Metal free TBHP-promoted intramolecular carbonylation of arenes: Via radical cross-dehydrogenative coupling: Synthesis of indenoquinolinones, 4-azafluorenones and fluorenones

Article abstract of DOI:10.1039/c6ob00998k

A metal-free, TBHP-promoted economical route is developed via the sp² C-H bond functionalization strategy for the synthesis of indenoquinolinones, 4-azafluorenones and fluorenones. Reactions provided excellent yield of the products under mild conditions. We have successfully synthesized 11H-indeno[1,2-b]quinolin-11-one, an antibacterial agent, in excellent yields.

Full text of DOI:10.1039/c6ob00998k

Organic &
Biomolecular Chemistry
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Metal free TBHP-promoted intramolecular
carbonylation of arenes via radical cross-
dehydrogenative coupling: synthesis of
indenoquinolinones, 4-azafluorenones and
fluorenones†
Cite this: DOI: 10.1039/c6ob00998k
Kalpana Mishra,a Ashok Kumar Pandey,b Jay Bahadur Singha and Radhey M. Singh*a
A metal-free, TBHP-promoted economical route is developed via the sp2 C–H bond functionalization
strategy for the synthesis of indenoquinolinones, 4-azafluorenones and fluorenones. Reactions provided
excellent yield of the products under mild conditions. We have successfully synthesized 11H-indeno
[1,2-b]quinolin-11-one, an antibacterial agent, in excellent yields.
Received 7th May 2016,
Accepted 27th May 2016
DOI: 10.1039/c6ob00998k
www.rsc.org/obc
Introduction
Quinoline derivatives are found in various alkaloids and well
recognized by both synthetic and medicinal chemists because of
their biological importances and use as synthetic building blocks.1
Indenoquinolinone derivatives are another important class of
molecules which possess interesting biological properties such
as 5-HT-receptor binding, anti-inflammatory, anti-malarial and
anti-tumor activities.2 Indenoquinolinone scaffold 1 shows
antibacterial activity against Gram-positive and Gram-negative
bacteria3 and its derivatives 2 have cytotoxic activity against
HeLa cells.4 Similarly, carboxamides 3 possess anticancer
activity and inhibit topoisomerase I/II (topo I/II) enzymes (IC50
35 nM–180 nM in the Jurkat human leukemia cell line)5
(Fig. 1). Owing to their biological importance both synthetic
chemists and pharmacologists are involved in developing new
methodologies for their synthesis.3–6 Recently, sp2 C–H bond
functionalization has been reported to be an important syn-
thetic route for C–C bond formation owing to its higher atom
economy and sustainability. In this context, transition metal
(TM) catalyzed C–H bond functionalization has been employed
in organic synthesis.7 However, challenges for controlled C–H
bond functionalization to gain regioselectivity persist.
Fig. 1 Bioactive molecules with a tetracyclic indenoquinolinone ring.
cross-dehydrogenative coupling (CDC) reaction8 and signified
its importance owing to economical and eco-friendly
approaches. In this domain, carbonylation of arenes with an
aldehydic group with or without a TM has been utilized in
C(sp2)–C(sp2) bond formation for the synthesis of complex
molecular assemblies.9 Studer et al. have reported a TBHP pro-
moted intramolecular CDC reaction using a TM as an initiator
for the synthesis of fluorenones and xanthones (Scheme 1).10
Later, Glorius et al. have reported the CDC reaction between
aldehydes and arenes using K2S2O8 and TBAB as an oxidant
and an additive respectively for the synthesis of fluorenones
(Scheme 1).11 A similar intramolecular CDC reaction using
only an oxidant is not explored for the synthesis of heterocyclic
and carbocyclic systems.
Recently, radical chemistry is found to be an alternative
route to TM-catalysis for C(sp2)–C(sp2) bond formation via
In our earlier studies, 2-chloroquinolinyl-3-carboxaldehydes
were used to develop new methodologies for the synthesis of
various benzo or hetero fused quinoline skeletons.12 In this
study, we report an aqueous TBHP-promoted intramolecular
CDC reaction for the synthesis of Indenoquinolinone, 4-aza-
fluorenones and fluorenones from 2-arylquinolinyl-3-carboxal-
dehyde, 2-arylpyridenyl-3-carboxaldehyde and 2-arylbenzenyl-
aDepartment of Chemistry, Centre of Advanced Studies, Institute of Science, Banaras
Hindu University, Varanasi-221005, India. E-mail: rmohan@bhu.ac.in
bDepartment of Chemistry, Indian Institute of Technology Ropar, Nangal Road,
Rupnagar, Punjab-140001, India. E-mail: ashokp.ansh@gmail.com
†Electronic supplementary information (ESI) available. CCDC 1472053. For ESI
and crystallographic data in CIF or other electronic format see DOI: 10.1039/
c6ob00998k
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Table 1 Optimization of reaction conditionsa
Oxidant
(equiv.)
Temp.
(°C)
Time
(h)
Yieldb
(%)
Entry
Solvent
1
2
3
4
5
6
7
8
TBHPc (2)
TBHP (3)
TBHP (4)
TBHP (6)
TBHP (8)
H2O2 d(3)
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (3)
TBHP (3)
Toluene
Toluene
Toluene
Toluene
Toluene
Toluene
DCEf
100
100
100
100
100
100
100
100
100
100
100
80
17
14
16
18
20
24
18
22
20
24
16
24
16
72
81
70
65
45
nre
68
40
51
40
71
63
72
THFg
9
DMSOh
CH3CN
Benzene
Toluene
Toluene
10
11
12
13
Scheme 1 Approaches for carbonylation of an aryl ring through intra-
molecular CDC reaction.
110
a 6a (1 equiv.), toluene (2 mL). b Isolated yield by flash column chrom-
atography. c tert-Butyl hydroperoxide. d Hydrogen peroxide. e No reac-
tion. f 1,2-Dichloroethane. g Tetrahydrofuran. h Dimethyl sulphoxide.
3-carboxaldehyde analogues respectively in good to excellent
yields (Scheme 1).13
paratively slow with a reduced yield of 7a with higher equiv. of
TBHP. The reaction with other oxidants such as 30% aqueous
H2O2 in toluene was examined and found to be unsuccessful
(entry 6). Further variation of solvents such as DCE, THF,
DMSO, CH3CN, and benzene (entries 7–11) and temperatures
from 80 °C to 110 °C (entries 12 and 13) did not provide better
yield of the product.
Results and discussion
We initially optimized the Suzuki coupling reaction conditions
for the preparation of 6 from precursor 4 and phenylboronic
acid 5 (Scheme 2).14 Similar conditions were also applied for
the preparation of pyridine and benzene analogues.
With the best annulation reaction conditions as 1 equiv. of
6a with 3 equiv. of TBHP in 2 mL toluene at 100 °C in hand,
the scope of this methodology was further examined with the
substituent variations at the phenyl ring in substrate 6
(Table 2). All reactions afforded annulated products 7a–f in
81–73% yields. An electron withdrawing group e.g. Br, Cl, and
F present at the para-position in the phenyl ring favors higher
yield of the products 7b, 7c and 7d. However, electron donat-
ing groups such as methyl or trifluoromethoxy at the para-posi-
tion in the phenyl ring reduced the yield of products 7e and 7f
(Table 2). Increasing and decreasing yields of the product
could be explained by −I and +I effects of the groups. The
scope of the reaction was also examined with the substituent
present in the quinoline moiety of 6 and the reaction afforded
the corresponding annulated products 7g–k in 88–76% yields
(Table 2). Electron donating groups present at 6 and 7 posi-
tions enhanced the yield of annulated products (7g–7i).
