Photochemical study of chalconoid-like compounds: Synthesis of 4-flavanoids

Article abstract of DOI:10.1002/jhet.1583

The photo-irradiation of chalconoid-like compounds; (2E,4E)-1-(2- hydroxyaryl)-4-methyl-5-phenylpenta-2,4-dien-1-ones to 4-flavanoids in solution phase has been described. The molecular scaffold of the probed substrates is responsive to intramolecular cyc

Full text of DOI:10.1002/jhet.1583

948
Photochemical Study of Chalconoid-like Compounds: Synthesis of
4-Flavanoids
Vol 51
*
Ramesh C. Kamboj, Dinesh Kumar, Surinder Berar, Geeta Sharma, and Rita Arora
Department of Chemistry, Kurukshetra University, Kurukshetra 136 119, India
*
E-mail: rckamboj@rediffmail.com
Received July 12, 2011
DOI 10.1002/jhet.1583
Published online 10 December 2013 in Wiley Online Library (wileyonlinelibrary.com).
CH3
R'
OH
R'
OH
CH3
R
4"
CH3
O
R
2'
R' 4'
OH
4
O
/
h
pyrex
4(a-e)
2"
Ba(OH)2
MeOH
2
1(a-e)
+
R
5'
1
MeOH
+
O
4"
CH3
1'
CH3
8
3(a-e)
R'
O
H
2
2'
2"
3
O
R
2
5
O
4(c'-e')
) R = R' = H; ) R = CH3, R' = H; ) R = H, R' = OCH3; ) R = Cl, R' = CH3; ) R = Cl, R' = H
a
b
c
d
e
The photo-irradiation of chalconoid-like compounds; (2E,4E)-1-(2-hydroxyaryl)-4-methyl-5-phenylpenta-
2,4-dien-1-ones to 4-flavanoids in solution phase has been described. The molecular scaffold of the probed
substrates is responsive to intramolecular cyclization as well as cis-trans isomerizations and photoproducts
corresponding to both of reactions have been realized also. The formation of photoproducts has been explained
on the basis of excited state intramolecular proton transfer that further depends upon the different substituents
present on the phenolic moiety.
J. Heterocyclic Chem., 51, 948 (2014).
INTRODUCTION
RESULTS AND DISCUSSION
Chalcones ((2E)-1,3-diarylprop-2-en-1-ones), the bichro-
mophoric molecules, considered as the precursors of flavo-
noids and isoflavonoids, are abundant in fruits, vegetables,
spices, tea, and soy-based foodstuff and have been shown
to display a diverse array of pharmacological activities
[1–5]. These bichromophoric systems are good models for
study of the photo-induced electron transfer process [6]. In
addition, chalcones find various applications as organic
brightening additives [7], potential nonlinear optical proper-
ties [8], and fluorescent probes for micellar solutions [9].
Photochemically, the chalconoids are known to undergo
cycloadditions [10–13] and cis-trans isomerizations [14].
The 2′-hydroxychalcones are extensively studied photochem-
ically and they are known to undergo photo-oxygenations
[15] and excited state intramolecular proton transfers (ESIPT)
[16–20] instead of cycloadditions. In the present study, we
report the solution phase photoreactions of the chalconoid-
like compounds having extended conjugation, (2E,4E)-1-(2-
hydroxyaryl)-4-methyl-5-phenylpenta-2,4-dien-1-ones and
also the effect of various substituents on the formation and
distribution of the photoproducts arising through ESIPT.
The substituted dienones 3(a–e), chalconoid-like com-
pounds in the present study, were synthesized by the
condensation of suitable acetophenone with an a-methyl-
cinnamaldehyde using Ba(OH)2 as base (Scheme 1). Their
structures were ascertained from their spectral parameters
(vide experimental). The compound 3d in its IR spectrum
(KBr) exhibited strong absorption band at 1632cm-1 that
1
may be assigned to C=O of enone moiety. Its H NMR
(300MHz, CDCl3) spectrum had a broad singlet at d 12.79
because of 2′-OH that disappears on D2O shake. The protons
H-3′ and H-6′ were revealed at d 7.04 (1H, s) and 7.81 (1H,
s), respectively. The resonances because of H-2 and H-3
appeared as doublets at d 7.07 and 7.36, respectively, with
J value of 15.0 Hz indicating (E)-configuration at C2–C3
double bond. The five protons because of phenyl ring were
1
placed as a multiplet between d 7.31–7.42. The H NMR
spectrum also showed the presence of two methyl groups
at d 2.20 (s, C4–CH3) and 3.40 (s, C4′–CH3).
