The Rh(iii)-catalysed C-H/N-H annulation of 2-thienyl- And 2-phenyl-quinazolin-4(3: H)-ones with diphenylacetylene

Article abstract of DOI:10.1039/d1nj00935d

A series of 4,5-diphenyl-7H-thieno[2′,3′:3,4]pyrido[2,1-b]quinazolin-7-ones was synthesized via the Rh(iii)-catalyzed annulation of 2-thienylquinazolin-4(3H)-ones with diphenylacetylene. 2-Phenylquinazolin-4(3H)-one amide alcoholysis and double C-H functionalization proceeded under the same reaction conditions with the formation of 2,3,7,8-tetraphenyl-1H-benzo[d,e][1,8]-naphthyridine derivatives. All compounds possess fluorescence properties in MeCN and toluene solutions as well as in the solid state. The aggregation induced emission (AIE) properties and the ability to detect Fe3+ cations were evaluated.

Full text of DOI:10.1039/d1nj00935d

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The Rh(III)-catalysed C–H/N–H annulation
of 2-thienyl- and 2-phenyl-quinazolin-4(3H)-ones
Cite this: DOI: 10.1039/d1nj00935d
with diphenylacetylene†
ab
Tatyana N. Moshkina,a Emiliya V. Nosova,
Ekaterina F. Zhilina,b Pavel A. Slepukhin,
Valery N. Charushinab
*
Galina N. Lipunova,ab
Igor L. Nikonovab and
ab
A series of 4,5-diphenyl-7H-thieno[20,30:3,4]pyrido[2,1-b]quinazolin-7-ones was synthesized via the Rh(III)-
catalyzed annulation of 2-thienylquinazolin-4(3H)-ones with diphenylacetylene. 2-Phenylquinazolin-4(3H)-
one amide alcoholysis and double C–H functionalization proceeded under the same reaction conditions
with the formation of 2,3,7,8-tetraphenyl-1H-benzo[d,e][1,8]-naphthyridine derivatives. All compounds
possess fluorescence properties in MeCN and toluene solutions as well as in the solid state. The aggregation
induced emission (AIE) properties and the ability to detect Fe3+ cations were evaluated.
Received 24th February 2021,
Accepted 5th April 2021
DOI: 10.1039/d1nj00935d
rsc.li/njc
2-[5-(4-diethylaminophenyl)thiophen-2-yl]quinazolin-4(3H)-
one represents a promising fluorescence molecule with a
Introduction
Heteroatom-containing polycyclic compounds with a highly quantum yield up to 71% in toluene.8 Applicability of
planar structure represent an important class of materials for carbazolyl-substituted quinazolinones as hosts for phos-
potential applications in advanced organic electronics. They phorescent OLEDs has also been explored.9 Moreover, the
demonstrate superior photophysical properties as a result of quinazolinone structure can serve as a ligand for the construc-
extended p-conjugation, narrow HOMO–LUMO gaps, long tion of complexes. For example, strong emission with high
wavelength absorption and emission, lower oxidation and/or fluorescence quantum yield in solution and in solid state was
reduction potentials, strong p–p interactions, and higher achieved in asymmetric difluoroboron quinazolinone-pyridine
mechanical strength.1–5 Particularly, the rigid p-conjugated dyes.10,11 A wide scope of metal complexes of benzazines with
heterocyclic systems based on phenanthroimidazole can be possible application as emitters for application in OLEDs has
used for the creation of organic light emitting diodes (OLEDs) been described as well.12,13
due to strong blue emission. Moreover, a thiophene-fused
Different synthetic approaches for building polycyclic chromo-
phenanthroimidazole derivative showed a selective fluorescent phores with p-extended structures are described in the
response for Fe3+.6 Polyconjugated systems of dithienoquina- literature.14–16 For example, the construction of quinazolinone-
zolines and benzo[f]thieno[3,2-h]quinazolines are considered as fused polycyclic frameworks can be reached by annulation of
prospective materials for organic electronics.7
additional rings to parent molecules by transition-metal-catalysed
2-Aryl(heteryl)quinazolinones are widely studied hetero- C–H bond functionalization. It is well known that C–H activation
cyclic compounds, and many studies are being conducted to represents one of the most attractive approaches due to easy
explore the biological activity of quinazolinone derivatives. operation, atom- and step-economy, easily available starting
However, their molecular framework possesses a strong materials, high efficiency, and environmental friendliness.
electron-withdrawing ability and can be used as an acceptor Therefore,
a large library of C5/C6-benzene-fused isoquin-
fragment to form push–pull molecules with intramole- olino[1,2-b]quinazolinones was obtained by means of C–H
cular charge transfer (ICT) characteristics. It was shown that activation.17–20
Several methods were devised to modify starting quinazoli-
a Department of Organic and Biomolecular Chemistry, Ural Federal University,
Yekaterinburg, Russia. E-mail: emilia.nosova@yandex.ru
nones by annulation with alkynes. Some of them include Pd-
catalysed aerobic oxidative reactions,21 one-pot Co(III)-catalysed
annulation of 2-aryl(heteryl)quinazolinone-bearing electron-
donating and -withdrawing groups,22 and Ru-catalysed regiose-
lective annulation of 2-styryl and 2-aryl quinazolinones under
mild reaction conditions.23,24 Notably, the synthesis of fused
b Postovsky Institute of Organic Synthesis, Ural Division of the Russian Academy of
Sciences, Yekaterinburg, Russia
† Electronic supplementary information (ESI) available. CCDC 2004850, 2004711
and 1999651. For ESI and crystallographic data in CIF or other electronic format
see DOI: 10.1039/d1nj00935d
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heteroarenes can be achieved by [RuCl2(p-cymene)]2-catalysed
aerobic, oxidative dehydrogenation followed by cross-coupling/
annulation of dihydroquinazolinones in a one-pot process
without purification of intermediates or addition of copper
salts.25 Moreover, Cp*Rh(III) complexes have proved to be highly
active catalysts in C–H activation for
a vast number of
transformations.6,26–31 Particularly, C6-substituted isoquinolino
[1,2-b]quinazolines were synthesized via Rh(III)-catalysed C–H annu-
lation with sulfoxonium ylides.30
Despite the rapid development of chemistry and the biolo-
gical application of quinazolinone-fused molecules, their
photophysical properties have been inadequately investigated.
There is great potential for the application of quinazolinone-
fused derivatives as photoluminescent materials. It is note-
worthy that molecules based on quinazolinone have been
shown to be good candidates for organic optical materials such
as transistors or bio-probes.19,32 Moreover, the rotation of
phenyl residues can provide the opportunity to realise
aggregation-enhanced emission (AEE) or aggregation-induced
emission (AIE).
Fig. 1 The cyclisation of 2-(thiophen-2-yl)quinazolin-4-one via paths
1 and 2.
