DABCO: An efficient catalyst for pseudo multi-component reaction of cyclic Ketone, Aldehyde and Malononitrile

Article abstract of DOI:10.2174/1570178614666170426163442

Designing efficient methods for the synthesis of complex molecules with predefined functionalities is a challenging task in modern organic chemistry. In this context, multicomponent reactions (MCRs), by virtue of their applications, constitute a central a

Full text of DOI:10.2174/1570178614666170426163442

403
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Letters in Organic Chemistry, 2017, 14, 403-408
LETTER ARTICLE
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DABCO: An Efficient Catalyst for Pseudo Multi-component Reaction of
Cyclic Ketone, Aldehyde and Malononitrile
BENTHAM
S
CIENCE
Sarika M. Chinchkar, Jayavant D. Patil, Suyog N. Korade, Gavisiddappa S. Gokavi,
Rajendra V. Shejawal and Dattaprasad M. Pore*
Department of Chemistry, Shivaji University, Kolhapur 416 004, India
Abstract: Background: Designing efficient methods for the synthesis of complex molecules with pre-
defined functionalities is a challenging task in modern organic chemistry. In this context, multi-
component reactions (MCRs), by virtue of their applications, constitute a central academic and indus-
trial investigation domain. Recently, MCRs involving vinylogous Michael addition have attracted increas-
ing interest as one of the most useful key reactions for the synthesis of poly substituted benzene deriva-
tives such as spiro[cyclohexanes-1,3’-indoline]-2’,3-diones, spiroacenaphthylene, benzo[α]cyclooctenes,
etc. Therefore, development of an efficient method for a MCR which encompass vinylogous Michael
addition as vital reaction is of current interest.
Methods: We explored catalytic efficiency of DABCO in the multi-component reaction of cyclic ke-
tone, aldehyde and two moles of malononitrile for the synthesis of functionalized condensed bicyclic
A R T I C L E H I S T O R Y
compounds viz tetrahydroindenes, tetrahydronaphthalenes, hexahydrobenzo[7] annulenes and hexahydro-
benzo[8]annulenes.
Received: February 02, 2016
Revised: March 09, 2017
Accepted: April 05, 2017
Results: The reaction conditions were optimized by screening of catalyst and solvent. Employing op-
timized reaction conditions library of bicyclic compounds viz. tetrahydroindenes, tetrahydronaphthale-
DOI:
10.2174/1570178614666170426163442
nes, hexahydrobenzo[7]annulenes and hexahydrobenzo[8]annulenes were synthesized in short time du-
ration. The synthesized products were characterized by 1H, 13C, IR and MS. Spectral data obtained was
in good agreement with the structure of products.
Conclusion: We disclosed DABCO catalyzed multi-component reaction of aldehyde, cyclic ketone and
malononitrile furnished corresponding tetrahydronaphthalenes, tetrahydroindalenes, hexahydrobenzo[7]
annulenes and hexahydrobenzo[8]annulenes, with a high level of complexity. Notably, this methodol-
ogy provides a facile access to various multi-functional compounds. The operational simplicity and
good yields, combined with step and atom-economic aspects, clean reactions yielded pure products,
hence no requirement of tedious chromatographic purification makes this synthetic strategy highly at-
tractive and promising approach from sustainable and practical chemistry.
Keywords: Aldehyde, DABCO, hexahydrobenzo[7]annulenes, hexahydrobenzo[8]annulenes, multi-component, tetrahydroin-
denes.
1. INTRODUCTION
highly functionalized skeleton offering interesting opportuni-
ties for molecular diversity [13-15]. Conversely, existence of
a variety of intermediates in case of such MCRs makes the
prediction of product(s) difficult under different experimen-
tal conditions from same precursors [16-18].
Designing of efficient methods for the synthesis of com-
plex molecules with predefined functionalities is a challeng-
ing task in modern organic chemistry [1-5]. Especially, when
the method involves green principles and simple molecules
as starting materials. In this context, multi-component reac-
tions (MCRs), by virtue of their applications, constitute a
central academic and industrial investigation domain [6-12].
