A novel and efficient synthetic method of benzo[f]chromen-1-ones and phenyl-4h-chromen-4-one through photooxidative cyclization of 6-[(E)-2-arylvinyl]-4H-pyran-4-ones and 6-[(1E,3E)-4-phenylbuta-1,3-dien-1-yl]-4H-pyran-4-one

Article abstract of DOI:10.1002/jhet.1694

A rapid and efficient microwave-assisted transformation of 2-pyrones into 4-pyrones is reported. Then, a new photocatalytic oxidative cyclization of 6-[(E)-2-arylvinyl]-2-methyl-4H-pyran-4-ones and 2-methyl-6-[(1E,3E)-4-phenylbuta-1,3-dien-1-yl]-4H-pyran-

Full text of DOI:10.1002/jhet.1694

1240
A Novel and Efficient Synthetic Method of Benzo[f]chromen-1-ones and
Phenyl-4H-chromen-4-one through Photooxidative Cyclization of 6-[(E)-
2-Arylvinyl]-4H-pyran-4-ones and 6-[(1E,3E)-4-Phenylbuta-1,3-dien-1-yl]-
4H-pyran-4-one
Vol 51
c
d
b
b
e
Nabila Aït-Baziz,a,b Safouane M. Hamdi, Artur M. S. Silva, Yahia Rachedi, Maamar Hamdi, and Mohamed Trari
*
aCentre de Recherche Scientifique et Technique en Analyses Physico-Chimiques, BP 248 RP, 16004 Algiers, Algeria
bFaculté de Chimie, Laboratoire de Chimie Organique Appliquée (Equipe Hétérocycles), Université des Sciences et de la
Techniques Houari Boumediene USTHB, BP 32, 16111 Algiers, Algeria
cLaboratoire de Biochimie, Institut Fédératif de Biologie, Centre Hospitalo-Universitaire de Toulouse et Université de
Toulouse, TSA 40031, 31059 Toulouse cedex 3, France
dDepartment of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal
eFaculté de Chimie, Laboratoire de Stockage et de Valorisation des Energies Renouvelables, Université des Sciences et de
la Techniques Houari Boumediene USTHB, BP 32, 16111 Algiers, Algeria
*
E-mail: safouane.hamdi@univ-tlse3.fr
Received December 18, 2011
DOI 10.1002/jhet.1694
Published online 30 January 2014 in Wiley Online Library (wileyonlinelibrary.com).
A rapid and efficient microwave-assisted transformation of 2-pyrones into 4-pyrones is reported. Then, a
new photocatalytic oxidative cyclization of 6-[(E)-2-arylvinyl]-2-methyl-4H-pyran-4-ones and 2-methyl-6-
[(1E,3E)-4-phenylbuta-1,3-dien-1-yl]-4H-pyran-4-one with UV light in the presence of a catalytic amount
of CuAlO2 is described. We obtained new 3-methyl-1H-benzo[f]chromen-1-ones and 2-methyl-5-phenyl-
4H-chromen-4-one that were fully characterized by spectroscopic techniques.
J. Heterocyclic Chem., 51, 1240 (2014).
INTRODUCTION
[(2E,4E)-5-phenylpenta-2,4-dienoyl]-2H-pyran-2-one 3 by a
Knoevenagel condensation.
Chromone derivatives constitute a large family of natu-
rally occurring heterocyclic compounds. Their synthesis
as well as their biological and pharmacological activities
have deserved a great attention during the last decades
[1]. Besides, dehydroacetic acid (DHAA) 1 (3-acetyl-4-
hydroxy-6-methyl-2H-pyran-2-one) is often investigated
because of its use for the synthesis of important organic
compounds used as food additives, antihypertensive, antimi-
crobial, insecticidal, and cosmetics [2–5]. Recently, we have
reported a simple procedure for the synthesis of substituted
alkenes by microwave-assisted Knoevenagel condensation
of DHAA 1 with benzaldehydes [6]. This method offers
important advantages over conventional heating conditions,
because it is a solvent free process, with shorter reaction
times, better yields, lower costs, and environmentally friendly.
Scheme 1 presents the reported general procedure for the
formation of 4-hydroxy-6-methyl-3-[(2E)-3-phenylprop-2-
enoyl]-2H-pyran-2-one 2a–f and 4-hydroxy-6-methyl-3-
The conversion of 2-pyrones (2 and 3) into 4-pyrones (4
and 5) (Scheme 2) has already been reported in the literature
[7–9] by a conventional reflux of 2-pyrones in a 1:1 mixture
of acetic acid/HCl for at least 8 h. A sequence of hydrolysis,
decarboxylation, and cyclization reactions was proposed by
Birch et al. to explain this transformation [8].
Taking into account our interest and knowledge on the use
of compound 2 as starting material in several early studies
[6,10,11] and on the photooxidative cyclization of (E)-2-
styrylchromones into benzo[a]xanthene-12-ones [12,13],
we decided to study the transformation of 2-pyrones 2a–f
and 3 into 4-pyrones 4a–f and 5, under microwave irradiation
and to compare these results with those using conventional
reflux. Finally, we developed a new synthetic method of
3-methyl-1H-benzo[f]chromen-1-ones 6a–f and 2-methyl-5-
phenyl-4H-chromen-4-one 7 by photocatalytic oxidative
cyclization of 6-[(E)-2-arylvinyl]-2-methyl-4H-pyran-4-ones
© 2014 HeteroCorporation

September 2014
Original Synthesis of Benzochromenones by Photocyclization
1241
Scheme 1
Scheme 2
the reaction time (from 4–5 h to 8–10min). It is also note-
worthy that we performed the rapid (8min) and efficient
(90% of yield) synthesis of 5 under microwave-assisted
transformation of 3.
4a–f and 2-methyl-6-[(1E,3E)-4-phenylbuta-1,3-dien-1-yl]-
4H-pyran-4-one 5, using CuAlO2 and catalyst.
RESULTS AND DISCUSSION
The structure of products 4a–f and 5 were confirmed
by mass spectrometry, 1H and 13C NMR, UV, and IR spec-
troscopy. Mass spectra of 4a–f confirm the decarboxyl-
According to Scheme 2, we carried out the acid-catalyzed
transformation of compounds 2a–f and 3 into 4a–f and 5
through conventional reflux heating conditions and micro-
wave-based procedures (the main reaction data are presented
in Table 1). From the results presented in Table 1, one can
conclude that synthesis of 4a–f was carried out under micro-
wave irradiation that provided increase in yield (0–17%), but
the most important aspect to notice is the huge reduction on
1
ation of compound 2. From the H NMR spectra, one can
assign the signals corresponding to the resonances of H-5
(as doublet) and H-3 (as double quartet) at respectively
dH 6.21–6.37 ppm (4JH5–H3 = 2.3 Hz) and dH 6.10–6.12
(4JH3–CH3 = 0.7 Hz). The resonances of H-10 and H-20 appear
as doublets at dH 7.00–7.24 and 7.53–7.95ppm (in some
Table 1
Comparison of conventional heating and microwave-based conversion of 2-pyrones 2a–f and 3–4-pyrones 4a–f and 5.
Products
Substituent R
H
Procedures
Reaction time (min)
Yield (%)
T (ꢀC)c
4a
4b
4c
4d
4e
4f
5
Aa
Bb
Aa
Bb
Aa
Bb
Aa
Bb
Aa
Bb
Aa
Bb
Aa
Bb
240
10
300
10
300
10
300
10
300
10
300
10
240
8
62
70
70
70
68
75
74
80
65
82
83
90
86
90
–
134
–
134
–
135
–
134
–
135
–
135
–
4-CH3
4-Cl
4-NO2
3-CH3
3-NO2
H
130
aReaction mixture submitted to the thermal reflux, using acetic acid/HCl (50%/50%) as solvent. bReaction mixture irradiated in a MW oven dedicated to
organic synthesis at 200 W, using acetic acid/HCl (75%/25%) as solvent. cTemperature at the end of the reaction.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

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N. Aït-Baziz, S. M. Hamdi, A. M. S. Silva, Y. Rachedi, M. Hamdi, and M. Trari
Vol 51
cases H-20 appears under a multiplet corresponding to the
resonances of the aromatic compounds). The coupling con-
however, the resonance of the new non-protonated C-10b of
6a–f and C-4a of 7 appear at dC 121.7–129.9 ppm.
stant value 3JH1 –H2 = 16.0–16.3 Hz suggests a trans config-
uration for this vinylic group. The same holds for the two
vinylic groups C10 = C20 and C30 = C40 of compound 5,
In the case of the compounds 4e and 4f bearing meta-CH3
and -NO2 substituents, we can consider two possibilities of
cyclization give rise to structures I or II (Figure 1). The
analysis of the HMBC spectra of 6e and 6f confirmed the
cyclization on the para-position relatively to the substituent,
because a connectivity between the proton H-10 and the
carbon C-10b of the pyran ring was observed (Figure 1).
This finding and some other connectivities observed in the
HMBC spectra of compounds 6a–f are in perfect agreement
with the structure II.
For the formation of compounds 6a–e and 7, one can
envisage the photochemical excitation of the enone system
followed by oxidative cyclization (Scheme 4). CuAlO2 has
been elaborated through the nitrate route in order to obtain
a large surface to volume ratio and to shorten the traveled
carriers’ path [15]. It crystallizes in the delafossite structure
and absorbs over the whole solar spectrum. In addition
to being inexpensive, CuAlO2 also shows an excellent
chemical stability over the whole pH range and can be
easily recovered at the end of the reaction. The proposal
mechanism for the formation of 6a–f and 7 may involve a
trans ! cis isomerisation of the vinylic system, which facil-
itates the cyclization by photocatalytic oxidative cyclization
according to the reaction sequence depicted in Scheme 4.
0
0
which are also, according to the coupling constants (3JH1 –
0
3
3
0
0
0
0
0
= 16.2 Hz, JH3 –H4 = 16.0 Hz and JH2 –H3 = 11.0 Hz),
H2
in the trans-s-trans configuration [13]. Overall, the data
confirm that the compounds obtained are those expected and
that the proposed sequence of hydrolysis, decarboxylation,
and cyclization reactions occurred [8].
The next step in our study was the cyclization of 4a–f
and 5 according to the conditions described by previous
reports [12,13]; that is exposition of chloroform or ethanol
solutions of these compounds to daylight and UV irradia-
1
tion. The progress of the reactions was followed by H
NMR for 2 weeks but no change had been detected. This
result prompted us to use a known photocatalytic oxidative
cyclization using delafossite as catalyst. The delafossite
family has attracted much attention because of their
technological importance for catalytic, photocatalytic and
more recently environment-friendly properties [14].
The photooxidative cyclization of 4a–f and 5 was
performed in ethanol using CuAlO2 (10% of the mass of
subtract) previously prepared from CuO, Al(NO3)3, and
HNO3 [15] (Scheme 3). The mixture was maintained in a
double-walled pyrex reactor and exposed to UV light for
24 h, and in each case, one pure product has been isolated
in a high yield (averaging 90–95%).
The mass spectra of compounds 6a–f and 7 [15] confirmed
that a dehydrogenation reaction occurred because the
molecular ions indicate the loss of 2 Da peaks relatively to
those of the starting materials 2a–f and 3, respectively. From
the analysis of the 1H NMR spectra and HSQC experiments
of all compounds 6a–f and 7, one can assign the resonance
of H-3 (6a–f) and H-2 (7) as a quartet (4 J~0.7Hz) at dH
6.01–6.10 ppm and confirm the absence of the resonance due
to H-5 of the starting materials 2a–f and 3. In the 13C NMR
of 4-pyranones 4a–f and 5, the signals corresponding to
the resonance of protonated C-3 appear at dC 113–115 ppm;
Figure 1. Two possibilities of cyclization give rise to structures I or II.
Scheme 3
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

September 2014
Original Synthesis of Benzochromenones by Photocyclization
1243
Scheme 4
CONCLUSION
CuAlO2 has been synthesized by chemical co-precipitation
[15]. Stoichiometric amounts of CuO (pre-fired at 400 ꢀC) and
Al(NO3)3.9H2O were dissolved in concentrated HNO3 (6 N).
The blue solution was dehydrated in a sand bath until dryness.
Then, the amorphous powder was fired in an air oven at 700 ꢀC.
The reaction was completed usually after two thermal treatments
at 950 ꢀC. Unreacted Cu2O was removed by soaking the powder
in NH4OH (5 N). The end product exhibits a blue color and the
phase was confirmed by XRD using CuK2 radiation.
We have demonstrated that the conversion of 4-hydroxy-
6-methyl-3-[(2E)-3-arylprop-2-enoyl]-2H-pyran-2-ones 2a–f
and 4-hydroxy-6-methyl-3-[(2E,4E)-5-phenylpenta-2,4-dienoyl]-
2H-pyran-2-one 3 into 2-methyl-6-[(E)-2-arylvinyl]-4H-pyran-
4-ones 4a–f and 2-methyl-6-[(1E,3E)-4-phenylbuta-1,
3-dien-1-yl]-4 H-pyran-4-one 5 is greatly facilitated by micro-
wave irradiation. Moreover, the reaction times are dramati-
cally reduced. Further, we have shown that compounds 4a–f
and 5 undergo an efficient photocatalytic oxidative cycliza-
tion, using CuAlO2 as catalyst, to give 3-methyl-1H-benzo
[f]chromen-1-ones 6a–f and 3-methyl-9-phenyl-1H-benzo[f]
chromen-1-one 7. Studies of the reactivity of these new com-
pounds as well as their biological applications are in progress.
General procedure for the synthesis of 2-methyl-6-[(E)-2-
arylethenyl]-4H-pyran-4-ones 4a-f and 2-methyl-6-[(1E,3E)-
4-phenylbuta-1,3-dienyl]-4H-pyran-4-one 5.
A solution of 3-
[(2E)-3-arylprop-2-enoyl]-4-hydroxy-6-methyl-2H-pyran-2-ones 2a–
f or 4-hydroxy-6-methyl-3-[(2E,4E)-5-phenylpenta-2,4-dienoyl]-2H-
pyran-2-one 3 (5 mmol) in of acetic acid (10 mL) and of HCl
(10 mL) was refluxed with stirring for 4–5 h. After extraction by
chloroform (3 ꢂ 50 mL) and washing by diethyl ether, compounds
4a–f and 5 were obtained without crystallization. The purity was
then confirmed by thin layer chromatography.
EXPERIMENTAL
2-Methyl-6-[(E)-2-phenylethenyl]-4H-pyran-4-one (4a). This
compound was obtained as yellow powder. Yield: 66%; mp
121–122 ꢀC.1H NMR (DMSO-d6): d 2.33 (d, 3H, 2-CH3,
JCH3-H3 = 0.7 Hz), 6.11 (dq, 1H, H-3, JH3–CH3 = 0.7 Hz,
JH3–H5 = 2.3 Hz), 6.30 (d, 1H, H-5, JH5–H3 = 2.03 Hz), 7.03
The microwave-assisted organic reactions were performed in
an Ethos SYNTH microwave (Milestone Inc., Shelton, CT) dedi-
cated to the organic synthesis. The photooxidative cyclization
was performed in a small-sized pyrex reactor (250 mL), with a
double jacket connected to a thermostated bath, regulated at
30 ꢁ 0.1 ꢀC. The light source consisted of halogen lamp (500
W, OSRAM, Munich, Germany). Melting points were deter-
mined on a Stuart scientific SPM3 apparatus fitted with a micro-
scope and are uncorrected. 1H and 13C NMR spectra were
recorded in DMSO solutions, on a Bruker Avance 300 spectrom-
eter (Bruker Biospin SAS, Wissembourg, France), operating at
300.13 and 75.47 MHz, respectively; the chemical shifts are
expressed in ppm (d) and coupling constants (J) are giving in
Hz. 1H and 13C NMR assignments were made by using HSQC
and HMBC experiments. Electron impact mass spectra were
obtained at 70eV electron impact ionization using Nermag R 10-
10C quadruple mass spectrometer (Nermag SA, Rueil Malmaison,
France). Infrared spectra were recorded on a Magna-IR 550 series II
Nicolet apparatus, using potassium bromide pellets. UV spectra
were recorded on Cary 50 Scan UV-Visible spectrometer (Agilent
Technologies, Massy, France) in chloroform solutions(Spectralab
Scientific Inc., Ontario, Canada). A (8/2v/v) mixture of CH2Cl2/
CH3OH has been used for the TLC analysis.
(d, 1`H, H-10, JH1 –H2 = 16.3 Hz), 7.55 (m, 6H, H-2 and H-Ph);
13C NMR (DMSO-d6): d 19.1 (2-CH3), 113.0 (C-5), 113.4
(C-3), 120.0 (C-10), 127.4 (C-50,70), 128.8 (C-40,80), 134.7
(C-30), 129.4 (C-60) 134.9 (C-20), 161.3 (C-6), 165.3 (C-2),
178.1 (C-4); EIMS: m/z (rel. int.) 212 (M+., 74); IR: (n, cm-1)
3050, 1668, 1612, 1392; UV: lmax 334 (e 152.100). Anal.
Calcd for C14H12O2: C 79.22, H 5.70. Found: C 79.15, H 5.38%.
6-Methyl-2-[(E)-2-(4-methyphenyl)ethenyl]-4H-pyran-4-one
(4b). This compound was obtained as yellow powder. Yield 70%;
mp. 120–121 ꢀC; 1H NMR (DMSO-d6): d 2.31 (d, 3H, 2-CH3,
JCH3–H3 = 0.7 Hz), 2.31 (s, 3H, 60-CH3), 6.12 (dq, 1H, H-3,
0
0
JH3-CH3 =0.7Hz, JH3–H5 = 2.4 Hz), 6.21 (d, 1H, H-5, JH5–H3
0
=2.3 Hz), 7.05 (d, 1H, H-10, JH1 –H2 = 16.0 Hz), 7.54 (m, 5H, H-2
0
0
13
and C6H4); C NMR (DMSO-d6): d 19.1 (2-CH3), 21.3 (60-CH3),
113.1 (C-5), 113.6 (C-3), 119.8 (C-10), 127.3 (C-30), 130.1
(C-50,70), 128.1 (C-40,80), 125.3 (C-20), 160.4 (C-60), 161.8 (C-6),
165.1 (C-2), 178.0 (C-4); EIMS: m/z (rel. int.) 242 (M+., 53); IR:
(n, cm-1) 3000, 1662, 1618, 1381; UV: lmax 333 (e 156.100). Anal.
Calcd for C15H14O2: C 79.62, H 6.24. Found: C 79.48, H 6.10%.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

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N. Aït-Baziz, S. M. Hamdi, A. M. S. Silva, Y. Rachedi, M. Hamdi, and M. Trari
Vol 51
2-[(E)-2-(4-Chlorophenyl)ethenyl]-6-methyl-4H-pyran-4-one
UV: lmax 323 (e 126.000). Anal. Calcd for C16H14O2: C
80.65, H 5.92. Found: C 80.48, H 5.87%.
(4c).
This compound was obtained as yellow small crystals.
Yield 72%; mp 110–111 ꢀC; 1H NMR (DMSO-d6): d 2.31 (d, 3H,
2-CH3, JCH3–H3 = 0.8 Hz), 6.10 (dq, 1H, H-3, JH3–CH3 = 0.8 Hz,
General procedure for the synthesis of 3-methyl-1H-benzo
[f]chromen-1-ones 6a-f and 2-methyl-5-phenyl-4H-chromen-
4-one 7. A mixture of 6-[(E)-2-arylethenyl]-2-methyl-4H-pyran-
4-ones 4a–f or 2-methyl-6-[(1E,3E)-4-phenylbuta-1,3-dienyl]-4H-
pyran-4-one 5 (5 mmol) and CuAlO2 (10% in mass of subtract) in
ethanol (30 mL) was subjected to halogen lamp illumination with
stirring for 24 h. After filtration and crystallization in ethanol,
compounds 6a–f and 7 were obtained.
3-Methyl-1H-benzo[f]chromen-1-one (6a). This compound
was obtained as colored powder. Yield 94%; mp. 190–191 ꢀC; 1H
NMR (DMSO-d6): d 2.10 (d, 3H, 3-CH3), 6.01 (q, 1H, H-2), 7.41
(d, 1H, H-5), 7.64 (d, 1H, H-10), 7.70 (m, 1H, H-9), 7.76 (m, 1H,
H-8), 7.91 (dd, 1H, H-7), 8.15 (dd, 1H, H-6); 13C NMR (DMSO-
d6): d 19.2 (3-CH3), 113.3 (C-2), 117.1 (C-5), 122.6 (C-10b),
126.7 (C-8), 127.5 (C-10), 128.6 (C-9), 128.8 (C-6a), 130.1
(C-10a), 130.8 (C-7), 138.7 (C-6), 157.2 (C-4a), 166.1 (C-3),
179.8 (C-1); EIMS: m/z (rel. int.) 210 (M+., 90); IR: (n, cm-1)
3030, 1643, 1629, 1315; UV: lmax 322 (e 123.900). Anal. Calcd
for C14H10O2: C 79.98, H 4.79. Found: C 79.72, H, 4.63%.
JH3–H5 = 2.3 Hz), 6.29 (d, 1H, H-5, JH5–H3 = 2.3 Hz), 7.03 (d, 1H,
H-10, JH1 –H2 = 16.2Hz), 7.53 (m, 5H, H-2 and C6H4); 13C NMR
(DMSO-d6): d 19.1 (2-CH3), 113.2 (C-5), 113.5 (C-3), 120.8
(C-10), 133.3 (C-30), 128.6 (C-50,70), 129.1 (C-40,80), 133.6 (C-20),
133.9 (C-60), 161.6 (C-6), 165.3 (C-2), 178.6 (C-4); EIMS: m/z
(rel. int.) 246 (M+., 80); IR: (n, cm-1) 3000, 1678, 1612, 1386;UV:
lmax 335 (e 148.900). Anal. Calcd for C14H11ClO2: C 68.16, H
4.49. Found: C 68.02, H, 4.36%.
0
0
0
2-[(E)-2-(4-Nitrophenyl)ethenyl]-6-methyl-4H-pyran-4-one
(4d). This compound was obtained as colored powder. Yield:
1
81%; mp. 208–209 ꢀC; H NMR (DMSO-d6): d 2.33 (d, 3H, 2-
CH3, JCH3–H3 = 0.7 Hz), 6.11 (dq, 1H, H-3, JH3–CH3 = 0.7 Hz,
JH3–H5 = 2.3 Hz), 6.37 (d, 1H, H-5, JH5–H3 = 2.3 Hz), 7.24 (d,
1H, H-10, JH1 -H20 = 16.2 Hz), 7.95 (m, 5H, H-20 and C6H4); 13C
0
NMR (DMSO-d6): d 19.1 (2-CH3), 113.6 (C-5), 114.6 (C-3),
124.4 (C-10), 141.5 (C-30),123.9 (C-50,70), 128.4 (C-40,80), 132.2
(C-20), 129.4 (C-60), 160.5 (C-6), 165.5 (C-2), 178.6 (C-4);
EIMS: m/z (rel. int.) 257(M+., 100); IR: (n, cm-1) 3040, 1676,
1601,1389; UV: lmax 331 (e 148.200). Anal. Calcd for
C14H11NO4: C 65.37, H 4.31. Found: C 65.20, H 4.27%.
