Novel approaches for the synthesis of a library of fluorescent chromenopyrimidine derivatives

Article abstract of DOI:10.1021/co300141j

A library of some new fluorescent chromenopyrimidine derivatives has been synthesized by new approaches. Water-promoted and one-pot reaction can produce new dialkylylamino)-5H-chromeno[2,3-d]pyrimidin-2-yl) phenols. These compounds can also be produced using domino reaction. Two parallel methods are compared. Novel N-alkyl-N-phenyl-5H-chromeno[2,3-d]-pyrimidin-4-amines and 4-alkoxy-5H-chromeno[2, 3-d]pyrimidines are synthesized by Lewis-acid catalyzed reactions. The fluorescence emission intensity of the four compounds from each of libraries after excitation in 290 nm is measured. Compound 2-(4,5-bis(N-methyl-N-phenylamino)-5H-chromeno[2,3-d]pyrimidin-2-yl)phenol was isolated as a byproduct. The details of an interesting exchangeable intramolecular H- bonding of two of the new compounds are reported by X-ray analysis data.

Full text of DOI:10.1021/co300141j

Research Article
pubs.acs.org/acscombsci
Novel Approaches for the Synthesis of a Library of Fluorescent
Chromenopyrimidine Derivatives
Afsaneh Zonouzi,*,† Fatemeh Hosseinzadeh,† Nastaran Karimi,† Roghieh Mirzazadeh,†
and Seik Weng Ng‡,§
†School of Chemistry,University College of Science, University of Tehran, Tehran, Iran
‡Department of Chemistry, University of Malaya, 50603 Kuala Lumpour, Malaysia
§Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
S
* Supporting Information
ABSTRACT: A library of some new fluorescent chromeno-
pyrimidine derivatives has been synthesized by new
approaches. Water-promoted and one-pot reaction can
produce new dialkylylamino)-5H-chromeno[2,3-d]pyrimidin-
2-yl) phenols. These compounds can also be produced using
domino reaction. Two parallel methods are compared. Novel
N-alkyl-N-phenyl-5H-chromeno[2,3-d]-pyrimidin-4-amines
and 4-alkoxy-5H-chromeno[2, 3-d]pyrimidines are synthesized
by Lewis-acid catalyzed reactions. The fluorescence emission
intensity of the four compounds from each of libraries after
excitation in 290 nm is measured. Compound 2-(4,5-bis(N-methyl-N-phenylamino)-5H-chromeno[2,3-d]pyrimidin-2-yl)phenol
was isolated as a byproduct. The details of an interesting exchangeable intramolecular H- bonding of two of the new compounds
are reported by X-ray analysis data.
KEYWORDS: green procedure, chromenopyrimidine, fluorescent, intramolecular H-bonding, one-pot reaction, Lewis acid
using a one-pot reaction of salicylaldehyde derivatives,
malononitrile, and some other secondary amines. We have
found that imino-2H-chromen-3-carbonitrles (iminocoumar-
ines) 2 are produced as intermediates in the above-mentioned
reaction. When we started the reaction by iminocoumarines,
salicylaldehydes and secondary amines in H2O as the solvent,
the products 6 were obtained again. We compared these two
parallel procedures. The present research also focused on the
reaction of iminocoumarines 2 with aromatic amines and
alcohols as nucleophiles. When we used aromatic secondary
amines instead of aliphatic amines in the above procedure, the
yields were poor, probably because of their lower nucleophil-
icity. Between the different Lewis acids used, 15 mol % CuCl
proved to be the best. Using this catalyst, a small library of
compounds 7 was produced. Finally, we tested the reaction of
iminocoumarines in alcohol as solvent. Although there are
some reports on the synthesis of chromenopyrimidine
derivatives in alcohols as solvent, to our surprise, alcohols
acted as a reactant and produced the compounds 8. In this
procedure, inexpensive Lewis acid ZnCl2 catalyzed the reaction.