Similarly, the 1H NMR assignments of other compounds
3(a–c) and 3e were found to be consistent with their
structures.
© 2013 HeteroCorporation

July 2014
Photochemical Study of Chalconoid-like Compounds
949
Scheme 1. Synthesis and photo-irradiation of chalconoids 3(a–e).
CH3
(Z)
R'
R
OH
R'
OH
CH3
4"
CH3
O
R
4'
2'
R'
OH
O
/
h
pyrex
2"
4(a-e)
Ba(OH)2
MeOH
2
1(a-e)
+
R
5'
MeOH
1
+
O
4"
CH3
CH3
H
8
3(a-e)
R'
O
B
H
2
2'
2"
A
Hb
3
O
R
2
5
Ha
O
4(c'-e')
Yield (%)b
Photoproduct
Yield (%)a
-R'
Photoproduct
-R
------
4a
4b
36
41
4a'
4b'
4c'
4d'
4e'
-H
-CH3
-H
-H
-H
------
25
-OCH3
4c
4d
4e
32
29
-CH3
-H
-Cl
-Cl
45
39
28
a - yield calculated from1H NMR; b - isolated yield
The photo-irradiation of these chalconoids 3(a–e) in dry
methanol (1.0 mM) for 90 min with pyrex filtered light using
125 W medium pressure mercury lamp under N2 atm.
produced the respective seq cis-isomers 4(a–e) and the flava-
noids 4(c′–e′) as shown in Scheme 1. The structures of these
photoproducts were confirmed by their spectral data (vide
experimental). In the IR spectrum of photoproduct 4d′, the
absorption band for C=O group shifted towards higher value
(1687 cm-1) that indicated the lack of conjugation to C=O
group in the flavanoid 4d′. Also, in the 1H NMR
(300MHz, CDCl3) spectrum of the photoproduct 4d′, the
resonances because of H-2, Ha-3, and Hb-3 protons were
placed at d 4.95 (1H, dd, J2,3Hb = 2.7 Hz, J2,3Ha = 12.9 Hz),
2.99 (1H, dd, J3Ha,2 = 12.9, J3Ha,3Hb = 16.8 Hz), and d 2.76
(1H, dd, J3Hb,2 = 2.7, J3Hb,3Ha = 16.8 Hz), respectively. The
two methyl resonated at d 2.01 (3H, s, C7–CH3) and 2.39
(3H, s, C1–CH3). The three singlets at d 6.68, 6.95, and
7.86 were assigned to the H-2′, H-8, and H-5, respectively.
The five protons (H-2"–H-6") of the phenyl ring resonated
in the aromatic region as an unresolved multiplet
d 7.092–7.39. The similar 1H NMR patterns were displayed
by the other photoproducts 4(c’–e’).
calculations (Table 1) showed that the energy differences
between the two possible conformers X and Y (Fig. 1) of
flavanoid 4d′ is small; therefore, the two conformers may
1
exist in equilibrium. This ambiguity was resolved by H
NMR spectroscopy where J2,3 coupling constants are infor-
mative to address the conformational aspects of the ring B,
and it has been widely applied in analogous studies [21–23].
The relatively large J2,3Ha value (12.9 Hz) in compound
4d′ confirms the preferred pseudo-diaxial conformation of
H-2 and Ha-3, thus placing the bulkier styryl group in
pseudo-equatorial orientation (conformation X; Fig. 1). In
order to support the preference of conformation X over the
Table 1
Expected coupling constants for the two conformations of 4d′.
Conformation X
Conformation Y
(Ekcal/
(Ekcal/mol = 9.090)
mol = 9.234)
Coupling
protons
Observed
J (Hz)
Φ
J (Hz)a
Φ
J (Hz)a
As far as stereochemical features concern, generally, the
half-chair conformation is favored for chroman ring that
mainly arises from the restricted rotation imposed by the
benzene ring [21–23]. The MM2 minimized energy
H-2 and Ha-3 177.11
12.9
3.8
57.89
60.77
4.2
4.3
12.9
2.7
H-2 and Hb-3
61.53
aExpected value.