I2-mediated cascade cyclization of 2-aminobenzamides or anthra-
nilic acids with 2-(phenylethinyl)aldehydes.34,35 Noteworthy, the
cyclometallation process based on 2-thienylquinazoline deriva-
tives proceeds at the C–N1 site.36,37
The synthesis of the quinazolinone derivatives 5a–d is sum-
marised in Scheme 1. The quinazoline-3H-ones 4a,b were
obtained as described in previous works.8,38 For the synthesis of
the remaining compounds 4c,d, a similar procedure was applied.
The condensation of anthranilamide 1 with the corresponding
2-thiophencarboxaldehyde 2a–d and subsequent oxidation with
copper(II) chloride led to the 2-(thiophen-2-yl)quinazolin-4(3H)-
ones 4a–d.
The 2,3-dihydroquinazolin-4(1H)-ones 3a,b,d were isolated
as intermediate products, and the presence of signal around
5.9 ppm corresponding to the aliphatic CH group proves the
proposed structures (see ESI†). In the case of benzoannulated
aldehyde 2c, Schiff base 3c was formed, and the signal from the
NQCH group at d 8.95 ppm confirms this fact.
Herein, we report the design, synthesis, and characterization
of a series of 4,5-diphenyl-7H-thieno[20,30:3,4]pyrido[2,1-b]qui-
nazolin-7-ones with varying substituents on a thiophen moiety.
Readily available thiophenecarboxaldehydes and aminoamides
were used as starting materials for the synthesis of key quina-
zolinone intermediates. The alkyl-substituted thiophenecarbox-
aldehyde was applied as the starting material to increase the
solubility of the target compound. Remarkably, polycyclic com-
pounds based on 2-(thiophen-2-yl)quinazolin-4(3H)-ones bearing
substituents at the thiophene ring have not yet been described.
Additionally, we compared the behaviour of 2-thienyl- and 2-
phenyl-quinazolin-4(3H)-one under the same reaction conditions.
The photophysical properties of the synthesized molecules were
investigated in solution and in solid state. We also investigated
their AIE characteristics and applicability for the detection of Fe3+
cation.
Compounds 5a–d were obtained according to a previously
published procedure.27 Quinazoline-3H-ones 4a–d were annu-
lated with diphenylacetylene in hexafluoroisopropanol (HFIP)
at 70 1C for 12 h using [RhCp*Cl2]2 as a catalyst (4 mol%),
CsOAc (30 mol%) as a base,27 and 4,5-diphenyl-7H-thieno
[20,30:3,4]pyrido-[2,1-b]quinazolin-7-ones 5a–d were obtained
in moderate yields.
Results and discussion
Synthesis
Modification of 4,5-diphenyl-7H-(5-bromo)thieno[20,30:3,4]pyrido
The quinazolinone core includes two nitrogen atoms ready for
C–N bond formation. Therefore, linear and angular annulation
may occur, resulting in two regioisomers (Fig. 1). In the synth-
esis mentioned in the Introduction, cyclisation occurs with
regioselective products. In these cases, the N3 atom of quina-
zolinone participates in the formation of annulated derivatives
in a pathway that is more preferable due to the stability of the
quinazoline-4(3H)-one tautomer.23 Interestingly, 2-(2-bromophenyl)
quinazolin-4(3H)-ones in reaction with benzylamines under
Cu-catalysed conditions can be converted into two diverse
quinazolinone-fused scaffolds, depending on the presence of an
oxygen atmosphere.32
[2,1-b]quinazolin-7-one 5b by
a Pd-catalysed cross coupling
reaction39 allowed us to obtain quinazolinone derivative 5e with
an electron-donating diphenylaminophenyl residue at the thiophene
ring (Scheme 2, upper line). It is worth noting that an attempt failed
to synthesize bromo-derivative 5b from unsubstituted parent 4,
5-diphenyl-7H-thieno[20,30:3,4]pyrido[2,1-b]quinazolin-7-one 5a by
treatment with N-bromosuccinimide (NBS) in DMF at 80 1C for
6 h. It was established that the mentioned conditions led to double
bromination at the benzene ring, and 4,5-diphenyl-7H-thieno[20,30:
3,4]pyrido[2,1-b]quinazolin-7-one 5f was isolated as the main pro-
duct (Scheme 2, bottom line). This result was proven by NMR
spectroscopy, as the 1H NMR spectrum of 5f showed two hydrogen
atoms of a benzene ring appearing as two doublets, with a coupling
Cyclization of 2-(2-arylethinylphenyl)-substituted quinazoli-
none under Fe(III)-catalysed conditions leads to C–N1 annulated
products.33 The same regioisomers were obtained in Ag(I)- or
4
constant of J 2 Hz, while signals from thiophene fragments were
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located at 6.92 and 7.73 ppm (3J 5.2 Hz), and their positions were
close to those of compound 5a (see ESI†).
The structures for the remainder of compounds 3–5 were
also confirmed by 1H NMR spectroscopy as well as mass-
spectrometry and elemental analysis. Additionally, target pro-
ducts 5a–d, f were characterized by 13C NMR spectroscopy. In
the mass spectra of all quinazolinone derivatives 5a–e, the
peaks for molecular ions corresponding to the required [M+]
(404 for compound 5a, 482 for compound 5b, 488 for com-
pound 5c, 454 for compound 5d, 647 for compound 5e, and
562 for compound 5e) were registered. For 4,5-diphenyl-7H-
thieno-[20,30:3,4]pyrido[2,1-b]quinazolin-7-one 5a and 5b, X-ray
single crystal diffraction studies were performed (Fig. 2).
According to the XRD data, two independent molecules with
similar geometry were crystallized in the centrosymmetric
space groups of the triclinic system for compound 5a.
Due to the stereoeffects of the aryl substituents, the tetra-
cyclic moiety of the molecules is non-planar, and some atoms
(as well C7) deviated from the least-squared plane more than
0.3 Å. The deviations from the least-squared plane are 0.75 Å for
the O1 atom of the CQO group and more than 0.7 Å for the C22
atom of the aryl substituent. Both aryl substituents are turned
on the high angles toward the tetracyclic moiety. Any signifi-
cantly shortened intermolecular contacts were not observed in
the crystal.
Scheme 1 The synthesis of quinazolinones 5a–d.
Scheme 2 The synthesis of quinazolinones 5e and 5f. i: 4-(diphenylami-
no)phenylboronic acid, PdCl2(PPh3)2, PPh3, K2CO3, toluene, EtOH, and
argon, at 85 1C.
Fig. 2 The molecular structures of 5a and 5b using thermal ellipsoids of
50% probability.
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Similar to 5a, two independent molecules of compound 5b
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were crystallized in the triclinic system, and the geometry of
molecules 5b was similar to that of 5a. Compound 5b was
characterized by a distorted polycyclic system and the deviation
of the oxygen atom of the carbonyl group from the plane of the
heterocycle, as in the case of its counterpart 5a. Both molecules
were organized in dimers in a crystal by means of inter-
molecular polar contacts between the oxygen of the carbonyl
group and the hydrogen of the phenylene fragment of the
tetracyclic system as well as due to T-shaped shortened contacts
between the Br atom and the phenyl substituent of a neigh-
bouring molecule. The other shortened observed contacts did
not lead to a significant deviation from the geometry of non-
specific van der Waals interactions.
Bearing in mind that the Ru(II)-catalysed annulation of 2-
phenylquinazolinone 6 with diphenylacetylene results in the
formation of 5,6-diphenyl-8H-isoquinolono[1,2-b]quinazolin-8-
one,24 we were interested in the process of quinazolinone 6
undergoing Rh(III)-catalysed annulation (Scheme 3).
Fig. 3 The molecular structure of 7 using thermal ellipsoids of 50%
probability.
in the 19F NMR spectrum related to CF3 groups provides
additional evidence for the formation of the ester moiety.
Finally, we were able to confirm the structure of compound 7
by X-ray crystallography (Fig. 3). According to the XRD data, the
tricyclic moiety of molecule 7 is planar. The aryl substituents
were turned at high angles (60–901) towards the heterocycle.
Any significantly shortened intermolecular contacts in the
crystal were not observed.
The difference in the behaviour of 2-thienyl and 2-phenyl
quinazolinones (4, 6) can be explained by the electron-donating
nature of the thienyl substituent. Therefore, the carbon atom of
the CQO group has a weaker electrophilic centre in thienyl
derivative 4 than in phenyl derivative 6. Notably, amide alco-
holysis in pyridoquinazolinone coursed by trifluoroethanol has
been previously described.23
Although the same reaction conditions were used as those
for the transformation of 2-thienyl counterparts 5a–d, the
desired isoquinolino-quinazolinone 8 was isolated only in trace
amounts. The data set indicates that the main product repre-
sents the formation of benzonaphthyridine derivative 7 because
of amide alcoholysis and the double C–H functionalisation
process. Furthermore, the reaction conditions were optimized
by the 1 : 2 ratio of starting materials (quinazolinone 6 and
diphenylacetylene, respectively), and product 7 was obtained in
good yield.
1
Synthesized compound 7 was characterized by MS, H, 13C,
and 19F NMR spectral analysis. The relative intensity of the
molecular ion peak in the mass spectra of 7 is 75%, and
it should be noted that the 100% peak refers to the ion [M–C(O)
1
OCH(CF3)2]+. The multiplets in the H NMR at d 6 ppm and in
the 13C NMR at d 67 ppm correspond to the aliphatic CH group,
and this result indicates that the HFIP fragments were incor-
porated into the structure. The presence of two sets of signals
UV/Vis and fluorescence properties
The optical properties of 5a–f, 7, and 8 were investigated with
UV/Vis and photoluminescence spectroscopy in acetonitrile
(MeCN) and toluene solutions at room temperature. The
obtained data are summarized in Table 1 and are given in the
ESI.†
Quinazolin-7-ones 5a–f, 7, 8 were established to show broad
long-wave absorption bands in the region of 335–450 nm,
which can be attributed to p–p* transitions. The most red-
shifted absorption bands were attained with the incorpo-
ration of electron-donating amino substituents coupled with
the extension of the conjugated p-system (compound 5e).
The presence of alkyl (C6H13) or halogen (Br) residues in the
thiophene ring (5b, 5c) as well as the presence of halogens (Br)
in the benzene ring (5f) did not significantly affect the shape of
the absorption band and was reflected in a redshift of the
absorption maximum as compared to 5a. When proceeding from
4,5-diphenyl-7H-thieno[20,30:3,4]pyrido[2,1-b]quinazolin-7-one (5a)
to the 5,6-diphenyl-8H-isoquinolino[1,2-b]quinazolin-8-one (8)
counterpart, the absorption maximum was bathochromically
Scheme 3 The formation of the 2,3,7,8-tetraphenyl-1H-benzo[d,e][1,8]-
naphthyridine derivative 7.
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Table 1 Optical properties of compounds 5a–f, 7, and 8
Absorption
Photoluminescence
Comp. Solvent l (nm)/e (103 Mꢀ1 cmꢀ1
)
Excitation lmax (nm)
Emission, lmax (nm) FF,a
%
Stokes shift, nst (cmꢀ1
)
5a
5b
5c
5d
5e
5f
7
Toluene 383/13.3; 367/12.5; 287/22.7
MeCN 378/15.8; 283/29.8
Toluene 415/9.2; 387/18.1; 374/18.2; 288/36
MeCN 385/14.8; 284/30.9
Toluene 385/20.1; 370/18.9; 289/35.2
MeCN 380/16.7; 285/32.6
Toluene 419/12.9; 396/20.9; 378/18.9; 337/20; 286/31.9
383, 367, 287
378, 283
415, 387, 374, 288
385, 284
385, 370, 289
380, 285
480
480
485
485
485
475
o1
o1
1
5267
5622
5221
5355
5355
5263
4634
4957
3640
5799
4458
4630
5238
8594
—
o1
1
o1
2
419, 396, 278, 337, 286 485
413/25.9; 391/43.4; 374/38.5; 334/39.3; 275/77.6 413, 391, 374, 334, 275 485
MeCN
o1
Toluene 423/32.5; 376/35.2; 296/38.9
423, 376, 296
417, 374, 291
392, 296
386; 292
433, 350
346
—
470, 500
550
475
470
560
520
—
15
MeCN
Toluene 392/19.7; 296/28.5
MeCN 386/23.2; 292/35.5
Toluene 433/5.4; 350/22.9
MeCN 346/14.2
417/19.3; 374/20.7; 291/23.5
29
1
o1
o1
o1
—
Acetone 434/5.9; 412/6.9; 348/22
8
Toluene 392/13.6; 372/19.2; 355/16.8
392, 372, 355
388, 368, 351, 286
430, 510
430, 510
o1
5902
6165
MeCN
388/12.8; 368/18.3; 351/16.1; 286/37.8
o1
a
Fluorescence quantum yield determined relative to 3-aminophthalimide in ethanol as the standard (FF = 60%).40 Excitation at 380 nm.
shifted in both solvents. Broad long-wave absorption bands with a
maximum at 350 nm (for toluene solution) and 346 nm (for MeCN pounds. The position of emission maxima for 5a, 5b, 5d, and
solution) were observed for benzonaphthyridine derivative 7. 8 proved to be independent from their solvent nature. For 5c,
The solvent effect was different for the obtained com-
Compounds 5a–f, 7, and 8 exhibited photoluminescent 5f, and 7, the solvent effect was expressed as negative solvato-
properties (Table S1, ESI†). Depending on the structure and chromism, i.e., a hypsochromic shift of fluorescence maxima.