However, the methyl group at the 8-position lowered the yield
of 7j. An electron withdrawing group present at the 7-position
also lowered the yield of product 7k to 76%.
The required precursor 6a was examined to find the
optimal annulation reaction conditions for the formation of
Indenoquinolinone derivative 7a (Table 1). Initially, the reac-
tion of 6a was examined under free-radical conditions using 2
equiv. of 70% tert-butyl hydroperoxide (TBHP)15 in 2 mL of
toluene at 100 °C under an argon atmosphere (Table 1). We
were delighted that the reaction proceeded without a TM with
a single spot on TLC and an annulated product 7a was
obtained in 72% yield within 17 h (entry 1). Both the rate of
reaction and yield of the product improved using 3 equivalents
of TBHP and gave 7a in 81% yield within 14 h (entry 2).
Inspired from the higher dosages of TBHP on the progress of
the reaction and yield, we increased the number of equiv. of
TBHP in different batches to see the productivity of the reac-
tion (entries 3, 4 and 5). The reaction was found to be com-
The scope of annulation reactions was further evaluated
with the substrates having electron donating groups at both
quinoline and phenyl rings. The reactions of the substrates
with electron donating groups in the quinoline ring and the
Scheme 2 Preparation of the starting material.
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Table 2 Substrate scopea
present in the phenyl ring could be responsible for lower yield
of the product.
In continuation of substrate variation, pyridine analogues
were also evaluated under optimal reaction conditions.
5-Phenyl-3-arylnicotinealdehyde derivatives were examined
and afforded the products 7p, 7q and 7r in excellent yields.
The shorter reaction times and excellent yields demonstrated
that the pyridine is more reactive than its benzofused ana-
logues (quinolines). During our investigations, we obtained
the single crystal structure of 7r (Table 2, for details see the
ESI†).16 This methodology was further examined with arene
analogues for the synthesis of fluorenone derivatives. All reac-
tions proceeded smoothly and afforded the fluorenones 7s–u,
in 81–62% yield (Table 2).
We gain insight into the intramolecular CDC reaction that
proceeded by a free radical mechanism. We performed the
CDC reaction of 6a in the presence of TEMPO (2 equiv.) as a
free radical quencher under the optimized reaction conditions
(Scheme 3). The reaction did not proceed upon prolonged
heating and the starting material was isolated, which supported
the free radical mechanism of the reaction.
Depending upon product formation and literature
reports,17 we proposed the free radical mechanism of the reac-
tion in Scheme 4. Initially, upon heating tBuOOH could
undergo O–O homolytic bond fission to produce tBuO and OH
radicals. The tBuO radical might abstract hydrogen atom
Scheme 3 Intramolecular CDC reaction in the presence of TEMPO.
a 6 (1 equiv.), tert-butyl hydroperoxide (3 equiv.). b Isolated yield by
flash column chromatography.
trifluoromethoxy group in the phenyl ring were examined
under optimal reaction conditions and afforded the products
Scheme 4 Proposed reaction mechanism for intramolecular CDC
7l–o in 78–68% yield (Table 2). The trifluoromethoxy group reaction.
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from aldehydic carbon of 6a and generate the carbonyl radical (4 × 5 mL). The collected organic phase was washed with
intermediate A. Intermediate A underwent acylation at the water, brine and dried over anhydrous Na2SO4. The solvent
ortho-position of the phenyl ring and generated the cyclohexa- was removed under reduced pressure and the obtained residue
dienyl radical B. An acidic proton in intermediate B might was purified by column chromatography (hexane : ethyl acetate
have undergone deprotonation in aqueous tBuOOH to produce = 18 : 2) to afford starting materials 6.
the cyclohexadienyl radical anion C. Intermediate C underwent
2-Phenylquinoline-3-carbaldehyde (6a). 2-Chloroquinoline-
the single electron transfer (SET) process to reduce tBuOOH 3-carbaldehyde (0.19 g, 1.00 mmol), phenylboronic acid
into a tBuO radical and a hydroxide anion. During this SET (0.15 g, 1.20 mmol), tBuOK (0.11 g, 1.00 mmol), reaction time:
process intermediate C gave the final product 7a. The newly 2 h, yield: 0.21 g, 92%, white solid, mp: 98 °C, IR (KBr): ν 1693,
generated hydroxide anion continued the propagation step of 1156, 753 cm−1 1H NMR (300 MHz, CDCl3): δ 10.17 (s, 1H),
,
the mechanism.
8.84 (s, 1H), 8.21 (d, J = 8.7 Hz, 1H), 8.00 (d, J = 8.1 Hz, 1H),
7.86 (t, J = 7.2 Hz, 1H), 7.69–7.54 (m, 6H), 13C NMR (75 MHz,
CDCl3): δ 191.4, 160.2, 149.6, 138.1, 138.0, 137.7, 132.5, 130.2,
129.5, 129.4, 129.3, 128.8, 128.7, 127.6, 127.4, 126.3.
Conclusions
2-(4-Bromophenyl)quinoline-3-carbaldehyde (6b). 2-Chloro-
quinoline-3-carbaldehyde (0.09 g, 0.47 mmol), (4-bromo-
phenyl)boronic acid (0.12 g, 0.57 mmol), tBuOK (0.05 g,
0.50 mmol), reaction time: 3 h, yield: 0.14 g, 95%, white solid,
In conclusion, we have developed a metal-free, eco-friendly
and economical TBHP promoted intramolecular CDC reaction
towards the synthesis of Indenoquinolinone, 4-azafluorenone
and fluorenone derivatives. We have economically synthesized
molecule 7a which is known for its antibacterial activity
against Gram-positive and Gram-negative bacteria. Bioactive
analysis of other analogues is under investigation.
1
mp: 150 °C, H NMR (300 MHz, CDCl3): δ 10.17 (s, 1H), 8.85
(s, 1H), 8.20 (d, J = 8.1 Hz, 1H), 8.02 (d, J = 8.1 Hz, 1H), 7.89 (t,
J = 7.8 Hz, 1H), 7.76–7.56 (m, 5H), 13C NMR (75 MHz, CDCl3):
δ 190.9, 158.9, 149.6, 138.6, 136.7, 132.8, 131.9, 131.8, 130.9,
129.6, 129.4, 128.8, 127.7, 127.3, 126.4, 124.14.
