Solvent-free multicomponent assembling of isatins, malononitrile, and dimedone: Fast and efficient way to functionalized spirooxindole system

Article abstract of DOI:10.1007/s00706-015-1617-2

Solvent-free sodium acetate catalyzed multicomponent reaction of isatins, malononitrile, and dimedone initiated by grinding in mortar results in the fast and efficient formation of substituted spirooxindoles in 90-99 % yields. The developed solvent-free f

Full text of DOI:10.1007/s00706-015-1617-2

Monatsh Chem
DOI 10.1007/s00706-015-1617-2
ORIGINAL PAPER
Solvent-free multicomponent assembling of isatins, malononitrile,
and dimedone: fast and efficient way to functionalized
spirooxindole system
Michail N. Elinson1 Fedor V. Ryzhkov1 Tatiana A. Zaimovskaya2 Mikhail P. Egorov1
•
•
•
Received: 17 September 2015 / Accepted: 23 November 2015
Ó Springer-Verlag Wien 2015
Abstract Solvent-free sodium acetate catalyzed multi-
component reaction of isatins, malononitrile, and dimedone
initiated by grinding in mortar results in the fast and effi-
cient formation of substituted spirooxindoles in 90–99 %
yields. The developed solvent-free fast multicomponent
approach to the substituted spirooxindoles—the pharma-
cologically perspective substances with spasmolytic,
diuretic, anticoagulant, anticancer, and antianaphylactic
activities—is beneficial from the viewpoint of diversity-
oriented large-scale processes and represents fast efficient
and environmentally benign solvent-free synthetic concept
for multicomponent reactions strategy.
Introduction
The multicomponent reactions (MCRs) are known as a new
simple and efficient methodology to produce biologically
active compounds and has become an important area of
research in organic, combinatorial, and medicinal chem-
istry [1]. The MCR strategy offers significant advantages
over conventional linear-type synthesis due to its flexible,
convergent, and atom efficient nature [2, 3]. Thus, the
success of combinatorial chemistry in drug discovery
process is considerably dependent on further advances in
heterocyclic MCR methodology and, according to the
current synthetic requirements of ‘green chemistry’, envi-
Graphical abstract
ronmentally
benign
solvent-free
multicomponent
procedures are particularly welcome.
The heterocyclic spirooxindole ring system is a widely
distributed structural framework in a number of pharma-
ceuticals and natural products [4], including such cytostatic
alkaloids as spirotryprostatins A, B, and strychnophylline
[5]. The unique structural array and the highly pronounced
pharmacological activity displayed by the class of
spirooxindole compounds have made them attractive syn-
thetic targets [6–8]. Among the oxygen-containing
heterocycles spiro-fused with oxindole ring system, 4H-
chromenes are of particular utility as they belong to
‘privileged medicinal scaffolds’—certain molecular
frameworks serving for the generation of ligands for
functionally and structurally discreet biological receptors
[9, 10]. Functionally substituted 4H-chromenes have
received considerable attention due to their useful biolog-
ical properties, which include spasmolytic, diuretic,
anticoagulant, anticancer, and antianaphylactic activities
[11–13]. The current interest to 5,6,7,8-tetrahydro-4H-
chromene derivatives bearing nitrile functionality, espe-
cially to 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene-
Keywords Solvent-free Á Catalysis Á Carbanions Á
Cyclization Á Heterocycles Á Green chemistry
& Michail N. Elinson
elinson@ioc.ac.ru
1
N. D. Zelinsky Institute of Organic Chemistry, Russian
Academy of Sciences, Moscow, Russian Federation
2
A. V. Topchiev Institute of Petrochemical Synthesis, Russian
Academy of Sciences, Moscow, Russian Federation
123

M. N. Elinson et al.
3-carbonitriles, arises from their potential application in the
treatment of human neurodegenerative disorders [14, 15].
In recent years, multicomponent condensation reactions
have been reported for the synthesis of spirooxindoles via
condensation of isatin, 1,3-cyclic diketones, and malononi-
trile under different catalytic conditions [16–21]. Among the
catalysts are tetrabutylammonium fluoride (10 mol%) [16]
(2008), sodium stearate (12 mol%) (2010) [17], lipase from
porcinepancreas (20 mol%) (2011) [18], triphenylphosphine
(10 mol%) (2012) [19], SBA-15-DABCO (10 mol%) (2014)
[20], and even HAuCl4 (5 mol%) in polyethylene glycol as
solvent (2012) [21]. Multicomponent condensation under
catalytic conditions and ultrasound irradiation was also used
to ensure decreasing reaction time of this process to
10–20 min [22–24]. Electrocatalytic variant for this process
is also known [25] as well as non-catalytic process by reflux
reagents in propanol [26].
Thus, each of the known procedures for the synthesis of
corresponding spiro[4H-chromene-4,30-oxindole] system
from isatin, 1,3-cyclic diketones, and malononitrile has its
merits; however, fast, facile, and efficient solvent-free
multicomponent method for this process has yet to be
developed.
Considering our results on the ‘solvent-free’ multicom-
ponent transformations of carbonyl compounds and C–H
acids [29–36] as well as the certain biomedical application
of spirooxindoles mentioned above, we were prompted to
design a convenient fast and facile ‘solvent-free’ method-
ology for the efficient synthesis of substituted
spirooxindoles based on multicomponent assembling of
isatins, malononitrile, and dimedone.
Results and discussion
The demand for both clean and efficient chemical syn-
theses in the last decade is becoming more urgent. Thus,
solvent-free multicomponent reactions are one of the most
usual solutions to modernize classical procedures by
making them cleaner, safer and easier to perform. It is often
claimed that the best solvent is no solvent [27].
As it follows from introduction, we were interested in
designing a ‘one-pot’ fast convenient and facile ‘solvent-
free’ methodology for the efficient synthesis of function-
alized spirooxindole system based on isatins 1a–1k,
malononitrile, and dimedone assembling (Scheme 1;
Tables 1 and 2).
The only known solvent-free process for synthesis of
spirooxindole uses complex ZnO nano-rods catalyst espe-
cially prepared by multistep procedure from Zn(OAc)2 and
PEG 2000 by the action of ammonium hydroxide in
deionized water (reflux, 6 h) [28]. The crude catalyst was
centrifuged and washed twice with deionized water and
absolute ethanol. Then, again deionized water was added
and the mixture was refluxed for the additional 9 h. At the
final step, catalyst was dried at 100 °C in an oven over the
night. But in the end of this solvent-free procedure, ethanol
is needed for isolation and crystallization desired
spirooxindoles [28].
On the first stage of our research, the direct transformation
of isatin 1a, malononitrile, and dimedone into 2-amino-7,7-
dimethyl-20,5-dioxo-5,6,7,8-tetrahydrospiro[chromene-4,30-
indoline]-3-carbonitrile (2a) by grinding in mortar without
any catalyst and solvent was studied (Table 1, entries 1 and
2).
Under these simple conditions, spirooxindole 2a was
obtained in 79 and 90 % yields, respectively, in 15 and
30 min reaction time. With 10 mol% of KF or NaOAc as
catalysts, 15 min reaction time is sufficient to ensure 92
and 95 % yields of 2a (Table 1, entries 3 and 4). Addition
R3
R1
N
Scheme 1
O
O
O
R
CN
CN
R
NaOAc
CN
2
2
O
+
+
grinding
N
R1
O
O
O
NH2
R3
1a-k
2a-k
a: R1 = H, R2 = H, R3= H
b: R1 = H, R2 = Cl, R3 = H
c: R1 = H, R2 = Br, R3 = H
f: R1 = H, R2 = Br, R3 = Br
g: R1 = Me, R2 = H, R3 = H
h: R1 = 4-Cl-Bn, R2 = H, R3 = H
j: R1 = Ac, R2 = H, R3 = H
k: R1 = Ts, R2 = H, R3 = H
d: R1 = H, R2 = NO2, R3 = H
e: R1 = H, R2 = Me, R3 = Me
123

Solvent-free multicomponent assembling of isatins, malononitrile, and dimedone: fast and…
Scheme 2
reaction time was increased to 20 and 30 min, respec-
Table 1 Multicomponent transformation of isatin 1a, malononitrile,
and dimedone into 2-amino-7,7-dimethyl-20,5-dioxo-5,6,7,8-tetrahy-
drospiro[chromene-4,30-indoline]-3-carbonitrile (2a)
tively, to reach more than 90 % yield. The necessity to
use prolonged reaction time for isatins 1j, 1k may be due
to the electron withdrawing substituent at N-atom of
isatin.
Entry Additive of Base
water/cm3
Quantity of
base/mol%
Time/ Product Yield/
min
%
With the above results taken into consideration and
the mechanistic data on NaOAc-catalyzed catalytic sol-
vent-free multicomponent processes [30–32], the
following mechanism for the sodium acetate catalyzed
assembling of isatins 1, malononitrile, and dimedone into
substituted spirooxindoles 2 is proposed. The initiation
step of the catalytic cycle begins with the sodium ace-
1
2
3
4
5
–
–
–
–
1
–
–
15
30
15
15
15
2a
2a
2a
2a
2a
79b
90a
92a
95a
93a
–
–
KF
10
NaOAc 10
NaOAc 10
3 mmol of isatin 1a, 3 mmol of dimedone, 3 mmol of malononitrile
grinding at 25 °C
tated induced deprotonation of
a
molecule of
a
Isolated yield
malononitrile, which leads to the malononitrile anion
formation (Scheme 2).
b
NMR data
Thefollowingprocessrepresentsatypicalmulticomponent
reaction. Knoevenagel condensation of the malononitrile
anion with isatin 1 takes place with the elimination of a
hydroxide anion and formation of Knoevenagel adduct 3 [37].
The subsequent hydroxide-promoted Michael addition of
dimedone to electron-deficient Knoevenagel adduct 3 results
in the anions A and B formation. Further cyclization of anion
B and protonation with the participation of the next molecule
of small quantity of water in this case has no noticeable
influence on the result of the reaction.
Under the optimal conditions thus found (10 mol%
NaOAc as catalysts, 15 min grinding in mortar), isatins
1a–1k, malononitrile, and dimedone were transformed
into corresponding substituted spirooxindoles 2a–2k in
90–99 % yields (Table 2). But, in the case of 2j and 2k,
123

M. N. Elinson et al.
Table 2 Multicomponent transformation of isatins 1a–1k, malononitrile, and dimedone into 2-amino-7,7-dimethyl-20,5-dioxo-5,6,7,8-tetrahy-
drospiro[chromene-4,30-indoline]-3-carbonitriles 2a–2k
Entry
Isatin
R1
R2
R3
Time/min
Product
Yield/%a
1
1a
1b
1c
1d
1e
1f
H
H
H
15
15
15
15
15
15
15
15
15
20
15
30
2a
2b
2c
2d
2e
2f
95
96
90
95
91
95
98
95
85
99
51
91
2
H
Cl
Br
NO2
Me
Br
H
H
3
H
H
4
H
H
5
H
Me
Br
H
6
H
7
1g
1h
1j
Me
4-Cl-Bn
Ac
Ac
Ts
2g
2h
2j
8
H
H
9
H
H
10
11
12
1j
H
H
2j
1k
1k
H
H
2k
2k
Ts
H
H
3 mmol of isatin 1, 3 mmol of dimedone, 3 mmol of malononitrile, 0.3 mmol NaOAc grinding at 25 °C
a
Isolated yield
General procedure
Isatin (3 mmol), 0.198 g malononitrile (3 mmol),
of malononitrile leads to the corresponding spirooxindole 2
formation with the regeneration of malononitrile anion at the
last step of the catalytic cycle (Scheme 2).
1
0.420 g dimedone (3 mmol), and 0.025 g sodium acetate
(0.3 mmol) were grinded with the pestle in mortar at
ambient temperature for 15 min. The resulting mixture was
air dried. Crude solid was then put on filter, rinsed with
water (2 9 2 cm3), and dried with water pump.
Thus, the simple NaOAc-catalyzed procedure can pro-
duce
a
fast efficient and selective solvent-free
multicomponent transformation of isatins, malononitrile,
and dimedone into substituted spirooxindoles in excellent
90–99 % yields. This new process opens an efficient and
convenient solventless multicomponent way to create
substituted spirooxindoles, the pharmacologically active
substances with known spasmolytic, diuretic, anticoagu-
lant, anticancer, and antianaphylactic activities and
promising compounds for different biomedical applica-
tions. This new solvent-free multicomponent procedure
utilizes simple equipment; it is easily carried out and is
valuable from the viewpoint of environmentally benign
diversity-oriented large-scale processes.
2-Amino-7,7-dimethyl-20,5-dioxo-5,6,7,8-tetrahy-
drospiro[chromene-4,30-indoline]-3-carbonitrile
(2a)
Yield 95 %; m.p.: 305–307 °C (Ref. [25] 305–307 °C).
2-Amino-50-chloro-7,7-dimethyl-20,5-dioxo-5,6,7,8-tetrahy-
drospiro[chromene-4,30-indoline]-3-carbonitrile
(2b)
Yield 96 %; m.p.: 293–295 °C (Ref. [23] 294–296 °C).
2-Amino-50-bromo-7,7-dimethyl-20,5-dioxo-5,6,7,8-tetrahy-
drospiro[chromene-4,30-indoline]-3-carbonitrile
(2c)
Experimental
All melting points were measured with a Gallenkamp
1
Yield 90 %; m.p.: 305–307 °C (Ref. [23] 306–308 °C).
melting-point apparatus. H and 13C NMR spectra were
2-Amino-7,7-dimethyl-50-nitro-20,5-dioxo-5,6,7,8-tetrahy-
drospiro[chromene-4,30-indoline]-3-carbonitrile
(2d)
recorded in DMSO-d6 with a Bruker Avance II 300 spec-
trometer at ambient temperature. Chemical shift values are
relative to Me4Si. IR spectra were recorded with a Bruker
ALPHA-T FT-IR spectrometer in KBr pellets. Mass
spectra (EI, 70 eV) were obtained directly with a Kratos
MS-30 spectrometer. HRMS (ESI) was measured on a
Bruker micrOTOF II instrument; external or internal cali-
bration was done with Electrospray Calibrant Solution
(Fluka). All chemicals used in this study were commer-
cially available.
Yield 95 %; m.p.: 302–304 °C (Ref. [23] 302–304 °C).
2-Amino-50,7,7,70-tetramethyl-20,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,30-indoline]-3-carbonitrile
(2e)
1
Yield 91 %; m.p.: [360 °C (Ref. [3] [360 °C); H NMR
(300 MHz, DMSO-d6): d = 1.00 (s, 3H, CH3), 1.03 (s, 1H,
123

Solvent-free multicomponent assembling of isatins, malononitrile, and dimedone: fast and…
CH3), 2.08–2.16 (m, 2H, CH2), 2.17 (s, 3H, CH3), 2.18 (s,
3H, CH3), 2.55 (s, 2H, CH2), 6.58 (s, 1H, Ar), 6.76 (s, 1H,
Ar), 7.16 (s, 2H, NH2), 10.31 (s, 1H, NH) ppm.
2H, CH2), 7.16 (s, 2H, NH2), 7.34–7.45 (m, 4H, Ar),
7.70–7.92 (m, 4H, Ar) ppm; 13C NMR (75 MHz, DMSO-
d6): d = 21.1, 27.0 (2C), 27.4 (2C), 32.0, 49.3, 56.5, 110.3,
112.4, 112.5, 116.5, 123.8, 125.1, 127.5, 127.5, 128.9,
129.7, 132.4, 138.2, 145.4, 167.7, 174.7, 194.6, 204.7 ppm;
IR (KBr): v = 3320, 2197, 1753, 1686, 1667,1353, 1225,
1190, 1180, 572 cm-1; HRMS (ESI): m/z = 512.1247
[M ? Na], calcd for C26H23N3O5SNa 512.1251; MS (EI,
70 eV): m/z (%) = 334 (2), 291 (1), 234 (1), 155 (48), 91
(100), 84 (21), 83 (48), 66 (19), 65 (51), 56 (29).
2-Amino-50,70-dibromo-7,7-dimethyl-20,5-dioxo-5,6,7,8-
tetrahydrospiro[chromene-4,30-indoline]-3-carbonitrile
(2f, C19H15Br2N3O3)
Yield 95 %; m.p.: 301–303 °C; 1H NMR (300 MHz,
DMSO-d6): d = 1.02 (s, 6H, 2CH3), 2.17 (s, 2H, CH2),
2.50–2.63 (m, 2H, CH2), 7.30 (s, 1H, Ar), 7.42 (s, 2H,
NH2), 7.60 (s, 1H, Ar), 10.91 (s, 1H, NH) ppm; 13C NMR
(75 MHz, DMSO-d6): d = 27.1, 27.6, 32.0, 32.5, 41.5,
45.8, 48.2, 49.8, 56.3, 102.4, 113.8, 117.1, 125.4, 132.9,
137.8, 141.1, 158.9, 164.9, 195.2 ppm; IR (KBr):
v = 3285, 2194, 1736, 1659, 1598, 1461, 1351, 1148,
Acknowledgments The authors gratefully acknowledge the finan-
cial support of the Russian Foundation for Basic Research (Project
No. 13-03-00096a).
1054, 557 cm-1
;
HRMS (ESI): m/z = 515.9351
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