solvent nature, the maxima of the emission bands were in the For example, the emission maximum was shifted by 10 nm in
range of 470–560 nm. The excitation spectra proved to coincide the blue region upon passing from toluene to acetonitrile for
with the absorption spectra. The maxima of fluorescence for 5b, compound 5c. In the case of benzonaphthyridine derivative 7,
5c, 5d, and 5e were redshifted in comparison with unsubsti- the negative influence of solvent polarity on fluorescence was
tuted 5a in toluene due to the presence of electron-donating the strongest (560 nm and 520 nm in toluene and MeCN,
groups in the thiophene fragment. Incorporation of bromines respectively). In this case, with the increase in solvent polarity,
into the benzene portion of quinazolin-7-one led to the oppo- the ground-state structure of the quinazolin-7-ones became
site effect at 470/475 nm and 480/480 nm (MeCN/toluene more stabilized than the excited state, because the ground
solutions) for 5f and 5a, respectively. The main emission state is more dipolar than the excited state.
maximum of phenyl-contained compound 8 (510 nm, in bold)
The emission band proved to exhibit a bathochromic shift of
was shifted by 30 nm to the red region in regards to the 80 nm upon increasing the solvent polarity for 5e. The observed
thiophene-containing analog.
correlation is typical for compounds that undergo an intermo-
lecular photoinduced electron transfer leading to a high polarity
state that is stabilized by solvent. Thus, derivative 5e exhibited
satisfactory sensitivity to solvent polarity as well as rather strong
fluorescence, and additional emission solvatochromism measure-
ments were obtained for this compound. Diphenylaminophenyl
derivative 5e emits luminescence, from blue in cyclohexane,
n-heptane, and toluene to yellow in MeOH. Fig. 4 displays the
normalised spectra in various solvents upon UV irradiation of
compound 5e.
The emission quantum yield of considered compounds
5a–d, f, 7, 8 is rather poor and does not exceed 2%; see
Table 1. Only diphenylaminophenyl-substituted quinazolinone
5e demonstrated moderate quantum yield (15% in toluene and
29% in acetonitrile solution).
Additionally, all compounds 5a–f, 7, 8 emitted in solid state
(powder), and the emission spectra have been registered and
given in the ESI.† According to the obtained data, the emission
maxima of quinazolines 5a–f are located at 493, 506, 476, 501,
508, and 512 nm, respectively (Table S1, ESI†). The emission
Fig. 4 The normalized emission spectra of 5e in different solvents.
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maxima for 2-phenylquinazolinone-based molecule 8 appears observed quenching fluorescence at fw = 10%, and then,
at 521 nm, naphthyridine derivative 7 demonstrates emission fluorescence is absent in the range of 10–60% (fw). The aggrega-
maximum at 568 nm. Redshifts of 8–38 nm observed in emis- tion state of 7 is formed at fw 4 60%. In addition, the
sion maxima in the solid state (compounds 5a, b, d–f, 7, 8) fluorescence emission of 7 in the aggregated state is redshifted
compared to toluene solution could be due to the presence of compared with pure MeCN, 540 and 490 nm.
intermolecular interactions existing in the solid state. Hexyl
The ability of compounds 5a–d, f, 7 to sense Fe3+ was
derivative 5c exhibited an emission that was hypsochromically investigated. For this reason, the emission spectrum in pure
shifted by 9 nm in the solid state in relation to its toluene acetone solution was registered. There was a 100-fold enhance-
solution. It is likely that the hexyl moiety prevents close packa- ment of the fluorescence intensity of an acetone solution of 7
ging of the molecules in the solid state.
after the addition of Fe3+, as shown in Fig. 6(a). In addition, the
The fluorescence measurements indicated that the emission fluorescence change was detected under a UV lamp by the
intensity of compounds reached 4.2% in the solid state naked eye (Fig. 6(b), inset).
(Table S1, ESI†). In comparison to the solution state, quinazo-
Fe3+ probably coordinates with the CQO groups and nitro-
linones 5a, c, d, 8 emitted a greater intensity that can be gen atoms of 7, and therefore, the structural rigidity is
ascribed to restriction of intramolecular motion (RIM) mec- enhanced and the p-electron distribution changes. The for-
hanisms. The quantum yields of the bromo-substituted deriva- mation of Fe3+ complexes by means of lone pairs of electrons
tives 5b, 5f and compounds 5f, 7 were less than 1%, and may be for the nitrogen and carbonyl groups has been previously
attributed to the heavy atom effect or specific intermolecular demonstrated.42,43 No changes were observed in the fluores-
interactions.
cence emission spectra of a solution of 7 by adding other metal
We investigated the aggregation induced emission (AIE) ions, namely Cu2+ and Cr3+, which are two of the most common
properties41 of 5a–f, 7, 8 and used them as fluorescent probes interferents for Fe3+ detection (Fig. 6(b)).44 Adding Fe3+ into
for Fe3+ detection6 to illustrate their utility. The AIE properties solutions of 5a–d, f resulted in fluorescence quenching that
of 5a–d, 7, 8 were confirmed by adding water to a series of may be due to Fe3+ behaving like a Lewis acid (see the ESI† and
MeCN solutions (Fig. S29–S34; see the ESI†). The fluorescence Fig. S35–S39).
spectra of 5a–c, 8 in the MeCN/H2O mixtures with various water
fractions (fw) are presented at an excitation wavelength of 378–
390 nm. As an example, the spectrum of quinazolinone 5c in a
MeCN/water mixture with different water fractions is shown in
Fig. 5. Quinazolin-7-ones 5a–d, 8 showed one weak fluorescence
Experimental
Methods
peak in pure MeCN. The spectral characteristics of 5a–d, 8
showed no significant change on average for fw in the range
from 0% to 70%. When the water fraction increased to more
than 70%, the fluorescence strength significantly increased due
to the formation of the aggregation state of 5a–d, 8. The
enhanced fluorescence intensity may be due to the change in
the aggregate morphology. In the case of 7, at first, it is
Unless otherwise indicated, all common reagents and solvents
were used from commercial suppliers without further purifica-
tion. Melting points were measured on a Boetius instrument.
Thin-layer chromatography (TLC) and column chromatography
were carried out on SiO2. The 1H NMR (400 Hz), 13C NMR
(100 MHz), and 19F NMR (376 MHz) spectra were obtained on
a Bruker Avance II DMX400 spectrometer using CDCl3 or
Fig. 5 (a) The fluorescence spectra of 10 mM 5c in MeCN/H2O mixtures with different water fractions (fw). (b) A plot of I/I0 at 475 nm versus the
composition of the MeCN/H2O mixture for 5c (Eex = 385 nm).
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Fig. 6 Selective Fe3+ detection using 7: (a) fluorescence emission spectra (lex = 350 nm) of an acetone solution of 7 with different concentrations of
Fe3+ (10–70 mM). (b) Fluorescence emission spectra (lex = 350 nm) for an acetone solution of 7 (50 mM) with Cu2+ and Cr3+ (50 mM). Inset: A photo of
acetone solutions of 7 without (1) or with (2) Fe3+ under a UV lamp (lex = 365 nm).
DMSO-d6 as the solvent. The 1H NMR spectra of compound 7 were Least Squares minimization. All non-hydrogen atoms were
recorded at room temperature at 600 MHz on a Bruker DRX-600 refined using an anisotropic approximation; H-atoms were
spectrometer. The 19F NMR spectra were recorded with CFCl3 placed in the calculated positions and isotropically refined in
(C6F6 was used as a secondary reference, dF – 162.9 ppm). Mass the ‘‘rider’’ model.
spectra were recorded on a Shimadzu GCMS-QP2010 Ultra instru-
ment with electron ionization (EI) of the sample. Elemental
Crystal data for 5a. C26H16N2OS, M = 404.47, triclinic,
a
= 8.9557(7) Å, b = 9.9486(8) Å, c = 22.5422(17) Å,
analysis (C, H, N) was performed using
a
PerkinElmer a = 98.812(6)1, b = 91.216(9)1, g = 97.590(6)1, V = 1965.6(3) Å3,
2400 elemental analyser. UV/Vis spectra were recorded for space group P1, Z = 4, m(Mo Ka) = 0.186 mmꢀ1. On the angles
1 ꢁ 10ꢀ5 M solutions with a Shimadzu UV-2600 spectro- 3.50 o y o 31.01, 17 949 reflections measured, 10 435 unique
photometer. Photoluminescent spectra were recorded for (Rint = 0.0644), which were used in all calculations. Goodness to
1 ꢁ 10ꢀ6 M solutions on a Varian Cary Eclipse fluorescence fit at F2 1.001. The final wR2 = 0.2254 (all data) and R1 = 0.0740
%
spectrophotometer. The emission spectra in different solvents (I 4 2s(I)). Largest diff. peak and hole 0.366 and ꢀ0.364 e Åꢀ3
.
%
were recorded using a Horiba FluoroMax-4. UV/Vis and fluores-
Crystal data for 5b. C26H15BrN2OS, M = 483.37, triclinic,
cence spectra were recorded using standard 1 cm quartz cells at a = 12.3877(11) Å, b = 13.2907(12) Å, c = 14.7438(13) Å,
room temperature. Fluorescence spectra in the solid state were a = 105.626(8)1, b = 107.407(8)1, g = 103.726(8)1, V = 2092.9(3)
3
measured using an integrating sphere Quanta-f F-3029 with a Å , space group P1, Z = 4, m(Mo Ka) = 2.085 mmꢀ1. On the angles
%
Horiba FluoroMax-4 spectrofluorometer.
3.64 o y o 28.28, 21 802 reflections measured, 10 261 unique (Rint
For Fe3+ detection, test solutions containing 50 mM 5a–f and = 0.0747), which were used in all calculations. Goodness to fit at F2
7 and 10x mM Fe3+ (x = 1, 2, 3, 4, 5, 6, 7) were prepared by adding 0.982. The final wR2 = 0.1862 (all data) and R1 = 0.0624 (I 4 2s(I)).
100x mL FeCl3ꢂ6H2O acetone solution (0.4 mM) and (2000–100x) Largest diff. peak and hole 0.644 and ꢀ0.648 e Åꢀ3
.
%
mL acetone to 2 mL of 7 acetone solution (0.1 mM). Solutions
Crystal data for 7. C45H28F6N2O2, M = 742.69, triclinic,
containing other metal ions (Cu2+ and Cr3+) were prepared a = 10.8731(13) Å, b = 12.7566(16) Å, c = 14.5064(19) Å,
using Cu(NO3)2ꢂ6H2O and CrCl3ꢂ6H2O instead of FeCl3ꢂ6H2O. a = 66.069(12)1, b = 86.317(10)1, g = 85.015(10)1, V = 1831.2(4) Å3,
space group P1, Z = 2, m(Mo Ka) = 0.104 mmꢀ1. On the angles
3.50 o y o 26.37, 12 984 reflections measured, 7267 unique
(Rint = 0.0732), which were used in all calculations. Goodness to fit
at F2 1.001. The final wR2 = 0.1826 (all data) and R1 = 0.0718
%
Compound 5e did not dissolve in acetone.
Crystallography
Single crystal XRD experiments were performed for an orange
block (0.47 ꢁ 0.31 ꢁ 0.11 mm) of compound 5a, yellow prism
(0.45 ꢁ 0.35 ꢁ 0.25 mm) of compound 5b, and yellow prism
(0.44 ꢁ 0.36 ꢁ 0.27 mm) of compound 7 on an Xcalibur 3
(I 4 2s(I)). Largest diff. peak and hole 0.200 and ꢀ0.268 e Åꢀ3
.
%
The results of the X-ray diffraction analysis for compounds
5a, 5b, and 7 were deposited with the Cambridge Crystallo-
graphic Data Centre (CCDC 2004850, 2004711, and 1999651,
respectively).†
automated diffractometer using
a
standard procedure
(graphite-monochromated Mo Ka-irradiation, T = 295(2) K,
o-scanning with 11 steps). An empirical absorption correction
was applied. Using Olex2,45 the structures were solved with the
ShelXS structure solution program using Direct Method and
Synthetic procedures
Preparation of intermediates. The quinazoline-4(3H)-ones
refined with the ShelXL46 refinement package using full-matrix 4a,b were obtained from 2-aminobenzamide
1 and the
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appropriate thiophen-2-carboxaldehyde 2 in two steps using 279 [M + 1]+ (20), 278 [M]+ (84), 159 (13), 150 (27), 133 (10), 120
previously developed methods.8,38 The compounds 4c,d were (11), 119 (64), 105 (18), 104 (51), 103 (14), 92 (26), 91 (100), 90
synthesized using a similar procedure.
(21), 89 (29), 79 (10), 78 (17), 79 (23), 51 (21), 50 (12), 45 (74), 43
(80), 42 (15), 39 (20); molecular formula C16H10N2OS; requires
2-(5-Hexylthiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one
(3c). A solution of 2-aminobenzamide 1 (0.50 g, 3.7 mmol) in [M]+ 278. Elemental analysis: found C, 69.06; H, 3.60; N,
ethanol (20 mL) and 5-hexylthiophen-2-carboxaldehyde 2c (0.72 10.03%; requires C, 69.04; H, 3.62; N, 10.06%.
g, 3.7 mmol) was refluxed for 3 h. The mixture was cooled, and
Starting 2-phenyl-3H-quinazolin-4-one 6 was obtained by
the solvent was evaporated. The product was washed with EtOH treatment of anthranilamide with benzoyl chloride as pre-
(5 mL) to obtain a pale yellow solid, yield 82%, m.p. 165–167 1C. viously described.47
1H NMR (400 MHz, DMSO-d6), d: 0.88 (3H, m, CH3), 1.30 (6H,
m, 2CH2), 1.59 (2H, m, CH2), 2.72 (2H, t, 3J = 7.5 Hz, CH2), 5.89
General procedure for the synthesis of compounds 5a–d
(1H, s, 2-H), 6.61 (1H, m, 40-H), 6.67 (1H, m, benzo), 6.73 (1H, d, The synthesis of products 5a–d was accomplished using a
3J = 7.7 Hz, benzo), 6.88 (1H, d, 3J = 3.9 Hz, 30-H), 7.05 (1H, br s, protocol similar to a previously published procedure.27 To a
3
NH), 7.21 (1H, m, benzo), 7.60 (1H, d, J = 7.6 Hz, benzo), 8.20 suspension of corresponding 2-(thiophen-2-yl)quinazoline-
(1H, br s, NH). MS (m/z, Irel%): 315 [M + 1]+ (17), 314 [M]+ (63), 4(3H)-one 4a–d (0.90 mmol) in HFIP (3 mL), diphenylacetylene
313 [M ꢀ H]+ (100), 281 (30), 229 (11), 147 (48), 121 (12), 120 (0.19 g, 1.08 mmol), [RhCp*Cl2]2 (22 mg, 36 mmol), and CsOAc
(95), 119 (18), 97 (30), 92 (30), 65 (10); molecular formula (0.05 g, 0.27 mmol) were added. The mixture was stirred at
C
18H22N2OS; requires [M]+ 314. Elemental analysis: found C, 70 1C for 12 h in a round-bottom pressure flask.
68.73; H, 7.08; N, 8.89%; requires C, 68.75; H, 7.05; N, 8.91%.
4,5-Diphenyl-7H-thieno[20,30:3,4]pyrido[2,1-b]quinazolin-7-
2-((Benzo[b]thiophen-2-ylmethylene)amino)benzamide (3d) one (5a) was synthesized following a general procedure. The
was synthesized using a procedure similar to that used for 3c. reaction mixture was cooled, and acetone (2 mL) was added.
After cooling, the precipitate was filtered and washed with The formed precipitate was filtered and washed with acetone
MeCN to obtain
a colourless solid, yield 91%, m.p. (1 mL) and hexane (1 mL). Yellow solid, yield 33%, m.p.
:
204–206 1C. 1H NMR (400 MHz, DMSO-d6), d: 7.31 (1H, d, 262–264 1C (lit. m.p. 250–251 1C).22 1H NMR (400 MHz, CDCl3),
3J = 8.1 Hz), 7.35 (1H, m), 7.42–7.50 (2H, m), 7.54 (1H, m), 7.60 d: 6.90 (1H, d, J = 5.2 Hz, 3-H), 7.08 (4H, m, Ph), 7.16 (3H, m,
(1H, br s, NH2), 7.98 (2H, m), 8.09 (2H, m), 8.38 (1H, br s, NH2), Ph), 7.23 (3H, m, Ph), 7.36 (1H, m, 10-H), 7.66 (1H, d, J = 5.2
3
3
8.95 (1H, s, NQCH). MS (m/z, Irel%): 281 [M + 1]+ (18), 280 [M]+ Hz, 2-H), 7.79 (2H, m, 8-H, 9-H), 8.17 (1H, d, 3J = 8.0 Hz, 11-H).
(79), 279 [M ꢀ H]+ (74), 247 (12), 160 (11), 147 (54), 146 (21), 134 13C NMR (100 MHz, DMSO-d6), d: 118.8, 124.8, 124.9, 124.9,
(54), 121 (11), 120 (100), 119 (35), 92 (52), 91 (11), 65 (21), 64 125.7, 126.6, 126.7, 126.8, 127.2, 127.9, 128.8, 130.1, 131.9,
(12), 63 (13); molecular formula C16H12N2OS; requires [M]+ 280. 134.7, 134.7, 135.6, 136.0, 136.3, 141.8, 144.8, 146.8, 160.2.
Elemental analysis: found C, 68.58; H, 4.33; N, 9.97%; requires MS (m/z, Irel%): 405 [M + 1]+ (31), 404 [M]+ (100), 403 (30), 375
C, 68.55; H, 4.31; N, 9.99%.
(12); molecular formula C
26H16N2OS; requires [M]+ 404.
2-(5-Hexylthiophen-2-yl)quinazoline-4(3H)-one (4c). 2-(5- Elemental analysis: found C, 77.18; H, 4.02; N, 6.92%; requires
Hexylthiophen-2-yl)-2,3-dihydroquinazolin-4(1H)-one 3c (0.94 C, 77.20; H, 3.99; N, 6.93%.
g, 3.0 mmol) was dissolved in ethanol (20 mL), CuCl2 (0.54 g,
The reagents were stirred in HFIP (5 mL) for 14 h following a
4 mmol) was added, and the reaction mixture was refluxed for general procedure. After cooling, the precipitate was filtered
5 h. After cooling, the formed quinazolinone 4c was filtered and and washed with acetone (1 mL) and hexane (1 mL). The
washed with EtOH (3 mL) and hexane (3 mL) to obtain a pale product was extracted with CHCl3 and purified by column
1
yellow solid, yield 80%, m.p. 175–177 1C. H NMR (400 MHz, chromatography on SiO2, with the eluent gradually changing
DMSO-d6), d: 0.90 (3H, m, CH3), 1.32–1.40 (6H, m, 2CH2), 1.69 from hexane to hexane/EtOAc (1/1). Yellow solid, yield 30%,
(2H, m, CH2), 2.84 (2H, t, 3J = 7.5 Hz, CH2), 6.85 (1H, d, 3J = 3.9 m.p. 265–266 1C. 1H NMR (400 MHz, CDCl3), d: 6.86 (1H, s,
3
Hz, 40-H), 7.41 (1H, m, 7-H), 7.57 (1H, d, J = 7.7 Hz, 5-H), 7.74 3-H), 7.03–7.08 (4H, m, Ph), 7.16–7.18 (3H, m, Ph), 7.25 (3H, m,
(1H, m, 6-H), 8.01 (1H, d, 3J = 3.9 Hz, 30-H), 8.09 (1H, d, 3J = 8.2 Ph), 7.34–7.38 (1H, m, 10-H), 7.77 (2H, m, 8H, 9-H), 8.15 (1H, d,
Hz, 8-H), 12.44 (1H, s, NH). MS (m/z, Irel%): 313 [M + 1]+ (14), 3J = 8.0 Hz, 11-H). 13C NMR (100 MHz, CDCl3), d: 119.5, 121.9,
312 [M]+ (65), 242 (25), 241 [M ꢀ C5H11]+ (100); molecular 124.7, 125.2, 126.2, 127.4, 127.6, 127.7, 128.3, 128.3, 128.8,
formula C18H20N2OS; requires [M]+ 312. Elemental analysis: 130.4, 133.9, 134.8, 135.6, 136.2, 137.1, 142.2, 144.1, 147.5,
found C, 69.18; H, 6.47; N, 8.92%; requires C, 69.20; H, 6.45; 161.1. MS (m/z, Irel%): 485 [M + 3]+ (29), 484 [M + 2]+ (100),
N, 8.97%.
483 [M + 1]+ (50), 482 [M]+ (95), 481 (22), 201 (29), 194 (16);
2-(Benzo[b]thiophen-2-yl)quinazoline-4(3H)-one (4d) was molecular formula C26H15BrN2OS; requires [M]+ 482. Elemental
synthesized using a method similar to that used to obtain 4c analysis: found C, 77.18; H, 4.02; N, 6.92%; requires C, 64.60; H,
in MeOH, with refluxing for 11 h. Colourless solid, yield 50%, 3.13; N, 5.80%.
m.p. 4 300 1C. 1H NMR (400 MHz, DMSO-d6), d: 7.43–7.48 (3H,
m, 7-H, 50-H, 60-H), 7.69 (1H, d, J = 8.2 Hz, 5-H), 7.79 (1H, m, zolin-7-one (5c) was synthesized following a general procedure.
6-H), 7.91 (1H, dd, J = 6.7 Hz, J = 1.4 Hz, 40-H or 70-H), 7.95 The reaction mixture was cooled and partially evaporated,
(1H, d, 3J = 7.4 Hz, 40-H, 70-H), 8.15 (1H, dd, 3J = 7.9 Hz, 4J = 1.3 acetone (2 mL) was added, and the formed precipitate was
Hz, 8-H), 8.54 (1H, s, 30-H), 12.80 (1H, br s, NH). MS (m/z, Irel%): filtered and washed with acetone (1 mL) and hexane (1 mL).
4,5-Diphenyl-7H-(5-hexyl)thieno[20,30:3,4]pyrido[2,1-b]quina-
3
3
4
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The product was purified by column chromatography on SiO2, molecular formula C44H29N3OS; requires [M]+ 647. Elemental
with the eluent gradually changing from hexane to hexane/ analysis: found C, 81.56; H, 4.54; N, 6.47%; requires C, 81.58; H,
EtOAc (1/1). Pale yellow solid, yield 30%, m.p. 150–152 1C. 4.51; N, 6.49%.
1H NMR (400 MHz, CDCl3), d: 0.88 (3H, t, 3J = 6.1 Hz, CH3), 1.30
4,5-Diphenyl-9,11-dibromo-7H-benzo[b]thieno[20,30:3,4]pyrido-
(4H, m, 2CH2), 1.38 (2H, m, CH2), 1.72 (2H, m, CH2), 2.87 (2H, t, [2,1-b]quinazolin-7-one (5f). To a suspension of 5a (0.12 g,
3J = 7.6 Hz, CH2), 6.57 (1H, s, 3-H), 7.06 (4H, m, Ph), 7.16 (3H, 0.3 mmol) in DMF (3 mL), a solution of NBS (0.127 g, 0.72 mmol)
m, Ph), 7.23 (3H, m, Ph), 7.33 (1H, m, 10-H), 7.76 (2H, m, 8-H, 9- in DMF (2 mL) was added. The mixture was stirred at 80 1C for
H), 8.15 (1H, d, J = 8.01 Hz, 11-H). 13C NMR (100 MHz, CDCl3), 6 h. After cooling and partial evaporation, water (3 mL) was added.
d: 14.2, 22.6, 28.9, 31.1, 31.5, 31.6, 119.2, 122.5, 124.6, 125.6, The formed precipitate was filtered off and washed with hexane
126.1, 127.2, 127.3, 127.4, 127.6, 128.1, 128.9, 130.5, 130.9, (2 mL). The product was purified by column chromatography on
134.6, 136.2, 136.4, 136.7, 142.5, 145.2, 147.8, 154.9, 161.4. SiO2, with hexane/EtOAc eluent (5/1). Yellow solid, yield 40%,
1
MS (m/z, Irel%): 490 [M + 2]+ (11), 489 [M + 1]+ (36), 488 [M]+ m.p. = 249–251 1C. H NMR (400 MHz, CDCl3), d: 6.92 (1H, d,
(100), 417 [M ꢀ C5H11]+ (15); 43 (13); molecular formula 3J = 5.3 Hz, 3-H), 7.06 (4H, m, Ph), 7.16 (3H, m, Ph), 7.25 (3H, m,
3
4
C
32H28N2OS; requires [M]+ 488. Elemental analysis: found C, Ph), 7.73 (1H, d, J = 5.3 Hz, 2-H), 8.15 (1H, d, J = 2.0 Hz), 8.25
78.63; H, 5.80; N, 5.72%; requires C, 78.66; H, 5.78; N, 5.73%. (1H, d, J = 2.0 Hz). 13C NMR (100 MHz, CDCl3), d: 117.1, 121.1,
6,7-Diphenyl-8H-benzo[40,50]thieno[20,30:3,4]pyrido[2,1-b]qui- 122.0, 125.7, 126.6, 127.5, 127.6, 127.7, 128.2, 128.9, 129.5, 130.3,
nazolin-8-one (5d). 6,7-Diphenyl-8H-benzo[40,50]thieno[20,30:3,4] 133.1, 134.2, 135.6, 135.9, 136.4, 140.4, 142.8, 144.2, 145.7, 159.8. MS
pyrido[2,1-b]quinazolin-8-one (5d) was synthesized following a (m/z, Irel%): 565 [M + 5]+ (16), 564 [M + 4]+ (57), 563 [M + 3]+ (35), 562
general procedure. After cooling, the precipitate was filtered and [M + 2]+ (100), 561 [M + 1]+ (27), 560 [M]+ (50), 484 (19), 483 (13), 482
washed with acetone (1 mL) and hexane (1 mL). The product was (19), 374 (20), 373 (23), 372 (24), 281 (11), 186 (14), 77 (13); molecular
purified by column chromatography on SiO2, with the eluent formula C26H14Br2N2OS; requires [M]+ 560. Elemental analysis: found
4
gradually changing from hexane to hexane/EtOAc (4/1). Yellow C, 55.52; H, 2.54; N, 4.95%; requires C, 55.54; H, 2.51; N, 4.98%.
1
solid, yield 34%, m.p. 4300 1C. H NMR (400 MHz, CDCl3), d:
1,1,1,3,3,3-Hexafluoropronan-2-yl-2-(2,3,7,8-tetraphenyl-1H-
3
6.49 (1H, d, J = 8.3 Hz,), 7.06 (1H, m), 7.15–7.20 (7H, m, Ph), benzo[d,e][1,8]-naphthyridin-1-yl)benzoate (7) was synthesized
7.31–7.35 (3H, m), 7.35–7.42 (2H, m), 7.80 (1H, m, 10-H), 7.86 following a previously published procedure.27 To a suspension
3
3
(1H, d, J = 8.0 Hz, 9-H), 7.95 (1H, d, J = 8.0 Hz), 8.19 (1H, d, of 2-(phen-2-yl)quinazoline-4(3H)-one 6 (0.9 mmol) in HFIP
3J = 8.0 Hz, 12-H). 13C NMR (100 MHz, CDCl3), d: 119.4, 123.2, (6 mL), diphenylacetylene (0.39 g, 2.16 mmol), [RhCp*Cl2]2
124.9, 125.3, 125.5, 126.2, 126.5, 127.2, 127.4, 127.7, 128.1, 128.5, (45 mg, 72 mmol), and CsOAc (0.1 g, 0.54 mmol) were added.
129.0, 131.0, 134.8, 135.8, 135.9, 136.0, 136.7, 137.5, 142.9, 145.2, The mixture was stirred at 70 1C for 12 h in a round-bottom
147.7, 161.0. MS (m/z, Irel%): 456 [M + 2]+ (11), 455 [M + 1]+ (36), pressure flask. The reaction mixture was cooled, and acetone
454 [M]+ (100), 453 (15), 227 (12); molecular formula (2 mL) was added. The formed precipitate was then filtered off
C30H18N2OS; requires [M]+ 454. Elemental analysis: found C, and washed with acetone (1 mL) and hexane (1 mL). The
79.25; H, 3.97; N, 6.14%; requires C, 79.27; H, 3.99; N, 6.16%.
product was purified by column chromatography on SiO2, with
4,5-Diphenyl-7H-(5-(4-diphenylaminophenyl))thieno[20,30:3,4]- CH2Cl2 eluent. Yellow solid, yield 52%, m.p. 218–220 1C.
pyrido[2,1-b]quinazolin-7-one (5e). 4,5-Diphenyl-7H-(5-(4-diphen- 1H NMR (600 MHz, CDCl3), d: 6.01 (1H, m, CH(CF3)2), 6.60
ylaminophenyl))thieno[20,30:3,4]-pyrido[2,1-b]quinazolin-7-one (5e) (1H, d, 3J = 7.4 Hz), 6.88–7.05 (13H, m), 7.12–7.26 (5H, m),
was synthesized using a protocol similar to a previously published 7.27–7.32 (5H, m), 7.39 (1H, m), 7.43 (1H, m), 8.01 (1H, dd,
procedure.39 To a suspension of 4,5-diphenyl-7H-(5-bromo)thieno 3J = 8.0 Hz, 4J = 1.5 Hz). 13C NMR (100 MHz, CDCl3), d: 66.90 (m,
[20,30:3,4]pyrido[2,1-b]quinazolin-7-one 5b (0,10 g, 0.21 mmol) in CH(CF3)2), 116.3, 118.6, 119.6, 120.2, 122.3, 125.5, 126.6, 126.8,
toluene (10 mL), 4-(diphenylamino)phenylboronic acid (0.07 g, 126.9, 127.0, 127.6, 127.7, 127.8, 128.0, 128.0, 128.3, 128.9,
0.25 mmol), PdCl2(PPh3)2 (15 mg, 0.02 mmol), PPh3 (10 mg, 130.3, 131.3, 131.5, 131.6, 131.8, 132.8, 134.9, 135.2, 136.6,
0.04 mmol), solution of K2CO3 (0.2 g, 1.4 mmol) in water 137.1, 138.9, 139.5, 140.9, 141.3, 141.7, 149.1, 152.6, 162.6.
(1.2 mL), and EtOH (1.2 mL) were added. The mixture was stirred 19F NMR (376 MHz, CDCl3), d: ꢀ73.15 (m), ꢀ72.73 (m). MS
at 85 1C for 14 hours under an argon atmosphere in a round- (m/z, Irel%): 744 [M + 2]+ (20), 743 [M + 1]+ (55), 742 [M]+ (75),
bottom pressure flask. After cooling the mixture, EtOAc/water (1/1, 741 (10), 549 (19), 548 (63), 547 (100) [M ꢀ C(O)OCH(CF3)2]+,
10 mL) was added. The organic layer was separated, and the 546 (12), 469 (10), 371 (11), 287 (11), 273 (17), 272 (10), 265 (14),
aqueous layer was extracted with additional EtOAc (2 ꢁ 10 mL). 264 (11), 234 (14), 233 (11), 77 (10); molecular formula
The combined organic extracts were dried over MgSO4, and the
solvent was evaporated under reduced pressure. The product was C, 79.25; H, 3.97; N, 6.14%; requires C, 72.77; H, 3.80; N, 3.77%.
purified by column chromatography on SiO2, gradually changing 5,6-Diphenyl-8H-isoquinolino[1,2-b]quinazolin-8-one (8). Pale
C
45H28F6N2O2; requires [M]+ 742. Elemental analysis: found
from hexane to hexane/EtOAc (1/9). Yellow solid, yield 69%, m.p. 4 yellow solid, yield o5%, m.p. 240–242 1C (lit. m.p.
1
280 1C. H NMR (400 MHz, CDCl3), d: 6.93 (1H, s, 3-H), 7.03–7.17 249–250 1C).22 1H NMR (400 MHz, CDCl3), d: 7.08–7.13 (7H, m,
3
(16H, m), 7.26 (3H, m), 7.28–7.33 (4H, m), 7.50 (2H, d, 3J = 7.9 Hz), Ph), 7.19 (1H, d, J = 7.7 Hz, 4-H), 7.27 (3H, m, Ph), 7.41 (1H, m,
3
7.78 (2H, m, 8-H, 9-H), 8.16 (1H, d, J = 8.0 Hz, 11-H). MS (m/z, 11-H), 7.57 (1H, m 2-H or 3-H), 7.64 (1H, m, 2-H or 3-H), 7.82 (1H,
3
Irel%): 649 [M + 2]+ (18), 648 [M + 1]+ (54), 647 [M]+ (100), 485 (10), m, 10-H), 7.89 (1H, m, 9-H), 8.17 (1H, d, J = 7.9 Hz, 12-H), 9.13
484 (38), 483 (18), 482 (33), 404 (29), 324 (34), 201 (13), 57 (12); (1H, d, 3J = 7.9 Hz, 1-H). MS (m/z, Irel%): 399 [M + 1]+ (31), 398 [M]+
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NJC
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(100), 397 (38), 381 (11), 369 (14); molecular formula C28H18N2O;
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a transformation into the 2,3,7,
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tion for Basic Research (grant number 19-33-90014) and Grants
Council of the President of the Russian Federation (grant number
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