH), 129.9 (2 × CH), 130.0
(C), 131.3 (CH), 132.3 (C), 135.1 (C), 135.2 (C), 138.2 (=CH),
154.9 (C), 156.8 (HC=N), 162.0 (C), 166.9 (C=O), 167.3 (C=O).
HRMS (ESI+): m/z calcd for C22H22Cl2N3O4S [M+H]+:
494.0703, found: 494.0704.
4.7. Cyclization to 2-hydrazono-1,3-thiazin-4-ones 11
Isothiosemicarbazones 5c and 5h were left standing at room
temperature for weeks to give crystals of the corresponding 2-
hydrazono-1,3-thiazin-4-ones 11c and 11h. 2-Hydrazono-1,3-
thiazin-4-one 11s was obtained directly through the work-up of
the corresponding MCR reaction from 4-methoxy-substituted
allylic bromide 1b, thiosemicarbazide and 4-nitrobenzaldehyde in
ethanol as described in section 4.4.
Acknowledgements
We are grateful to the Central de Análises (Departamento de
Química, UFSC) for the spectroscopic analysis. Special thanks
are due to CEBIME/UFSC (Laboratório Multiusuário de
Espectrometria de Massas) and LAMEB/UFSC (Laboratório
Multiusuário de Estudos em Biologia). The authors are grateful
to CNPq (Conselho Nacional de Desenvolvimento Científico e
Tecnológico, Brazil) and CAPES (Coordenação de
Aperfeiçoamento de Pessoal de Nível Superior, Brazil) for
fellowships. Supports from INCT-Catalysis (Brazilian Research
Council) and FINEP (Financiadora de Estudos e Projetos) are
also gratefully acknowledged.
4.7.1.
(2Z,5Z)-5-Benzylidene-2-[(E)-4-
chlorobenzylidene]hydrazono-1,3-thiazin-4-one (11c)
Obtained as a 3:1 mixture of isomers. Yield 70% (247 mg);
yellow solid, mp 185.1-186.0 °C. IR (neat) νmax/cm-1: 3439, 2925,
1
2851, 1679, 1626, 1573, 1489, 1289, 1087, 822. H NMR (400
MHz, CDCl3): Data for the major isomer: δ 3.96 (s, 2H), 7.34-
7.48 (m, 7H), 7.68-7.71 (m, 2H), 7.78 (s, 1H), 8.47 (s, 1H), 9.67
(s, NH); Data for the minor isomer: δ 4.04 (s, 2H), 7.34-7.48 (m,
7H), 7.71-7.73 (m, 2H), 7.88 (s, 1H), 8.36 (s, 1H), 9.78 (s, NH).
13C NMR (100 MHz, CDCl3): Data for the major isomer: δ 24.9
(CH2), 125.9 (C), 129.0-134.3 (CAr + CHAr), 136.8 (C), 139.3
(=CH), 140.3 (C), 157.1 (HC=N), 163.7 (C), 166.2 (C). HRMS
(ESI+): m/z calcd for C18H14ClN3OS [M+H]+: 356.0619, found:
356.0613.
Appendix A. Supplementary data
Supplementary data for this article (1H and 13C NMR spectra
for all novel compounds) can be found online at https://doi.org/
Crystallographic data for 5h (CCDC 1987926), 5l (CCDC
1987929), 5n (CCDC 1987928), 11c (CCDC 1987930), and 11h
(CCDC 1987927) have been deposited at the Cambridge
Crystallographic Database Centre and can be found at
http://www.ccdc.ac.uk
4.7.2.
(2Z,5Z)-2-[(E)-4-Chlorobenzylidene]hydrazono-5-(4-
methoxybenzylidene)-1,3-thiazin-4-one (11h)
Yield 4% (15 mg); yellow solid, 178.9-180.0 °C. IR (neat)
νmax/cm-1: 3449, 3172, 2931, 2837, 1677, 1603, 1573, 1509,
1
1256, 1173, 1030, 824. H NMR (200 MHz, CDCl3): δ 3.86 (s,
References
3H), 4.00 (s, 2H), 7.00 (d, J = 8.6 Hz, 2H), 7.33 (d, J = 8.3 Hz,
2H), 7.40 (d, J = 8.6 Hz, 2H), 7.70 (d, J = 8.3 Hz, 2H), 7.73 (s,
1H), 8.33(s, 1H), 8.41 (bs, 1H). HRMS (ESI+): m/z calcd for
C19H16ClN3O2S [M+H]+: 386.0725, found: 386.0727.
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UNIVERSIDADE FEDERAL DE SANTA CATARINA - DEPARTAMENTO DE QUÍMICA
Florianópolis, SC BRASIL 88040-900
HIGHLIGHTS
‰ Isothiosemicarbazones were readily prepared through multicomponent synthesis
‰ The transformations proceed under mild conditions with high yields and selectivity
‰ Unexpected cyclization to the 1,3-thiazinone framework expanded the scope of
the MCR
‰ All compounds were obtained in high purity without the need for chromatography
stages
‰ Isothiosemicarbazones showed cytotoxic activity toward aggressive breast cancer
cells
__________________________
Marcus Mandolesi Sá
Full Professor - Organic Chemistry
Chemistry Department - UFSC
Prof. Dr. Marcus Mandolesi Sá
Departamento de Química – UFSC
Tel: +55-48-37219967; Fax: +55-48-37216850
marcus.sa@ufsc.br; marcus.mandolesi.sa@pq.cnpq.br

Declaration of interests
☒ The authors declare that they have no known competing financial interests or personal relationships
that could have appeared to influence the work reported in this paper.
☐The authors declare the following financial interests/personal relationships which may be considered
as potential competing interests:
none