The last decade has witnessed tremendous development in
Michael addition based MCRs as they allow a rapid access to
Recently, MCRs involving vinylogous Michael addition
has attracted increasing interest as one of the most useful key
reactions for the synthesis of poly substituted benzene de-
rivatives [19] like spiro[cyclohexanes-1,3’-indoline]-2’,3-
diones [20], spiroacenaphthylene [21], benzo[α]cyclooctenes
[22], etc. Therefore, the development of an efficient method
for MCRs which encompasses vinylogous Michael addition
as vital reaction is of current interest.
*Address correspondence to this author at the Department of Chemistry,
Shivaji University, Kolhapur 416 004, India; Tel: 8087268810;
E-mail: p_dattaprasad@rediffmail.com
1875-6255/17 $58.00+.00
© 2017 Bentham Science Publishers

404 Letters in Organic Chemistry, 2017, Vol. 14, No. 6
Chinchkar et al.
2. RESULTS AND DISCUSSION
hexahydrobenzo[8]annulenes through Knoevenagel-vinylogous
Michael addition. Presumably, such change in the nature of
final product of the reaction is due to the difference in ba-
sicity of DABCO and LiOEt. The influence of a strong base,
LiOEt, resulted into the formation of benzo[α]cyclooctenes
while the presence of a mild base, DABCO, furnished func-
tionalized hexahydrobenzo[8]annulenes (Scheme 1).
In continuation of our research program dedicated to de-
signing of multi-component transformations proceed through
Michael addition [27-29], in the present manuscript, we de-
scribed the influence of DABCO on the product of the MCR
between aldehyde, two moles of malononitrile and a cyclic
ketone viz. cyclopentanone, cyclohexanone, cycloheptanone
as well as cyclooctanone. The method furnished functional-
ized condensed bicyclic compounds viz. tetrahydroindenes,
tetrahydronaphthalenes, hexahydrobenzo[7]annulenes and
hexahydrobenzo[8]annulenes, respectively through viny-
logous Michael addition (Scheme 2).
Added advantage of the present method is that the prod-
uct can be isolated by simple filtration and purified by wash-
ing with EtOH. Therefore, the developed method was simple
and involving clean work-up procedure. The product was
1
1
identified by IR, H, 13C NMR and MS. H NMR spectrum
indicates a remarkable singlet at δ = 4.38 of vinylic proton.
In 13C NMR signals due to carbonyl of aldehyde and ketone
get disappeared and appearance of signals of nitrile carbons
at δ 117.35 and 124.56 confirmed the structure of product 4i
(Table 2). MS analysis also supported the expected structure
by demarking molecular ion peak at 328 (m/z).
A literature survey of multi-component reaction of alde-
hyde, two moles of malononitrile and a cyclic ketone reveals
that existence of product is dependent on the nature of cata-
lyst used. It is noteworthy that the influence of strong base,
LiOEt on present multi-component reaction leads benzo[α]
cyclooctenes (4’, Scheme 1) which proceed through domino
Knoevenagel condensation-Vinylogous Michael addition-
Thorpe-Ziegler cyclization-tautomerization-elimination [22].
On the other hand mild catalyst furnished corresponding
functionalized condensed bicyclic compounds [23-26] (4,
Scheme 1). However, scanty methods are available for pre-
sent multi-component reaction [22-26]. Hence, we are inter-
ested in investigating the effect of a mild base, DABCO on
the said transformation.
The reaction was carried out in different solvents to in-
vestigate the most suitable solvent for this transformation.
Ethanol was found to be superior to other solvents such as
CH3CN, CH2Cl2, THF, CH3OH and H2O in terms of ob-
tained yield. (Entries 1-6, Table 1) To increase yield, in light
with our earlier experience with mixed solvent system [28],
we further investigated the effect of ethanol: water system.
(Entries 7-15, Table 1). Delightfully, after some attempts, we
were pleased to notice that when mixed solvent (7:3 v/v;
EtOH:H2O) was used, the reaction of benzaldehyde, cyclooc-
tanone and two moles of malononitrile provided desired
hexahydrobenzo[8]annulenes in 90 % yield in the presence
of 20 mol % DABCO at reflux condition. (Entry 9, Table 1)
As the reaction proceeds via charged reactive intermediates,
we hypothesized that the corresponding transition states
would be stabilized by water, which has a relatively high
static permittivity (εT = 78.4) [30], thus small quantity of
water played a crucial role.
NC
LiOEt,
H2N
O
O
H2O, Reflux
CN
4'
S. Maharani etal work
H
DABCO
+
3
1
Then the effect of amount of DABCO was also studied.
(Entries 16-19, Table 1) Interestingly, 20 mol % of DABCO
was found to be effective. Lower loading of DABCO led
to shrank yields (Entries 16-18, Table 1). Exceeding 20 %
of DABCO did not affect the yield of product (Entry 19,
Table 1).
EtOH: H2O
70: 30
NC
CN
2
Reflux
NC
NC
H2N
CN
4
After optimization of the reaction conditions, to delineate
this approach, particularly regarding construction of library,
this methodology was evaluated by using various aldehydes
(aromatic and heteroaromatic) as well as several cyclic ke-
tones such as cyclopentanone, cyclohexanone, cyclohepta-
none and cyclooctanone (Table 2).
Present work
Scheme (1). Synthesis of functionalized hexahydrobenzo [8] an-
nulenes.
For optimization of the conditions, the reaction between
benzaldehyde, cyclooctanone and two moles of malononitrile
was selected as a model reaction. The starting materials were
mixed together and the reaction was performed using cata-
lytic quantity of DABCO (20 mol %) in ethanol medium at
ambient temperature. The reaction yielded a mixture of uni-
dentified products at ambient temperature. However, under
reflux conditions, pleasingly we obtained functionalized con-
densed bicyclic compounds instead of benzo[α]cyclooctenes
(Scheme 1). It is noteworthy that, DABCO catalyzed multi-
component reaction of cyclohexanone, aldehyde and two
moles of malononitrile also generated a family of functionalized
Interestingly, when cyclic ketones viz. cyclopentanone,
cyclohexanone, cycloheptanone and cyclooctanone were
employed, the products formed were classified as tetrahy-
droindenes, tetrahydronaphthalenes, hexahydro-2H-benzo[7]
annulenes and hexahydrobenzo[8]annulenes, respectively.
Under optimized reaction conditions all reactions proceed
smoothly resulted corresponding products in excellent yields
(Scheme 2).
Furthermore, the reaction in the presence of aromatic
aldehydes bearing simple, electron donating as well as elec-
tron withdrawing groups also occurred smoothly and corre-

DABCO An Efficient Catalyst for Pseudo Multi-component Reaction
Letters in Organic Chemistry, 2017, Vol. 14, No. 6 405
sponding polyfunctionalized bicyclic compounds were in
good yields.
The plausible mechanism is depicted in Scheme 3. Ini-
tially, DABCO influenced Knoevenagel condensation of
aldehyde and malononitrile as well as cyclic ketone and
malononitrile furnished 5 and 6, respectively. Subsequent
vinylogous Michael addition of 5 on 6 yielded the desired
product (TM) 4 through transition state 7.
Table 1. Optimization of conditions for multi-component
reaction of benzaldehyde, cyclooctanone and two
moles of malononitrilea.
Table 2. Synthesis of combinatorial library of polyfunctional-
ized bicyclic compounds by multi-component ap-
proacha
DABCO
(mol %)
Yieldb
(%)
Entry
Solvent
1
2
CH3CN
20
20
20
20
20
20
20
20
20
20
20
20
20
20
20
05
10
15
30
--
Aldehyde
1
Cyclic Ketone
3
Time
(h)
Yieldb
(%)
DCM
--
Sr. No
3
THF
--
a
b
c
d
e
f
R= H
R= 4-Cl
n=1
n=1
n=1
n=1
n=1
n=0
n=2
n=2
n=3
n=3
1
1
1
1
1
1
1
1
1
1
88
90
92
90
90
94
92
94
90
90
4
CH3OH
46
75
38
82
78
90
75
56
54
47
43
40
55
73
80
90
5
EtOH
6
H2O
R= 3-MeO, 4-OH
R= 3,4,5-MeO
R= 3-CHO
R=4-MeO
R=4-MeO
R=4-Cl
7
EtOH:H2O [9:1]
EtOH:H2O [8:2]
EtOH:H2O [7:3]
EtOH:H2O [6:4]
EtOH:H2O [5:5]
EtOH:H2O [4:6]
EtOH:H2O [3:7]
EtOH:H2O [2:8]
EtOH:H2O [1:9]
EtOH:H2O [7:3]
EtOH:H2O [7:3]
EtOH:H2O [7:3]
EtOH:H2O [7:3]
8
9
10
11
12
13
14
15
16
17
18
19
g
h
i
Thiophene
R= H
j
aReaction conditions: Aldehyde (1 mmol), cyclic ketone (1 mmol), malononitrile (2
b
mmol), catalyst (20 mol %), ethanol: water :: 70:30 (5 mL), reflux temperature , Iso-
lated yield.
3. EXPERIMENTAL
3.1. General
aReaction condition: Benzaldehyde (1 mmol), cyclooctanone (1 mmol), malononitrile
(2 mmol), catalyst, solvent (5 mL), Time: 1h; bIsolated yield.
IR spectra were recorded on an Agilent cary 630 and
Perkin-Elmer FT-IR 783 spectrophotometer. NMR spectra
were recorded on a BrukerAC-300 MHz spectrometer in
DMSO-d6 using tetramethylsilane as internal standard. Mass
spectra were recorded on a Shimadzu QP2010 GCMS. Ele-
mental analyses were performed on a EURO EA3000 vector
model.
4'
R
5'
3'
2'
O
6'
O
DABCO
1'
H
4
(20 mol%)
5
R
NC
3
9
8
n
n
+
NC
6
EtOH:H2O
2
1
3.2. General Procedure
3
H2N
7
1
70:30
NC
CN
Δ
CN
4
3.2.1. Synthesis of Tetrahydronaphthalenes
2
A mixture of aldehyde (1 mmol, 1a: 0.102 mL, 2b: 0.140
g, 3c: 0.152 g, 4d: 0.196 g, 5e: 0.134 g), cyclohexanone (1
mmol, 0.103 mL), malononitrile (2 mmol, 0.111 mL) and
DABCO (20 mol %, 0.022 g) in EtOH: H2O (7:3; 5 mL) was
stirred at reflux temperature and stirring was continued till
completion of the reaction as indicated by TLC.
Scheme (2). Synthesis of combinatorial library of polyfunctional-
ised bicyclic compounds.
The broad tolerance of functional groups on the alde-
hydes inspired us to extend the study to dialdehyde such as
isophathalaldehyde. We were pleased to find that multi-
component reaction of isophathaladehyde, cyclohexanone
and two moles of malononitrile under the optimal reaction
conditions furnished desired bis-polyfunctionalized tetrahy-
dronaphthalene in high yield (Entry e, Table 2).
3.2.2. Synthesis of Tetrahydroindalenes
A mixture of aldehyde (1 mmol, 6f: 0.121 mL), cy-
clopentanone (1 mmol, 0.088 mL), malononitrile (2 mmol,
0.111 mL) and DABCO (20 mol %, 0.022 g) in EtOH: H2O

406 Letters in Organic Chemistry, 2017, Vol. 14, No. 6
Chinchkar et al.
NH2
NC
NC
CN
R
CN
CN
NC
NC
H
N
O
H
_
N
4
6
6'
3
CN
H
CN
CN
N
2
_
N
CN
2'
N
N
H
H
+
-
N
CN
NC
NC
NC
NC
O
CN
CN
R
H
H
R
R
N
H
1
H
N
6'
5
7
Scheme (3). A plausible mechanism for DABCO catalyzed pseudo multi-component synthesis of polyfunctionalized bicyclic compounds
(7:3; 5 mL) was stirred at reflux temperature and stirring was
continued till completion of the reaction as indicated by
TLC.
112.39 (CN), 116.01(CN), 122.60(CN), 126.85(C1), 128.29
(C’4), 128.94(C’3,C’5), 129.28(C’2,C’6), 132.18(C9), 134.17
(C’1), 142.71(C2) ppm; MS (EI): 300, 272, 209, 91 m/z;
CHN analysis calcd for C19H16N4: 75.98 (C), 5.37 (H), 18.65
(N); Found 74.89 (C), 5.15 (H), 18.57 (N).
3.2.3. Synthesis of Hexahydrobenzo[7]annulene
Entry b, Table 2: Pale yellow solid; Mp: 235-238oC;
FT-IR-ATR (νmax, cm -1): 3418, 3340, 3251, 3227, 2946, 2932,
2866, 2832, 2212, 1642, 1601, 1493, 1446, 1429, 1391,
1350, 1339, 1278, 1269, 1212, 1163, 1094, 1015, 837, 805,
A mixture of aldehyde (1 mmol, 7g: 0.121 mL, 8h: 0.140
g), cycloheptanone (1 mmol, 0.118 mL), malononitrile (2
mmol, 0.111 mL) and DABCO (20 mol %, 0.022 g) in
EtOH: H2O (7:3; 5 mL) was stirred at reflux temperature and
stirring was continued till completion of the reaction as indi-
cated by TLC.
1
781, 752, 704, 671; H-NMR (300 MHz, CDCl3): δ 0.90-
1.03(m, 1H, C5H), 1.60-1.70 (m, 2H, C5H,C6H), 1.80 (s,
1H, C6H), 2.28-2.35 (m, 2H, C7H), 2.81-2.89 (m, 1H,
C10H), 3.07-3.11 (d, 1H, J= 12Hz, C4H), 4.90 (s, 2H, -
NH2), 6.07-6.08 (t, 1H, J= 3 Hz, C8H), 7.43-7.51 (m, 4H,
ArH) ppm, 13C-NMR (75 MHz, CDCl3): 21.72(C5), 25.38
(C6), 27.09(C7), 34.72(C10), 43.44(C4), 51.67(C3), 112.00
(CN), 114.93(CN), 125.91(C1), 127.13(C’2, C’6), 129.82
(C’3, C’5), 132.26(C9), 135.92(C’1, C’4), 140.07(C2) ppm;
MS (EI): 334, 209, 127, 125 m/z; CHN analysis calcd for
C19H15N4Cl: 68.16 (C), 4.25 (H), 16.73 (N); Found 68.06
(C), 4.19 (H), 16.51 (N).
Entry c, Table 2: White solid; Mp: 206-210oC; FT-IR-
ATR (νmax, cm -1): 3463, 3405, 3340, 3241, 2206, 1655, 1599,
1516, 1462, 1433, 1380, 1262, 1214, 1169, 1129, 1103, 1046,
1009, 921, 882, 854, 820, 765, 739, 683, 634; 1H-NMR (300
MHz, DMSO-d6): δ 0.80-0.92 (q, 1H, J= 12 Hz, C5H), 1.47-
1.67 (m, 3H, C5H, C6H), 2.06-2.22 (m, 2H, C7H), 2.69-2.78
(t, 1H, J= 12Hz, C4H), 3.74-3.78 (d, 3H, J= 12 Hz, C’3-
OMe), 5.71 (s, 1H, C8H), 6.75-7.10 (m,3H, C’2, C’5, C’6),
7.33 (s, 2H, -NH2), 9.24 (s, 1H, C’4-OH) ppm; 13C-NMR (75
MHz, DMSO-d6): δ 21.51(C5), 25.35(C6), 27.45(C7), 34.70
(C10), 43.89(C4), 51.32(C3), 56.24(C-OMe), 81.98(C8),
111.27 (CN), 113.05(CN), 113.44(CN), 116.25(C1), 119.87
(C’6), 120.64(C’2), 125.62(C’5), 129.52(C’3), 144.11(C’4),
147.73(C’1), 148.19(C2) ppm; MS (EI): 346, 222, 137, 103,
77 m/z; CHN analysis calcd for C20H18N4O2: 69.35 (C), 5.24
(H), 16.17 (N), 9.24 (O); Found 68.90 (C), 5.12 (H), 16.05
(N), 9.93 (O).
3.2.4. Synthesis of and Hexahydrobenzo[8]annulenes
A mixture of aldehyde (1 mmol, 9i: 0.093 mL, 10j:
0.102 mL), cyclooctanone (1 mmol, 0.132 mL), malononi-
trile (2 mmol, 0.111 mL) and DABCO (20 mol %, 0.022 g)
in EtOH: H2O (7:3; 5 mL) was stirred at reflux temperature
and stirring was continued till completion of the reaction as
indicated by TLC.
After completion of reaction, the precipitated solid was
filtered, washed with ethanol (3 mL) and dried over vacuum
to afford corresponding product. All the products were char-
1
acterized by spectral analysis viz. IR, H and 13C NMR as
well as MS.
3.3. Spectral Data of Synthesized Compounds
Entry a, Table 2: Whitish yellow solid; Mp: 238-240oC;
FT-IR-ATR (νmax, cm -1): 3411, 3333, 3225, 2929, 2206, 1641,
1594, 1492, 1448, 1387, 1340, 1270, 1206, 1155, 1099, 1032,
946, 915, 871, 834, 808, 779, 704, 638; 1H-NMR (300 MHz,
DMSO-d6): δ 0.81-0.89 (q, 1H, J= 12, 3 Hz, C5H), 1.50 (s,
1H, C5H), 1.53-1.54 (d, 1H, J= 3 Hz, C6H), 1.65-1.68 (s,
1H, C6H), 2.07-2.17 (m, 2H, C7H), 2.71-2.74 (d, 1H, J= 12
Hz, C10H), 3.02-3.06 (d, 1H, J= 12 Hz, C4H), 5.77 (s, 1H,
C8H), 6.55 (s, 2H, C2-NH2), 7.24-7.47 (m, 5H, ArH)
ppm;13C-NMR (75 MHz, DMSO-d6): 21.50(C5), 25.31(C6),
27.34 (C7), 34.70(C10), 43.05(C4), 52.42(C3), 84.32(C8),

DABCO An Efficient Catalyst for Pseudo Multi-component Reaction
Letters in Organic Chemistry, 2017, Vol. 14, No. 6 407
Entry d, Table 2: Pale yellow solid; Mp: 210-212oC;
FT-IR-ATR (νmax, cm -1): 3419, 3334, 3225, 2936, 2866,
2214, 1647, 1599, 1446, 1392, 1341, 1270, 1207, 1159, 1100,
7.01 (d, 2H, J=9 Hz, ArH), 7.37-7.42 (dd, 1H, J= 3,3 Hz,
ArH) ppm; 13C-NMR (75 MHz, CDCl3): 24.96(C5), 28.30
(C6), 30.41(C7), 31.96(C8), 39.28(C11), 52.95(C4), 55.30
(C-OMe), 87.74(C9), 111.10(C3), 111.79(CN), 114.84(CN),
115.87 (CN), 127.23(C’3, C’5), 130.04(C’2, C’6), 130.17
(C’1, C’4), 133.04(C1), 141.46(C10), 160.62(C2) ppm; MS
(EI): 344, 315, 287, 185, 147, 121 m/z; CHN analysis calcd
for C21H20N4O: 73.23 (C), 5.85 (H), 16.27 (N), 4.65 (O);
Found 72.89 (C), 5.81 (H), 15.98 (N), 5.32 (O).
1
1041, 958, 918, 852, 803, 733, 606; H-NMR (300 MHz,
DMSO-d6): δ 0.85-0.97 (q, 1H, J= 9, 12 Hz, C5H), 1.48-1.72
(m, 3H, C5H, C6H), 2.08-2.23 (m, 2H, C7H), 2.77-2.84 (t,
1H, J= 9Hz, C10H), 3.41-3.45 (d, 1H, J= 12Hz, C4H), 3.76
(s, 3H, -OMe), 3.77 (s, 3H,-OMe ), 3.80 (s, 3H, -OMe), 5.73
(s, 1H, C8H), 6.83-6.87 (d,2H, J= 12Hz, C’2, C’6), 7.31 (s,
2H, -NH2) ppm; 13C-NMR (75 MHz, DMSO-d6): δ 21.41
(C5), 25.33(C6), 27.34(C7), 34.52(C10), 43.41(C-OMe),
51.63 (C-OMe), 56.57(C4), 60.54(C3), 82.11(C8), 104.75
(CN), 110.76 (CN), 112.86(CN), 113.32(C1), 116.58 (C’6),
120.92 (C’2), 129.31 (C’5), 130.59(C’4), 138.42(C’2),
143.99 (C9), 152.96 (C’1), 153.55(C2) ppm; MS (EI): 262,
247, 219, 188, 161 m/z; CHN analysis calcd for C22H22N4O3:
67.68 (C), 5.68 (H), 14.35 (N), 12.29 (O); Found 67.56 (C),
5.68 (H), 14.25 (N), 12.51 (O).
Entry h, Table 2: White solid; Mp: 188-190oC; FT-IR-
ATR (νmax, cm -1): 3632, 3446, 3394, 3342, 2205, 1637, 1620,
1592, 1575, 1523, 1490, 1473, 1440, 1412, 1402, 1017, 958,
1
918, 852, 803, 733, 606; H-NMR (300 MHz, CDCl3): δ
1.32-1.55 (m, 4H, C5H, C6H), 1.75-1.85 (m, 4H, C7H,
C8H), 2.27-2.43 (m, 2H, C4H, C11H), 4.98 (s, 2H, -NH2),
6.24-6.27 (t, 1H,J= 6 Hz, C9H), 7.44-7.50 (m, 4H, ArH)
ppm; 13C-NMR (75 MHz, CDCl3): 24.86(C5), 28.26(C6), 30.31
(C7), 32.02(C8), 39.16(C11), 42.38(C4), 52.94(C3), 87.74
(C9), 110.72(CN), 111.39(CN), 115.61(CN), 129.78(C’3,
C’5), 130.21(C’2, C’6), 130.51(C’4), 132.38(C’1), 133.85
(C1), 135.91(C10), 141.02(C2) ppm; MS (EI): 348, 294,
223, 160, 127, 125 m/z; CHN analysis calcd for C20H17N4Cl:
68.86 (C), 4.91 (H), 16.06 (N); Found 68.56 (C), 4.91 (H),
15.51 (N).
Entry e, Table 2: Pale yellow solid; Mp: 216-220oC; FT-
IR-ATR (νmax, cm -1): 3417, 3339, 3259, 2972, 2940, 2862,
2833, 2249, 2215, 1651, 1600, 1488, 1449, 1394, 1351, 1339,
1269, 1210, 1175, 1154, 1041, 959, 919, 883, 851, 804, 73,
1
697; H-NMR (300 MHz, DMSO-d6): δ 0.92-0.96 (m, 2H,
C5H), 1.03-1.08 (t, 1H, J= 6Hz, C5H), 1.37-1.68 (m, 7H,
C5H, C6H, C7H), 2.16 (m, 5H, C7H, C10H), 2.50-2.67 (m,
3H, C4, C10), 5.73 (s, 1H, C8H), 7.32 (s, 4H, -NH2), 7.51-
7.77 (m, 4H, ArH) ppm; 13C-NMR (75 MHz, DMSO-d6): δ
18.95 (C5), 21.47(C6), 25.25(C7), 34.72(C10), 43.22(C4),
50.48 (C3), 82.19(C8), 112.66(CN), 113.41(CN), 116.56 (CN),
120.91(C1), 125.25(C’3), 127.75(C’4), 128.86(C’2), 129.21
(C’6), 129.59(C’5), 133.32(C9), 135.77(C’1), 143.72(C2)
ppm; MS (EI): 522, 495, 468, 378, 376, 209, 167, 140, 104,
91, 81, 55 m/z; CHN analysis calcd for C32H26N8: 73.54 (C),
5.01 (H), 21.44 (N); Found 68.03 (C), 5.39 (H), 18.87 (N).
Entry j, Table 2: Pale yellow solid; Mp: 225-228oC; FT-
IR-ATR (νmax, cm -1): 3422, 3308, 3200, 2932, 2911, 2850,
2208, 1644, 1580, 1491, 1471, 1450, 1387, 1357, 1306, 1280,
1206, 1181, 1159, 1039, 1034, 1004, 924, 837, 814, 758, 715,
701, 678; 1H-NMR (300 MHz, DMSO-d6): δ 1.33 (s, 1H, C5H),
1.50 (s, 4H, C5H, C6H, C7H), 1.64 (s, 3H, C7H, C8H), 1.81-
1.85 (m, 1H, C8H), 2.22-2.30 (m, 1H, C9H), 2.37-2.42 (m,
1H, C9H), 3.72 (s, 2H, -NH2), 4.38 (s, 1H, C10H), 7.35 (s,
3H, ArH), 7.39 (s, 2H, ArH) ppm; 13C-NMR (75 MHz,
DMSO-d6): 25.34(C5), 26.73(C6), 27.99(C7), 29.11(C8), 29.62
(C9), 31.21(C12), 42.26(C4), 51.26(C3), 79.69(C10), 112.01
(CN), 114.83(CN), 117.35(CN), 124.56(C’3, C’5), 126.85
(C’2, C’6), 128.98(C’4), 129.18(C’1), 129.63(C1), 134.43
(C10), 144.40(C2) ppm; MS (EI): 328, 300, 271, 246, 212,
144, 115, 91 m/z; CHN analysis calcd for C21H20N4: 76.80 (C),
6.14 (H), 17.06 (N); Found 76.39 (C), 6.15 (H), 16.60 (N).
Entry f, Table 2: Yellow solid; Mp: 202-205oC; FT-IR-
ATR (νmax, cm -1): 3409, 3331, 3245, 3045, 3010, 2959, 2935,
2910, 2857, 2842, 2215, 1651, 1613, 1586, 1514, 1474, 1451,
1442, 1394, 1307, 1280, 1256, 1179, 1152, 1119, 1028, 981,
840, 821, 802, 779, 764, 751, 700, 658; 1H-NMR (300 MHz,
DMSO-d6): δ 1.13-1.26 (m, 1H,C5H), 1.87-1.93 (q, 1H, J=
6, 6 Hz, C5H), 2.25-2.38 (m, 2H, C6H), 3.24 (s, 2H, C4H,
C9H), 3.78 (s, 3H, C’4-OMe), 5.51 (s, 1H,C7H), 6.91-6.93
(d, 2H, J= 6 Hz, ArH), 7.24 (s, 2H,-NH2), 7.36-7.39 (d, 2H,
J= 9 Hz, ArH) ppm; 13C-NMR (75 MHz, DMSO-d6): 29.73
(C5), 31.38(C6), 43.24(C9), 44.29(C4), 51.94(C3), 55.38 (C-
OMe), 112.33(C7), 112.74(CN), 114.26(CN), 116.05 (CN),
116.55 (C’2, C’6), 120.41(C’3, C’5), 126.25(C’4), 130.87
(C1), 135.17(C8), 146.00(C’1), 160.21(C2)ppm; MS (EI):
316, 289, 121, 91 m/z; CHN analysis calcd for C19H16N4O:
72.14 (C), 5.10 (H), 17.71 (N), 5.06 (O); Found 71.44 (C),
5.05 (H), 16.71 (N), 6.98 (O).
Entry g, Table 2: White solid; Mp: 208-210oC; FT-IR-
ATR (νmax, cm -1): 3442, 3353, 3260, 3222, 3012, 2914, 2843,
2200, 1638, 1611, 1592, 1514, 1443, 1399, 1311, 1285, 1249,
1185, 1121, 1030, 965, 923, 839, 808, 786, 750, 717, 695,
673; 1H-NMR (300 MHz, CDCl3): δ 1.28-1.63 (m, 4H, C5H,
C6H), 1.73-1.89 (m, 3H,C7H), 2.28-2.40 (m, 2H, C8H),
3.09-3.10 (d, 1H, J= 3Hz, C4H, C11H), 3.86 (s, 3H, C’-OMe),
4.94 (s, 1H, -NH2), 6.21-6.25 (d, 1H, J= 6 Hz, C9H), 6.98-
CONCLUSION
In conclusion, we disclosed DABCO catalyzed multi-
component reaction of aldehyde, cyclic ketone and malono-
nitrile furnished corresponding tetrahydronaphthalenes, tet-
rahydroindalenes, hexahydrobenzo[7]annulenes and hexahy-
drobenzo[8]annulenes, with a high level of complexity. No-
tably, this methodology provides facile access to various
multi-functional compounds. The operational simplicity and
good yields, combined with step and atom-economic aspects,
clean reactions yielded pure products, hence no requirement
of tedious chromatographic purification makes this synthetic
strategy highly attractive and promising approach from view-
point of sustainable and practical chemistry.
CONSENT FOR PUBLICATION
Not applicable.

408 Letters in Organic Chemistry, 2017, Vol. 14, No. 6
Chinchkar et al.
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CONFLICT OF INTEREST
[15]
The authors confirm that this article content has no con-
flict of interest.
ACKNOWLEDGEMENTS
[16]
[17]
Author DMP thank UGC, New Delhi for financial assis-
tance [F. No.42-394/2013 (SR)].
SUPPLEMENTARY MATERIAL
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Babu, T.H.; Joseph, A.A.; Muralidharan, D.; Perumal, P.T. A novel
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