Journal of Heterocyclic Chemistry
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950
R. C. Kamboj, D. Kumar, S. Berar, G. Sharma, and R. Arora
Vol 51
CH3
H
H
CH3
H3C
Cl
H3C
Cl
2
2
O
O
A
A
B
B
3
3
Hb
Hb
Ha
Ha
O
O
(Conformation X)
(Conformation Y)
(Conformation X)
styryl pseudo-equatorial
ring B half-chair
(Conformation Y)
styryl pseudo-axial
ring B half-chair
Figure 1. MM2 energy minimized structures of expected conformations of compound 4d′.
conformation Y, the dihedral angles (Φ) and the expected J
values along with the steric energies are calculated [24] with
Chem3D Ultra 8.0 (PerkinElmer, Melville, NY) software
(Table 1).
phenyl ring ensuring the stability and proceeds effec-
tively via a thermal 6p-electrocyclic process. It has been
studied [25] that the photochemical rearrangement of
3-chromanone derivatives takes place via enolization
and a similar mechanism has been proposed for the
photochemical ring opening reaction of substituted 4-
flavanones [26]. The calculation of heat of formation
(ΔHf) by MOPAC-PM3 program for the transition
states I–IV of compound 3d is tabulated in Table 2.
A closer look of Table 2 shows that the conversion of
I ! II! III is an endothermic process and thus requires
the photochemical energy. The conversion III ! IV is
exothermic and can proceed well with the dissipation of
energy. In the photocyclization of the chalconoids
(Scheme 2), the first step is the transfer of phenolic proton
to the carbonyl oxygen to form enol-II. The ease of hydro-
gen transfer is related to the type and energy of excited state
of carbonyl group involved and the acidity of the phenolic
proton that further depends upon the different substitution.
The electron-releasing groups (ꢀOCH3 and –CH3 in 3c and
3d, respectively) at para position to the carbonyl chromo-
phore make it more basic [27] by lowering the energy
of its p–p* excited state and enhancing the ESIPT for
photocyclization. Also, the electron-withdrawing group
(ꢀCl in 3d and 3e) para to the phenolic oxygen
The observed 3J values found in the present case for 4d′
are in accordance with the J† values calculated (Table 1)
for conformation X, where H-2 and Ha-3 are in pseudo-
diaxial orientation and styryl group in pseudo-equatorial
position (Fig. 1).
The photoconversion of the chalconoids 3(c–e) into
flavanoids 4(c′–e′) described earlier (Scheme 1) can be
visualized to occur through p–p* excitation [20] of carbonyl
group that resulted in ESIPT. In the ground state structure,
the strong intramolecular hydrogen bonding between the
phenolic proton and the carbonyl oxygen of these com-
pounds 3(a–e) leads to a six-membered cyclic transition state
I (Scheme 2) that is supported well by the 1H NMR spectra
(dOH ~ 12.79 for 3d). The photo-irradiation of chalconoids
resulted in intramolecular proton transfer to give the enol
(II) in seq trans configuration (Scheme 2), which in turn
produced III that cyclized to give IV via a thermal
6p-electrocyclic ring-closure. The intermediate IV sub-
sequently tautomerizes to yield 4-flavanoids. The cycli-
zation of III–IV is likely to be highly favorable
because of the restoration of aromatic character of the
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

July 2014
Photochemical Study of Chalconoid-like Compounds
951
Scheme 2. Photoconversion of chalconoids 3(a–e).
R
A
O
CH3
R
O
CH3
(Z)
R'
R'
(E)
h
O
O
H
H
I (seq trans)
seq cis
4(a-e)
ESIPT
h
CH3
R
O
CH3
*
R
O
CH3
R'
R
O
R'
R'
(E)
(E)
(E)
OH
O
O
H
H
III
II (seq trans)
6 e-cyclisation
CH3
CH3
R'
O
O
R'
O
(E)
tautomerisation
R
R
OH
IV
4(c'-e')
Table 2
photoproducts corresponding to those reactions under the
conditions were realized here.
ΔHf for the transition states of compound 3d leading to the formation of
4d′.
State
I
II
III
IV
EXPERIMENTAL
ΔHf (kcal/mol)
ꢀ18.80
ꢀ15.34
3.21
ꢀ12.41
General.
Melting points were determined in open
capillaries and are thus uncorrected. 1H NMR spectra were
recorded on a 300 MHz Bruker spectrometer using TMS as
internal standard. IR spectra were recorded on a Buck Scientific
500 spectrophotometer using KBr pellets. TLC plates were
coated with silica gel G (suspended in CHCl3-MeOH), and
iodine vapors were used as visualizing agent. The columns for
purification were packed with Silica gel 100–200 mesh in
petroleum ether (60–80ꢁC)-benzene and left overnight before
use. The elution was carried out with increasing proportion of
benzene in petroleum ether-benzene mixture. A total of 99.9%
dry N2 gas was continuously bubbled through the reaction
solution to maintain inert atmosphere during photolysis.
increases the acidity of phenolic proton and make its transfer
to carbonyl more facile. Therefore, the chalconoids 3c, 3d,
and 3e furnished cyclised photoproducts (4c′, 4d′, and 4e′,
respectively) in addition to the products arising through
cis-trans isomerization (4c, 4d, and 4e, respectively),
whereas chalconoids 3a and 3b produced only the seq cis
isomeric products (4a and 4b, respectively) with no forma-
tion of cyclised product corresponding to 4d′ (Scheme 1).