There is also an interesting, exchangeable, intramolecular H-
bonding in these structures. The details of this H-bonding has
been presented for two of the derivatives.
INTRODUCTION
■
Development of efficient methods and strategies for the
combinatorial synthesis of organic compounds is of interest,
especially for the organic compounds with potential biological
and medicinal activities.1 On the one hand, multicomponent
reactions (MCRs) are of increasing significance in organic and
medicinal chemistry. MCRs allow organic compounds to be
synthesized in a few steps or in a one-pot operation.2 On the
other hand, optoelectronic devices, such as fiber switchers,
tunable lasers and amplifiers, and modulators with various
applications need compounds emitting in the blue spectral
region. There are many reports on using fluorescent
compounds in biochemical and medical research.3 Design of
new multicomponent synthetic approaches for the synthesis of
diverse fluorescent compounds can be interesting. Among
various synthetic strategies in the literature for the synthesis of
pyrimidine derivatives, some reports the synthesis of libraries of
these compounds.4 In 2010, we reported a multicomponent,
one-pot solvent-free, microwave-assisted synthesis of
chromeno[2,3-d]pyrimidines by a condensation reaction of 2-
hydroxybenzldehyde derivatives (salicylaldehyde), malononi-
trile and secondary amines.5a Following our previous research
on multicomponent reactions,5 we now report novel
approaches for the synthesis of a library of fluorescent
chromenopyrimidine derivatives. We have used water without
the aid of microwave irradiation or any catalysts to synthesize
dialkylamino-5H-chromeno[2,3-d]pyrimidin-2-yl-phenols 6
Received: November 29, 2012
Revised: March 25, 2013
© XXXX American Chemical Society
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clean purification of the products (filtration followed by
recrystallization).
Reaction times and yields of the new compounds synthesized
RESULTS AND DISCUSSION
■
One of the key areas of green chemistry is the elimination of
catalysts and solvents in chemical processes or the replacement
of hazardous solvents with relatively benign solvents. H2O is
the best solvent for this purpose.6 Considering this point and in
continuation of our quest for developing a one-pot procedure
for heterocylic frameworks,5 we now report new environ-
mentally benign approaches for the synthesis of a library of
some new fluorescent chromenopyrimidine derivatives 6, 7, 8,
and 9. Diverse reagents which have been used in the present
approaches are listed in Chart 1.
by this procedure are listed in Scheme 1.
Scheme 1. Synthesis of Water-Promoted One-Pot Reaction
of 6
Amino-5H-chromeno[2,3-d]pyrimidine-2-yl-phenols 6 have
been produced in water by heating the reaction mixtures at
about 80 °C for 8−10 h. Using H2O afforded a simple and
Chart 1. Diverse of Reagents
Imino-2H-chromen-3-carbonitrles (iminocoumarines) are
interesting, reactive compounds because of their potential to
react with both electrophiles and nucleophiles. In continuation
of our previous research and to better clarify the reaction
mechanism, a different synthesis of the same products was
designed as a parallel procedure. Using iminocoumarins as the
reactants (they can be synthesized by the condensation of
salicylaldehydes and malononitrile7), salicylaldehydes and
secondary amines in H2O as solvent produced the same
products 6. Times and yields of the reactions were similar
across the tested conditions (8−10 h, 77−90% listed in Scheme
2)
Scheme 2. Synthesis of 6
For the synthesis of amino-5H-chromeno[2,3-d]pyrimidine-
2-yl-phenols, the water-promoted one-pot reaction is the better
and simpler procedure among these parallel procedures. In
2010, Bazgir and co-workers have reported the synthesis of
compound 6{2,1,3} using a one-pot reaction of 2-iminocou-
marin, salicylaldehyde and secondary amines in the presence of
LiClO4 (15 mol %) in EtOH, 15 h.8 Although the presented
domino reaction is similar to their report, using H2O as solvent,
without any hazardous catalyst, makes the present method
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easier and safer. We report similar reactions with other
reactants, in H2O as the solvent and without using any
hazardous catalyst.
Scheme 4. Synthesis of Compounds 7 Using CuCl (15 mol
%)
As an extension of our interest in studying water-promoted
reactions, we tried to use aromatic secondary amines in similar
manner. Phenylalkyl amines were submitted to a similar
reaction in H2O, but the yields were poor, probably as a result
of the relatively lower nucleophilicity of phenylalkyl amines. We
have found that the mentioned amines, iminocoumarines and
benzaldehydes can condense in the presence of inexpensive
Lewis acids. The selectivity of different Lewis acids for the
synthesis of N-methyl-N-phenyl-5H-chromeno[2,3-d]-
pyrimidin-4-amine derivatives 7 are shown in Scheme 3.
Since CuCl was the best catalyst in this procedure, we report
this new procedure using 15 mol % CuCl (Scheme 4).
Scheme 3. Synthesis of Compounds 7{1,1,1} in the Presence
of Lewis Acids at 85−90 °C
Scheme 5. Synthesis of Compound 8{2,1,1} in the Presence
of Lewis Acids
Literature shows some reports on the reaction of
iminocoumarines in alcoholic solvents. In many of these
reports, amines act as nucleophiles. In 2008, Costa and co-
workers reported the condensation of salicylaldehyde and
malononitrile in the CH3OH and H2O media.9 They had
reported the synthesis of dimeric chromene derivatives. During
this dimerization process, CH3OH, as well as malononitrile,
could be added as nucleophile to the intermediate of the
reaction. Until now there has been no other report on the use
of reaction of alcohol as a reactant for the synthesis of
pyrimidine derivatives. In the present work, the alcohol could
not react as a nucleophile without a catalyst, probably because
of the lower nucleophylicity of alcohols. When Lewis acids were
used as catalysts, surprisingly primary alcohols, salicylaldehydes,
and iminocoumarines condensed to produced 4-alkoxy-5H-
chromen[2,3-d]pyrimidines 8 (Scheme 5). These one-pot and
three-component reactions were run under reflux in the
corresponding alcohols for 4−8 h. Secondary and tertiary
alcohols reacted in lower yields (10−20%); therefore, we
recommend this method only for primary alcohols, which
afforded higher yields (63−85%).
and yields for the synthesis of 4-methoxy-5H-chromen[2,3-
d]pyrimidine 8{2,1,1}.
ZnCl2 10 mol % was optimal for the preparation of
compound 8{2,1,1}, but the same catalyst amount was not
efficient for alcohols other than MeOH. Larger amounts of
ZnCl2 were tested and 15 mol % proved the best. Using this
amount a small library of compounds 8 was prepared (Scheme
6).
When the aromatic secondary amine (N-methylaniline 3{1})
was used in excess amounts the reaction proceeded as seen in
Scheme 7, and compound 9 was produced in a 20% yield as a
byproduct. Mixture of 2 mmol of salicylaldehyde 1{2} and
iminocoumarine 2{1} in excess amounts of N-methylaniline
3{1} (5−7 mL) was heated for 24 h (Scheme7). Unfortunately
our attempts to synthesize other similar derivatives were not
successful, probably due to steric hindrance.
Various Lewis acids have been used as catalysts. Scheme 5
shows the catalysts and their optimal amounts, reaction times
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∠O1−H···N1 = 135°, and details of the O1−H···N2 bond are
Scheme 6. Synthesis of 8 Using ZnCl2(15 mol %)
́
́
́
d(O1···N2) = 2.57 Å, d(O1−H) = 0.85 Å, d(H···N2) = 1.77 Å,
∠O1−H···N2 = 158°.
Single crystals of 7{2,1,3} were obtained from methanol. Its
ORTEP diagram is shown in Figure 2. For this compound an
Scheme 7. Synthesis of 9
Figure 2. ORTEP diagram of 7{2,1,3}.
In chemical biology and medicinal chemistry, compounds
containing H-bonding can provide access to new pharmaco-
phores leading to opportunities for the discovery of new tools
to probe biological systems.10 Some of the compounds
reported here have an exchangeable H-bond. The details of
the H-bondings for the compounds 6{2,1,3} and 7{2,1,3} are
presented as follows:11 Single crystals of 6{2,1,3} were obtained
from a mixture of methanol and acetone.11 Its X-ray structure
was obtained and showed an exchangeable intramolecular
hydrogen bond arising from free rotation around the C6−C7
between O1−H group of aryl ring and N1 or N2 atoms of
pyrimidine ring. (Figure 1). Details of the O1−H···N1bond are
exchangeable intramolecular hydrogen bond arising from free
rotation around the C11−C12 between O2−H group of aryl ring
and N1 or N2 atoms of pyrimidine ring was identified by X-ray
analysis data. Details of the O2−H···N1 bond are d(O2···N1 =
́
́
́
2.60 Å, d(O2−H) = 0.84 Å, d(H···N1) = 1.81 Å, ∠O2−H···N1 =
158°, and details of the O2−H···N2 bond are d(O2···N2) = 2.56
́
́
́
Å, d(O2−H) = 0.84 Å, d(H···N2) = 1.78 Å, ∠O2−H···N2 =
153°.
All of the new compounds reported here are insoluble in
water and show blue to green fluorescence. For example the
fluorescence of some of the new compounds are shown in
Figure 3.
Fluorescence molecular spectroscopy of some of new
compounds has been studied. Each sample (0.5 mL) in
CHCl3 (10−10 mol L−1) was first coated on a glass sheet and
dried at room temperature, then placed in a 1 cm length quartz
cell. The excited and emission slits were adjusted on 5−7 nm.
The fluorescence emission intensity of the four compounds
from each of small libraries 6, 7, and 8 after excitation in 290
nm was shown in Figure 4. We are hopeful that the library of
the fluorescent compounds 6, 7, 8, and 9 can play a significant
role in biochemical research and technology upgrading.
́
́
́
d(O1···N1 = 2.49 Å, d(O1−H) = 0.84 Å, d (H···N1) = 1.82 Å,
CONCLUSION
■
The novel approaches reported here provide concise routes for
the synthesis of some new fluorescent chromenopyrimidine
derivatives 6, 7, 8, and 9. These procedures show some
significant advantages compared to the previously reported
ones. Synthesis of compounds 6 can be described as
environmentally benign; the novel water-promoted, one-pot
procedure of their synthesis is compared to the domino
procedure. These parallel procedures have a clear advantage
Figure 1. X-ray crystal structure of 6{2,1,3}.
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Figure 3. Photo of some new compounds under lamp λ = 366 nm TL8W/08F8T5/BLC Philips made in Holland.12
alcohols in the solvent-free synthesis of compounds 7 and 8,
respectively. High atom economy, easy procedures, and fairly
high yields of these one-pot reactions provide obvious
advantages. Further investigation of this method is currently
in progress to establish its scope and utility. All of the new
compounds are insoluble in water and show blue to green
fluorescence. The fluorescence emission intensity of the four
compounds from each of libraries 6, 7, and 8 after excitation in
290 nm are measured. Also, we here report an interesting
exchangeable intramolecular H-bonding for the compounds
6{2,1,3} and 7{2,1,3}.
EXPERIMENTAL PROCEDURES
■
Chemicals and solvents were obtained from Merck (Germany)
and Fluka (Switzerland) and were used without further
purification. Column chromatography purifications were
performed using silica gel (0.015−0.04 mm, mesh-size) and
TLC analyses were performed on precoated plastic sheets (25
DCUV‑254). Melting points were measured on Barnstead
Electrothermal melting point apparatus and were not corrected.
Elemental analysis for C, H, and N were performed using a
Thermo Finnigan Flash EA1112 instrument. IR spectra were
measured on a Bruker EQUINOX 55 spectrophotometer as
ATR method. 1H NMR and 13C NMR spectra were determined
in CDCl3 on a Bruker 500 spectrophotometer and chemical
shifts were expressed in parts per million downfield from
tetramethylsilane. Mass spectra were recorded on a Finnigan-
MAT 8430 spectrometer at an ionization potential of 70 eV.
The fluorescence emissions were obtained by a luminescence
PERKIN ELMER LS 50B spectrometer.
4-Bromo-2-(7-bromo-4-(diethylamino)-5H-chromeno-
[2,3-d]pyrimidin-2-yl)phenol (6{7,4}). Water-Promoted
One-Pot Reaction. To a magnetically stirred mixture of 5-
bromo-2-hydroxy benzaldehyde 1{7} (2 mmol) and malononi-
trile 5 (1 mmol) in a 50 mL three-necked flask with a
thermometer, diethylamine (1−2 drops) were added at 5 °C
and the reaction mixture was stirred for 20 min. Diethylamine
Figure 4. Fluorescence emission spectra of compounds 6, 7, and 8
after excitation in 290 nm.
over the previous ones, which used hazardous catalyst or
solvents. Moreover, inexpensive Lewis acids were used to help
nucleophilic addition of aromatic secondary amines and
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(4.5 mmol) was added dropwise to the above mixture and
stirred for 10 min at room temperature. Then 3−4 mL of H2O
was added to the reaction mixture and heated at about 80 °C
for 8−10 h. When the iminocoumarine spot (Rf ≈ 0.4, silica gel,
ethyl acetate/n-hexane 1:4) disappeared, the product was
filtered, washed with cold water, and recrystallized from EtOH.
The colorless crystals of product were collected in 83% yield.
Water-Promoted Domino Reaction. 4-Bromo-2-(7-
bromo-4-(diethylamino)-5H-chromeno[2,3-d]pyrimidin-
2-yl)phenol (6{7,3,4}). To a magnetically stirred mixture of
iminocoumarine 2{3} (2 mmol) and salicylaldehyde 1{7} (2
mmol) in a 50 mL three-necked flask fitted with a thermometer
dimethylamine 3{4} 40% (3.5 mmol) was added at 5 °C
before; the reaction mixture was left to stir for 20 min at room
temperature. Addition of 5−6 mL of H2O and heating at about
80 °C for 8−10 h produced a solid product which was collected
as colorless crystals and recrystallized from chloroform and
ethyl acetate as cosolvents in 85% yields.
Colorless crystals; mp 178−179 °C. IR (KBr): 3034, 1631,
1617, 1255, 1182, 1063, 813, 748 cm−1. 1H NMR (CDCl3, 500
MHz): δH 1.29−1.37 (6H, t, 2CH3of Et), 3.59−3.63 (4H, q, J =
7.08 Hz, 2CH2 of Et), 4.06 (2H, s, CH2), 6.89−6.91, 7.08−
7.10, 7.38−7.40, 7.34−7.46, 8.51−8.52 (6H, 5m, H−Ar), 13.
31(br s, OH) ppm. 13C NMR (CDCl3, 125 MHz): δC 14.09
(CH3 of Et), 26.10 (CH2), 45.33 (CH2 of Et), 98.96, 111.26,
117.17, 119.11, 119.96, 120.59, 121.82, 131.72, 131.78, 131.81,
135.89, 149.77, 159.88, 160.85, 164.71 (Ar, imine carbons).
MS: m/z 507, 505 (M+, M+ + 2), 478,476 (M+, M+ + 2 −
C2H5), 435, 433 (M+, M+ + 2 − N(C2H5)2), 425(M+ − HBr),
353 (M+ − N (C2H5)2, HBr), 72 (N+ (C2H5)2), 57 (N+ C3H7).
Anal. Calcd for C21H19Br2 N3O2: C, 49.93; H, 3.77; N, 8.32.
Found: C, 49.96; H, 3.81; N, 8.35.
Lewis Acid-Catalyzed Synthesis of N-Methyl-N-phe-
nyl-2-p-tolyl-5H-chromeno[2,3-d]pyrimidin-4-amine
(7{3,1,1}). To a magnetically stirred mixture of iminocoumarine
2{1} (2 mmol) and benzaldehyde derivatives 1{3} (2 mmol) in
CH2Cl2 (2 mL), CuCl (15 mol %) was added gently. Then N-
methyl aniline 3{1} (3 mmol) was added to the above mixture.
The reaction mixture was stirred for 20 min at room
temperature and refluxed for 7−8 h. The progress of the
reaction was monitored by TLC. When the product’s spot (Rf
≈ 0.8 in silica gel, ethyl acetate/n-hexane (1:5)) was visible and
the spot for iminocoumarine at Rf ≈ 0.4 disappeared, the
reaction was completed. The final product was purified by
column chromatography using ethyl acetate/n-hexane 1:6 as
eluent and recrystallized in ethanol 80% yield.
(2 mL), ZnCl2 (15 mol %) was added gently. The reaction
mixture was stirred for 20 min at room temperature and
refluxed for 4 h. The progress of the reaction was monitored by
TLC. When the spot for the product (Rf ≈ 0.8 in silica gel,
ethyl acetate/n-hexane (1:5)) was visible, the final product was
purified by column chromatography using ethyl acetate/n-
hexane 1:6 as eluent and recrystallized in ethanol with an 80%
yield.
Colorless crystals; mp 200−201 °C. IR (KBr): νmax 2989,
1
1600, 1541, 1187, 1155, 1074, 1028. H NMR (CDCl3, 500
MHz): δH 3.03 (2H, s, CH2) 4.15(3H, s, CH3O), 6.94−7.00,
7.11−7.14, 7.16−7.20, 7.25−7.37, 8.41−8.43 (8H, 5m, Ar),
12.78(1H, br s) ppm. 13C NMR (CDCl3, 125 MHz): δC 21.29
(CH2), 54.26 (CH3 of CH3O), 94.41, 116.84, 117.31, 117.88,
118.43, 124.16, 127.76, 128.70, 128.75, 132.62, 136.82, 149.81,
159.78, 161.70, 167.13, (Ar, imine carbons). MS: m/z 306
(M+), 291 (M+ − CH3), 277 (M+ − CH3O). Anal. Calcd for
C18H14N2O3: C, 70.58; H, 4.61; N, 9.15. Found: C, 70.64; H,
4.69; N, 9.20.
Synthesis of 2-(4,5-Bis(N-methyl-N-phenylamino)-5H-
chromeno[2,3-d]pyrimidin-2-yl)phenol (9). To a magneti-
cally stirred mixture of salicylaldehyde 1{2} (2 mmol) and
iminocoumarine 2{1} (2 mmol) in a 50 mL three-necked flask
with a thermometer, N-methyl aniline 3{1} (5 mL) was added
at 5 °C. The reaction mixture was heated for 24 h at 50 °C. The
progress of the reaction was monitored by TLC. The spot for
the product 7{2,1,1} is appeared at Rf ≈ 0.6, and the spot for
compound 9 appeared at Rf ≈ 0.74 (ethyl acetate/n-hexane
1:4). The residue was purified by column chromatography
using ethyl acetate/n-hexane 1:5 as byproduct. The colorless
crystals of 9 were obtained in 20% yield.
Colorless crystals; mp 132−133 °C. IR (KBr): νmax 2926,
1609, 1585, 1171, 1099 cm−1. 1H NMR (CDCl3, 500 MHz): δH
2.78, 3.51 (6H, 2s, CH3N), 4.12 (1H, s, CH), 6.43−6.45, 6.67−
6.68, 6.76−6.77, 6.97−7.00, 7.04−7.07, 7.18−7.21, 7.24−7.33,
7.43−7.48, 8.54−8.56 (18H, 10m, H−Ar), 13.36(1H, br s)
ppm. 13C NMR(CDCl3, 125 MHz): δC 31.10 (CH), 39.97,
42.38(2CH3 of CH3N), 101.50, 112.89, 117.38, 118.11, 119.07,
119.37, 124.77, 125.03, 125.49, 126.35, 128.17, 128.20, 128.95,
129.71, 130.31, 133.41, 133.73, 146.70, 148.55, 149.67, 159.15,
160.96, 162.76 (Ar, imine carbons). MS: m/z 486 (M+), 469
(M+ − CH3), 380 (M+ − NCH3Ph), 376 (M+ − PhOH, CH3),
376 (M+ − C13H14NO), 105, 91, 77. Anal. Calcd for
C31H26N4O2: C, 76.52; H, 5.39; N, 11.51. Found: C, 76.54;
H, 5.41; N, 11.57.
ASSOCIATED CONTENT
* Supporting Information
Colorless crystals; mp 169−170 °C. IR (KBr): νmax 2920,
■
1
1597, 1570, 1158, 1110, 1088 cm−1. H NMR (CDCl3, 500
S
MHz): δH 2.47 (3H, s, CH3 of CH3−Ar), 3.14 (2H, s, CH2),
3.67 (3H, s, CH3 of CH3N), 6.81−6.83, 6.96−6.99, 7.17−7.18,
7.22−7.27, 7.31−7.33, 7.40−7.43, 8.43−8.45 (13H, 7m,
aromatic protons) ppm. 13C NMR (CDCl3, 125 MHz): δC
21.99 (CH3 of CH3−Ar), 25.90(CH2), 42.56 (CH3 of CH3N),
97.39, 117.30, 120.36, 124.24, 125.59, 125.90, 128.18, 128.55,
129.11, 129.50, 130.05, 135.16, 141.15, 147.54, 150.89, 162.23,
164.03, 165.50 (Ar, imine carbons). MS: m/z 379 (M+), 364
(M+ − CH3), 349 (M+ − 2CH3), 302 (M+ − Ar), 273 (M+ −
CH3, Ar), 91, 77. Anal. Calcd for C25H21N3O: C, 79.13; H,
5.58; N, 11.07. Found: C, 79.12; H, 5.57; N, 11.10.
General information, general procedure, spectral and analytical
characterization, NMR spectra of the products, and the photo
of 22 new compounds under lamp λ = 366 nm. This material is
available free of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
■
*Tel: 98-21-66403672. Fax: 98-21-66405141. E-mail:
zonouzi@khayam.ut.ac.ir.
Funding
We wish to thank the Iran National Science Foundation
(INSF) for the financial support.
Lewis Acid-Catalyzed Synthesis of 2-(4-methoxy-5H-
chromeno[2,3-d]pyrimidin-2-yl)phenol (8{2,1,1}). To a
magnetically stirred mixture of iminocoumarine 2{1} (2
mmol) and salicylaldehyde 1{2} (2 mmol) in CH3OH 4{1}
Notes
The authors declare no competing financial interest.
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D.; Bender, A.; Welch, M.; Spring, D. R. The discovery of antibacterial
agents using diversity-oriented synthesis. Chem. Commun. 2009,
2446−2462.
(11) Crystallographic data for the structure of compound 6{2,1,3}
and 7{2,1,3} reported in this paper have been deposited with the
Cambridge Crystallographic Data Center as supplementary publica-
tions CCDC 737003 and 891212 respectively. These data can be
obtained free of charge via www.ccdc.com.ac.uk/data_request/cif.
(12) The photo is taken under lamp λ = 366 nm TL8W/08F8T5/
BLC Philips made in Holland.
REFERENCES
■
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