2-(4-Chloro-phenyl)quinoline-3-carbaldehyde (6c). 2-Chloro-
quinoline-3-carbaldehyde (0.19 g, 1.00 mmol), (4-chloro-
phenyl)boronic acid (0.19 g, 1.20 mmol), tBuOK (0.11 g,
1.00 mmol), reaction time: 3 h, yield: 0.25 g, 94%, white solid;
Experimental
General information
1H NMR and 13C NMR spectra were recorded at ambient temp-
erature using a JEOL spectrometer operating at 300 MHz and
75 MHz respectively. 19F NMR spectra were recorded at
500 MHz. Data are reported as follows: chemical shifts in ppm
from internal tetramethylsilane (TMS) on the δ scale, multi-
plicity (s = singlet, d = doublet, t = triplet, q = quartet, m =
multiplet), coupling constants (Hz) and integration. Melting
points were measured using a Buchi melting-point apparatus
in an open capillary tube and are uncorrected. IR spectra were
recorded on Varian 3300 FTIR spectrophotometers in cm−1
units. High resolution mass spectra (HRMS) were obtained on
TOF/6500 Series QTOF B.05.00 (B5042.0). Thin-layer chromato-
graphy (TLC) was performed on glass plates (7.5 × 2.5 and 7.5
× 5.0 cm) coated with silica gel GF 254 and various combi-
nations of ethyl acetate and hexane were used as eluents.
Boronic acids and TBHP are commercially available. Solvents
were purified according to standard procedures. The developed
chromatogram was analyzed by UV light. Column chromato-
graphy was performed using silica gel (mess size 100–200).
Data of compounds 6a, 6e, 6i and 6j are reported18 in the
literature.
1
mp: 114 °C, H NMR (300 MHz, CDCl3): δ 10.17 (s, 1H), 8.85
(s, 1H), 8.21 (d, J = 8.4 Hz, 1H), 8.11 (d, J = 7.5 Hz, 1H), 8.02 (d,
J = 8.1 Hz, 1H), 7.89 (t, J = 6.9 Hz, 1H), 7.64 (d, J = 8.4 Hz, 2H),
7.56–7.45 (m, 3H), 13C NMR (75 MHz, CDCl3): δ 191.0, 171.5,
158.9, 149.5, 138.7, 136.2, 133.7, 132.9, 131.5, 130.2, 129.5,
128.0, 128.4, 127.8, 127.6, 126.5.
2-(4-Fluoro-phenyl)quinoline-3-carbaldehyde (6d). 2-Chloro-
quinoline-3-carbaldehyde (0.19 g, 1.00 mmol), (4-fluorophenyl)
boronic acid (0.17 g, 1.20 mmol), tBuOK (0.11 g, 1.00 mmol),
reaction time: 2 h, yield: 0.23 g, 92%; white solid, mp: 96 °C,
1H NMR (300 MHz, CDCl3): δ 10.18 (s, 1H), 8.85 (s, 1H), 8.20
(d, J = 8.7 Hz, 1H), 8.03 (d, J = 8.1 Hz, 1H), 7.89 (t, J = 8.4 Hz,
1H), 7.71–7.63 (m, 3H), 13C NMR (75 MHz, CDCl3): δ 191.1,
165.3, 162.0, 159.1, 149.5, 138.54, 138.5, 133.9, 133.8, 132.8,
132.2, 132.1, 129.5, 129.4, 127.6, 127.6, 126.4, 116.2, 115.98,
115.7.
2-p-Tolylquinoline-3-carbaldehyde (6e). 2-Chloro-quinoline-
3-carbaldehyde (0.19 g, 1.00 mmol), (p-tolylphenyl)boronic
acid (0.16 g, 1.20 mmol), tBuOK (0.11 g, 1.00 mmol), reaction
1
time: 2 h, yield 0.22 g, 90%, white solid, mp: 116 °C, H NMR
(300 MHz, CDCl3): δ 10.18 (s, 1H), 8.82 (s, 1H), 8.19 (d, J = 8.4
Hz, 1H), 8.00 (d, J = 8.1 Hz, 1H), 7.85 (t, J = 7.5 Hz, 1H),
7.62–7.57 (m, 3H), 7.36 (d, J = 6.9 Hz, 2H), 2.46 (s, 3H), 13C
General procedure for synthesis of starting materials 6
A solution of 2-chloroquinoline-3-carbaldehyde (1 equiv.), aryl- NMR (75 MHz, CDCl3): δ 191.7, 160.3, 149.7, 139.5, 138.1,
boronic acid (1.2 equiv.), Pd(PPh3)4 (2 mol%) and potassium 138.0, 134.9, 132.5, 130.2, 129.6, 129.4, 127.7, 127.3, 126.3,
tert-butoxide (1 equiv.) in benzene : water (4 : 1, 3 mL) was 21.3.
heated at 80 °C under a nitrogen atmosphere for 2 h. Benzene
2-(4-Trifluoromethoxyphenyl)quinoline-3-carbaldehyde (6f).
was evaporated under reduced pressure. Water (20 mL) was 2-Chloroquinoline-3-carbaldehyde (0.09 g, 0.50 mmol), (4-tri-
added to the reaction mixture and extracted with ethyl acetate fluoromethoxyphenyl)boronic acid (0.12 g, 0.60 mmol), tBuOK
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(0.05 g, 0.50 mmol), reaction time: 2 h, yield: 0.13 g, 90%, yield: 0.15 g, 94%, white solid, mp: 160 °C, 1H NMR (300 MHz,
white solid, mp: 116 °C, 1H NMR (300 MHz, CDCl3): δ 10.19 (s, CDCl3), δ 10.17 (s, 1H), 8.76 (s, 1H), 8.09 (d, J = 8.4 Hz, 1H),
1H), 8.86 (s, 1H), 8.20 (d, J = 8.4 Hz, 1H), 8.03 (d, J = 8.1 Hz, 7.78–7.71 (m, 4H), 7.41 (d, J = 8.1 Hz, 2H), 2.59 (s, 2H), 13C
1H), 7.90 (t, J = 8.1 Hz, 1H), 7.75–7.64 (m, 3H), 7.42 (d, J = 8.1 NMR (75 MHz, CDCl3): δ 191.0, 157.9, 150.0, 150.0, 148.2,
Hz, 2H), 13C NMR (75 MHz, CDCl3): δ 190.8, 158.7, 150.2, 138.0, 137.8, 136.6, 135.3, 131.7, 129.2, 128.0, 127.5, 126.5,
149.5, 138.7, 138.6, 136.4, 132.9, 132.8, 131.7, 131.7, 129.5, 121.1, 21.6.
129.4, 127.8, 127.5, 126.5, 121.1.
6-Methoxy-2-(4-trifluoromethoxy-phenyl)-quinoline-3 carbal-
7-Methoxy-2-phenylquinoline-3-carbaldehyde (6g). 2-Chloro- dehyde (6m). 2-Chloro-6-methoxyquinoline-3-carbaldehyde
7-methoxyquinoline-3-carbaldehyde (0.11 g, 0.51 mmol), (0.11 g, 0.50 mmol), 4-trifluoromethoxyphenylboronic acid
phenylboronic acid (0.07 g, 0.62 mmol), tBuOK (0.06 g, (0.10 g, 0.60 mmol), tBuOK (0.05 g, 0.50 mmol), reaction time:
0.51 mmol), reaction time: 3 h, yield: 0.12 g, 92%, white solid, 3 h, yield: 0.15 g, 92%, white solid, mp: 134 °C, 1H NMR
1
mp: 130 °C, H NMR (300 MHz, CDCl3): δ 10.12 (s, 1H), 8.75 (300 MHz, CDCl3): δ 10.17 (s, 1H), 8.73 (s, 1H), 8.08 (d, J =
(s, 1H), 7.87 (d, J = 9 Hz, 1H), 7.65 (d, J = 5.7 Hz, 2H), 7.53 (t, 9 Hz, 1H), 7.71 (d, J = 8.7 Hz, 2H), 7.55–7.51 (m, 2H), 7.40 (d,
J = 6 Hz, 3H), 7.27 (s, 1H), 3.98 (s, 3H), 13C NMR (75 MHz, J = 8.1 Hz, 2H), 7.23 (s, 1H) 3.98 (s, 3H), 13C NMR (75 MHz,
CDCl3): δ 191.3, 163.5, 161.1, 151.8, 137.9, 137.4, 130.5, 130.2, CDCl3): δ 191.2, 158.6, 156.4, 149.9, 145.9, 136.8, 136.5, 131.7,
129.3, 128.6, 125.8, 121.7, 121.2, 107.2, 55.8.
130.9, 130.6, 127.6, 127.6, 126.2, 121.1, 105.9, 55.8.
7-Methyl-2-phenylquinoline-3-carbaldehyde (6h). 2-Chloro-7-
8-Methyl-2-(4-trifluoromethoxy-phenyl)-quinoline-3-carbal-
methylquinoline-3-carbaldehyde (0.20 g, 1.00 mmol), phenyl- dehyde
(6n).
2-Chloro-8-methylquinoline-3-carbaldehyde
boronic acid (0.15 g, 1.20 mmol), tBuOK (0.11 g, 1.00 mmol), (0.10 g, 0.50 mmol), 4-trifluoromethoxyphenylboronic acid
reaction time: 2 h, yield: 0.22 g, 90%, white solid, mp: 108 °C, (0.10 g, 0.60 mmol), tBuOK (0.05 g, 0.50 mmol), reaction time:
1H NMR (300 MHz, CDCl3): δ 10.15 (s, 1H), 8.73 (s, 1H), 8.09 2 h, yield: 0.14 g, 90%, white solid, mp: 80 °C, 1H NMR
(d, J = 8.4 Hz, 1H), 7.74 (s, 1H), 7.70–7.65 (m, 3H), 7.54 (d, J = (300 MHz, CDCl3): δ 10.22 (s, 1H), 8.80 (s, 1H), 7.85 (d, J =
6 Hz, 3H), 2.57 (s, 3H), 13C NMR (75 MHz, CDCl3): δ 191.6, 8.1 Hz, 1H), 7.80–7.72 (m, 3H), 7.53 (t, J = 7.5 Hz, 3H), 7.41 (d,
159.4, 148.3, 137.9, 137.5, 137.3, 137.2, 135.0, 130.2, 129.2, J = 8.1 Hz, 2H), 2.85 (s, 3H), 13C NMR (75 MHz, CDCl3):
128.6, 128.0, 127.6, 126.4, 21.5.
δ 191.2, 157.1, 150.1, 148.6, 138.8, 137.8, 136.9, 132.8, 132.1,
6-Methoxy-2-phenylquinoline-3-carbaldehyde (6i). 2-Chloro- 127.5, 127.3, 126.4, 122.2, 120.9, 118.8, 17.8.
6-methoxyquinoline-3-carbaldehyde (0.11 g, 0.50 mmol),
8-Ethyl-2-(4-trifluoromethoxyphenyl)-quinoline-3-carbalde-
phenylboronic acid (0.07 g, 0.60 mmol), tBuOK (0.05 g, hyde (6o). 2-Chloro-8-ethylquinoline-3-carbaldehyde (0.10 g,
0.50 mmol), reaction time 3 h, yield: 0.12 g, 94%, white solid, 0.50 mmol), 4-trifluoromethoxyphenylboronic acid (0.10 g,
1
mp: 130 °C, H NMR (300 MHz, CDCl3): δ 10.16 (s, 1H), 8.71 0.50 mmol), tBuOK (0.56 g, 0.60 mmol), reaction time: 2 h,
1
(s, 1H), 8.09 (d, J = 9.3 Hz, 1H), 7.66 (d, J = 5.7 Hz, 2H), yield: 0.15 g, 88%, white solid, mp: 88 °C, H NMR (300 MHz,
7.56–7.48 (m, 5H) 3.96 (s, 3H), 13C NMR (75 MHz, CDCl3): CDCl3): δ 10.21 (s, 1H), 8.80 (s, 1H), 7.84 (d, J = 8.4 Hz, 1H),
δ 191.7, 158.4, 158.1, 146.0, 137.9, 136.4, 131.0, 130.2, 129.1, 7.78–7.71 (m, 3H), 7.56 (t, J = 7.5 Hz, 1H), 7.41 (d, J = 8.1 Hz,
128.7, 127.8, 127.5, 125.8, 105.9, 55.7.
2H), 3.38–3.31 (q, 2H), 1.40 (t, J = 7.8 Hz, 3H), 13C NMR
8-Methyl-2-phenylquinoline-3-carbaldehyde (6j). 2-Chloro-8- (75 MHz, CDCl3): δ 191.2, 156.9, 150.1, 148.0, 143.5, 138.9,
methylquinoline-3-carbaldehyde (0.20 g, 1.00 mmol), phenyl- 138.9, 136.9, 132.0, 131.2, 127.7, 127.2, 127.2, 126.4, 120.9,
boronic acid (0.15 g, 1.20 mmol), tBuOK (0.11 g, 1.00 mmol), 24.5, 15.0.
reaction time: 2 h, yield: 0.22 g, 92%, white solid, mp: 84 °C,
2,5-Diphenylpyridine-3-carbaldehyde
(6p).
2-Chloro-5-
1H NMR (300 MHz, CDCl3): δ 10.22 (s, 1H), 8.80 (s, 1H), 7.84 phenylnicotinaldehyde (0.10 g, 0.46 mmol), phenylboronic
(d, J = 8.1 Hz, 1H), 7.76–7.70 (m, 3H), 7.57–7.49 (m, 4H), 2.86 acid (0.67 g, 0.55 mmol), tBuOK (0.05 g, 0.50 mmol), reaction
(s, 3H), 13C NMR (75 MHz, CDCl3) δ 191.8, 158.6, 148.6, 138.3, time 3 h, yield 0.11 g, 90%, light yellow, mp: 90 °C, H NMR
1
138.2, 138.1, 137.7, 132.5, 130.6, 129.2, 128.5, 127.2, 127.1, (300 MHz, CDCl3): δ 10.13 (s, 1H), 9.12 (s, 1H), 8.50 (s, 1H),
126.2, 17.9.
7.70–7.63 (m, 4H), 7.55–7.43 (m, 6H), 13C NMR (75 MHz,
7-Chloro-2-phenylquinoline-3-carbaldehyde (6k). 2-Chloro-7- CDCl3): δ 191.8, 160.8, 160.7, 151.8, 136.8, 136.3, 135.5, 133.7,
chloroquinoline-3-carbaldehyde (0.11 g, 0.50 mmol), phenyl- 130.4, 129.6, 129.3, 129.3, 128.7, 127.1.
boronic acid (0.07 g, 0.60 mmol), tBuOK (0.05 g, 0.50 mmol),
2-(4-Fluorophenyl)-5-phenylpyridine-3-carbaldehyde
(6q).
reaction time: 2 h, yield: 0.12 g, 88%, white solid, mp: 142 °C, 2-Chloro-5-phenylnicotinaldehyde (0.10 g, 0.46 mmol), 4-fluoro-
1H NMR (300 MHz, CDCl3): δ 10.15 (s, 1H), 8.81 (s, 1H), 8.22 phenylboronic acid (0.08 g, 0.55 mmol), tBuOK (0.05 g,
(d, J = 9 Hz, 1H), 7.94 (d, J = 8.4 Hz, 1H), 7.69–7.65 (m, 3H), 0.50 mmol), reaction time: 3 h, yield: 0.11 g, 90%, white solid,
1
7.59–7.55 (m, 3H), 13C NMR (75 MHz, CDCl3): δ 191.1, 161.3, mp: 94 °C, H NMR (300 MHz, CDCl3): δ 10.12 (s, 1H), 9.10 (s,
149.8, 138.8, 137.9, 137.3, 135.4, 132.2, 130.5, 130.2, 129.7, 1H), 8.49 (s, 1H), 7.69–7.62 (m, 4H), 7.56–7.4 (m, 3H),
128.8, 128.7, 127.7, 124.7, 117.4.
7.28–7.22 (m, 1H), 13C NMR (75 MHz, CDCl3): δ 191.4, 165.4,
6-Methyl-2-(4-trifluoromethoxyphenyl)quinoline-3-carbalde-
162.1, 159.5, 151.8, 136.2, 135.7, 133.9, 133.0, 132.9, 132.3,
hyde (6l). 2-Chloro-6-methylquinoline-3-carbaldehyde (0.10 g, 132.2, 129.3, 129.2, 128.8, 127.1, 116.0, 115.7.
0.50 mmol), 4-trifluoromethoxyphenylboronic acid (0.10 g,
5-Phenyl-2-(4-trifluoromethoxyphenyl)pyridine-3-carbaldehyde
0.60 mmol), tBuOK (0.05 g, 0.50 mmol), reaction time: 3 h, (6r). 2-Chloro-5-phenylnicotinaldehyde (0.10 g, 0.46 mmol),
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4-trifluoromethoxyphenylboronic acid (0.12 g, 0.55 mmol), green, mp: 206 °C, H NMR (300 MHz, CDCl3): δ 8.39 (s, 1H),
tBuOK (0.05 g, 0.50 mmol), reaction time: 2 h, yield: 0.14 g, 8.11 (d, J = 8.4 Hz, 1H), 7.96 (t, J = 8.1 Hz, 2H), 7.88 (d, J =
88%, white solid, mp: 92 °C, 1H NMR (300 MHz, CDCl3): 7.8 Hz, 1H), 7.82–7.76 (m, 2H), 7.55 (t, J = 7.5 Hz, 1H), 13C
δ 10.14 (s, 1H), 9.12 (s, 1H), 8.51 (s, 1H), 7.69 (d, J = 8.4 Hz, NMR (75 MHz, CDCl3): δ 189.4, 161.2, 150.6, 142.4, 138.8,
4H), 7.56–7.47 (m, 3H), 7.41 (d, J = 8.1 Hz, 2H), 13C NMR 138.2, 133.0, 132.4, 130.6, 129.8, 127.6, 127.5, 127.4, 126.6,
(75 MHz, CDCl3): δ 191.1, 159.1, 151.8, 136.1, 136.0, 135.5, 126.0, 123.2, HRMS (ESI) exact mass calcd for C16H8BrNOH:
133.9, 131.9, 131.9, 129.3, 129.3, 128.9, 128.9, 127.1, 121.0.
309.9868 (M + H)+, found: 309.9879 (M + H)+.
4,5-Dimethoxybiphenyl-2-carbaldehyde (6s). 2-Bromo-4,5-
2-Chloroindeno[1,2-b]quinolin-11-one (7c). 2-(4-Chloro-
dimethoxybenzaldehyde (0.12 g, 0.49 mmol), phenylboronic phenyl)quinoline-3-carbaldehyde (0.13 g, 0.49 mmol), TBHP
acid (0.07 g, 0.58 mmol), tBuOK (0.05 g, 0.50 mmol), reaction (1.5 mmol), reaction time: 18 h, yield: 0.11 g, 88%, light
1
1
time: 2 h, yield: 0.11 g, 95%, brown solid, mp: 80 °C, H NMR yellow, mp: 170 °C, H NMR (300 MHz, CDCl3): δ 8.37 (s, 1H),
(300 MHz, CDCl3): δ 9.81 (s, 1H), 7.54 (s, 1H), 7.46–7.42 (m, 8.13–8.02 (m, 2H), 7.87 (d, J = 8.1 Hz, 1H), 7.80 (t, J = 8.4 Hz,
3H), 7.38 (d, J = 6.6 Hz, 2H), 6.86 (s, 1H), 3.97 (s, 6H), 13C NMR 1H), 7.63 (d, J = 8.4 Hz, 1H), 7.57–7.45 (m, 2H), 13C NMR
(75 MHz, CDCl3) δ 191.1, 153.4, 148.7, 141.5, 137.5, 130.1, (75 MHz, CDCl3): δ 189.4, 170.9, 161.1, 150.5, 141.9, 138.7,
128.3, 127.9, 126.8, 112.6, 108.6, 56.1, 56.1.
137.9, 135.3, 133.6, 132.4, 130.6, 130.1, 128.4, 127.5, 124.4,
4,5-Dimethoxy-4′-trifluoromethoxy-biphenyl-2-carbaldehyde 123.1, HRMS (ESI) exact mass calcd for C16H8NOH: 266.0373
(6t). 2-Bromo-4,5-dimethoxybenzaldehyde (0.12 g, 0.49 mmol), (M + H)+, found: 266.0377 (M + H)+.
4-trifluoromethoxyphenylboronic acid (0.12 g, 0.58 mmol),
2-Fluoro-indeno[1,2-b]quinolin-11-one (7d). 2-(4-Fluoro-
tBuOK (0.05 g, 0.50 mmol), reaction time: 2 h, yield: 0.15 g, phenyl)quinoline-3-carbaldehyde (0.12 g, 0.49 mmol), TBHP
92%, white solid, mp: 84 °C, 1H NMR (300 MHz, CDCl3): δ 9.80 (1.5 mmol), reaction time: 23 h, yield: 0.10 g, 84%, light
1
(s, 1H), 7.54 (s, 1H), 7.41 (d, J = 8.7 Hz, 2H), 7.31 (d, J = 8.1 Hz, yellow, mp: 148 °C, H NMR (300 MHz, CDCl3): δ 8.37 (s, 1H),
2H), 6.82 (s, 1H), 3.98 (s, 6H), 13C NMR (75 MHz, CDCl3): 8.09 (t, J = 8.4 Hz, 2H), 7.87 (d, J = 7.8 Hz, 1H), 7.71 (t, J =
δ 190.5, 153.5, 149.1, 149.1, 139.7, 136.3, 131.5, 127.0, 120.8, 7.8 Hz, 1H), 7.56–7.47 (m, 2H), 7.36 (t, J = 8.4 Hz, 1H), 13C
112.5, 108.8, 56.3, 56.2.
NMR (75 MHz, CDCl3): δ 193.0, 161.8, 150.7, 147.1, 145.0,
Biphenyl-2-carbaldehyde (6u). 2-Bromobenzaldehyde (0.18 g, 139.8, 138.2, 132.8, 132.3, 130.7, 130.6, 129.8, 127.3, 123.7,
1.00 mmol), phenylboronic acid (0.15 g, 1.20 mmol), tBuOK 123.6, 122.5, 122.2, 122.2, 111.5, 111.2, 19F NMR (500 MHz,
(0.11 g, 1.00 mmol), reaction time: 2 h, yield: 0.16 g, 90%, CDCl3):
δ
−107.07, HRMS (ESI) exact mass calcd for
yellow liquid, H NMR (300 MHz, CDCl3): δ 9.98 (s, 1H), 8.02 C16H8BrNOH: 250.0668 (M + H)+, found: 250.0661 (M + H)+.
(d, J = 7.8 Hz, 1H), 7.63 (t, J = 7.5 Hz, 1H), 7.51–7.36 (m, 6H), 2-Methylindeno[1,2-b]quinolin-11-one (7e). 2-(p-Tolyl)quino-
13C NMR (75 MHz, CDCl3): δ 192.1, 144.8, 133.8, 133.6, 131.7, line-3-carbaldehyde (0.12 g, 0.49 mmol), TBHP (1.5 mmol),
1
131.6, 130.8, 127.9, 127.8, 115.6, 115.3.
reaction time: 17 h, yield: 0.09 g, 77%, brown solid, mp:
166 °C, H NMR (300 MHz, CDCl3): δ 8.29 (s, 1H), 8.06 (d, J =
8.4 Hz, 1H), 7.94 (d, J = 7.5 Hz, 1H), 7.82 (d, J = 7.8 Hz, 1H),
7.72 (t, J = 6.9 Hz, 1H), 7.60 (s, 1H), 7.50 (d, J = 8.1 Hz, 1H),
1
Procedure for the synthesis of indenoquinolinones,
4-azafluorenones, fluorenones (7)
A solution of 2-phenylquinoline-3-carbaldehyde (1 equiv.), 2.44 (s, 3H), 13C NMR (75 MHz, CDCl3): δ 191.0, 162.2, 150.5,
TBHP (3 equiv.) and toluene (2 mL) was heated at 100 °C 142.3, 141.4, 137.7, 136.3, 132.2, 131.9, 130.4, 129.6, 127.5,
under an argon atmosphere for 14 to 24 h. After the com- 127.4, 127.0, 124.6, 121.7, 21.6, HRMS (ESI) exact mass calcd
pletion of the reaction, the solvent was evaporated under for C17H11NOH: 246.0919 (M + H)+, found: 246.0922 (M + H)+.
reduced pressure. Water was added to the reaction mixture
2-Trifluoromethoxyindeno[1,2-b]quinolin-11-one (7f). 2-(4-
and extracted with EtOAc. The organic phase was washed with Trifluoromethoxyphenyl)quinoline-3-carbaldehyde (0.08 g,
water, brine and dried over anhydrous Na2SO4. The solvent 0.25 mmol), TBHP (0.75 mmol), reaction time: 20 h, yield:
was removed under reduced pressure and the obtained residue 0.06 g, 73%, light yellow, mp: 190 °C, 1H NMR (300 MHz,
was purified by column chromatography (hexane : ethyl acetate CDCl3): δ 8.41 (s, 1H), 8.12 (t, J = 8.4 Hz, 2H), 7.89 (d, J = 8.1
= 18 : 2) to afford 7a–u.
Hz, 1H), 7.80 (t, J = 8.1 Hz, 1H), 7.66 (s, 1H), 7.61–7.45 (m, 2H),
Indeno[1,2-b]quinolin-11-one (7a). 2-Phenylquinoline-3-carb- 13C NMR (75 MHz, CDCl3): δ 189.3, 160.8, 151.8, 150.6, 141.9,
aldehyde (0.11 g, 0.47 mmol), TBHP (1.42 mmol), reaction 139.2, 133.1, 132.5, 130.6, 130.1, 129.9, 128.4, 127.6, 127.5,
time: 14 h, yield: 0.88 g, 81%, white solid, mp: 142 °C, 127.0, 123.4, 116.3, 19F NMR (500 MHz, CDCl3): δ −57.69,
IR (KBr): ν 1717, 1622, 775, 733 cm−1 1H NMR (300 MHz, HRMS (ESI) exact mass calcd for C17H8F3NO2H: 316.0585 (M +
,
CDCl3): δ 8.38 (s, 1H), 8.21 (t, J = 7.2 Hz, 2H), 7.89–7.66 (m, 4H), H)+, found: 316.0594 (M + H)+.
7.56–7.49 (m, 2H), 13C NMR (75 MHz, CDCl3): δ 190.8, 162.0,
7-Methoxyindeno[1,2-b]quinolin-11-one (7g). 7-Methoxy-2-
150.6, 143.8, 137.4, 135.5, 132.4, 132.0, 131.5, 130.4, 129.8, phenylquinoline-3-carbaldehyde (0.13 g, 0.50 mmol), TBHP
127.6, 127.2, 127.0, 124.1, 121.8, HRMS (ESI) exact mass calcd (1.5 mmol), reaction time: 13 h, yield: 0.11 g, 88%, yellow
1
for C16H9NOH: 232.0762 (M + H)+, found: 232.0768 (M + H)+.
solid, mp: 154 °C, H NMR (300 MHz, CDCl3): δ 8.29 (s, 1H),
2-Bromoindeno[1,2-b]quinolin-11-one (7b). 2-(4-Bromo- 8.06 (d, J = 7.2, 1H), 7.82–7.73 (m, 2H), 7.66 (t, J = 7.2 Hz, 1H),
phenyl)quinoline-3-carbaldehyde (0.08 g, 0.26 mmol), TBHP 7.50 (s, 2H), 7.17 (d, J = 8.7 Hz, 1H), 3.99 (s, 3H), 13C NMR
(0.77 mmol), reaction time: 16 h, yield: 0.07 g, 91%, light (75 MHz, CDCl3): δ 190.9, 163.0, 162.9, 152.7, 143.6, 137.4,
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135.2, 132.2, 132.2, 131.4, 125.1, 123.9, 122.5, 121.5, 119.6, carbaldehyde (0.09 g, 0.25 mmol), TBHP (0.75 mmol), reaction
108.7, 55.7, HRMS (ESI) exact mass calcd for C17H11NO2H: time: 16 h, yield: 0.06 g, 72%, yellow solid, mp: 158 °C, 1H
262.0868 (M + H)+, found 262.0874 (M + H)+.
NMR (300 MHz, CDCl3): δ 8.28 (s, 1H), 8.07–8.00 (m, 2H), 7.62
7-Methyl-indeno[1,2-b]quinolin-11-one (7h). 7-Methyl-2-phenyl- (s, 1H), 7.48–7.40 (m, 2H), 7.16 (s, 1H), 3.95 (s, 3H), 13C NMR
quinoline-3-carbaldehyde (0.12 g, 0.50 mmol), TBHP (75 MHz, CDCl3): δ 189.6, 158.6, 151.3, 146.4, 142.3, 138.7,
(1.50 mmol), reaction time: 16 h, yield: 0.10 g, 83%, yellow 131.8, 131.0, 130.1, 128.6, 128.4, 127.6, 127.3, 124.4, 122.9,
1
solid, mp: 130 °C, H NMR (300 MHz, CDCl3): δ 8.31 (s, 1H), 116.4, 108.7, 55.7, 19F NMR (500 MHz, CDCl3): δ −57.66,
8.07 (d, J = 7.2 Hz, 1H), 7.90 (s, 1H), 7.82–7.74 (m, 2H), 7.66 (t, HRMS (ESI) exact mass calcd for C17H11NO2H: 346.0691
J = 7.2 Hz, 1H), 7.51 (d, J = 7.2 Hz, 1H), 7.35 (d, J = 7.8 Hz, 1H), (M + H)+, found: 346.0686 (M + H)+.
13
2.57 (s, 3H), C NMR (75 MHz, CDCl3): δ 191.0, 162.2, 150.8,
6-Methyl-2-trifluoromethoxyindeno[1,2-b]quinolin-11-one (7n).
143.9, 143.0, 137.5, 135.4, 134.1, 132.2, 131.4, 130.1, 129.3, 8-Methyl-2-(4-trifluoromethoxy-phenyl)-quinoline-3-carbalde-
126.4, 125.6, 124.0, 121.7, 22.0, HRMS (ESI) exact mass calcd hyde (0.08 g, 0.25 mmol), TBHP (0.75 mmol), reaction time:
for C17H11NOH: 246.0919 (M + H)+, found: 246.0923 (M + H)+.
20 h, yield: 0.06 g, 70%, light green solid, mp: 148 °C, 1H
8-Methoxy-indeno[1,2-b]quinolin-11-one (7i). 6-Methoxy-2- NMR (300 MHz, CDCl3): δ 8.34 (s, 1H), 8.11 (d, J = 8.1 Hz,
phenylquinoline-3-carbaldehyde (0.07 g, 0.25 mmol), TBHP 1H), 7.70 (d, J = 7.5 Hz, 1H), 7.63 (d, J = 6.3 Hz, 1H),
(0.75 mmol), reaction time: 15 h, yield: 0.06 g, 83%, yellow 7.49–7.40 (m, 2H), 2.84 (s, 3H), 13C NMR (75 MHz, CDCl3):
1
solid, mp: 156 °C, H NMR (300 MHz, CDCl3): δ 8.26 (s, 1H), δ 189.7, 159.6, 151.5, 149.5, 142.4, 139.0, 138.2, 133.1, 133.1,
8.02 (d, J = 8.7 Hz, 1H), 7.79 (d, J = 7.2 Hz, 1H), 7.64 (t, J = 6.9 132.8, 128.5, 127.4, 127.3, 127.1, 126.49, 123.1, 116.2, 17.8,
Hz, 1H), 7.79–7.41 (m, 3H), 7.14 (s, 1H), 3.94 (s, 3H), 13C NMR 19F NMR (500 MHz, CDCl3): δ −57.71, HRMS (ESI) exact mass
(75 MHz, CDCl3): δ 190.9, 159.7, 158.3, 145.7, 143.7, 135.5, calcd for C17H11NO2H: 330.0742 (M + H)+, found 330.0700
131.4, 131.0, 130.5, 128.8, 128.3, 128.0, 124.0, 121.6, 108.6, (M + H)+.
105.3, 55.5, HRMS (ESI) exact mass calcd for C17H11NO2H:
262.0868 (M + H)+, found: 262.0862 (M + H)+.
6-Ethyl-2-trifluoromethoxyindeno[1,2-b]quinolin-11-one (7o).
8-Ethyl-2-(4-trifluoromethoxyphenyl)-quinoline-3-carbaldehyde
6-Methylindeno[1,2-b]quinolin-11-one
(7j).
8-Methyl-2- (0.08 g, 0.25 mmol), TBHP (0.75 mmol), reaction time: 20 h,
phenylquinoline-3-carbaldehyde (0.06 g, 0.25 mmol), TBHP yield: 0.06 g, 68%, light green solid, mp: 110 °C, 1H NMR
(0.75 mmol), reaction time: 15 h, yield: 0.08 g, 77%, light (300 MHz, CDCl3): δ 8.36 (s, 1H), 8.12 (d, J = 8.1 Hz, 1H), 7.71
1
green, mp: 144 °C, H NMR (300 MHz, CDCl3): δ 8.32 (s, 1H), (d, J = 7.8, 1H), 7.65 (s, 2H), 7.47 (t, J = 7.8 Hz, 2H), 3.34 (q, J =
8.10 (d, J = 7.5 Hz, 1H), 7.81 (d, J = 7.5 Hz, 1H), 7.71–7.59 (m, 7.8 Hz, 2H), 1.40 (t, J = 7.2 Hz, 3H), 13C NMR (75 MHz, CDCl3):
3H), 7.49 (t, J = 7.5 Hz, 1H), 7.40 (t, J = 7.8 Hz, 1H), 2.85 (s, 189.7, 159.5, 151.5, 148.9, 144.1, 142.5, 139.0, 133.2, 131.4,
3H), 13C NMR (75 MHz, CDCl3): δ 191.3, 160.8, 149.4, 144.3, 128.5, 127.4, 127.3, 126.5, 123.1, 116.3, 24.6, 15.1, 19F NMR
138.1, 137.3, 135.4, 132.6, 132.5, 131.2, 128.4, 127.5, 126.8, (500 MHz, CDCl3): δ −57.69, HRMS (ESI) exact mass calcd for
126.6, 124.0, 121.7, 17.9, HRMS (ESI) exact mass calcd for C17H11NO2H: 344.0898 (M + H)+, found: 344.0855 (M + H)+.
C17H11NO2H: 246.0919 (M + H)+, found: 246.0921 (M + H)+.
7-Chloroindeno[1,2-b]quinolin-11-one (7k). 7-Chloro-2- dine-3-carbaldehyde (0.13 g, 0.50 mmol), TBHP (1.5 mmol),
3-Phenylindeno[1,2-b]pyridin-5-one (7p). 2,5-Diphenylpyri-
phenylquinoline-3-carbaldehyde (0.13 g, 0.50 mmol), TBHP reaction time: 12 h, yield: 0.10 g, 84%, light yellow solid, mp:
1
(1.50 mmol), reaction time 17 h, yield: 0.10 g, 76%, light 170 °C, H NMR (300 MHz, CDCl3): δ 8.87 (s, 1H), 8.13 (t, J =
1
yellow solid, mp: 196 °C, H NMR (300 MHz, CDCl3): δ 8.34 (s, 6.3 Hz, 3H), 7.92 (s, 1H), 7.77 (s, 1H), 7.62 (d, J = 6 Hz, 2H),
1H), 8.10 (t, J = 9.3 Hz, 2H), 7.83 (t, J = 8.1 Hz, 2H), 7.71 (t, J = 7.53–7.46 (m, 3H), 13C NMR (75 MHz, CDCl3): δ 191.6, 171.5,
7.2 Hz, 1H), 7.57–7.49 (m, 2H), 13C NMR (75 MHz, CDCl3): 163.5, 152.1, 143.1, 136.9, 135.5, 135.1, 133.6, 130.9, 130.1,
δ 190.4, 163.0, 151.1, 143.5, 138.1, 137.5, 135.6, 132.0, 131.9, 129.9, 129.2, 128.6, 128.4, 126.9, 124.3, 121.1, HRMS (ESI)
131.3, 129.1, 128.1, 127.2, 126.0, 124.2, 122.0, HRMS (ESI) exact mass calcd for C18H1oNOH: 258.0919 (M + H)+, found:
exact mass calcd for C17H11NO2H: 266.0373 (M + H)+, found: 258.0929 (M + H)+.
266.0377 (M + H)+.
7-Fluoro-3-phenylindeno[1,2-b]pyridin-5-one (7q). 2-(4-Fluoro-
8-Methyl-2-trifluoromethoxyindeno[1,2-b]quinolin-11-one (7l). phenyl)-5-phenylpyridine-3-carbaldehyde (0.07 g, 0.25 mmol),
6-Methyl-2-(4-trifluoromethoxyphenyl)quinoline-3-carbaldehyde TBHP (0.75 mmol), reaction time: 15 h, yield: 0.06 g, 88%,
(0.08 g, 0.25 mmol), TBHP (0.75 mmol), reaction time: 16 h, light yellow solid, mp: 192 °C, 1H NMR (300 MHz, CDCl3):
yield: 0.06 g, 78%, light green solid, mp: 148 °C, 1H NMR δ 8.83 (s, 1H), 8.09 (s, 1H), 7.88–7.83 (m, 1H), 7.60 (d, J = 6.9
(300 MHz, CDCl3): δ 8.32 (s, 1H), 8.11 (d, J = 8.4 Hz, 1H), 8.02 Hz, 2H), 7.53–7.42 (m, 4H), 7.41–7.29 (m, 1H), 13C NMR
(d, J = 8.4 Hz, 1H), 7.63 (d, J = 9.6 Hz, 3H), 7.49 (d, J = 7.8 Hz, (75 MHz, CDCl3): δ 192.1, 165.6, 163.1, 152.7, 152.6, 142.3,
1H), 2.54 (s, 3H), 13C NMR (75 MHz, CDCl3): δ 189.5, 160.1, 136.49, 129.9, 129.2, 128.6, 126.9, 122.7, 122.6, 122.5, 122.3,
151.5, 149.1, 142.1, 139.0, 137.7, 134.6, 132.4, 129.7, 129.5, 121.9, 121.7, 121.1, 121.6, 119.4, 112.1, 111.7, 19F NMR
129.5, 127.5, 127.5, 127.0, 123.1, 116.3, 21.4, 19F NMR (500 MHz, CDCl3): δ −108.26, HRMS (ESI) exact mass calcd for
(500 MHz, CDCl3): δ −57.69, HRMS (ESI) exact mass calcd for C18H9FNOH: 276.0825 (M + H)+, found: 276.0834 (M + H)+.
C17H11NO2H: 330.0742 (M + H)+, found: 330.0739 (M + H)+.
8-Methoxy-2-trifluoromethoxyindeno[1,2-b]quinolin-11-one 5-Phenyl-2-(4-trifluoromethoxyphenyl)pyridine-3-carbaldehyde
(7m). 6-Methoxy-2-(4-trifluoromethoxy-phenyl)-quinoline-3- (0.09 g, 0.25 mmol), TBHP (0.75 mmol), reaction time: 16 h,
3-Phenyl-7-trifluoromethoxyindeno[1,2-b]pyridin-5-one (7r).
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yield: 0.08 g, 90%, light yellow solid, mp: 190 °C, 1H NMR
(300 MHz, CDCl3): δ 8.86 (s, 1H), 8.11 (s, 1H), 7.90 (d, J = 8.1
Hz, 1H), 7.6 (t, J = 7.5 Hz, 3H), 7.53–7.43 (m, 4H), 13C NMR
(75 MHz, CDCl3): δ 190.0, 162.6, 152.8, 151.2, 141.5, 136.9,
136.8, 136.6, 130.0, 130.0, 129.3, 129.3, 128.7, 128.7, 127.3,
126.9, 126.9, 122.2, 116.9, 19F NMR (500 MHz, CDCl3):
δ −57.69; HRMS (ESI) exact mass calcd for C19H8NO2H:
342.0742 (M + H)+, found: 342.0774 (M + H)+.
2,3-Dimethoxyfluoren-9-one (7s). 4,5-Dimethoxybiphenyl-2-
carbaldehyde (0.06 g, 0.25 mmol), TBHP (0.75 mmol), reaction
time: 20 h, yield: 0.05 g, 81%, brown solid, mp: 156 °C, 1H
NMR (300 MHz, CDCl3): 7.47 (d, J = 6.9 Hz, 1 H), 7.30 (q, J =
7.5 Hz, 2H), 7.18 (s, 1H), 7.11 (t, J = 6.3 Hz, 1H), 6.92 (s, 1H),
3.94 (s, 3H), 3.85 (s, 3H), 13C NMR (75 MHz, CDCl3): δ 193.1,
154.5, 149.7, 143.9, 139.4, 134.7, 134.1, 128.1, 126.8, 123.7,
119.0, 107.1, 103.4, 56.3, 56.2, HRMS (ESI) exact mass calcd for
C15H12O3H: 241.0865 (M + H)+, found: 241.0829 (M + H)+.
2,3-Dimethoxy-7-trifluoromethoxyfluoren-9-one (7t). 4,5-
Dimethoxy-4′-trifluoromethoxy-biphenyl-2-carbaldehyde (0.08 g,
0.25 mmol), TBHP (0.75 mmol), reaction time: 19 h, yield:
0.06 g, 70%, orange solid, mp: 150 °C, 1H NMR (300 MHz,
CDCl3): 7.36 (t, J = 8.7 Hz, 2H), 7.24 (s, 1H), 7.19 (s, 1H), 6.98 (s,
1H), 4.01 (s, 3H), 3.93 (s, 3H), 13C NMR (75 MHz, CDCl3):
δ 191.2, 154.9, 149.9, 149.3, 142.2, 138.6, 136.6, 127.1, 126.1,
119.9, 116.9, 107.4, 107.3, 103.5, 56.4, 56.2, 19F NMR (500 MHz,
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δ
−57.91, HRMS (ESI) exact mass calcd For
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1
0.06 g, 62%, light green solid, mp: 60 °C, H NMR (300 MHz,
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Acknowledgements
KM is thankful to UGC and DRDO for a fellowship. AKP and
JBS are thankful to CSIR, New Delhi for SRF. RMS is thankful
to DRDO for funding ERIP/ER/1203055/M/01/1471. RMS is
thankful to Prof. Ganesh Pandey, Director, CBMR, Lucknow,
India for providing HRMS data of all samples.
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