In all these compounds 3(a–e), no photoproduct through
cycloaddition reaction was obtained although their basic
skeleton seems to afford those.
Synthesis of chalconoids 3(a–e)
(2E,4E)-1-(2-Hydroxyphenyl)-4-methyl-5-phenylpenta-2,4-dien-
1-one (3a).
A solution of 2-hydroxyacetophenone (1.36 g;
0.01 mol) and a-methyl cinnamaldehyde (1.46 g; 0.01 mol) in
absolute methanol and dehydrated S200 barium hydroxide
(0.02 mol) was refluxed on water bath for 20 min. The solution was
cooled and poured onto crushed ice; it was then acidified with conc.
HCl to give a yellow solid. The solid was filtered, washed with
water, and crystallized from ethanol to give the yellow needles 3a.
Yield 78%; mp 116ꢁC; UV–vis (MeOH) lmax: 204, 247, 339 nm;
IR nmax (cm-1): 1663 (C=O), 3320 (OH); 1H NMR (CDCl3,
300 MHz) d 12.83 (1H, s, OH), 7.99 (1H, dd, Jm =1.8, Jo =8.7Hz,
H-6′), 7.50 (1H, dt, Jm =1.5Hz, Jo =7.8Hz, H-5′), 7.58 (1H, dt,
Jm =1.5Hz, Jo =8.4Hz, H-4′), 7.64 (1H, d, Jtrans = 15.3 Hz, H-3),
7.06 (1H, d, Jtrans = 15.3 Hz, H-2), 6.98 (1H, s, H-5), 7.26–7.40
(5H, m, Phenyl protons), 2.17 (3H, s, 4-CH3).
CONCLUSION
It may be concluded that on photo-irradiation, the
substituted (2E,4E)-1-(2-hydroxyaryl)-4-methyl-5-phenyl-
penta-2,4-dien-1-ones endured cis-trans isomerization
and cyclization to 4-flavanoids. The cyclization efficiency
of the investigated substrates depends upon the electron
density on phenolic oxygen as well as on the carbonyl
group. Although, the molecular structure of these sub-
strates is consenting to the cycloadditions, but no
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R. C. Kamboj, D. Kumar, S. Berar, G. Sharma, and R. Arora
Vol 51
3), 7.21 (1H, d, Jtrans = 15.3 Hz, H-2), 6.79 (1H, s, H-5), 7.29–7.44
(5H, m, Phenyl protons), 2.35 (3H, s, 5′-CH3), 2.20 (3H, s, 4-CH3).
Photolysis of (2E,4E)-1-(2-hydroxy-4-methoxyphenyl)-4-methyl-
5-phenyl penta-2,4-dien-1-one (3c). A methanolic solution of 3c
(1.0 mM) furnished 4c and 4c’ on photolysis for 90 min.
(2E,4Z)-1-(2-Hydroxy-4-methoxyphenyl)-4-methyl-5-phenylpenta-
2,4-dien-1-one (4c). Yield 32%; IR nmax (cm-1): 1630 (C=O), 3322
(OH); 1H NMR (CDCl3, 300 MHz) d 13.43 (1H, s, OH), 7.78 (1H, d,
Jo =8.4Hz, H-6′), 6.49 (1H, dd, Jm =2.4Hz, Jo =8.4Hz, H-5′), 6.47
(1H, d, Jo =2.4Hz, H-3′), 8.02 (1H, d, Jtrans = 15.0 Hz, H-3), 7.14
(1H, d, Jtrans = 15.0 Hz, H-2), 6.94 (1H, s, H-5), 7.30–7.41 (5H, m,
Phenyl protons), 3.85 (3H, s, OCH3), 2.19 (3H, s, 4-CH3).
2,3-Dihydro-7-methoxy-2-((E)-1-phenylprop-1-en-2yl)chromen-
4-one (4c′). Yield 25%; White solid; mp 90ꢁC; IR nmax (cm-1):
1680 (C=O); 1H NMR (CDCl3, 300 MHz) d 7.85 (1H, d,
Jm = 2.4 Hz, H-5), 6.61 (1H, dd, Jm =2.4Hz, Jo = 8.7 Hz, H-6),
7.28–7.39 (5H, m, Phenyl protons), 6.50 (1H, d, Jm =2.4Hz, H-8),
6.69 (1H, s, H-2′), 4.98 (1H, dd, J2,3Hb =2.4, J2,3Ha = 13.2 Hz, H-2),
3.85 (3H, s, OCH3), 2.98 (1H, dd, J3Ha,2 = 13.2, J3Ha,3Hb = 16.8 Hz,
Ha-3), 2.62 (1H, dd, J3Hb,2 =2.4, J3Hb,3Ha =16.8Hz, Hb-3), 2.02
(3H, s, CH3); 13C NMR (CDCl3, 75.4MHz) d 190.99, 166.66,
163.60, 134.86, 129.08, 128.24, 128.70, 128.50, 127.08, 114.77,
110.14, 100.82, 83.36, 55.66, 41.64, 29.50, 13.88; Mass (m/z,
+Q1): 329 ([M + 1]+, 100); Anal. Calcd. for C19H17ClO3: C, 69.41;
H, 5.21. Found: C, 69.39; H, 5.13.
The other substrates 3(b–e) were synthesized by reacting substi-
tuted 2-hydroxyacetophenone 1(b–e) with a-methylcinnamaldehyde
2 under the reaction conditions as used for compound 3a.
(2E,4E)-1-(2-Hydroxy-5-methylphenyl)-4-methyl-5-phenylpenta-
2,4-dien-1-one (3b).
Yield73%;Yellowsolid;mp95ꢁC;UV–vis
(MeOH)lmax:204, 248, 337 nm;IRnmax (cm-1):1634(C=O), 3328
(OH);1HNMR(CDCl3,300 MHz)d12.74(1H,s,OH),7.65(1H,d,
Jm = 1.5 Hz,H-6′),7.31(1H,dd,Jm = 1.5 Hz,Jo = 8.4 Hz,H-4′),6.93
(1H,d,Jo = 8.4 Hz,H-3′),7.75(1H,d,Jtrans = 15.0 Hz,H-3), 7.18 (1H,
d, Jtrans = 15.0 Hz, H-2), 7.03 (1H, s, H-5), 7.29–7.45 (5H, m, Phenyl
protons), 2.36 (3H, s, 5′-CH3), 2.21 (3H, s, 4-CH3).
(2E,4E)-1-(2-Hydroxy-4-methoxyphenyl)-4-methyl-5-phenylpenta-
2,4-dien-1-one (3c). Yield 69%; Yellow solid; mp 104ꢁC; UV–vis
(MeOH) lmax: 205, 256, 336 nm; IR nmax (cm-1): 1633 (C=O), 3320
(OH); 1H NMR (CDCl3, 300 MHz) d 13.53 (1H, s, OH), 7.18 (1H, d,
Jo =9.0Hz, H-6′), 6.50 (1H, dd, Jm =2.4Hz, Jo =9.0Hz, H-5′), 6.50
(1H, d, Jo =2.4Hz, H-3′), 7.74 (1H, d, Jtrans =15.0Hz, H-3), 7.13
(1H, d, Jtrans = 15.0 Hz, H-2), 7.03 (1H, s, H-5), 7.28–7.43 (5H, m,
Phenyl protons), 3.88 (3H, s, OCH3), 2.20 (3H, s, 4-CH3).
(2E,4E)-1-(5-Chloro-2-hydroxy-4-methylphenyl)-4-methyl-5-
phenylpenta-2,4-dien-1-one (3d). Yield 76%; Yellow solid; mp
92ꢁC; UV–vis (MeOH) lmax: 208, 258, 336 nm; IR nmax (cm-1):
1
1632 (C=O), 3317 (OH); H NMR (CDCl3, 300 MHz) d 12.79
(1H, s, OH), 7.81 (1H, s, H-6′), 7.04 (1H, s, H-3′), 7.36 (1H, d,
Jtrans = 15.0Hz, H-3), 7.07 (1H, d, Jtrans = 15.0 Hz, H-2), 6.91
(1H, s, H-5), 7.31–7.42 (5H, m, Phenyl protons), 3.40(3H, s,
4′-CH3), 2.20 (3H, s, 4-CH3).
Photolysis of (2E,4E)-1-(5-Chloro-2-hydroxy-4-methylphenyl)-
4-methyl-5-phenylpenta-2,4-dien-1-one (3d).
Photo-irradiation
of methanolic solution of 3d (1.0 mM) delivered 4d and 4d′ in
90 min.
(2E,4E)-1-(5-Chloro-2-hydroxyphenyl)-4-methyl-5-phenylpenta-
2,4-dien-1-one (3e) [28].
