Iridium-Catalysed Cascade Synthesis of Oxindoles Using Diazo Compounds: A Quick Entry to C-7-Functionalized Oxindoles

Article abstract of DOI:10.1002/ejoc.201700214

A cascade iridium-catalysed oxindole synthesis was achieved using pyridyl-protected anilines and bis(2,2,2-trifluoroethyl) 2-diazomalonate. The developed protocol is simple and scalable, and has a broad scope and excellent regioselectivity. The pyridyl directing group can easily be removed. The method was further extended to give C-7-functionalized oxindole derivatives in a straightforward manner. The role of bis(2,2,2-trifluoroethyl) 2-diazomalonate for oxindole preparation has been explored.

Full text of DOI:10.1002/ejoc.201700214

A Journal of
Accepted Article
Title: Iridium Catalysed Cascade Synthesis of Oxindoles using Diazo
Compound: A Quick Entry to the C7-Functionalized Oxindoles
Authors: Ujjwal Karmakar, Debapratim Das, and Rajarshi Samanta
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201700214
Link to VoR: http://dx.doi.org/10.1002/ejoc.201700214
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10.1002/ejoc.201700214
European Journal of Organic Chemistry
FULL PAPER
Iridium Catalysed Cascade Synthesis of Oxindoles using Diazo
Compound: A Quick Entry to the C7-Functionalized Oxindoles
Ujjwal Karmakar, Debapratim Das, and Rajarshi Samanta*[a]
Abstract: A cascade iridium catalyzed oxindole synthesis was
achieved successfully using pyridyl-protected anilines and bis (2,2,2-
trifluoroethyl) 2-diazomalonate. The developed protocol is simple,
scalable and distinguished by a brilliant scope with excellent
regioselectivity profile. The pyridyl directing group can easily be
removed. The method was further extended to afford C7
functionalized oxindole derivatives in straightforward manner. The
role of bis(2,2,2-trifluoroethyl) 2-diazomalonate for oxindole
preparation has been explored.
step economic method to construct oxindole moiety from cheap
feedstocks is highly necessary. Classically, concerted insertion
of diazo compounds using transition metals into unactivated C-H
bonds has enough regioselectivity issues. On the contrary,
transition metal catalyzed directed C-H bond metalation, metal-
carbene formation using diazo compounds followed by migratory
insertion has an admirable degree of regioselectivity.[9[10][11]
Introduction
Since the advancement of transition metal catalyzed C-H bond
functionalization reactions, the studies directed towards the
development of novel strategies for the construction of any
organic framework especially nitrogen containing scaffolds has
revamped significantly.[1] Being a very basic scaffold among
many nitrogen containg heterocyclic moities, oxindole has
attracted a considerable attention from the synthetic organic
community due to its ubiquitous presence in numerous complex
natural prodcuts and pharmaceutically active compounds.[2] As a
result, many classical methods were developed over the time for
the synthesis of oxindole scaffold.[3][4] Unfortunately, most of
these reported methods require a pre functionalized precurs or
drastic conditions.[5] Additionally, a bulk of these reported
methods delivered to 3-substituted or 3,3-disubstituted oxindoles,
[6][7] whereas the methods to prepare 3-substitution free oxindole
are rather rare in the literature.[8] In the search of more benign
and user friendly methods, recently direct C-H functionalization
has been strategically used to prepare this important scafflod. In
a pioneering discovery, Buchwald and co-workers elegantly
demonstrated the Pd(0) catalyzed parent oxindoles formation
Scheme 1. Previous transition metal catalyzed oxindole syntheses via C-H
bond functionalizations.
During our recent progress in directed C-H bond
functionaliation using diazo compounds,[12] we realized that there
are certain α-diazo malonates which undergo in regioselective
alkylation followed by rapid decarboxylation under a specific
condition. Considering this realization, we hypothesized that the
transtion metal catalyzed reaction of directing group protected
anilines and above mentioned α-diazo malonate will directly
provide basic oxindole scaffolds via the cascade ortho alkylation,
cyclocondensation followed by rapid decarboxylation. To
establish this hypothesis, we decided to screen the reaction with
different transition metal catalysts. Among them Ir(III) catalysts
got siginificant attention due to its versatile reactivity profile.[13]
We disclose herein, a cascade Ir(III) catalyzed synthesis of
from the N-substituted chloroacetanilides (Scheme 1a).[8a]
A
Ru(II) catalyzed C-H insertion into the methoxy substituted
aromatic ring was reported by Yu group to provide oxindole
derivatives (Scheme 1b).[8b] Another Pd(0) catalyzed elegant and
concise method to synthesize oxindole derivatives was reported
by Takemoto and co-workers via C(sp3)-H activation starategy
(Scheme 1c).[8c] Recently, Li group described a Au(I)/Ag(I)
catalyzed direct oxindole synthesis from N-arylynamides
(Scheme 1d).[8d] Incidentally, all of these aforementioned
methods proceeded through intramolecular fashion having
specially functionalized precursors. Therefore, development of a
oxindoles
using
N-aryl-2-aminopyridine
and
bis(2,2,2-
trifluoroethyl) 2-diazomalonate (Scheme 1e). However, during
our manuscript preparation, in a similar fashion, Ir(III) catalyzed
oxindole synthesis was reported from acetanilides by Patel
group using diazotized Meldrum's acid.[14]
Results and Discussion
[a]
U. Karmakar, D. Das, Dr. R. Samanta
Department of Chemistry
Indian Institute of Technology Kharagpur
Kharagpur 721302, India
E-mail: rsamanta@chem.iitkgp.ernet.in
Supporting information for this article is given via a link at the end of
the document.
We commenced our studies by evaluating N-phenyl-2-amino-
pyridine with bis(2,2,2-trifluoroethyl) 2-diazomalonate under
Ir(III) catalysis. Detail screening of several solvents, additives
were performed to obtain the desired product in good yields
(See supporting information for more details). We were delighted
to find the desired oxindole derivative 3a in 72% isolated yield
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10.1002/ejoc.201700214
European Journal of Organic Chemistry
FULL PAPER
using the [Cp*IrCl2]2 (5 mol%), AgNTf2 (20 mol%), LiOAc.2H2O
(20 mol%) in 2,2,2-trifluoroethanol at 70 °C. Strikingly, the
screening of silver salts and acetate sources as additives
became important factors to optimize the product yield.
Moreover, under our optimized conditions, more expensive
[Cp*RhCl2]2 catalyst also provided comparable yield of the
desired product. But, the use of [Ru(p-cymene)Cl2]2 as catalyst
remained unproductive. Further, pyrimidine protected aniline
derivative was successfully converted into the corresponding
oxindole compound under the developed conditions albeit in
reduced 33% isolated yield (Scheme 2, 3af). Other substrates
like acetyl or tosyl protected anilines were not able to offer the
desired products under the optimized conditions. Notably,
coupling of N-phenyl-2-amino-pyridine with dimethyl 2-
diazomalonate did not provide any desired product under our
developed conditions. Unequivocally enough, the structure of
the oxindole compound 3a was confirmed by the single crystal
X-ray analysis (see supporting information).
substituted oxindole derivatives smoothly (scheme 2, 3a-3h).
During the transformation, halogen substitutions at the para
position of the aniline derivatives were firmly tolerated, keeping
the option open for further functionalization (Scheme 2, 3i-3k).
N-Phenyl-2-aminopyridines bearing the electron withdrawing
groups at the para position of the phenyl ring were reacted
efficiently with moderate to good yields (Scheme 2, 3l-3o).
The efficacy of this protocol was further explored through
the aniline derivatives having meta substitution with variable
electronic and steric properties (Scheme 2, 3p-3v). Interestingly,
all of these cases, oxindoles have formed from less sterically
crowded side with admirable regioselectivity. In addition, this
catalytic system was shown to be compatible with the aniline
derivatives having ortho substitutions with different electronic or
steric properties (Scheme 2, 3w-3ac). It is noteworthy to
mention that the halogens at the ortho position were remain
unaltered during the operation though activation of the C-X bond
at the ortho position of the attached directing group is a common
phenomenon in the transition metal catalyzed transformations.
The disubstitutions at the other places of aniline substrates were
well tolerated (Scheme 2, 3ad-3ae).
Having devised an optimized reaction procedure, we surveyed
the substrate scope and limitations of the developed method.
Initially, 4-substituted aniline derivatives were explored for the
oxindole synthesis.
As a demonstration of scalability, thirty fold higher amount of the
starting material, N-Phenyl-2-aminopyridine (1a) was converted
into its corresponding oxindole (3a) in 51% isolated yield (see
supporting information) using much lower [Cp*IrCl2]2 catalyst
loading.
NHPy
[Cp*IrCl2]2 (5 mol%)
AgNTf2 (20 mol%)
F3CH2CO2C
H
O
R
+
N2
R
N
Py
LiOAc.2H2O (20 mol%)
CF3CH2OH
F3CH2CO2C
3
1
2
R1 = H, , 72% [
3a
x-ray
]
R1
F3CO
MeO
3b
= Me, , 51%
O
O
O
= Et, 3c, 52%
nBu, 3d, 58%
N
N
N
=
Py
3h
Py
Py
t
3e
= Bu, , 64%
52%,
3g
54%,
Br
3f
= Ph, , 52%
F
Cl
NC
O
O
O
O
N
N
N
N
Py
Py
Py
3l
Py
51%, 3i
61%, 3j
49%, 3k
58%,
O
MeO2C
O
F3C
Me
O
O
O
N
Py
Me
N
N
N
3p
60%,
3o Py
60%,
Py
3n
53%,
Py
3m
61%,
O
O
NC
O
O
N
N
N
N
Br
O
F
Cl
Py
Py
Py
Py
3t
51%,
3q
3s
54%,
34%,
3r
59%,
O
O
O
N
N
N
F3C
N
MeO2C
Py
Py
Py
Cl
F
Py
3u
66%,
3v
54%,
55%, 3w
63%, 3x
Me
Me
Me
O
O
O
Scheme 3. [a] Scope of 7-alkylated oxindole derivatives. Reaction Conditions:
3a (0.1 mmol), 4 (0. 12 mmol), [Cp*IrCl2]2 (5 mol%), AgNTf2 (20 mol%), 12 h,
80 °C, 1,2-DCE. [b] Scope of 7-aminated oxindole derivatives. Reaction
Conditions: 3a (0. 1 mmol), 6 (0.12 mmol), [Cp*IrCl2]2 (5 mol%), AgNTf2 (20
mol%), NaOAc (50 mol%), 12 h, 40 °C, 1,2-DCE. [c] Pyridyl deprotection:
Reaction Conditions: (i) MeOTf, CH2Cl2 (ii) NaBH4, MeOH
O
N
N
N
N
Py
Py
Py
Br
Py
Me
48%, 3y
3z
59%,
3ab
3aa
61%,
63%,
51%,
F
Br
Me
O
O
O
O
N
N
N
N
Py
3ac
Py
Pym
Br
Py
3af
33%,
3ae
45%,
3ad
58%,
During the development, we realized that suitably positioned
directing group in the oxindole moiety can directly influence to
introduce different functional groups in oxindoles with admirable
degree of regioselectivity. To establish that idea, we examined
the possibility of the direct regioselective alkylation and
amination of the substrate 3a. We were delighted to see that C7
Alkylated oxindole scaffolds were obtained in high yields through
Ir(III) catalysed transformations using various α-diazoketo esters
Scheme 2. Scope with various aniline derivatives: Reaction Conditions: 1 (0.1
mmol), 2 (0.2 mmol), [Cp*IrCl2]2 (5 mol%), AgNTf2 (20 mol%), LiOAc.2H2O (20
mol%), CF3CH2OH (0.1 M), 10-20 h, 70 °C.
We were pleased to see that the electron donating groups at the
para position of aniline derivatives provided the corresponding
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10.1002/ejoc.201700214
European Journal of Organic Chemistry
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(Scheme 3a).[15] Furthermore, in another post synthetic
modification, 3a could be converted into its C7 aminated
products via Ir(III) catalyzed amination reactions using sulfonyl
azides as the aminating agent (Scheme 3b).[16] The structure of
7a was undoubtedly confirmed by the single x-ray crystal
analysis (see supporting information). Finally, the 2-pyridyl
directing group was successfully removed from 3a via the two
step quaternization-hydride reduction at room temperature to
provide parent oxindole 8 (Scheme 3c) in 72% isolated yield.[17]
To elucidate the plausible reaction mechanism, number of
control experiments was carried out (see supporting information).
Competition experiments were executed to search for the
electronic preference of the developed reaction protocol. To gain
insight into the preference for electronically variable N-phenyl-2-
amino-pyridines, 1g and 1m [Scheme 4a] were exposed to
corresponding ester group followed by concomitant
decarboxylation offered the desired oxindole 3a.
bis(2,2,2-trifluoroethyl)
2-diazomalonate
under
standard
conditions. The result revealed that the rate of the reaction
favors to furnish 3m over 3g. This indicates that anilines with
electron withdrawing groups were electronically more favourable
for this transformation over substrates having electron donating
groups. Next to identify the possibilty of a iridacycle species as
an intermediate in the following reaction, a stable cyclometaleted
Ir(III) complex 9 was prepared via Jones protocol in 74% yield
(Scheme 4b).[18a,b] Unambiguously enough, the anlytical data of 9
was identical with the literature known compound.[13k] Thus, the
catalytic activity of the iridacycle complex 9 was scrutinized
under the above mentioned optimized conditions with
comparable yield (Scheme 4c). These results could be
described with the fact that the reaction might proceed via the
formation of the cyclometaleted complex 9.
Figure 1. Proposed Mechanism
Conclusions
In conclusion, a cascade Ir(III) catalyzed method for oxindole
synthesis has been realized, which is efficient, user friendly and
scalable. Starting materials for this reaction are easily available
cheap aniline derivatives. The reaction proceeded with excellent
regioselectivity with wide functional group tolerance. Moreover,
the pyridyl group has been utilized to get access of C7
functionalized oxindoles using Ir(III) catalysis and can be
removed. The role of bis(2,2,2-trifluoroethyl) 2-diazomalonate
has been explored. This operationally simple method will
definitely find its own applications in the syntheses of oxindole
containing complex architectures.
Experimental Section
Commercially available compounds were used without further purification.
Solvents for elution in column were distilled. Analytical thin layer
Scheme 4. Control experiments
chromatography (TLC) was performed on pre- coated silica gel 60 F254
.
Visualization on TLC was achieved by the use of UV light (254 nm).
Column chromatography was undertaken on silica gel (230-400 mesh).
1H NMR spectra were recorded on BRUKER ULTRA SHIELD (400 MHz
and 600 MHz). Chemical shifts were quoted in parts per million (ppm)
referenced to the appropriate solvent peak or 0.0 ppm for
tetramethylsilane. The following abbreviations were used to describe
peak splitting patterns when appropriate: br= broad, s= singlet, d=
doublet, t=triplet, q=quartet, dd=doublet of doublet, m=multiplet. Coupling
constants, J, were reported in hertz unit (Hz). 13C NMR spectra were
recorded on BRUKER (150 MHz and 100 MHz) and were fully decoupled
by broad band proton decoupling. Chemical shifts were reported in ppm
referenced to the centre of a triplet at 77.16 ppm of CDCl3. 19F NMR
spectra were recorded on BRUKER (376 MHz). Infrared (IR) spectra
were recorded using Spectrum BX FT-IR instrument from Perkin Elmer.
Frequencies are given in reciprocal centimetres (cm-1), only selected
absorbance peaks are reported. High resolution mass spectra were
obtained from waters XEVO-G2QTOF by using TOF MS ES+ method.
Materials were obtained from commercial suppliers or prepared
[9][13][14]
Based on the previous literature reports
and our
preliminary mechanistic investigations, a plausible mechanistic
pathway was proposed (Figure 1). Initially, a cationic Ir(III)
species was generated with the help of Ag salt and acetate
source via ligand exchange. Then coordination of Ir(III) species
to the pyridine nitrogen and subsequent ortho-C-H bond
metalation of 1a offered iridacycle intermediate A.[18c] In general,
during this step, the acetate base enhances the abstraction of
polarized ortho proton in intramolecular mode of fashion.
Following this, the bis(2,2,2-trifluoroethyl) 2-diazomalonate (2)
reacted with A to furnish the metal-carbene complex B which
underwent the migratory insertion to afford the intermediate C.
Next the proto-demetalation of intermediate
C provided
intermediate D with the regeneration of the active Ir(III) catalyst.
Subsequently, the immediate nucleophilic attack of nitrogen
center towards the highly electrophilic carbonyl center of the
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10.1002/ejoc.201700214
European Journal of Organic Chemistry
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according to standard procedures unless otherwise noted. Melting points
were determined using a local hotstage melting-point apparatus.
General procedure for iridium (III) catalyzed oxindole Synthesis: N-
Phenyl-2-aminopyridine derivatives (0.1 mmol) were dissolved in 1 mL
2,2,2-trifluroethanol in a 10 mL screw cap vial. Then [Cp*IrCl2]2 (5 mol%),
AgNTf2 (20 mol%), LiOAc.2H2O (20 mol%) and bis(2,2,2-trifluoroethyl) 2-
diazomalonate 2 (2 equiv.) were added to the reaction mixtures at room
temperature and the reaction mixtures were stirred for 10-22 h at 70 °C.
After completion of the reactions, products were purified by column
chromatography with hexane/ethyl acetate as eluent.
General procedure for the synthesis of substituted N-Phenyl-2-
aminopyridine compounds:[10k,19]
:
Procedure 1: (3a-3m, 3p-3u, 3w-3ae): To an oven-dried flask,
substituted aniline (1 mmol,), 2-bromopyridine (1 mmol, 1 equiv.) were
added. The reaction mixture was stirred at 160 °C for 10-20 h and
monitored by TLC. Upon completion, saturated NaHCO3 was added and
the mixture was extracted with ethyl acetate (3 × 15 mL). The combined
organic phase was washed with brine and dried over anhydrous Na2SO4.
The solid was filtered off and the filtrate was evaporated in vacuum. The
product was purified by flash column chromatography (n-hexane/EtOAc)
in 50-80% yield.
Genral procedure for Iridium (III) catalysed C7- alkylation of 3a with
diazomalonates:[15] 3a (0.1 mmol) was dissolved in 1 mL of 1,2-DCE in
a 10 mL screw cap vial. Then [Cp*IrCl2]2 (5 mol%), AgNTf2 (20 mol%)
and α-diazoketo esters (1.2 equiv.) were added to the reaction mixture at
room temperature. Then the reaction mixture was warmed to 80 °C for 12
h. After completion of the reaction, the reaction mixture was concentrated
and directly loaded to the column and product 5 was purified by flash
column chromatography using hexane/ethyl acetate mixture as the eluent.
Procedure 2: (3n, 3o, 3v): In a 50 mL round-bottom flask, Pd(OAc)2 (12
mg, 4 mol%), (±)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl [(±)-BINAP]
(45 mg, 4 mol%) were taken in anhydrous toluene (30 mL). The resulting
mixture was stirred under a stream of argon for 10 minutes. Then 2-
chloropyridine (1 mmol, 1 equiv.), substituted aniline (1.2 equiv.), cesium
carbonate (3 equiv.) were added to it. The reaction was fitted with a
condenser and heated to reflux with vigorous stirring under argon for 16
h. The solid was removed by filtration through celite, washed with CH2Cl2
(2 x 50 mL) and the solvent was removed under reduced pressure. The
product was purified by column chromatography in 40-60% yield using
hexane/ethyl acetate mixture as the eluent.
General procedure for Ir(III)-catalysed C7-amidation of 3a using aryl
sulfonyl azides:[16a,b] 3a (0.1 mmol) was dissolved in 1 mL of 1,2-DCE in
a 10 mL screw cap vial. Then [Cp*IrCl2]2 (5 mol%), AgNTf2 (20 mol%),
NaOAc (50 mol%) and aryl sulfonyl azide (1.2 equiv.) were added to the
reaction mixture. The reaction mixture was allowed to stir at room
temperature for 12 h. After completion of the reaction, the reaction
mixture was concentrated and directly purified by flash column
chromatography using hexane/ethyl acetate mixture as the eluent to
obtain product 7.
Synthesis of iridacycle complex:[18] N-(4-tert-Butylphenyl)pyridin-2-
amine 1e (0.2 mmol) was taken in a 10 mL round bottom flask charged
with a stirring bar and dissolved in 4 mL CH2Cl2. Then [Cp*IrCl2]2 (0.5
equiv.) and NaOAc (1.1 equiv.) were added to it and allowed to stir at
room temperature for overnight. After filtration, filtrate was concentrated
and washed with dry diethyl ether (10 mL x 2). Then the solvent was
removed to get iridacycle complex 9 at analytically pure form with 74%
yield. The analytical data was in well match with the reported literature
data.
Preparation of bis(2,2,2-trifluoroethyl) 2-diazomalonate:[20a,b] A 250
mL round-bottom flask equipped with a condenser was charged with
malonic acid (8.00 g, 76.9 mmol), 2,2,2-trifluoroethanol (30.0 mL, 412
mmol), dry benzene (40 mL) and conc. sulfuric acid (1 mL). The reaction
mixture was refluxed for 6 h under nitrogen atmosphere. The reaction
mixture was allowed to cool to room temperature, diluted with additional
benzene (80 mL) washed with 10% aqueous sodium carbonate (3 x 40
mL) and brine. The organic layer was dried over anhydrous Na2SO4 and
concentrated to get the product as colourless oil in 31 % yield (6.4 g).
The analytical data was found identical with the known literature data.[20a]
Bis(2,2,2-trifluoroethyl) malonate (5.00 g, 18.7 mmol,
1
equiv.),
Synthesis of 3e using catalytic amount of iridacycle complex: N-(4-
tert-Butylphenyl)pyridin-2-amine 1e (0.1 mmol) was taken in a 10 mL
screw cap vial and dissolved in 1 mL of 2,2,2-trifluoro ethanol. Then
iridacycle complex 9 (10 mol%), AgNTf2 (20 mol%), LiOAc.2H2O (20
mol%) and bis(2,2,2-trifluoroethyl) 2-diazomalonate 2 (2 equiv.) were
added to the reaction mixture. Then the mixture was allowed to stir at
70 °C for 12 h. The desired product 3e was isolated in 55% yield by flash
column chromatography using hexane/ethyl acetate mixture as the eluent.
triethylamine (2.84 mL, 20.5 mmol, 1.1 equiv.) and p- tosyl azide (4.93 g,
20.5 mmol, 1.1 equiv.) were dissolved in acetonitrile (40 mL) at room
temperature. The reaction mixture was stirred for 24 h. The solvent was
removed under reduced pressure. The crude was dissolved in
dichloromethane (50 mL), partitioned between dichloromethane and
water (60 mL). The organic layer was dried over anhydrous Na2SO4,
concentrated under reduced pressure and the product was purified by
silica gel column chromatography using hexane/ethyl acetate to get
yellow oil in 65 % yield (3.6 g). The analytical data was found identical
with the known literature data.[20b]
Removal of directing group:[17] Compound 3a (0.4 mmol) was dissolved
in dry CH2Cl2 (5 mL) in a 25 mL round bottom flask filled with nitrogen.
The reaction mixture was cooled to 0 °C. Then MeOTf (1.5 equiv.) was
added drop wise to the reaction mixture. After completion of addition, the
reaction mixture was allowed to warm to room temperature and allowed
to stir for 12 h. The volatile materials were evaporated off in vacuum.
Afterwards the residue was dissolved in dry MeOH (5 mL), filled with
nitrogen and cooled to 0 °C. Then NaBH4 (1.6 mmol, 4 equiv.) was
added to the mixture. The reaction mixture was allowed to warm to room
temperature and stirred for additional 12 h. The reaction mixture was
quenched with water and extracted with ethyl acetate. The organic layer
was dried over anhydrous sodium sulphate, concentrated on vaccuo. The
product 8 was finally purified by flash column chromatography in 72%
yield using hexane/ethyl acetate mixture as the eluent. The analytical
data was identical with the reported literature data.
General procedure for synthesis of diazo malonates:[21] Malonate (1
mmol) was dissolved in dry THF (10 mL), cesium carbonate (1.1 mmol,
1.1 equiv.) followed by p-tosyl azide (1.1 mmol, 1.1 equiv.) were added to
it at room temperature. The reaction was allowed to stir for 24 h at the
same temperature. After completion of the reaction, solvent was
evaporated under reduced pressure. Then diazo malonate was purified
by silica gel column chromatography using hexane/ethyl acetate.
General procedure for synthesis of aryl sulfonyl azides:[22] To a
solution of aryl sulfonyl chloride (1 mmol) in acetone (5 mL), a solution of
sodium azide (1.5 mmol, 1.5 equiv.) in water (5 mL) was added dropwise
at 0 °C. The reaction was allowed to warm up to room temperature and
stirred for overnight. Acetone was removed under reduced pressure and
the reaction mixture was extracted with dichloromethane twice. The
combined organic layer was dried over anhydrous Na2SO4 and the
solvent was removed under reduced pressure to give the product as
colorless oil.
Compound 3a: white solid; yield: 15.2 mg (72%). M.p. 66– 69 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.60 (dd, J = 5.0, 2.0 Hz, 1 H), 7.89–7.85 (m,
1 H), 7.75 (d, J = 8.1 Hz, 1 H), 7.56 (d, J = 8.1 Hz, 1 H), 7.31–7.24 (m, 3
H), 7.11 (t, J = 7.5 Hz, 1 H), 3.74 (s, 2 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 174.6, 149.5, 148.7, 143.5, 138.4, 127.9, 124.5, 124.2, 123.5,
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10.1002/ejoc.201700214
European Journal of Organic Chemistry
FULL PAPER
~
122.2, 120.3, 112.4, 36.5 ppm. FT-IR (KBr):
= 3036, 3016, 2935, 2856,
7.20 (s, 1 H), 7.15 (d, J = 8.7 Hz, 1 H), 3.76 (s, 2 H) ppm. 13C NMR (150
MHz, CDCl3): δ = 174.0, 149.3, 148.6, 145.3, 142.0, 138.5, 125.7, 122.4,

1722, 1587, 1483, 1462, 1439, 1365, 1325, 1241, 1202, 1170, 1049 cm-1.
HRMS (ESI): calcd. for C13H11N2O [M+H]+ 211.0866; found 211.0870.
121.1, 120.7 (q, J = 257.1 Hz), 119.9, 118.1, 113.5, 36.4 ppm. 19F NMR
~
(376 MHz, CDCl ): δ = –58.28 ppm. FT-IR (KBr):
= 3077, 2964, 2918,

3
2852, 1730, 1603, 1589, 1486, 1440, 1393, 1358, 1328, 1240, 1174 cm-1.
HRMS (ESI): calcd. for C14H10F3N2O2 [M+H]+: 295.0689; found 295.0682.
Compound 3b: White solid; yield: 11.5 mg (51%). M.p. 86–89 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.58 (dd, J = 4.9, 1.9 Hz, 1 H), 7.88–7.83 (m,
1 H), 7.76 (d, J = 8.1 Hz, 1 H), 7.47 (d, J = 8.1 Hz, 1 H), 7.26 (d, J = 3.4
Hz, 1 H), 7.12 (s, 1 H), 7.06 (d, J = 8.1 Hz, 1 H), 3.70 (s, 2 H), 2.35 (s, 3
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 174.7, 149.7, 148.6, 141.1,
Compound 3i: White solid; yield: 11.6 mg (51%). M.p.102–105 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.59 (dd, J = 4.9, 1.7 Hz, 1 H), 7.90–7.86 (m,
1 H), 7.80 (d, J = 8.1 Hz, 1 H), 7.62 (dd, J = 8.8, 4.6 Hz, 1 H), 7.30–7.26
(m, 1 H), 7.05 (dd, J = 8.1, 2.4 Hz, 1 H), 7.01–6.96 (m, 1 H), 3.75 (s, 2 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 174.2, 159.6 (d, J = 241.3 Hz),
149.5, 148.5, 139.4, 138.4, 125.8 (d, J = 8.9 Hz), 122.2, 119.9, 114.3 (d,
J = 22.8 Hz), 113.7 (d, J = 8.1 Hz), 112.1 (d, J = 24.7 Hz), 36.6 (d, J = 1.4
138.3, 133.0, 128.2, 125.2, 124.2, 122.0, 120.0, 112.3, 36.6, 21.2 ppm.
~
FT-IR (KBr):
= 3017, 2918, 2852, 1731, 1599, 1588, 1486, 1473, 1439,

1350, 1323, 1210, 1181, 1107 cm-1. HRMS (ESI): calcd. for C14H13N2O
[M+H]+ 225.1022; found 225.1020.
Hz) ppm. 19F NMR (376 MHz, CDCl3): δ = –119.71 ppm. FT-IR (KBr):
Compound 3c: White solid; yield: 12.5 mg (52%). M.p. 93–96 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.58 (dd, J = 4.8, 1.9 Hz, 1 H), 7.88–7.83 (m,
1 H), 7.76 (d, J = 8.1 Hz, 1 H), 7.49 (d, J = 8.1 Hz, 1 H), 7.31 –7.21 (m, 1
H), 7.15 (s, 1 H), 7.12–6.97 (m, 1 H), 3.71 (s, 2 H), 2.64 (q, J = 7.6 Hz, 2
H), 1.23 (t, J = 7.6 Hz, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 174.8,
~
= 3038, 2962, 2907, 2858, 1728, 1612, 1592, 1486, 1437, 1356, 1336,

1304, 1266, 1252, 1224, 1171 cm-1. HRMS (ESI): calcd. for C13H10FN2O
[M+H]+ 229.0772; found 229.0775.
149.6, 148.6, 141.3, 139.7, 138.3, 127.1, 124.2, 124.0, 122.0, 120.0,
Compound 3j: White solid, yield: 15 mg (61%). M.p.120–123 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.59 (dd, J = 5.0, 2.0 Hz, 1 H), 7.91–7.86 (m,
1 H), 7.79 (d, J = 8.1 Hz, 1 H), 7.59 (d, J = 8.6 Hz, 1 H), 7.30–7.24 (m, 3
H), 3.74 (s, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 173.9, 149.3,
~
112.3, 36.6, 28.7, 16.2 ppm. FT-IR (KBr):
= 3015, 2957, 2936, 2866,

1732, 1596, 1584, 1473, 1437, 1356, 1327, 1256, 1184, 1115 cm-1.
HRMS (ESI): calcd. for C15H15N2O [M+H]+ 239.1179; found 239.1185.
148.6, 142.0, 138.4, 128.8, 127.9, 125.9, 124.7, 122.3, 119.9, 113.9,
~
Compound 3d: white solid; yield: 15.5 mg (58%). M.p. 87–90 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.60 (dd, J = 5.0, 1.9 Hz, 1 H), 7.89–7.84 (m,
1 H) 7.77 (d, J = 8.2 Hz, 1 H), 7.49 (d, J = 8.2 Hz, 1 H), 7.35–7.20 (m, 1
H), 7.14 (s, 1 H), 7.08 (d, J = 8.2 Hz, 1 H), 3.72 (s, 2 H), 2.61 (t, J = 7.4
Hz, 2 H), 1.63–1.55 (m, 2 H), 1.40–1.31 (m, 2 H), 0.93 (t, J = 7.4 Hz, 3 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 174.7, 149.6, 148.6, 141.3, 138.2,
127.7, 124.5, 124.2, 122.0, 120.0, 112.2, 36.6, 35.4, 34.1, 22.3, 14.1
36.3 ppm. FT-IR (KBr):
= 2955, 2919, 1726, 1609, 1594, 1481, 1434,

1352, 1320, 1243, 1200, 1173, 1111 cm-1. HRMS (ESI): calcd. for
C
13H1035ClN2O [M+H]+ 245.0476; found 245.0477.
Compound 3k: White solid; yield: 14.2 mg (49%). M.p.135–138 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.57 (dd, J = 4.8, 1.9 Hz, 1 H), 7.89–7.85 (m,
1 H), 7.77 (d, J = 8.3 Hz, 1 H), 7.53 (d, J = 8.3 Hz, 1 H), 7.47–7.33 (m, 2
H), 7.29–7.27 (m, 1 H), 3.73 (s, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ
= 173.8, 149.2, 148.6, 142.5, 138.4, 130.8, 127.5, 126.3, 122.3, 120.0,
~
ppm. FT-IR (KBr):
= 2950, 2928, 2858, 1729, 1586, 1488, 1472, 1435,

1354, 1325, 1253, 1219, 1185, 1115 cm-1. HRMS (ESI): calcd. for
~
= 3048, 2911, 1723, 1605, 1593,
C
17H19N2O [M+H]+ 267.1492; found 267.1496.
116.2, 114.3, 36.2 ppm. FT-IR (KBr):

1479, 1439, 1356, 1318, 1238, 1204, 1169, 1109 cm-1. HRMS (ESI):
calcd. for C13H1079BrN2O [M+H]+ 288.9971; found 288.9979.
Compound 3e: White solid; yield: 17.1 mg (64%). M.p. 95–98 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.59 (dd, J = 5.0, 1.9 Hz, 1 H), 7.88–7.84 (m,
1 H), 7.78 (d, J = 8.2 Hz, 1 H), 7.53 (d, J = 8.2 Hz, 1 H), 7.36 (s, 1 H),
7.33–7.20 (m, 2 H), 3.74 (s, 2 H), 1.33 (s, 9 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 174.8, 149.7, 148.6, 146.6, 141.0, 138.2, 124.6, 123.9, 121.9,
Compound 3l: White solid; yield: 13.7 mg (58%). M.p. 133–136 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.59 (dd, J = 4.8, 1.9 Hz, 1 H), 7.92–7.87(m,
1 H), 7.74 (d, J = 8.1 Hz, 1 H), 7.69 (d, J = 8.1 Hz, 1 H), 7.58 (d, J = 9.0
Hz, 2 H), 7.32 (dd, J = 7.6, 4.8 Hz, 1 H), 3.77 (s, 2 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 173.7, 148.7, 148.6, 147.1, 138.7, 133.0, 127.9,
~
121.6, 119.9, 112.1, 36.8, 34.6, 31.7 ppm. FT-IR (KBr):
= 3059, 2996,

2959, 2866, 1724, 1585, 1489, 1471, 1435, 1350, 1325, 1265, 1238,
1200, 1177, 1120 cm-1. HRMS (ESI): calcd. for C17H19N2O [M+H]+
267.1492, found 267.1493.
~
125.2, 122.9, 120.2, 119.2, 113.2, 106.7, 35.8 ppm. FT-IR (KBr):
=

2953, 2909, 2223, 1728, 1588, 1474, 1433, 1340, 1331, 1245, 1151,
1109 cm-1; HRMS (ESI): calcd. for C14H10N3O [M+H]+ 236.0818; found
236.0834.
Compound 3f: White solid; yield: 14.9 mg (52%). M.p. 130–133 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.62 (dd, J = 5.0, 2.0 Hz, 1 H), 7.91–7.86 (m,
1 H), 7.80 (d, J = 8.1 Hz, 1 H), 7.67 (d, J = 8.1 Hz, 1 H), 7.61–7.48 (m, 4
H), 7.44 (t, J = 7.7 Hz, 2 H), 7.37–7.26 (m, 2 H), 3.81 (s, 2 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 174.6, 149.5, 148.7, 142.8, 141.0, 138.4,
Compound 3m: White solid; yield: 17 mg (61%). M.p.110–113 °C. 1H
NMR (400 MHz, CDCl3): δ =: 8.60 (dd, J = 5.0, 1.8 Hz, 1 H), 7.91–7.87
(m, 1 H), 7.76 (d, J = 8.2 Hz, 1 H), 7.69 (d, J = 8.2 Hz, 1 H), 7.54 (d, J =
9.4 Hz, 2 H), 7.31 (dd, J = 7.4, 4.9 Hz, 1 H), 3.79 (s, 2 H) ppm. 13C NMR
(150 MHz, CDCl3): δ = 174.1, 149.0, 148.7, 146.3, 138.5, 125.8, 125.6 (q,
J = 4.3Hz), 124.7, 124.4 (q, J = 272.9 Hz), 122.6, 121.5 (q, J = 3.5 Hz),
136.9, 129.0, 127.2, 127.0, 126.8, 124.8, 123.3, 122.2, 120.1, 112.9,
~
36.6 ppm. FT-IR (KBr):
= 3034, 2937, 1728, 1595, 1477, 1462, 1438,

1352, 1334, 1210, 1194, 1161, 1114 cm-1. HRMS (ESI): calcd. for
C19H15N2O [M+H]+ 287.1179; found 287.1173.
120.2, 112.6, 36.1 ppm. 19F NMR (376 MHz, CDCl3): δ = –61.72 ppm.
~
FT-IR (KBr):
= 3067, 2920, 2852, 1740, 1588, 1474, 1440, 1359, 1328,

1300, 1197, 1156, 1126, 1062 cm-1. HRMS (ESI): calcd. for C14H10F3N2O
Compound 3g: White solid, yield; 13 mg (54%). M.p. 105–108 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.57–8.55 (m, 1 H), 7.87–7.79 (m, 2 H),
7.59 (d, J = 8.6 Hz, 1 H), 7.26–7.22 (m, 1 H), 6.90 (s, 1 H), 6.81 (dd, J =
8.6, 2.7 Hz, 1 H), 3.81 (s, 3 H), 3.72 (s, 2 H) ppm. 13C NMR (100 MHz,
[M+H]+ 279.0740; found 279.0744.
Compound 3n: Yellow solid; yield: 13.4 mg (53%). M.p. 115–118 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.61 (dd, J = 4.9, 2.0 Hz, 1 H), 7.98–7.83 (m,
3 H), 7.74 (d, J = 8.1 Hz, 1 H), 7.62 (d, J = 8.1 Hz, 1 H), 7.31 (dd, J = 7.5,
4.8 Hz, 1 H), 3.78 (s, 2 H), 2.59 (s, 3 H) ppm. 13C NMR (150 MHz,
CDCl3): δ = 174.4, 156.4, 149.8, 148.4, 138.2, 137.0, 125.5, 121.8, 119.7,
~
113.5, 112.6, 111.1, 55.9, 36.9 ppm. FT-IR (KBr):
= 3059, 3005, 2943,

2831, 1726, 1600, 1488, 1477, 1438, 1355, 1332, 1301, 1255, 1237,
1179, 1035 cm-1. HRMS (ESI): calcd. for C14H13N2O2 [M+H]+ 241.0972;
found 241.0973.
CDCl3): δ = 197.0, 174.5, 149.0, 148.8, 147.5, 138.5, 132.8, 129.5, 124.5,
~
124.4, 122.7, 120.3, 112.1, 36.1, 26.6 ppm. FT-IR (KBr):
= 2928, 2856,

1727, 1709, 1677, 1611, 1476, 1437, 1367, 1330, 1266, 1166, 1122 cm-1.
HRMS (ESI): calcd. for C15H13N2O2 [M+H]+ 253.0972; found 253.0974.
1
Compound 3h: White solid, yield; 15 mg (52%). M.p. 85–88 °C. H NMR
(600 MHz, CDCl3): δ = 8.58 (dd, J = 5.0, 2.0 Hz, 1 H), 7.89–7.86 (m, 1 H),
7.78 (d, J = 8.1 Hz, 1 H), 7.65 (d, J = 8.7 Hz, 1 H), 7.30–7.27 (m, 1 H),
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700214
European Journal of Organic Chemistry
FULL PAPER
Compound 3o: White solid; yield: 16.1 mg (60%). M.p. 180–183 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.61 (dd, J = 4.8, 2.1 Hz, 1 H), 8.00 (d, J =
8.1 Hz, 2 H), 7.95–7.82 (m, 1 H), 7.74 (d, J = 8.1 Hz, 1 H), 7.60 (d, J =
8.1 Hz, 1 H), 7.31 (dd, J = 7.5, 4.7 Hz, 1 H), 3.91 (s, 3 H), 3.77 (s, 2 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 174.5, 166.9, 149.0, 148.8, 147.4,
1208, 1149, 1127, 1064 cm-1. HRMS (ESI): calcd. for C14H10F3N2O
[M+H]+ 279.0740; found 279.0737.
Compound 3v: White solid; yield: 14.5 mg (54%). M.p. 168–171 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.64 (dd, J = 4.9, 1.9 Hz, 1 H), 8.17 (s, 1 H),
7.94–7.81 (m, 2 H), 7.74 (d, J = 8.0 Hz, 1 H), 7.37 (d, J = 8.0 Hz, 1 H),
7.32–7.29 (m, 1 H), 3.90 (s, 3 H), 3.78 (s, 2 H) ppm. 13C NMR (100 MHz,
138.5, 130.4, 125.8, 125.4, 124.1, 122.6, 120.3, 112.1, 52.2, 36.1 ppm.
~
FT-IR (KBr):
= 3032, 2988, 2958, 2911, 1727, 1717, 1623, 1597, 1491,

1477, 1440, 1362, 1331, 1303, 1276, 1190, 1170, 1131 cm-1. HRMS
(ESI): calcd. for C15H13N2O3 [M+H]+ 269.0921; found 269.0919.
CDCl3): δ = 174.0, 166.9, 149.1, 148.9, 143.8, 138.5, 130.2, 129.4, 125.2,
~
124.3, 122.5, 120.2, 113.2, 52.4, 36.5 ppm. FT-IR (KBr):
= 3037, 2984,

2956, 2912, 1719, 1717, 1622, 1586, 1493, 1472, 1443, 1369, 1329,
1283, 1266, 1205, 1198, 1148 cm-1. HRMS (ESI): calcd. for C15H13N2O3
[M+H]+ 269.0921; found 269.0919.
Compound 3p: White solid; yield: 13.5 mg (60%). M.p. 80–83 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.61 (dd, J = 4.7, 2.0 Hz, 1 H), 7.89 –7.85
(m, 1 H), 7.71 (d, J = 8.0 Hz, 1 H), 7.33 (s, 1 H), 7.30–7.27 (m, 1 H), 7.17
(d, J = 7.4 Hz, 1 H), 6.92 (d, J = 7.4 Hz, 1 H), 3.69 (s, 2 H), 2.35 (s, 3 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 175.0, 149.4, 148.7, 143.5, 138.4,
1
Compound 3w: Greenish oil; yield: 12.5 mg (55%). H NMR (400 MHz,
CDCl3): δ = 8.60 (d, J = 4.5 Hz, 1 H), 7.89–7.84 (m, 1 H), 7.48 (d, J = 7.9
Hz, 1 H), 7.33 (dd, J = 7.3, 5.0 Hz, 1 H), 7.10 (d, J = 7.3 Hz, 1 H), 7.07 –
6.97 (m, 2 H), 3.78 (s, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 174.2,
149.2, 148.8, 147.9 (d, J = 247.7 Hz), 138.1, 130.7 (d, J = 8.8 Hz), 127.1
(d, J = 3.3 Hz), 124.0 (d, J = 6.6 Hz), 123.3, 121.9, 120.3 (d, J = 3.6 Hz),
138.0, 124.2, 124.1, 122.2, 121.1, 120.5, 112.9, 36.2, 22.0 ppm. FT-IR
~
(KBr):
= 3025, 2912, 2858, 1734, 1618, 1589, 1499, 1475, 1444, 1362,

1320, 1241, 1181, 1109 cm-1. HRMS (ESI): calcd. for C14H13N2O [M+H]+
225.1022; found 225.1025.
116.4 (d, J = 19.1 Hz), 36.6 (d, J = 2.1 Hz) ppm. 19F NMR (376 MHz,
~
1
Compound 3q: White solid; yield: 7.9 mg (34 %). M.p. 120–122 °C. H
CDCl ): δ = –124.86 ppm. FT-IR (neat):
= 3062, 2952, 2911, 2848,

3
NMR (400 MHz, CDCl3): δ = 8.60 (dd, J = 4.7, 2.0 Hz, 1 H), 7.91–7.87 (m,
1 H), 7.75 (d, J = 8.0 Hz, 1 H), 7.38 (d, J = 8.0 Hz, 1 H), 7.33–7.22 (m, 2
H), 6.84 (t, J = 8.4 Hz, 1 H), 3.77 (s, 2 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 173.8, 158.7, (d, J = 261.3 Hz), 149.2, 148.7, 145.3 (d, J =
8.7 Hz), 138.5, 129.6 (d, J = 8.3 Hz), 122.4, 120.2, 110.6 (d, J = 22.8 Hz),
1734, 1631, 1598, 1474, 1436, 1365, 1320, 1304, 1257, 1220, 1189, cm-
1. HRMS (ESI): calcd. for C13H10FN2O [M+H]+ 229.0772; found 229.0776.
Compound 3x: Gummy oil; yield: 15.5 mg (63%). 1H NMR (400 MHz,
CDCl3): δ = 8.62 (dd, J = 4.9, 2.0 Hz, 1 H), 7.89–7.85 (m, 1 H), 7.43 (d, J
= 8.0 Hz, 1 H), 7.37 (dd, J = 7.5, 4.9 Hz, 1 H), 7.19 (t, J = 7.5 Hz, 2 H),
7.00 (t, J = 7.8 Hz, 1 H), 3.75 (s, 2 H) ppm. 13C NMR (100 MHz, CDCl3):
110.5 (d, J = 20.4 Hz), 108.6 (d, J = 3.5 Hz), 33.2 ppm. 19F NMR (376
~
MHz, CDCl ): δ = –117.52 ppm. FT-IR (KBr):
= 3034, 2954, 2921,

3
2848, 1728, 1633, 1586, 1467, 1441, 1359, 1325, 1306, 1269, 1242,
1203, 1174 cm-1. HRMS (ESI): calcd. for C13H10FN2O [M+H]+ 229.0772;
found 229.0770.
δ = 175.2 , 149.4, 149.2, 140.4, 138.3, 130.2, 127.0, 124.0, 123.9, 123.8,
~
123.1, 116.6, 36.4 ppm. FT-IR (neat):
= 2964, 2927, 1722, 1608, 1591,

1465, 1437, 1363, 1315, 1223, 1195, 1164, 1127 cm-1. HRMS (ESI):
calcd. for C13H1035ClN2O [M+H]+ 245.0476; found 245.0486.
Compound 3r: White solid; yield: 14.5 mg (59%). M.p. 79–82 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.60 (dd, J = 4.7, 1.9 Hz, 1 H), 7.90 –7.85
(m, 1 H), 7.75 (d, J = 8.2 Hz, 1 H), 7.64 (d, J= 1.9 Hz, 1 H), 7.32–7.27 (m,
1 H), 7.21 (d, J = 7.9 Hz, 1 H), 7.09 (dd, J = 7.9, 2.0 Hz, 1 H), 3.70 (s, 2
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 174.4, 149.1, 148.7, 144.3,
Compound 3y: White solid; yield: 14 mg (48%). M.p. 139–142 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.57 (dd, J = 4.9, 1.9 Hz, 1 H), 7.89–7.85 (m,
1 H), 7.77 (d, J = 8.0 Hz, 1 H), 7.53 (d, J = 8.5 Hz, 1 H), 7.43 –7.38 (m, 2
H), 7.29–7.26 (m, 1 H), 3.73 (s, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ
138.5, 133.7, 125.2, 123.4, 122.5, 122.4, 120.0, 113.3, 36.0 ppm. FT-IR
= 173.8, 149.2, 148.6, 142.5, 138.4, 130.8, 127.5, 126.2, 122.3, 120.0,
~
~
(KBr):
= 2960, 2924, 1725, 1613, 1594, 1483, 1439, 1362, 1315, 1238,

116.2, 114.3, 36.2 ppm. FT-IR (KBr):
= 3010, 2912, 1724, 1608, 1594,

1197, 1172, 1105 cm-1. HRMS (ESI): calcd. for C13H1035ClN2O [M+H]+
245.0476; found 245.0481.
1479, 1439, 1357, 1318, 1239, 1205, 1169, 1110 cm-1. HRMS (ESI):
calcd. for C13H1079BrN2O [M+H]+ 288.9971; found 288.9969.
1
Compound 3z: White solid; yield: 15.4 mg (59%). M.p. 159–162 °C. 1H
NMR (600 MHz, CDCl3): δ = 8.67–8.66 (m, 1 H), 8.00–7.97(m, 1 H), 7.83
(d, J = 8.1 Hz, 1 H), 7.65 (d, J = 8.1 Hz, 1 H), 7.59 (d, J = 7.9 Hz, 1 H),
7.48–7.42 (m, 2 H), 7.37–7.34 (m, 1 H), 7.15–7.12 (m, 1 H), 6.68 (d, J =
8.7 Hz, 1 H), 3.90 (s, 2 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 176.7,
Compound 3s: White solid; yield: 15.5 mg (54%). M.p. 114–117 °C. H
NMR (400 MHz, CDCl3): δ = 8.60 (dd, J = 4.9, 2.0 Hz, 1 H), 7.89-7.84 (m,
1 H), 7.78 (d, J = 1.9 Hz, 1 H), 7.74 (d, J = 8.0 Hz, 1 H), 7.35 –7.18 (m, 2
H), 7.15 (d, J = 8.0 Hz, 1 H), 3.67 (s, 2 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 174.2, 149.0, 148.7, 144.5, 138.5, 126.3, 125.6, 123.0, 122.4,
~
121.4, 120.0 116.0, 36.0 ppm. FT-IR (KBr):
= 2954, 2920, 1718, 1610,

150.7, 149.8, 138.9, 138.8, 134.5, 129.2, 125.5, 125.4, 124.2, 123.9,
1590, 1480, 1436, 1362, 1314, 1237, 1199, 1176, 1104 cm-1. HRMS
~
123.6, 122.3, 122.1, 120.8, 120.7, 37.2 ppm. FT-IR (KBr):
= 3052,

(ESI): calcd. for C13H1079BrN2O [M+H]+ 288.9971; found 288.9977.
3005, 2922, 1724, 1590, 1570, 1466, 1437, 1400, 1367, 1345, 1179,
1142, 1094 cm-1. HRMS (ESI): calcd. for C17H13N2O [M+H]+ 261.1022;
found 261.1028.
Compound 3t: White solid, yield; 12 mg (51%). M.p. 116–119 °C. 1H
NMR (600 MHz, CDCl3): δ = 8.58 (dd, J = 5.0, 1.9 Hz, 1 H), 7.92–7.88 (m,
2 H), 7.80 (d, J = 8.2 Hz, 1 H), 7.39 (d, J = 3.8 Hz, 2 H), 7.31 (dd, J = 7.4,
4.9 Hz, 1 H), 3.91 (s, 2 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 172.7,
Compound 3aa: White solid; yield: 15.1 mg (63%). M.p. 81–84 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.60 (dd, J = 4.9, 1.9 Hz, 1 H), 7.88–7.83 (m,
1 H), 7.73 (d, J = 8.1 Hz, 1 H), 7.34 (s, 1 H), 7.26 (t, J = 6.1 Hz, 1 H),
7.06 (s, 1 H), 3.67 (s, 2 H), 2.26 (s, 3 H), 2.25 (s, 3 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 175.0, 149.6, 148.6, 141.4, 138.3, 136.1, 131.5,
148.9, 148.6, 144.2, 138.6, 128.9, 128.5, 126.3, 122.6, 119.9, 117.0,
~
116.8, 108.9, 35.9 ppm. FT-IR (KBr):
= 2921, 2909, 2227, 1730, 1596,

1454, 1435, 1357, 1325, 1246, 1152, 1112 cm-1. HRMS (ESI): calcd. for
C14H10N3O [M+H]+ 236.0818; found 236.0815.
125.6, 122.0, 121.4, 120.2, 113.5, 36.3, 20.4, 19.6 ppm. FT-IR (KBr):
~
= 3017, 2937, 2858, 1731, 1589, 1476, 1442, 1357, 1323, 1263, 1220,

Compound 3u: White solid; yield: 18. 4 mg (66%). M.p. 70–73 °C. 1H
NMR (600 MHz, CDCl3): δ = 8.62 (dd, J = 5.0, 1.8 Hz, 1 H), 7.98–7.84 (m,
2 H), 7.78 (d, J = 8.2 Hz, 1 H), 7.47–7.35 (m, 2 H), 7.31 (dd, J = 7.4, 4.9
Hz, 1 H), 3.78 (s, 2 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 174.0,
149.1, 148.7, 143.9, 138.5, 130.5 (q, J = 32.4 Hz), 128.1, 124.6, 124.2 (q,
J = 271.4 Hz), 122.5, 120.4 (q, J = 4.3 Hz), 120.0, 109.7 (q, J = 4.2 Hz),
1168, 1081 cm-1. HRMS (ESI): calcd. for C15H15N2O [M+H]+ 239.1179;
found 239.1185.
Compound 3ab: White solid; yield: 14.6 mg (61%). M.p. 75–78 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.63–8.59 (m, 1 H), 7.95 – 7.79 (m, 1 H),
7.45 (d, J = 7.9 Hz, 1 H), 7.34 (dd, J = 7.9, 4.9 Hz, 1 H), 6.96 (s, 1 H),
6.81 (s, 1 H), 3.67 (s, 2 H), 2.29 (s, 3 H), 1.67 (s, 3 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 176.0, 150.4, 149.4, 139.8, 138.4, 132.6, 131.8,
36.3 ppm. 19F NMR (376 MHz, CDCl3): δ = –62.27 ppm. FT-IR (KBr):
= 3135, 2945, 2918, 1717, 1618, 1585, 1468, 1439, 1365, 1324, 1302,
~

This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700214
European Journal of Organic Chemistry
FULL PAPER
125.0, 123.6, 123.4, 123.0, 120.9, 36.4, 20.9, 19.1 ppm. FT-IR (KBr):
(m, 1 H), 3.79 (s, 2 H), 2.24 (m, 2 H), 2.09 (m, 2 H), 1.23 (t, J = 7.2 Hz, 3
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 176.0, 175.5, 171.8, 149.5,
149.4, 142.8, 138.0, 137.2, 132.9, 125.1, 124.0, 123.3, 122.9, 122.8,
~
= 3010, 2922, 2856, 1722, 1589, 1471, 1437, 1353, 1324, 1264, 1219,

1193, 1036 cm-1. HRMS (ESI): calcd. for C15H15N2O [M+H]+ 239.1179;
found 239.1183.
~
118.4, 115.4, 100.7, 60.8, 36.4, 32.6, 29.9, 14.4 ppm. FT-IR (neat):
=

3058, 2980, 2933, 1730, 1638, 1467, 1440, 1398, 1361, 1265, 1220,
1163, 1071 cm-1. HRMS (ESI): calcd. for C22H23N2O4 [M+H]+ 379.1652,
found 379.1650.
Compound 3ac: Yellow solid; yield: 13.5 mg (45%). M.p. 137–140 °C.
1H NMR (400 MHz, CDCl3): δ = 8.62 (dd, J = 4.8, 1.9 Hz, 1H), 7.90–7.86
(m, 1 H), 7.43 (d, J = 7.7 Hz, 1 H), 7.38 (dd, J = 7.7, 4.9 Hz, 1 H), 7.14
(dd, J = 8.8, 2.6 Hz, 1 H), 7.10–6.91 (m, 1 H), 3.76 (s, 2 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 175.0, 158.7, (d, J = 245.8 Hz), 149.5, 148.8,
138.5, 138.3 (d, J = 2.4 Hz), 128.4 (d, J = 8.8 Hz), 124.5, 124.1, 120.0 (d,
J = 25.7 Hz), 111.8 (d, J = 24.0 Hz), 103.6 (d, J = 9.5 Hz), 36.7 (d, J =
1
Compound 7a: White solid; yield: 28.4 mg (75%). M.p. 105–108 °C. H
NMR (600 MHz, CDCl3): δ = 8.86 (s, 1 H), 8.61– 8.60 (m, 1 H), 7.82–7.79
(m, 1 H), 7.47 (dd, J = 7.8, 1.6 Hz, 1 H), 7.35–7.33 (m, 1 H), 7.27 (d, J =
7.8 Hz, 1 H), 7.22–7.04 (m, 2 H), 6.99 (s, 4 H), 3.66 (s, 2 H), 2.34 (s, 3 H)
ppm. 13C NMR (150 MHz, CDCl3): δ = 174.5, 148.6, 147.9, 143.3, 138.8,
137.0, 136.3, 129.4, 128.1, 126.6, 125.6, 124.3, 122.8, 122.6, 122.4,
1.8 Hz) ppm. 19F NMR (376 MHz, CDCl3): δ = –118.66 ppm. FT-IR (KBr):
~
= 3096, 2985, 2926, 2814, 1741, 1594, 1468, 1442, 1386, 1354, 1314,

~
= 3079, 2954, 2915, 1733, 1598,
1297, 1191, 1159, 1106 cm-1. HRMS (ESI): calcd. for C13H979BrFN2O
[M+H]+ 306.9877; found 306.9856.
122.1, 36.1, 21.6 ppm. FT-IR (KBr):

1458, 1438, 1359, 1337, 1261, 1166, 1091 cm-1. HRMS (ESI): calcd. for
C20H18N3O3S [M+H]+ 380.1063; found 380.1074.
Compound 3ad: White solid; yield: 14.5 mg (58%). M.p. 146–149 °C. 1H
NMR (400 MHz, CDCl3): δ = 8.60 (dd, J = 5.0, 1.8 Hz, 1 H), 7.88–7.84 (m,
1 H), 7.72 (d, J = 8.1 Hz, 1 H), 7.40 (s, 1 H), 7.34–7.19 (m, 1 H), 7.14 (s,
1 H), 3.69 (s, 2 H), 2.89 (t, J = 7.3 Hz, 4 H), 2.07 (m, 2 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 175.1, 149.7, 148.7, 143.8, 141.8, 139.1, 138.3,
Compound 7b: White solid; yield: 34.9 mg (83%). M.p. 111–114 °C. 1H
NMR (600 MHz, CDCl3): δ = 8.82 (s, 1 H), 8.68–8.53 (m, 1 H), 7.77–7.64
(m, 1 H), 7.58–7.45 (m, 1 H), 7.33–7.31 (m, 1 H), 7.22–7.14 (m, 5 H),
7.05–6.93 (m, 2 H), 3.65 (s, 2 H), 1.29 (s, 9 H) ppm. 13C NMR (150 MHz,
CDCl3): δ = 174.4, 156.2, 148.5, 147.7, 138.7, 136.9, 136.4, 128.6, 126.3,
125.7, 125.6, 124.4, 122.9, 122.5, 122.2, 36.1, 35.2, 31.2 ppm. FT-IR
122.1, 122.0, 120.5, 120.4, 108.7, 36.5, 33.4, 32.6, 25.9 ppm. FT-IR
~
(KBr):
= 3062, 3016, 2944, 2843, 1725, 1594, 1582, 1478, 1448, 1358,

~
= 3067, 2962, 2870, 2794, 1737, 1596, 1469, 1435, 1357, 1340,
1309, 1257, 1171, 1148 cm-1. HRMS (ESI): calcd. for C16H15N2O [M+H]+
251.1179; found 251.1180.
(KBr):

1313, 1267, 1155, 1113 cm-1. HRMS: calcd. for C23H24N3O3S [M+H]+
422.1533; found 422.1528.
1
Compound 3ae: White solid; yield: 15.5 mg (51%). M.p. 120–123 °C. H
NMR (600 MHz, CDCl3): δ = 8.71–8.48 (m, 1 H), 7.89–7.86 (m, 1 H),
7.74 (d, J = 8.1 Hz, 1 H), 7.49 (s, 1 H), 7.45 (s, 1 H), 7.29–7.27 (m, 1 H),
3.70 (s, 2 H), 2.40 (s, 3 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 174.2,
149.3, 148.6, 142.8, 138.4, 137.5, 128.1, 123.4, 122.3, 120.2, 118.5,
Compound 7c: White solid, yield: 21.2 mg (51%). M.p. 115–118 °C 1H
NMR (400 MHz, CDCl3): δ = 9.01 (s, 1 H), 8.61 (dd, J = 4.9, 2.0 Hz, 1 H),
7.82 (d, J = 8.3 Hz, 1 H), 7.74–7.51 (m, 6 H), 7.47–7.43 (m, 1 H), 7.29
(dd, J = 7.5, 4.7 Hz, 1 H), 7.20 (d, J = 5.0 Hz, 2 H), 7.00 (dd, J = 8.6, 2.0
Hz, 1 H), 6.77 (d, J = 8.1 Hz, 1 H), 3.61 (s, 2 H) ppm. 13C NMR (150 MHz,
CDCl3): δ = 174.3, 148.4, 147.8, 138.7, 136.9, 136.4, 134.7, 132.1, 129.2,
~
114.7, 35.9, 23.6 ppm. FT-IR (KBr):
= 2956, 2920, 1726, 1707, 1620,

1593, 1437, 1363, 1312, 1294, 1243, 1201, 1144 cm-1. HRMS (ESI):
calcd. for C14H1279BrN2O [M+H]+ 303.0128; found 303.0126.
128.91, 128.90, 128.5, 128.0, 127.7, 127.6, 125.6, 124.5, 123.0, 122.4,
~
122.2, 122.0, 121.9, 36.0 ppm. FT-IR (KBr):
= 3022, 2925, 2854, 1735,

1599, 1468, 1435, 1359, 1333, 1218, 1154, 1132 1073 cm-1. HRMS
(ESI): calcd. for C23H18N3O3S [M+H]+ 416.1063; found 416.1065.
Compound 3af: Amorphous solid; yield: 7 mg (33%). 1H NMR (400 MHz,
CDCl3): δ = 8.90 (d, J = 4.8 Hz, 2H), 7.61 (d, J = 8.0 Hz, 1H), 7.36–7.24
(m, 3H), 7.14 (t, J = 7.5 Hz, 1H), 3.79 (s, 2H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 174.2, 158.8, 156.2, 142.5, 127.9, 124.6, 124.0, 123.9,119.1,
Compound 9: Yellow solid; yield: 87.0 mg (74%); 1H NMR (400 MHz,
CDCl3): δ = 8.47 (d, J = 6.0 Hz, 1 H), 7.57 (d, J = 2.2 Hz, 1 H), 7.34–7.31
(m, 1 H), 6.75 (dd, J = 8.0, 2.2 Hz, 1 H), 6.59–6.47 (m, 3 H), 6.46 (s, 1 H),
1.44 (s, 15 H), 1.31 (s, 9 H) ppm. 13C NMR (150 MHz, CDCl3): δ = 154.9,
~
112.7, 36.7 ppm. FT-IR (KBr):
= 2929, 2850, 2431, 2370, 1736, 1613,

1565, 1482, 1467, 1411, 1368, 1323, 1219, 1167 cm-1. HRMS (ESI):
calcd.for C12H10N3O [M+H]+ 212.0818; found 212.0825.
154.2, 146.0, 138.1, 137.2, 136.6, 131.4, 120.0, 116.1, 112.2, 111.6,
~
1
87.7, 34.3 , 31.9, 8.8 ppm. FT-IR (KBr):
= 3291, 2959, 2907, 2865,

Compound 5a: Colourless oil; yield: 19.2 mg (62%). H NMR (400 MHz,
1618, 1473, 1375, 1358, 1297, 1256, 1224, 1160, 1032 cm-1. HRMS
CDCl3): δ = 15.96 (s, 1 H), 8.46 (dd, J = 4.8, 1.9 Hz, 1 H), 7.83–7.78 (m,1
H), 7.40–7.19 (m, 3 H), 7.12 (t, J = 7.7 Hz, 1 H), 6.97 (d, J = 7.7 Hz, 1 H),
3.79 (s, 2 H), 1.81 (s, 6 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 190.7,
(ESI): calcd. for C25H32N2Ir [M-Cl]+ 553.2195; found 553.2210.
175.5, 149.8, 149.5, 143.0, 138.5, 132.6, 125.7, 124.4, 123.5, 123.4,
~
122.5, 120.3, 111.3, 36.3, 24.3 ppm. FT-IR (neat):
= 3061, 2929, 2363,

Acknowledgements
1726, 1735, 1592, 1467, 1438, 1361, 1219, 1163, 1065 cm-1. HRMS
(ESI): calcd. for C18H17N2O3 [M+H]+ 309.1234; found 309.1233.
This work is supported by the SERB-DST, India
(YSS/2014/000383). Fellowships received from CSIR, India
(D.D.) and IIT Kharagpur (U.K.) is gratefully acknowledged. We
thank Mr. A. Jamadar for some initial contributions.
Compound 5b: Colourless oil; yield: 29.1 mg (86%). 1H NMR (400 MHz,
CDCl3): δ = 12.47 (s, 1H), 8.50 (dd, J = 4.7, 2.0 Hz, 1 H), 7.83–7.79 (m, 1
H), 7.34–7.24 (m, 3 H), 7.10 (t, J = 7.7 Hz, 1 H), 6.97 (d, J = 7.7 Hz, 1 H),
4.18–4.10 (m, 1 H), 4.08–4.00 (m, 1 H), 3.79 (s, 2 H), 1.73 (s, 3 H), 1.22
(t, J = 7.1 Hz, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 175.6, 174.2,
Keywords: C-H functionalization • oxindole • Iridium cataslysis •
171.6, 149.5, 142.8, 138.0, 132.7, 125.1, 123.9, 123.3, 122.9, 122.6,
~
metal carbenoid • cascade
118.8, 100.9, 60.8, 36.4, 20.0, 14.4 ppm. FT-IR (neat):
= 3062, 2983,

2929, 1728, 1641, 1641, 1467, 1440, 1400, 1359, 1335, 1267, 1231,
1164, 1092 cm-1. HRMS (ESI): calcd. for C19H19N2O4 [M+H]+ 339.1339;
found 339.1337.
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CDCl3): δ = 12.61 (s, 1 H), 8.52 (d, J = 5.0 Hz, 1 H), 7.84–7.80 (m, 1 H),
7.34–7.26 (m, 3 H), 7.11 (t, J = 7.6 Hz, 1 H), 6.97 (d, J = 7.6 Hz, 1 H),
5.75–5.65 (m, 1 H), 5.01–4.91 (m, 2 H), 4.20–4.12 (m, 1 H), 4.08–3.99
This article is protected by copyright. All rights reserved.

10.1002/ejoc.201700214
European Journal of Organic Chemistry
FULL PAPER
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Cascade Synthesis*
Ujjwal Karmakar, Debapratim Das, and
Rajarshi Samanta*
Page No. – Page No.
Iridium Catalysed Cascade Synthesis
of Oxindoles using Diazo Compound:
A Quick Entry to the C7-
Iridium(III) catalyzed cascade synthesis of oxindoles and its application towards the
synthesis of its C7 functionalized congeners
Functionalized Oxindoles
* Diazo Desire
This article is protected by copyright. All rights reserved.