3,9-Dimethyl-1H-benzo[f]chromen-1-one
(6b).
This
compound was obtained as colored small crystals. Yield 92%;
1
mp. 194–195 ꢀC; H NMR (DMSO-d6): d 2.10 (d, 3H, 3-CH3),
2-Methyl-6-[(E)-2-(3-methylphenyl)ethenyl]-4H-pyran-4-one
(4e). This compound was obtained as colored powder. Yield:
2.48 (d 3H, 9-CH3), 6.04 (q, 1H, H-2), 7.41 (d, 1H, H-5), 7.68
(d, 1H, H-10), 7.74 (m, 1H, H-9), 8.10 (dd, 1H, H-7), 8.06 (dd,
1H, H-6); 13C NMR (DMSO-d6): d 19.1 (3-CH3), 21.2 (9-CH3),
113.3 (C-2), 122.6 (C-10b), 117.0 (C-5),138.5 (C-6), 128.6
(C-6a), 135.3 (C-7), 120.1 (C-8), 140.0 (C-9), 122,8 (C-10),
133.1 (C-10a), 156.8 (C-4a), 166.1 (C-3), 179.8 (C-1); EIMS:
m/z (rel. int.) 240 (M+., 100); IR: (n, cm-1) 3024, 1644, 1623,
1
74% mp 113–114 ꢀC; H NMR (DMSO-d6): d 2.31 (d, 3H, 2-
CH3, JCH3–H3 = 0.7 Hz), 2.33 (s, 3H, 50-CH3) 6.12 (dq, 1H, H-3,
JH3–CH3 = 0.7 Hz, JH3–H5 = 2.3 Hz), 6.28 (d, 1H, H-5, JH5-
0
H3 = 2.3 Hz), 7.00 (d, 1H, H-10, JH1 –H20 = 16.1 Hz), 7.95 (m, 5H,
H-20 and C6H4); 13C NMR (DMSO-d6): d 19.8 (2-CH3), 21.3
(50-CH3), 114.1 (C-5), 113.3 (C-3), 119.3 (C-10), 124.7 (C-80),
128.1 (C-70), 128.8 (C-40), 130.5 (C-60), 134.8 (C-20 and C-30),
138.6 (C-50), 161.9 (C-6), 165.0 (C-2), 180.3 (C-4); EIMS: m/z
(rel. int.) 226 (M+., 100); IR: (n, cm-1) 3063, 1675, 1607, 1379;
UV: lmax 334 (e 172.800). Anal. Calcd for C15H14O2: C 79.62,
H 6.24. Found: C 79.48, H 6.12%.
1360; UV: lmax 322 (e 127.100). Anal. Calcd for C15H12O2:
C
80.34, H 5.39. Found: C 80.07, H 5.20%.
9-Chloro-3-methyl-1H-benzo[f]chromen-1-one (6c).
This
compound was obtained as colored powder. Yield 90%; mp
1
201–202 ꢀC; H NMR (DMSO-d6): d 2.08 (d, 3H, 3-CH3), 6.05
(q, 1H, H-2), 7.39 (d, 1H, H-5), 7.5 (d, 1H, H-10), 7.40 (m, 1H,
H-8), 7.86 (m, 1H, H-7), 8.07 (m 1H, H-6); 13C NMR (DMSO-d6):
d 19.2 (3-CH3), 113.3 (C-2), 117.1 (C-5), 120.0 (C-8),
121.7 (C-10b), 127.8 (C-6a), 132.5 (C-8), 133.0 (C-10a), 135.1
(C-7),138.9 (C-9 and C-6), 157.3 (C-4a), 166.1 (C-3), 179.7
(C-1); EIMS: m/z (rel. int.) 244 (M+., 100); IR: (n, cm-1) 3019,
1648, 1623, 1360; UV: lmax 323 (e 113.000) . Anal. calcd for
2-[(E)-2-(3-Nitrophenyl)ethenyl]-6-methyl-4H-pyran-4-one
(4f). This compound was obtained as yellow powder. Yield:
1
90%; mp. 181–182 ꢀC; H NMR (DMSO-d6): d 2.32 (s, 3H, 2-
CH3), 6.12 (s, 1H, H-3), 6.37 (d, 1H, H-5, JH5–H3 = 2.0 Hz),
0
7.08 (d, 1H, H-10, JH1 –H20 = 16.0 Hz), 7.80 (m, 5H, H-20 and
C6H4); 13C NMR (DMSO-d6): d 19.1 (2-CH3), 114.4 (C-5),
115.0 (C-3), 124.4 (C-10), 130.0 (C-30), 124.9 (C-40), 133.6 (C-60),
148.3 (C-30), 128.5 (C-40), 130.9 (C-20), 130.9 (C-50), 160.7 (C-6),
165.5 (C-2), 180.1 (C-4); EIMS: m/z (rel. int.) 257 (M+., 67); IR:
(n, cm-1) 3030, 1673, 1611, 1378; UV: lmax 332 (e 135.000).
Anal. Calcd for C14H11NO4: C 65.37, H 4.31. Found: C 65.20,
H 4.10%.
C
14H9ClO2: C 68.72, H 3.71. Found: C 68.47, H 3.59%.
3-Methyl-9-nitro-1 H-benzo[f]chromen-1-one (6d).
This
compound was obtained as colored powder. Yield 93%; mp
1
220–221 ꢀC; H NMR (DMSO-d6): d 2.11 (d, 3H, 3-CH3), 6.08
(q, 1H, H-2), 7.42 (d, 1H, H-5), 8.10 (m, 1H, H-6), 8.34 (d, 1H,
H-10), 8.40 (1H, H-8), 8.42 (m, 1H, H-7); 13C NMR (DMSO-d6):
d 19.2 (3-CH3), 112.9 (C-10), 113.3 (C-2), 114.9 (C-5), 121.8
(C-8), 127.1 (C-10b), 127.7 (C-7), 130.1 (C-6a), 130.2 (C-10a),
141.1 (C-6), 150.3 (C-9), 159.5 (C-4a), 166.2 (C-3), 179.8 (C-1);
EIMS: m/z (rel. int.) 255 (M+., 100); IR: (n, cm-1) 3023, 1650,
1629,1357; UV: lmax 322 (e 121.300). Anal. Calcd for
C14H9NO4: C 65.88, H 3.55. Found: C 65.72, H 3.47%.
2-Methyl-6-[(1E,3E)-4-phenylbuta-1,3-dienyl]-4H-pyran-4-
one (5).
This compound was obtained as yellow small
crystals. Yield 91%; mp 140–141 ꢀC; 1H NMR (DMSO-d6): d
2.32 (d, 3H, 2-CH3, JCH3–H3 = 0.7 Hz), 6.12 (dq, 1H, H-3,
JH3–CH3 = 0.7 Hz, JH3–H5 = 2.3 Hz), 6.36 (d, 1H, H-5, JH5–
H3 = 2.3 Hz), 6.93 (d, 1H, H-10, JH1 –H2 = 16.2 Hz), 7.12 (dd,
0
0
3
1H, H-20, JH2 –H1 = 16.2 Hz, JH2 –H3 = 11.0 Hz), 7.40 (dd, 1H,
0
0
0
0
3
H-30, JH3 –H2 = 11.0 Hz, JH3 –H4 = 16.0 Hz), 7.58 (m, 6H, H-
40, H-Ph); 13C NMR (DMSO-d6): d 19.1 (2-CH3), 113.0
(C-5), 113.5 (C-3), 120.1 (C-10), 125.5 (C-30), 127.5 (C-50,70),
129.2 (C-40,80), 128.8 (C-40), 131.1 (C-20), 134.7 (C-30),129.4
(C-50), 161.3 (C-6), 165.2 (C-2), 178.0 (C-4); EIMS: m/z (rel.
int.) 238 (M+., 59); IR: (n, cm-1) 3023, 1666, 1604, 1349;
3,8-Dimethyl-1H-benzo[f]chromen-1-one
(6e).
This
0
0
0
0
compound was obtained as colored small crystals. Yield 92%;
1
mp. 190–191 ꢀC; H NMR (DMSO-d6): d 2.10 (d, 3H, 3-CH3),
2.48 (s, 3H, 8-CH3), 6.04 (q, 1H, H-2), 7.41(d, 1H, H-5), 7.68
(d, 1H, H-10), 7.74 (m, 1H, H-9), 8.06 (dd, 1H, H-6), 8.10 (dd,
1H, H-7), 13C NMR (DMSO-d6): d 19.2 (3-CH3), 21.1 (8-CH3),
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

September 2014
Original Synthesis of Benzochromenones by Photocyclization
1245
REFERENCES AND NOTES
113.3 (C-2), 116.2 (C-5), 121.9 (C-10b), 125.1 (C-10), 128.5 (C-10a),
128.8 (C-6a), 130.3 (C-9), 132.8 (C-6), 135.8 (C-7 and C-8),
157.3 (C-4a), 166.1 (C-3), 1 79.8 (C-1); EIMS: m/z (rel. int.) 224 (M+.,
75); IR: (n, cm-1) 3010, 1643, 1612, 1325; UV: lmax 322 (e 121.400).
Anal. Calcd for C15H12O2: C 80.34, H 5.39. Found: C 80.10, H 5.23%.