Yield 83%; Yellow solid; mp 98ꢁC;
(2E,4Z)-1-(5-Chloro-2-hydroxy-4-methylphenyl)-4-methyl-5-
UV–vis (MeOH) lmax: 204, 243, 343 nm; IR nmax (cm-1):
phenylpenta-2,4-dien-1-one (4d). Yield 29%; IR nmax (cm-1):
1
1630 (C=O), 3314 (OH); H NMR (CDCl3, 300 MHz) d 12.83
1
1633 (C=O), 3317 (OH); H NMR (CDCl3, 300 MHz) d 12.79
(1H, s, OH), 7.83 (1H, d, Jm =2.7Hz, H-6′), 7.44 (1H, dd,
Jm =2.7Hz, Jo =9.0Hz, H-4′), 6.98 (1H, d, Jo =9.0Hz, H-3′), 7.78
(1H, d, Jtrans = 15.0 Hz, H-2), 7.09 (1H, d, Jtrans = 15.0 Hz, H-3), 7.06
(1H, s, H-5), 7.30–7.42 (5H, m, Phenyl protons), 2.21 (3H, s, 4-CH3).
Photolysis of chalconoids 3(a–e)
(1H, s, OH), 7.81 (1H, s, H-6′), 6.89 (1H, s, H-3′), 8.04 (1H, d,
Jtrans = 15.0 Hz, H-3), 7.10 (1H, d, Jtrans = 15.0 Hz, H-2), 6.99
(1H, s, H-5), 7.26–7.43 (5H, m, Phenyl protons), 2.39 (3H, s,
4′-CH3), 2.20 (3H, s, 4-CH3).
6-Chloro-2,3-Dihydro-7-methyl-2-((E)-1-phenylprop-1-en-2yl)
Photolysis of (2E,4E)-1-(2-hydroxyphenyl)-4-methyl-5-phenylpenta-
2,4-dien-1-one (3a). A deoxygenated solution of the compound 3a
(1.0mM) in dry methanol was irradiated with pyrex filtered
light from 125 W medium pressure mercury lamp for 90 min. The
color of the solution became light brown. Solvent was distilled off
under reduced pressure, and a gummy mass was obtained which
was then chromatographed over silica gel (100–200 mesh) using
benzene-petroleum ether as an eluent. Elution of the column gave
the starting compound and the isomeric photoproduct 4a.
(2E,4Z)-1-(2-Hydroxyphenyl)-4-methyl-5-phenylpenta-2,4-dien-
1-one (4a). Yield 36%; IR nmax (cm-1): 1665 (C=O), 3319 (OH);
1H NMR (CDCl3, 300 MHz) d 12.95 (1H, s, OH), 7.96 (1H, dd,
Jm =1.8Hz, Jo =8.7Hz, H-6′), 7.47 (1H, dt, Jm =1.2Hz,
Jo =7.8Hz, H-5′), 7.58 (1H, dt, Jm =1.5Hz, Jo =8.4Hz, H-4′), 8.06
(1H, d, Jtrans = 15.0 Hz, H-3), 7.09 (1H, d, Jtrans = 15.0 Hz, H-2),
7.01 (1H, s, H-5), 7.26–7.40 (5H, m, Phenyl protons), 2.18 (3H, s,
4-CH3).
chromen-4-one (4d′).
Yield 45%; White solid; mp 81ꢁC; IR
nmax (cm-1): 1687 (C=O); 1H NMR (CDCl3, 300 MHz) d 7.86
(1H, s, H-5), 6.95 (1H, s, H-8), 7.29–7.39 (5H, m, Phenyl protons),
6.68 (1H, s, H-2′), 4.95 (1H, dd, J2,3Hb =2.7, J2,3Ha = 12.9 Hz, H-2),
2.39 (3H, s, CH3), 2.99 (1H, dd, J3Ha,2 = 12.9, J3Ha,3Hb = 16.8 Hz,
Ha-3), 2.76 (1H, dd, J3Hb,2 =2.7, J3Hb,3Ha = 16.8 Hz, Hb-3), 2.01
(3H, s, CH3); 13C NMR (CDCl3, 75.4 MHz) d 189.23, 157.97,
143.30, 134.69, 132.68, 127.21, 126.41, 125.30, 126.84, 124.81,
118.28, 118.02, 81.23, 39.80, 29.09, 19.01, 12.05; Mass
(m/z, +Q1): 313 ([M + 1]+, 100); Anal. Calcd. for C19H17ClO2: C,
72.96; H, 5.48. Found: C, 72.92; H, 5.40.
Photolysis of (2E,4E)-1-(5-chloro-2-hydroxyphenyl)-4-methyl-5-
phenyl penta-2,4-dien-1-one (3e).
A methanolic solution of 3e
(1.0 mM) furnished 4e and 4e′ on photolysis for 90 min.
(2E,4Z)-1-(5-Chloro-2-hydroxyphenyl)-4-methyl-5-phenylpenta-
2,4-dien-1-one (4e).
Yield 28%; IR nmax (cm-1): 1631 (C=O),
3315 (OH); 1H NMR (CDCl3, 300 MHz) d 12.71 (1H, s, OH), 8.70
(1H, d, J= 18.4 Hz, H-3), 7.89 (1H, d, Jm =2.4Hz, H-6′), 7.05 (1H,
d, Jtrans = 18.4 Hz, H-2), 7.15 (1H, s, H-5), 7.27–7.39 (7H, m, H-4′,
5′, Phenyl protons), 2.21 (3H, s, 4-CH3).
Photolysis of (2E,4E)-1-(2-hydroxy-5-methylphenyl)-4-methyl-
5-phenyl penta-2,4-dien-1-one (3b). Photo-irradiation of metha-
nolic solution of 3b (1.0 mM) produced 4b in 90 min.
(2E,4Z)-1-(2-Hydroxy-5-methylphenyl)-4-methyl-5-phenylpenta-
6-Chloro-2,3-dihydro-2-((E)-1-phenylprop-1-en-2yl)chromen-4-
2,4-dien-1-one (4b).
Yield 41%; IR nmax (cm-1): 1632 (C=O),
one (4e′). Yield 39%; White solid; mp 84ꢁC; IR nmax (cm-1): 1698
3328 (OH); 1H NMR (CDCl3, 300MHz) d 12.63 (1H, s, OH), 7.63
(1H, d, Jm =1.5Hz, H-6′), 7.31(1H, dd, Jm =1.5Hz, Jo =8.4Hz, H-
4′), 6.91 (1H, d, Jo =8.4Hz, H-3′), 8.04 (1H, d, Jtrans = 15.3 Hz, H-
1
(C=O); H NMR (CDCl3, 300 MHz) d 7.79 (1H, d, Jm =2.7Hz,
H-5), 7.36 (1H, dd, Jm =2.7Hz, Jo = 9.0 Hz, H-7), 7.05–7.30
(5H, m, Phenyl protons), 6.94 (1H, d, Jo = 9.0 Hz, H-8), 6.61
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

July 2014
Photochemical Study of Chalconoid-like Compounds
953
[9] Jiang, Y. B.; Wang, X. J.; Lin, L. J Phys Chem 1994, 98, 2368.
[10] a) Kar, S.; Lahiri, S. Ind J Chem 2000, 40B, 1121; b) Si, Z. K.;
Zhang, Q.; Xue, M. Z.; Zhu, Y. Y.; Ming, L.; Sheng, Q. R.; Liu, Y. G.
Chin Chem Lett 2011, 22, 1025.
[11] Cibin, F. R.; Doddi, G.; Mencarelli, P. Tetrahedron 2003, 59, 3455.
[12] Cibin, F. R.; Bello, N. D.; Doddi, G.; Fares, B.; Mencarelli, P.;
Ullucci, E. Tetrahedron 2003, 59, 9971.
[13] Yayli, N.; Ucuncu, O.; Aydin, E.; Gok, Y.; Yasar, A.; Baltaci, C.;
Yildirium, N.; Kuruk, M. J Photochem Photobiol A: Chem 2005, 169, 229.
[14] a) Matsushima, R.; Fuzimoto, S.; Tokumura, K. Bull Chem
Soc Jpn 2001, 74, 827; b) Song, D.; Jung, K.; Moon, J.; Shin, D. Opt
Mater 2003, 21, 1.
(1H, s, H-2′), 4.90 (1H, dd, J2,3Hb = 2.4, J2,3Ha = 12.9Hz, H-2),
2.94 (1H, dd, J3Ha,2 = 13.2, J3Ha,3Hb = 16.8Hz, Ha-3), 2.62 (1H,
dd, J3Hb,2 = 2.4, J3Hb,3Ha = 16.8Hz, Hb-3), 1.94 (3H, s, CH3); 13C
NMR (CDCl3, 75.4 MHz) d 190.01, 157.83, 142.98, 135.01,
132.65, 127.26, 126.34, 125.31, 126.85, 124.76, 118.25, 117.97,
81.20, 40.18, 29.13, 12.02; Mass (m/z, +Q1): 299 ([M + 1]+, 100);
Anal. Calcd. for C18H15ClO2: C, 72.36; H, 5.06. Found: C, 72.25;
H, 5.05.
[15] a) Brack, T. L.; Conti, S.; Rodu, C.; Jurcsak, N. W.
Tetrahedron Lett 1999, 40, 3995; b) Montenegro, M. A.; Nazareno, M. A.;
Borsarelli, C. D. J Photochem Photobiol A: Chem 2007, 186, 47.
[16] Horiuchi, H.; Shirase, H.; Okutsu, T.; Matsushima, R.;
Hiratsuka, H. Chem Lett 2000, 96.
Acknowledgments. We thank the Council of Scientific and
Industrial Research (CSIR), New Delhi for the financial support
as junior research fellow for accomplishing this work.
[17] Matsushima, R.; Mizuno, H.; Kaziura, A. Bull Chem Soc Jpn
1994, 67, 1762.
[18] Matsushima, R.; Suzuki, M. Bull Chem Soc Jpn 1992, 65, 39.
[19] Matsushima, R.; Kato, K.; Ishigar, S. Bull Chem Soc Jpn
2002, 75, 2079.
REFERENCES AND NOTES
[1] a) Li, R.; Kenyon, G. L.; Cohen, F. E.; Chen, X.; Gong, B.;
Dominquez, J. N.; Davidson, E.; Kurzban, G.; Miller, R. E.;
Nuzum, E. O. J Med Chem 1995, 38, 5031; b) Venkatesan, P.;
Sumathi, S. J Heterocycl Chem 2010, 47, 81.
[20] a) Arai, T.; Norikane, Y. Chem Lett 1997, 339; b) Matsushima, R.;
Kageyama, H. J Chem Soc Perkin Trans II 1985, 743.
[21] Lap, B. V.; Williams, L. R.; Lim, C. H.; Jones, A. Aust J Chem
1979, 32, 619.
[22] Katritzky, A. R.; Ternai, B. J Heterocycl Chem 1968, 5, 745.
[23] Katekar, G. F. J Heterocycl Chem 1970, 7, 187.
[24] Haasnoot, C. A. G.; de Leeuw, F. A. A. M.; Altona, C.
Tetrahedron 1980, 36, 2783.
[2] Boeck, P.; Leal, P. C.; Yunes, R. A.; Filho, V. C.; López, S.;
Sortino, M.; Escalante, A.; Furlán, R. L. E.; Zacchin, S. J Archiv der
Parmarie 2005, 338, 85.
[3] Xia, Y.; Yang, Z.; Xia, P.; Bastow, K. F.; Nakanishi, Y.; Lee, K.
Bioorg Med Chem Lett 2000, 10, 699.
[4] a) Kim, Y. H.; Kim, J.; Park, H.; Kim, H. P. Biol Pharm Bull
2007, 30, 1450; b) Babasaheb, P. B.; Srikant, S. G. Bioorg Med Chem
2010, 18, 2060.
[25] Padwa, A.; Au, A.; Lee, G. A.; Owens, W. J Am Chem Soc
1976, 98, 3555.
[5] Kamboj, R. C.; Sharma, G.; Kumar, D.; Arora, R.; Sharma, C.;
Aneja, K. R. Int J ChemTech Res 2011, 3, 901.
[26] Nakashima, R.; Okamoto, K.; Matsuura, T. Bull Chem Soc Jpn
1976, 49, 3355.
[6] Bangal, P. R.; Lahiri, S.; Kar, S.; Chakravorti, S. J Lumin
1996, 69, 49.
[27] a) Greth, S.; Levy, O.; Markovits, M.; Shaw, A. Tetrahedron
1975, 31, 2803; b) Weller, A. Z Electrochem 1950, 60, 1144; c)
Goodman, J.; Brus, L. E. J Am Chem Soc 1978, 100, 7472; d) Rossetti, R.;
Haddon R. C.; Brus, L. E. J Am Chem Soc 1980, 102, 6913;
e) Becker, H. D. In The Chemistry of Hydroxyl Group; Patai, S. Ed.;
John Wiley and Sons Inc.: London, 1971; Part II, pp 894–920.
[28] Kamboj, R. C.; Berar, S.; Berar, U.; Thakur, M.; Gupta, S. C. J
Photochem Photobiol A: Chem 2009, 204, 122.
[7] Baeyens, P.; Krijl, G. Trans Inst Met Finish 1967, 45, 115.
[8] a) Wang, P.; Wu, S. J Lumin 1994, 62, 33; b) Poornesh, P.;
Shettigar, S.; Umesh, G.; Manjunatha, K. B.; Kamath, K. P.; Sarojini, B.
K.; Narayana, B. Opt Mater 2009, 31, 854; c) Shettigar, S.; Umesh, G.;
Chandrasekharan, K.; Sarojini, B. K.; Narayana, B. Opt Mater 2008,
30, 1297.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet