Substituent effects in the formation of a few acenaphthenone-2-ylidene ketones and their molecular docking studies and in silico ADME profile

Article abstract of DOI:10.1016/j.molstruc.2020.129209

We observed intriguing substituent effects in the reaction between 4-substituted acetophenones and acenaphthenequinone in the presence of KOH in methanol. In all cases, expected Claisen-Schimdt condensation was the first step. However, depending on the nature of 4-substituent on acetophenone, the initially formed condensation product remain unchanged or underwent Domino sequence of reactions to give three different 2:2 adducts arising through three distinct pathways. The interactions of acenaphthenone-2-ylidene ketones with the target proteins were performed by molecular docking studies. The prediction of in silico ADME belongings of the synthesized compounds revealed substantial drug-likeness characters based on Lipinski's rules.

Full text of DOI:10.1016/j.molstruc.2020.129209

Journal of Molecular Structure 1224 (2021) 129209
Contents lists available at ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstr
Substituent effects in the formation of a few
acenaphthenone-2-ylidene ketones and their molecular docking
studies and in silico ADME profile
Daly Kuriakose#, Roshini K. Thumpakara#, Jesna A, Jomon P. Jacob∗
Department of Applied Chemistry, Cochin University of Science and Technology, Kochi-682 022, Kerala, India
a r t i c l e i n f o
a b s t r a c t
Article history:
We observed intriguing substituent effects in the reaction between 4-substituted acetophenones and ace-
naphthenequinone in the presence of KOH in methanol. In all cases, expected Claisen-Schimdt condensa-
tion was the first step. However, depending on the nature of 4-substituent on acetophenone, the initially
formed condensation product remain unchanged or underwent Domino sequence of reactions to give
three different 2:2 adducts arising through three distinct pathways. The interactions of acenaphthenone-
2-ylidene ketones with the target proteins were performed by molecular docking studies. The prediction
of in silico ADME belongings of the synthesized compounds revealed substantial drug-likeness characters
based on Lipinski’s rules.
Received 24 July 2020
Revised 3 September 2020
Accepted 4 September 2020
Available online 4 September 2020
Keywords:
Claisen-Schimdt reaction
Aldol condensation
acenaphthenequinone
Acetophenone
© 2020 Elsevier B.V. All rights reserved.
Acenaphthenone-2-ylidene ketones
Molecular docking
1. Introduction
domino reaction sequence. These 2:2 domino products (4a, 5a, 6a)
were formed from a common Claisen-Schmidt condensed product
Claisen-Schimdt reaction, also called crossed-aldol condensa-
tion, is the condensation between aldehydes/ketones and carbonyl
compounds leading to the formation of β-hydroxycarbonyl com-
pounds which undergo subsequent dehydration to form α,β- un-
saturated carbonyl compounds. This reaction is generally catalysed
by acids or bases under room temperature or conventional heat-
ing [1,2] or microwave irradiation [3]. To avoid by-products and in-
crease the yield of the products several protocols are developed us-
ing different catalysts [4–8]. β-Hydroxycarbonyl compounds have
played a major role in synthetic organic chemistry [9–11] and α,β-
unsaturated carbonyl compounds are widely used in pharma in-
dustries [12–15].
3a [17] and the detailed mechanism of the above reaction was es-
tablished in our recent publication (Scheme 1) [18]. Even after re-
peated attempts we could neither isolate nor detect (GC-MS, LC-
MS) the 1:1 adduct 3a. However, we could successfully generate
3a by alternative routes (vide infra).
Molecular docking studies were exploited to show the possible
binding mode of the test molecule with its target protein aiming
to explain its anticancer activity [19–21]. To study the drug like
character of synthesised acenaphthenone-2-ylidene ketones (3a-f),
we have explained with the help of Swiss ADME software.
2. Results and Discussion
Acetophenone undergoes base catalysed Aldol condensation
with benzil to form α,β-unsaturated ketone as the stable
end product [16]. Based in this observation, we examined the
Claisen-Schimdt reaction between acetophenone (2a) and acenaph-
thenequinone (1) in methanol in the presence of KOH [17,18]. In-
terestingly, we obtained three complex molecules by Michael-aldol
We have repeated the Claisen-Schmidt reaction of acenaph-
thenequinone (1) with acetophenones having different substituents
at the 4-position (2b-f) to study the generality of the reac-
tion. We observed dramatic substituent dependence in these re-
actions. While 4-chloro and 4-methylacetophenone reacted with
acenapthenequinone to give three 2:2 adducts (4b, 4c - 5b, 5c -
6b, 6c) as described earlier [18], other acetophenone derivatives
behaved differently, 4-bromo, 4-methoxy and 4-phenyl substi-
tuted acetophenones gave the expected 1:1 adduct, 3d-f as the
only product (Scheme 1). The 2:2 adducts formed were separated
∗
Corresponding author.
E-mail address: jacobpjomon@yahoo.com (J.P. Jacob).
#
These two authors contributed equally.
https://doi.org/10.1016/j.molstruc.2020.129209
0022-2860/© 2020 Elsevier B.V. All rights reserved.

2
D. Kuriakose, R.K. Thumpakara and J. A et al. / Journal of Molecular Structure 1224 (2021) 129209
Scheme 1. Reaction between acenaphthenequinone (1) and acetophenones (2a-f).
Scheme 2. Wittig route for the synthesis of acenaphthenone-2-ylidene ketones (3a-f).
by column chromatography and purified by recrystallization. The
compounds were characterised by 1H, 13C NMR and SCXRD
[18,22,23] analyses. Inductive, mesomeric and steric factors could
not satisfactorily account for the dichotomous reaction sequence
of acetophenone-acenaphthenequinone reaction.
Diversity of the above reaction may depend on the geometry
or electronic factors of acenaphthenone-2-ylidene ketones (3a-f)
having different substituents. To study the effect of geometry, we
have computationally optimized the geometry of acenaphthenone-
2-ylidene ketones (3a-f) using the software Gaussian (Table 1).
Based on optimized structures collected in Table 1, it is clear
that acenaphthenone-2-ylidene ketones 3a-f have similar geome-
try and hence geometry is not a significant factor in controlling the
reactivity of 3. So the difference in reactivity of 3a-f may be due
to electromeric effects induced by substituents at the para position
of the benzoyl group in the 1:1 adducts, 3a-f. A clear correlation is
elusive since both electron withdrawing (Cl) and electron releasing
(CH3) substituents assist 2:2 adduct formation while both Br and
-OMe substituents rendered the initially formed 1:1 adducts un-
reactive towards further transformations under the conditions em-
ployed by us.
Our further investigations to unravel the mechanism of the re-
action pointed towards a remarkable substituent effect in control-
ling the reactivity of acenaphthenone-2-ylidene ketones (3a-f). We
have independently synthesised the intermediate acenaphthenone-
2-ylidene ketones 3a-f by adopting the Wittig route (Scheme 2).
ln this reaction sequence, phenacyl bromides 7a-f were first syn-
thesised by the bromination of various para-substituted acetophe-
nones 2a-f using diethyl ether as solvent in the presence of anhy-
drous aluminium chloride. Phenacyl bromide derivatives 7a-f were
converted to corresponding phenacyltriphenylphosphonium bro-
mides 8a-f by the reaction with triphenylphosphine. In the pres-
ence of sodium carbonate, corresponding ylides 9a-f were formed
and they reacted with acenaphthenequinone (1) to form required
acenaphthenone-2-ylidene ketones 3a-f.
3. Molecular docking
Independently synthesised acenaphthenone-2-ylidene ketones
3a-c were treated with KOH in methanol. While 3d-f remained
unchanged even after refluxing for 12 h, 3a-c underwent further
transformation to give the 2:2 adducts 4a-c within 4 h. This ob-
servation supports the reaction sequence depicted in Scheme 1 in-
dicating further transformations of 3 to give 4 and presumably, 5
and 6 attesting the role of remote substituents in the reactivity of
acenaphthenone-2-ylidene ketones 3a-f.
The AutoDock is an automatic docking programme designed
for the prediction of the binding among small molecules for-
example drug candidates and the receptor having known 3D struc-
ture [24–30]. Molecular docking studies were performed using
AutoDock 4.2 Vina software to confirm the anticancer activity of
acenaphthenone-2-ylidene ketones (3a-f) against different proteins
viz 4I4T, 4I55, 4YJ2 and 4YJ3. Crystal structure of the target pro-
teins were downloaded from the RSCB PDB website in the PDB

D. Kuriakose, R.K. Thumpakara and J. A et al. / Journal of Molecular Structure 1224 (2021) 129209
3
Table 1
Energy minimized structures of acenaphthenone-2-ylidene ketones (3a-f) using Gaussian.
Table 2
All interacting residues between acenaphthenone-2-ylidene ketones and selected target proteins.
Proteins
Molecules
All interacting residues
3a
3b
3c
3d
3e
3f
ARG F: 44, PHE F: 49, ARG F: 66, ALA F: 68, ASP F: 69, ALA F: 335.
VAL F: 13, ALA F: 68, LEU F: 314, ALA F: 335, PRO F: 336.
PHE F: 49, ALA F: 68, ASP F: 69, ARG F: 73
4I4T
ARG F: 44, ARG F: 46, PHE F: 49, ARG F: 66, ALA F:68, ASP F: 69, ALA F: 335.
ARG F: 44, LEU F: 47, PHE F: 49, ARG F: 66, ALA F: 68, ASP F: 69, ALA F: 335.
ARG F: 44, ARG F: 46, PHE F: 49, ARG F: 66, ALA F: 68, ASP F: 69, ALA F: 335.
3a
3b
3c
3d
3e
3f
GLY B: 10, CYS B: 12, GLU B: 71, ALA B: 99, ASN B: 101, THR B: 145, GLY B: 146, ASP B: 179.
GLN B: 11, CYS B: 12, GLU B: 71, ASN B: 101, GLY B: 144, VAL B: 171, PRO B: 173.
VAL B: 177, ASP B: 179, TYR B: 224, LEU B: 227, VAL C: 250, VAL C: 353.
CYS B: 12, SER B: 140, VAL B: 171, MET B: 172, PRO B 173.
4I55
GLN B: 11, CYS B: 12, GLU B: 71, ALA B: 99, ASN B: 101, GLY B: 144, VAL B: 177, ASP B: 179.
TYR B: 224, LEU C: 248, PRO C: 325, VAL C: 353.
3a
3b
VAL B: 177, SER B: 178, LEU C: 248, PRO C: 325, VAL C: 353, ILE C: 355.
VAL B: 177, SER B: 178, TYR B: 224, LEU B: 227, LEU C: 248,
PRO C: 325, VAL C: 353, ILE C: 355.
4YJ2
3c
VAL B:177, TYR B: 224, LEU C:248, PRO C: 325, VAL C: 353,
ILE C: 355.
3d
3e
3f
LYS B: 105, LYS C: 163.
CYS B: 12, GLN B: 15, GLU B: 71, ALA B: 99, GLY B: 144, THR B: 145, GLY B: 146, ASP B: 179.
SER B: 178, LEU C: 248, GLY C: 350, PHE C: 351, VAL C: 353.
3a
3b
3c
3d
3e
3f
VAL B: 177, LEU C: 248, PRO C: 325, ILE C: 355, VAL C: 353.
CYS B:12, GLU B: 71, ALA B: 99, ASN B: 101, GLY B: 144, THR B: 145, GLY B: 146, ASP B: 179, TYR B: 224.
GLY B: 11, CYS B: 12, TYR B: 224
4YJ3
VAL B: 177, VAL C: 250.
GLN B: 11, CYS B: 12, GLY B: 142, GLY B:143, TYR B: 224.
VAL B: 177, TYR B: 224, LYS C: 352.

4
D. Kuriakose, R.K. Thumpakara and J. A et al. / Journal of Molecular Structure 1224 (2021) 129209
Fig 1. 2D diagram of acenaphthenone-2-ylidene ketones docked into the binding site of anti-cancer proteins.

D. Kuriakose, R.K. Thumpakara and J. A et al. / Journal of Molecular Structure 1224 (2021) 129209
5
Table 3
Prediction of in silico ADME properties of the acenaphthenone-2-ylidene ketones, 3a-f.
Acenaphthenone-2-ylidene
ketones
Molecular
weight (g/mol)
Physicochemical parameters
Bioactivityscore
No. of H-bond
acceptor
No. of H-bond
No. of rotatable
bonds
˚
Mi log P
TPSA (A²)
donor
3a
3b
3c
3d
3e
3f
284.31
298.33
318.75
363.20
314.33
360.40
2.66
2.59
2.90
3.01
2.47
3.31
34.14
34.14
34.14
34.14
43.37
34.14
2
2
2
2
3
2
0
0
0
0
0
0
2
2
2
2
3
3
0.55
0.55
0.55
0.55
0.55
0.55
format [31]. Before docking, the water molecules and other co-
crystallized ligand molecules were removed from the target pro-
teins and polar hydrogens were added using PyMoL software [32].
The active site of the protein was explained within the grid size
Properties of absorption, distribution, metabolism, excretion
and toxicity are included in In silico ADME and are exploited to
predict the drug-likeness behaviour of the compounds based on
Lipinski’s rule of five [35–37]. According to Lipinski’s rule, Mi log
P values of compounds should be below 5, molecular weight is
lower than 500, H-bond acceptors should be smaller than 10, H-
bond donors should be lower than 5 and should have the bioactive
score is smaller than one.
˚
˚
˚
30A × 30A × 30A in order to incorporate the residues of the ac-
tive sites. The best fit conformation was analysed, which is based
on the binding score, hydrogen bonding and other hydrophobic
interactions. The binding interactions were visualized using Dis-
covery studio visualizer. Affinity of best docked position of the
molecule and protein target complex was determined by E-value
(kcal/mol). It provides the prediction of binding free energy for
docked molecule [21].
Mi Log P, is calculated by the methodology developed by Molin-
spiration [38] as a sum of fragment based contributions and cor-
rection factors. To determine the hydrophobic character of the
synthesized compounds we are using the parameter Mi log P,
which is necessary for analyzing the permeability skill of the com-
pounds across the cell membrane. In the present study about the
acenaphthenone-2-ylidene ketones 3a-f, Mi log P values are found
to be less than 5; it implies that the compounds should have
appreciable penetrable talent across the central nervous system.
The molecular weight of the synthesized compounds is less than
500. As per Lipinski regulation, these compounds have good drug-
likeness criteria.
4I4T crystal structure of the tubulin-RB3-TTL-Zampanolide com-
plex with binding energy (E) -9.20, -9.60, -8.80, -9.50, -9.30, -
10.70 kcal/mol for 3a, 3b, 3c, 3d, 3e and 3f respectively. Organ-
isms: Bos taurus, Rattus norvegicus, Gallus gallus. 4I55 Crystal
structure of the tubulin-stathmin-TTL complex with binding en-
ergy (E) -9.00, -9.10, -7.80, -8.40, -8.40, -9.30 kcal/mol for 3a, 3b,
3c, 3d, 3e and 3f respectively. 4YJ2 Crystal structure of tubulin
bound to MI-181 with binding energy (E) -8.60, -8.60, -8.80, -
8.50, -8.70, -9.70 kcal/mol for 3a, 3b, 3c, 3d, 3e and 3f respec-
tively. 4YJ3 crystal structure of tubulin bound with binding en-
ergy (E) -8.70, -8.80, -9.00, -8.10, -8.70, -9.40 kcal/mol for 3a,
3b, 3c, 3d, 3e and 3f respectively. From the above data, we
can clear that 2-(2-(biphenyl-4-yl)-2-oxoethylidene)acenaphthylen-
1(2H)-one (3f) shows good binding affinity to target proteins
as shown in Fig 1. So, we can use 3f as the best anticancer
drugs in the acenaphthenone-2-ylidene ketones (3a-f) series. These
acenaphthenone-2-ylidene ketones (3a-f) show good binding affin-
ity to the target proteins than the binding affinity of the com-
pounds to the same target proteins in a recently reported article
[33].
Here the number of H-acceptors is 2, 3 and the H-donor is
zero for acenaphthenone-2-ylidene ketones, 3a-f. Based on the Lip-
inski’s rule of five, the compounds possess many H- acceptors
and donors, they effectively interact with active sites. Topological
molecular polar surface area (TPSA) is a commonly analyzed fac-
tor related to H-bonding (O and N atom counts) and is necessary
to identify the cell permeability phenomena of 3a-f. It is a sig-
nificant parameter that was compared with the passive diffusion
through the cell wall; hence, it agreed to pass the drug candidates
inside the central nervous system. In the case of acenaphthenone-
2
˚
2-ylidene ketones 3a-f, acquires TPSA values below 140 A and
thereby possess good drug transport features and may be favoured
for oral administration.
By using Discovery studio visualizer, [34] we have to find the
docking interaction of hydrogen bonds (classical and non-classical)
and binding amino acid residues: alanine (ALA), asparagine (ASN),
arginine (ARG), aspartic acid (ASP), cysteine (CYS), glutamine
(GLN), glutamic acid (GLU), glycine (GLY), histidine (HIS), leucine
(LEU), lysine (LYS), serine (SER), threonine (THR), tryptophan (TRP),
tyrosine (TYR), valine (VAL) and phenylalanine (PHE) showed in
the 2D interaction diagram (Fig 1).
As per Lipinski’s rule, molecule having higher number of rotat-
able bond, they become more stretchy and convenient for interface
with the accurate active centre. Here the rotatable bonds are 2, 3
and have well-matched ability to interact with the living cells effi-
ciently.
According to the Lipinski’s rule, the compounds which possess
bioactivity scores greater than 0 have excellent drug likeness pro-
ficiency [39]. In this case, acenaphthenone-2-ylidene ketones 3a-f,
have the bioactivity score is 0.55 and are scrutinized by measur-
ing the activity score of GPCR (Human G-protein coupled recep-
tors) ligand, ion channel modulator, nuclear receptor ligand, kinase
inhibitor, protease inhibitor and enzyme inhibitor.
4. In silico ADME property prediction
Computational simulation studies provide a quick and eco-
nomic approach to determine the drug-like character of synthe-
sized acenaphthenone-2-ylidene ketones, 3a-f. SwissADME soft-
ware was used to measure their bioactive score value of the pre-
pared compounds. It was measured by estimating the different pa-
rameters Mi log P (partition coefficient), compound weight, heavy
atoms, hydrogen donors, hydrogen acceptors and rotatable bonds
Table 3.
5. Conclusion
Acenaphthenone-2-ylidene ketones were independently syn-
thesised and their propensity to undergo further transformations
under conditions employed for Claisen-Schimidt reaction was
examined. Geometry optimization using Gaussian, clearly revealed

6
D. Kuriakose, R.K. Thumpakara and J. A et al. / Journal of Molecular Structure 1224 (2021) 129209
that acenaphthenone-2-ylidene ketones have similar geometry,
hence geometry has no role in controlling the Claisen-Schimidt
reaction of acenaphthenone-2-ylidene ketones. Electromeric effects
induced by substituents at the para position of the benzoyl group
in the initially formed acenaphthenone-2-ylidene ketones may be
responsible for the observed difference in their reactivity towards
δ 200.32, 199.21, 141.13, 140.84, 138.10, 134.86, 133.25, 131.02,
130.87, 130.38, 129.23, 128.40, 128.33, 127.62, 126.12, 123.19,
118.29,96.43. MS (FAB): m/z 284 (M+), 105 Elemental analysis
calculated for C20H12O2: C 84.49, H 4.25. Found: C 84.43, H 4.39.
2-(2-oxo-2-p-tolylethylidene)acenaphthylen-1(2H)-one
(3b)
[17,18,40]: Yellow needles, Yield: 3.39 g (64%), mp: 143-145°C, IR
νmax (KBr): 1710, 1674 cm−1 (C=O), 1H NMR (CDCI3): δ 8.97-7.21
(11H, m, aromatic and vinylic protons), 2.40 (3H, singlet, methyl
protons) 13C NMR (CDCI3): δ 200.16, 199.34, 153.81, 144.29, 134.93,
134.47, 132.01, 131.34, 131.34, 130.31, 129.80, 129.51, 129.51, 129.64,
127.50, 127.17, 126.81, 122.52, 25.80. MS (FAB): m/z 295 (M+), 119.
Elemental analysis calculated for C21H14 O2: C 84.54, H 4.74. Found:
C 84.48, H 4.76.
further
transformations.
Anticancer
activity
of
the
acenaphthenone-2-ylidene ketones were analysed (in silico) using
AutoDock 4.2 Vina software. Drug likeness of the acenaphthenone-
2-ylidene ketones were established using SwissADME software
based on Lipinski’s rule of five.
6. Experimental section
2-(2-(4-chlorophenyl)-2-oxoethylidene)acenaphthylen-1(2H)-
one (3c) [17,18,40]: Yellow needles, Yield: 3.60
g (68%), mp:
6.1. General methods
187-189°C, IR νmax (KBr): 1716, 1668 cm−1 (C=O), 1H NMR
(CDCl3): δ 8.81-7.14 (11H, m, aromatic and vinylic protons), 13C
NMR (CDCl3): δ 200.4, 194.21, 140.93, 140.14, 139.10, 134.99,
132.05, 131.54, 130.77, 130.18, 129.08, 128.45, 128.39, 127.92,
126.85, 122.09, 117.99, 96.19. MS (FAB): m/z 318 (M+), 139. Ele-
mental analysis calculated for C20H11 ClO2: C 75.36, H 3.48. Found:
C 75.39, H 3.41.
All reactions were conducted in oven-dried glassware. Reagents
used were purchased from Sigma Aldrich Chemical Co. or Spec-
trochem and were used without further purification. Solvents used
for experiments were distilled and dried according to procedures
given in standard manuals. All reactions were monitored by thin
layer chromatography (TLC). Analytical thin layer chromatography
was performed on aluminium sheets coated with silica gel (Spec-
trochem); visualization was achieved by exposure to iodine vapours
or UV radiation. Solvent removal was done on a Heidolph rotary
evaporator. Gravity column chromatography was performed using
60-120 mesh silica gel (Spectrochem) and mixtures of hexane-ethyl
acetate were used for elution. Melting points were recorded on a
Neolab melting point apparatus. Infrared spectra were recorded us-
ing JASCO FTIR 4100 spectrometer. NMR spectra were recorded a
400 MHz on a Bruker FT-NMR spectrometer. Chemical shifts are re-
ported in δ (ppm) relative to TMS as the internal standard. Single
Crystal XRD was done by Bruker XRD Instrument. Elemental analy-
sis was performed using Elementar Systeme (Vario EL III). Molecular
mass was determined by fast atom bombardment (FAB) using JMS
600 JEOL mass spectrometer. Unless otherwise mentioned, all com-
mercially available solvents and reagents were used as received
and reactions were performed under normal conditions. Character-
ization data for 4a-c, 5a-c and 6a-c are available in earlier publi-
cations from our group [17,18].
2-(2-(4-bromophenyl)-2-oxoethylidene)acenaphthylen-1(2H)-
one (3d) [17,18,40]: Yellow needles, 2.62 g (57%), mp: 197-199°C,
IR νmax (KBr): 1710, 1663 cm−1 (C=O), 1H NMR (CDC13): δ 8.80-
7.12 (11H, m, aromatic and vinylic protons), MS (FAB): m/z 362
(M+), 183. Elemental analysis calculated for C20H11 BrO2: C 66.14,
H 3.05. Found: C 66.18, H 3.11.
2-(2-(4-methoxyphenyl)-2-oxoethylidene)acenaphthylen-
1(2H)-one (3e) [17,18,40]: Yield: 2.90 g (63%), mp: 161-163°C, IR
νmax (KBr): 1722, 1670 cm−1 (C=O), 1H NMR (CDCl3): δ 8.84-6.91
(11H, m, aromatic and vinylic protons), 3.88 (3H, singlet, methoxy
protons), 13C NMR (CDCl3): δ 193.66, 189.13, 164.04, 140.70,
138.22, 132.62, 131.31, 131.24, 130.80, 130.47, 129.84, 129.12,
128.37, 121.93, 117.69, 115.41, 114.62, 114.13, 113.98, 113.05, 110.99,
108.72, 107.71, 106.09, 104.37, 96.22, 55.40. MS (FAB): m/z 314
(M+), 135. Elemental analysis calculated for C21H14 O3: C 84.54; H
4.73. Found: C 84.50, H 4.69.
2-(2-(biphenyl-4-yl)-2-oxoethylidene)acenaphthylen-1(2H)-
one (3f) [17,18,40]: Yield: 2.76 g (60%), mp: 187-189°C, IR νmax
(KBr): 1715, 1650 cm−1 (C=O), 1H NMR (CDCl3) δ 8.78-7.25 (16H,
m, aromatic and vinylic protons), 13C NMR (CDCl3) δ 201.89,
194.87, 146.41, 140.11, 135.31, 132.47, 132.37, 131.43, 130.81, 129.47,
128.94, 128.83, 128.39, 128.23, 127.79, 127.40, 127.14, 126.69,
126.48, 124.04, 122.04, 117.87, 112.89, 109.54, 108.14, 96.22. MS
(FAB): m/z 360 (M+), 181. Elemental analysis calculated for
C26H16 O2: C 86.64, H 4.47. Found: C 86.68; H 4.42.
6.2. Common procedure for the synthesis of
acenaphthenone-2-ylidene ketones (3a-f) by Wittig’s reaction
Para substituted acetophenones (7a-f, 25 mmol) was slowly
added to a chloroform solution (6 mL) of triphenylphosphine (25
mmol) and the solution was filtered into anhydrous ether (1 Litre).
The precipitate formed was filtered, collected and dried. The prod-
uct formed was recrystallized from water in the form of white
powder (8a-f, 60-68%).
Declaration of Competing Interest
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared to
influence the work reported in this paper.
A
mixture of corresponding triphenylphosphonium bromide
(8a-f, 7.0 g) and 10% aqueous sodium carbonate (250 mL) was well
mixed for 15h. The mixture was filtered and insoluble portion was
taken up in hot benzene (200 mL). Some unreacted bromide was
removed by filtration; addition of petroleum ether to the benzene
filtrate afforded the compound 9a-f (58-65%) as white powder.
A solution of acenapthenequinone (1, 27 mmol) and triph-
enylphosphinebenzoylmethylene (9a-f, 27 mmol) in ethanol (30
mL) was stirred at room temperature for 2h. The product was
separated, filtered and purified by recrystallization from ethanol-
chloroform (1:3) mixture to give acenaphthenone-2-ylidene ke-
tones 3a-f (57-68%).
Supplementary materials
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.molstruc.2020.129209.
CRediT authorship contribution statement
Daly Kuriakose: Software, Formal analysis, Investigation, Data
curation, Writing - original draft. Roshini K. Thumpakara: Inves-
tigation, Writing - original draft, Data curation, Formal analysis.
Jesna A: Visualization, Investigation. Jomon P. Jacob: Conceptual-
ization, Methodology, Supervision.
2-(2-oxo-2-phenylethylidene)acenaphthylen-1(2H)-one
(3a)
[17,18,40]: Yellow needles, Yield: 3.18 g (60%), mp: 108-110°C, IR
νmax (KBr): 1722, 1671 cm−1 (C=O), 1H NMR (CDCI3): δ 8.97-
7.26 (12H, m, aromatic and vinylic protons), 13C NMR (CDCI3):

D. Kuriakose, R.K. Thumpakara and J. A et al. / Journal of Molecular Structure 1224 (2021) 129209
7
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