[1] Ellis, G. P. Chemistry of Heterocyclic Compound: Chromenes,
Chromanones and Chromones; John Wiley: New-York, 2007; Vol. 31, pp
1–10 and pp 495–555.
[2] Rehse, K.; Schinkel, W.; Siehann, U. Arch Pharm Pharm Med
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[3] Tkalcevic, K.; Durakovic, S.; Susnik-Rybarski, I.; Urakovic,
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38, 299.
[4] Piwowar, T. S. Int J Toxicol 1985, 4, 123.
[5] Gazzaniga, A.; Sangolli, M. E.; Giordano, F.; Conte, U.;
Semenzato, A.; Bettero, A. Int J Cosmetic Sci 1994, 16, 105.
[6] Ait-Baziz, N.; Rachedi, Y.; Chemat, F.; Hamdi, M. Asian J
Chem 2008, 20, 2610.
[7] Willey, R. H.; Jarboe, C. H.; Ellert, H. G. J Am Chem Soc
1955, 77, 5102.
[8] Birch, A. J.; Cameron, D. W.; Rickards, R. W. J Chem Soc
1960, 4395.
[9] Takeuchi, N.; Murase, M.; Ochi, K.; Tobinaga, S. J Chem Soc
Chem Commun 1976, 20, 820.
[10] Aït-Baziz, N.; Rachedi, Y.; Hamdi, M.; Silva, A. M. S.;
Balegroune, F.; Roisnel, T.; Sellier, N. J Heterocycl Chem 2004,
41, 587.
[11] Aït-Baziz, N.; Rachedi, Y.; Hamdi, M.; Silva, A. M. S. J Soc
Alger Chim 2007, 17, 195.
[12] Silva, A. M. S.; Pinto, D. C. G. A.; Cavaleiro, J. A. S.; Levai,
A.; Tamás, P. Arkivoc 2004, vii, 106.
[13] Silva, A. M. S.; Pinto, D. C. G. A.; Tavares, H.R.; Cavaleiro, J.
A. S.; Jimeno, M. L.; Elguero, J. Eur J Org Chem 1998, 2031.
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158, 257.
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2005, 78, 574.
3-Methyl-8-nitro-1H-benzo[f]chromen-1-one (6f).
This
compound was obtained as colored small crystals. Yield 93%;
1
mp 210–211 ꢀC; H NMR (DMSO-d6): d 2.09 (d, 3H, 3-CH3),
6.08 (q, 1H, H-2), 7.62 (d, 1H, H-5), 7.70 (d, 1H, H-10), 8.20
(m, 1H, H-9), 8.36 (dd, 1H, H-6), 8.92 (dd, 1H, H-7); 13C
NMR (DMSO-d6): d 19.2 (3-CH3), 113.3 (C-2), 125.0 (C-10b),
119.2 (C-5), 136.9 (C-6), 126.8 (C-6a), 131.1 (C-7), 147.9 (C-8),
124.6 (C-9), 126.9 (C-10), 132.2 (C-10a), 154.6 (C-4a), 166.2
(C-3), 180.1 (C-1); EIMS: m/z (rel. int.) 255 (M+., 55); IR: (n, cm-1)
3010, 1642, 1622, 1358; UV: lmax 322 (e 117.200). . Anal. Calcd.
for C14H9NO4: C 65.88, H 3.55. Found: C 65.72, H 3.49%.
2-Methyl-5-phenyl-4 H-chromen-4-one (7). This compound
1
was obtained as colored powder. Yield 95%; mp 190–191 ꢀC; H
NMR (DMSO-d6): d 2.12 (d, 3H, 2-CH3), 6.10 (q, 1H, H-3), 6.72
(d, 1H, H-8), 6.89 (d, 1H, H-7), 7.52–7.79 (m, 6H, H-6, H-Ph);
13C NMR (DMSO-d6): d 19.1 (2-CH3), 111.2 (C-3), 124.2 (C-6),
125.2 (C-8), 127.9 (C-30,50), 128.6 (C-20,60), 129.9 (C-4a), 130.2
(C-40), 133.8 (C-7), 140.1 (C-5), 153.7 (C-10), 157.4 (C-8a), 164.7
(C-2), 179.4 (C-4); EIMS: m/z (rel. int.) 236 (M+., 70); IR: (n, cm-1)
3001, 1649, 1623, 1376; UV: lmax 321 (e 123.000). Anal. calcd.
for C16H12O2: C 81.34, H 5.12. Found: C 81.22, H 4.95%.
Acknowledgment. Thanks are due to the University of Aveiro,
FCT, and FEDER for funding the Organic Chemistry Research
Unit (project PEst-C/QUI/UI0062/2011) and the Portuguese
National NMR Network (RNRMN).
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet