POP-Pd(ii) catalyzed easy and safe: In situ carbonylation towards the synthesis of α-ketoamides from secondary cyclic amines utilizing CHCl3 as a carbon monoxide surrogate

Article abstract of DOI:10.1039/c9nj05089b

A novel complex catalyst, POP-palladium(ii), has been synthesized. The developed catalyst has been characterized by XRD, EDX, scanning electron microscopy (FE-SEM), HR-TEM, FTIR spectroscopy, UV-vis spectroscopy, TGA and BET isotherm analysis. The reactiv

Full text of DOI:10.1039/c9nj05089b

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POP-Pd(II) catalyzed easy and safe in-situ carbonylation towards
the synthesis of α-ketoamides from secondary cyclic amines
utilizing CHCl3 as the carbon monoxide surrogate
Received 00th January 20xx,
Accepted 00th January 20xx
Sk Safikul Islam,a,b Sk Riyajuddin,c Rostam Ali Molla,d Nasima Yasmin,*,b Kaushik Ghosh,c Sk.
DOI: 10.1039/x0xx00000x
Manirul Islam*,a
www.rsc.org/
A novel complex catalyst, POP-Palladium(II)has been synthesized. The developed catalyst has been characterized by XRD,
EDX, Scanning electron micrographs (FE-SEM), HR-TEM, FTIR spectra, UV-Vis spectra, TGA and BET isotherm. The reactivity
of the incorporated Palladium(II) catalyst was tested for the in situ carbonylation of aryl iodides and secondary cyclic
amine to the respective α-ketoamides at 80 °C. A large number of aryl iodides combined with CO followed by 2° amines can
generate the corresponding α-ketoamides with high selectivity. This Pd(II)complex catalyst exhibits superb catalytic
activities and can also be easily recovered after the reaction by easy filtration method. The catalyst could be reused up to
six consecutive cycles without much loss in its activity.
Introduction
One strategy for synthesizing carbonyl compounds is the transition-
metal catalyzed C=O group insertion directly into an organic
compound.22In many cases, carbon monoxide is used as a source of
carbonyl installation. Because of the very toxic nature of CO and its
commercial availability in highly pressurized cylinders, safe handling
of carbon monoxide is quite the challenge. Thus, alternative CO
surrogates such as transition metal carbonyl complexes,23formic
acid,24 acid chlorides,25silacarboxylic acids,26 and others have been
developed to avoid its direct use. Although, every source of carbon
monoxide surrogates has its own competence but still it is
important to find out other inexpensive CO sources which are easily
available, less toxic, and involve simple reaction set up. Recently,
CHCl3 based carbonylation has shown great potential due to its cost
effectiveness, ready availability, and easy handling process. A well-
known synthetic approach for the generation of CO gas is hydrolysis
of chloroform under strongly basic aqueous hydroxide solution.27
There are some reported works in which CO generated from
chloroform has been used for aminocarbonylations,28 Pd-catalyzed
carboxylation,29 carbonylative Sonogashira coupling30 and Heck-
type domino cyclization.31
α-Ketoamides plays an important role in the preparation of natural
products.1,2 Several biologically active molecules, synthetic drugs
and pharmaceutical compounds were synthesized from α-
Ketoamides and their derivatives2-9(Figure 1). Further these
molecules are utilized as valuable intermediates for the
transformation of different functional group.10-17α-ketoamides have
also been explored for the production of heterocyclic skeleton such
as oxindoles, indoles, quinolines and β-lactams etc.18-21Hence,
developing an efficient and realistic approach towards the
generation of α-ketoamides having versatile functional groups is of
immense significance.
Various supported Palladium catalyzed carbonylation reaction of
aromatic halides is an important and effective method to synthesize
ketoamide in presence of CO.32,33 Several examples of α-ketoamides
formation under pressurized CO gas have been reported.34-40 But,
now a day, numerous examples of double carbonylation has been
recorded under an atmospheric CO pressure.41-45
Figure 1: α-Ketoamide containing biologically active compounds
a. Department of Chemistry, University of Kalyani, Kalyani, Nadia, 741235, W.B.,
India.Phone: + 91- 33-2582-8750, Fax: 91-33-2582-8282, E-mail:
manir65@rediffmail.com
b. Department of Chemistry, Aliah University, Kolkata-700160,W.B, India.E-mail:
yasminnasima@gmail.com; Tel Phone : +9133-23416506
c. Institute of Nano Science and Technology, Mohali, Punjab-160062, India.
d. Department of Chemistry, S. N. Bose Govt. Polytechnic College, Ratua, Malda, WB,
India
Only a few techniques were developed where CO generated from
CHCl3 precursor, was used in carbonylation reaction.46,47In a current
publication by Jain et al., a palladium catalyzedcarbonylation
reaction was reported for the synthesis of arylestersand arylketones
†
Electronic
Supplementary
Information
(ESI)
available:
See
DOI: 10.1039/x0xx00000x
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involving CHCl3 as source of CO.48In a previous communication
from our group, synthesis of aryl aldehydes and diaryl ketones was
described using CHCl3 as CO surrogates under palladium-catalyzed
carbonylation reaction.49Among various CO insertion techniques for
the synthesis of carbonyl substances from aryl halides, phosphine
free palladium catalyzed double carbonylation is a significant
approach.50A report by Han et al. highlighted Pd-catalyzed double
carbonylation for α-ketoamides synthesis under atmospheric CO at
room temperature fromaryl iodides and amines with PEG-400
solvent.51This homogeneous methodology motivated us to develop
a novel heterogeneous Pd catalyst and explore its application
towards the synthesis of α-ketoamides using CHCl3 as carbon
monoxide precursor. The developed protocol displayed excellent
activity with splendid yields without the use of any external
additive.
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Experimental
Preparation of catalyst
Scheme 1.Synthesis of POP supported Pd(II) catalyst
In a 250 ml RB, 15 ml dry DCE was taken followed by addition
of benzyl amine (0.321 g, 3 mmol) and benzene (0.234 g, 3
mmol). Then formaldehyde dimethyl acetal (0.912 g, 12 mmol)
and anhydrous iron(III) chloride (1.947 g, 12 mmol) was added
respectively to the solution. Under a N2 atmosphere the
Typical procedure for the synthesis of α-ketoamides
In a 25 ml sealed tube, aryl iodides (1 mmol), morpholine (1.2
mmol), CHCl3 (6 mmol) and KOH (12 mmol) were taken. Then
Pd@POP-2 catalyst (50 mg/2.3 mol %) was mixed in 4 ml of
polyethylene glycol and resulting solution was heated at 80 οC for a
time period of 16 h. After the reaction was complete, the reaction
mixture was settled down to RT and opened up the sealed tube.
Then the mixture was extracted with ethyl acetate and washed with
H2O as well as brine solution. The organic part was dried over
Na2SO4 and concentrated with rotary vapour under pressure. Finally
the product was purified by column chromatography (using ethyl
acetate and petroleum ether solvent).
°
reaction mixture was heated to 80 C for 18 h. Then the RB
containing reaction mixture was allowed to cool to RT. Next
reaction mixture was filtered and washed thoroughly with
CH3OH until the filtrate part became colourless. The residue
was dried at 80 °C for another 20 h. Then, by Soxhlet
apparatus, the solid part was washed with methanol for 48 h
to deliver a chocolate brown material. This chocolate brown
porous organic polymer material was named as POP-1.
In a 100 ml RB, the chocolate brown material (POP-1, 1.5 gm)
was taken in 20 ml of toluene and then 2-Formylpyridine (0.8
ml) was added drop by drop wise into the stirring solution.
Next the resulting mixture was refluxed for 20 hours. Then, the
reaction mixture was allowed to settle to achieve RT; the
porous polymeric ligand was filtered, thoroughly washed with
toluene followed by CH3OH. Ultimately, the polymer ligand
was dehydrated under vacuum for 24 hours. The porous ligand
as well as the final Schiff base was designated as POP-2.
Results and discussion
Characterization of the Pd@POP-2 Catalyst
The evaluation of Pd loading in Pd@POP-2has been conducted by
AAS and the loading of palladium in Pd@POP-2 was 4.86 %. Also
performed CHN analysis,the data of the analysis shown C= 73.56,
H= 6.24 and N= 4.12 % in the catalystPd@POP-2.
This POP-2 ligand (0.5 gm) and tBuONa (2.2 mmol) dissolved in
methanol (15 mL) was treated with 0.05 gm of Pd(OAc)2 and
the resulting mixture was stirred for 40 min. Then the reaction
In Figure 2, the X-ray diffraction pattern of the Pd@POP-2 catalyst is
shown. The XRD pattern of Pd@POP-2 exhibits a broad intense
diffraction peak at 2θ value (∼17°) indicating porous nature of the
material.52 In the X-ray diffraction pattern of the Pd@POP-2, no
intense diffraction peaks was observed except a hump around
410.TheXRD analysis indicating the Pd(II) species present in
catalyst.These data iscomparable with previous reported works to
confirm the of Pd(II).53
°
mixture was refluxed at 80 C for 24 hours. Finally, the Pd(II)
catalyst (Pd@POP-2) was filtered, washed carefully with
methanol, and dried at 40ο-50οC under vacuum. The chocolate
brown catalyst was named as Pd@POP-2 (Scheme 1).
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Figure 2:XRD pattern of Pd@POP-2 material
Fourier-transform infrared spectra of POP-2 and Pd@POP-2
materials are depicted in the Figure 3. The absorption peak was
observed at 3370 and 3420 cm-1 due to the -NH groups present in
the porous polymer POP-2 and the Pd@POP-2 materials. The
absorption bands near 1603 cm-1 and 1430 cm-1 corresponds to the
stretching vibrations of the C=C bonds in the benzene rings . The
peaks of sp3 C-H bonds in Pd@POP-2 and POP-2 materials was
found at 2910 cm-1 and 2909 cm-1.The absorption band near
~1070-1075 cm-1 indicates that the C-N bond present in the
materials.
Figure 4:UV-Vis spectra of mesoporous POP-2 and Pd@POP-2
Figure 5 demonstrates N2 adsorption/desorption isotherm of
the complexes Pd@POP-2. According to IUPAC, the adsorption
isotherm showed the type IV isotherms for Pd@POP-2 catalyst
with a H2 hysteresis loop in the high pressure region55 of 0.4-
0.8 relative pressure (P/P0) of N2. The catalyst Pd@POP-2
showed steady increase in N2 adsorption with a hysteresis and
next rise in the high relative pressure region indicating that the
complex consists of mesopores.56The Brunauer-Emmett-Teller
(BET) surface area of the new Pd@POP-2 material is 652.558
m²/g.By employing the non-local density functional theory
(NLDFT) the pore size distributions of the sample have been
drawn from the adsorption isotherm. Peak pore of dimensions
ca. 2.0 nm indicates that the sample is mesoporous in nature.
Figure 3:FT-IR spectra of POP-2 and Pd@POP-2
UV-Vis absorbance spectra of POP-2 and Pd@POP-2 were
investigated in Figure 4.In case of POP-2, the electronic absorption
spectrum exhibits two peak near 218 nm and 272 nm due to n→π*
and π→π* transitions, respectively. A visible change was found in
absorption spectrum of Pd@POP-2 material. This synthesized
complex shows fresh absorption peaks at 295 nm and 350 nm. It
can be ascribed to the CT between the central palladium atom and
coordinated atoms.54
Figure 5: The N2 adsorption/desorption isotherm of Pd@POP-2.The plot of pore size
distributions employing NLDFT method is shown in the inset.
To examine the structural morphology of Pd@POP-2 complex field
emission scanning electron microscopy (FE-SEM) has been
performed (Figure 6). Different images demonstrate different
magnifications. Pd@POP-2 displayed stone like particle morphology
with some mesopores present in this complex which could be
responsible for inter-particle porosity as seen from the BET
adsorption analysis. Energy dispersive spectroscopy analysis of X-
rays (EDAX) data of the Pd@POP-2 also signifies the presence of
palladium particles over the surface of the polymer material.
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Figure 7: The TEM images of Pd@POP-2 at different scales (a) 200 nm, (b) 50 nm, (c) 50
nm and (d) 20 nm respectively
The thermal stability of the complex Pd@POP-2 was studiedusing
TGA-DTA at a heating rate of 10 οC/min over a temp range of 0-700
°C. The thermo gravimetric analysis curve of the mesoporous
polymer anchored Pd@POP-2 catalyst is provided in Figure 8. The
palladium complex was stable up to approx. 350 °C, after that the
catalyst degraded. After 350 °C, there was a gradual decrease in
weight.The thermal analysis data suggests that polymer
incorporated Pd complex decomposed completely approx. 550 °C.
Figure 6: FE-SEM image and EDAX of Pd@POP-2 material
The TEM images of Pd@POP-2 catalyst are presented in Figure
7.The images of the catalyst specify that it is porous material and
Palladium metal is dispersed on the outer surface of the porous
organic polymer. Besides that, no agglomeration of Pd metal is
observed in the entire sample grid. From Figure 7 it is clear that
uniform anchoring of Pd(II) metal at the surface of POP-2 complex.
Dark spots in the TEM images indicated the existence of Pd metal
throughout the sample and diameter of the palladium particles is
about 5-10 nm.TEM image indicated that the shape of palladium
particles is spherical shape.
Figure 8:TGA plot of the Pd@POP-2 material
Catalytic Activity
Synthesis of α-ketoamides over Pd@POP-2 through in situ
carbonylation
As palladium incorporated complex catalysts illustrate outstanding
catalytic activity in variety of important industrial processes as well
as extensively applied for C-C coupling,57 we also endeavored to
explore the catalytic activity of the Pd@POP-2 catalyst in the in situ
carbonylation reaction and eventually succeeded in obtaining the
product α-ketoamides from aryl iodides substrates (Scheme 2).
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Initial studies were focused on the practical application of the Table 1: Effect of base and solvent on carbonylation of iodobenzene
View Article Online
DOI: 10.1039/C9NJ05089B
catalytic actions and to standardize the conditions of the reaction
for the generalized synthesis of α-ketoamides.
Entry
Base
Solvent
Isolated
Yield (%)a
Pd incorporated polymer catalyst which has high specific surface
area and intrinsic porosity was used for the conversion of aromatic
iodides to their respective α-ketoamides under thermal condition.
Potassium hydroxide was used as a standard base and polyethelene
glycol (600) as a solvent for the in situ double carbonylation. Excess
amount of CHCl3and base utilized to get the selective α-ketoamides.
The heterogeneous reaction was carried out in a sealed tube where
CHCl3 was utilized for internal carbon monoxide source under basic
condition at 80 °C for 16 h.
1
2
NaOH
LiOH
Mg(OH)2
KOH
Toluene
Toluene
Toluene
Toluene
PEG-600
DMSO
54
30
20
85
88
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30
25
0
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3
4
5
KOH
6
KOH
7
KOH
dioxane
CH3CN
DMF
Scheme 2: POP-Pd(II) catalyzedα-ketoamides synthesis of aryl
iodides
8
KOH
9
KOH
In our preliminary attempts, iodobenzene was taken as an ideal
substrate for the recognition of the optimum reaction
conditions(scheme 3). To monitor the reactivity of the polymer
supported Pd@POP-2 catalyst a variety of reaction parameter is
checked. Numerous solvents and bases were used to find out the
suitable reaction conditions (Table 1). To determine of valuable
conditions for the Palladium catalysed carbonylation reaction, the
conversion was carried out under several temperatures and time
interval (Table 2).
10
KOH
H2O
Reaction conditions:PhI (1 mmol), morpholine (1.2 mmol), CHCl3 (6
mmol), Base (12 mmol), Pd@POP-2 (50 mg/2.3 mol %), PEG-600
solvent(4 ml), 80 °C, 16 h.PPh3(40 mg)was used for 1 to 10 except 5.
aIsolated yield of α-ketoamides.
Table 2: Effect of reaction temp and time on carbonylation reaction
Entry
1
2
3
4
5
6
7
8
Temperature (°C)
Time (h)
8
Yield (%)a
40
50
60
70
80
80
80
90
100
100
34
44
56
77
88
88
88
86
84
82
10
12
14
16
18
20
16
16
Scheme 3: Pd@POP-2 catalyzedcarbonylation of iodobenzene
Base plays a vital role for this catalytic conversion. Inorganic
hydroxides were found to be more effective for this reaction
according to the investigational results (Table 1). A variety of bases
such as LiOH, NaOH and Mg(OH)2 were examined but in all cases
observed yield was lower than that of KOH. KOH was observed to
be the most effective base for the transformation in presence of
CHCl3 in polyethene glycol medium at 80 °C resulting 88%
conversion.For study of the effect of solvent, PEG-600 was replaced
by DMSO, dioxane, CH3CN, DMF and water for the carbonylation
reaction. Polyethelene glycol turned out to be the most competent
solvent giving maximum yield.
9
10
14
Reaction conditions:PhI (1 mmol), morpholine (1.2 mmol), CHCl3 (6
mmol), Base (12 mmol), Pd@POP-2 (50 mg/2.3 mol %), PEG-600
solvent(4 ml), 80 °C, 8-20 h.aIsolated yield of α-ketoamides.
The reaction was conducted for several time intervals varying from
8 h to 20 h. The best result was observed at 16 h. Therefore 16 h
was chosen as the suitable time for the carbonylation reaction
providing upto 88% yield (Table 2). Like other parameter we also
checked the temperature at a range of 40 °C to 100 °C. It was found
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that 80 °C was the standardised temperature for the catalytic
carbonylation transformation (Table 2). The double carbonylation
reaction was carried out in presence of other palladium sources
such as Pd(OAc)2, PdCl2, and PdCl2(PPh3)2 and the observed yields
were found to be 68%,55% and 65% respectively. The reaction was
unsuccessful with catalytic Pd/C.Comparatively our catalyst
Pd@POP-2 affordedmuch better yield (88%).
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DOI: 10.1039/C9NJ05089B
Entry
Aryl
halides
Product
Conversion
(%)a/ Isolated
Yield (%)b
TON
90a/88b
39
1.
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The quantitative effect of the Pd@POP-2 was optimized during the
phase of the reaction. The yield of the product was also
investigated by utilizing the amount of the catalyst (Figure 9).We
carried out the catalytic reaction with varying the quantity of
Pd@POP-2 from 5 mg to 60 mg. Using 50 mg of catalyst maximum
yield of 88% was obtained as amount of active sites increases. Using
more than 50 mg (2.3 mol %) Pd@POP-2 catalyst, no further
86a/84b
37
35
2.
3.
transformation occurred. As
a
result, 50 mg supported
heterogeneous catalyst was selected to be ideal amount for the
conversion.
81a/80b
82a/79b
36
4.
64a/62b
76a/74b
28
33
5.
6.
Figure 9: Catalyst loading effect on in-situcarbonylation reaction
After several parameter optimizations, a variety of aryl iodide and
amines were explored to expand the scope of the reaction (Table
3). Substituted iodobenzene with either electron donor or electron
withdrawing moiety under optimum condition converted to their
corresponding α-ketoamides with good to excellent yields. Strong
electron donating group in the aryl iodides such as methoxy and
methyl, resulted in superior yields than 1-bromo-4-iodobenzene
(Table 3, entries 2-4 and 8-10).For the catalytic reactions, mainly
the yield of the ketoamide product was observed but from the
Table 3, only aryl halide containing bromo group in the aryl ring
leads to the monocarbonylated side products51with yield 6%.We
checked the reaction in presence of acyclic secondary amine very
poor yield was obatined.
92a/90b
88a/86b
40
38
7.
8.
Table 3: POP supported Pd (II) catalyzedcarbonylation of aryl
iodides
82a/81b
81a/79b
36
35
9.
10.
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63a/61b
27
34
11.
12.
1.
2.
3.
Pd(OAc)2
Na2CO3,
PEG-600-
400,CO
(balloon),
RT
94
98
90
51
79a/76b
mPMF–
Pd0
Catalyst
K3PO4,CO
(20 atm),
DMF (5.0
mL) at 90 °C,
12 h
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α-
ketoamide
synthesis
Reaction conditions:aryl iodides (1 mmol), morpholine/piperidine
(1.2 mmol), CHCl3 (6 mmol), KOH (12 mmol), Pd@ POP-2 (50 mg/
2.3 mol %), PEG-600 solvent(4 ml), 80 °C, 16 h.
Pd@POP-
2
CHCl3 (6
mmol), KOH
(12 mmol),
PEG-600
solvent(4
ml), 80 °C,
16 h
This
Study
In Scheme 4,at first chloroform in presence of base gives carbene
intermediate, which on reaction with excess base, produced carbon
monoxide gas. Once the CO is generated then in presence of aryl
iodide and amine formed the corresponding α-ketoamides. We
have suggested the mechanism of the reaction pathway according
to literatures report.51,59 The nitrogen rich POP-2 support is
stabilizing Palladium (0) metal generated from Pd(II).58The
responsible factor for the carbonylation reaction is the active sites
present in the catalyst. Generally, it is postulated that Pd(0)
complex forms an organopalladium halide complex by O.A
(oxidative addition) of an aryl iodide. Then the process would
provide an acylpalladium halide which includes migratory insertion
4.
5.
Pd(dba)2 HBF4P(tBu)3,
68
84
60
61
CO
generator
,DBU
(1mmol),
THF (5 mL),
RT
of
a coordinated carbon monoxide. The CO coordinated
acylpalladium species would combine with a nucleophile to give α-
Pd/CTFs
CO
ketoamides.
(balloon),
K2CO3 (0.4
mmol) in
CH3CN (1
mL) at 70 οC
for 24 h
Scheme 4: Proposed mechanism for CO formation
Heterogeneity test
In order to assess the heterogeneous nature of our designed
Pd@POP-2 materials we have performed the hot filtration test
under the optimized condition. In the synthesis of α-ketoamide
using CO surrogates, the catalyst was separated out from reaction
mixture after 10 h under the optimization condition (yield 68 %)
and further reaction was continued with the filtrate. It was
observed that no further conversion took place after filtration of
the catalyst from reaction mixture. Alternatively as measured by
AAS analysis, it was also found that the palladium did not leach into
the solution. No metal trace was detected in the filtrate and in the
catalyst same metal loading was noted as that of fresh catalyst
(4.86 %). So, our study clearly demonstrated that our porous
Pd@POP-2 catalyst was stable and maintained heterogeneous
nature throughout the reaction.
Comparative studies of the Pd@POP-2 with other reported
catalytic system
The performance of the catalyst Pd@POP-2 was shown to be
excellent towards the carbonylation reaction. The polymer
incorporated Pd catalyst plays an important function in this
outstanding activity. A comparative study is shown in Table 4.
Table 4: Comparative studies of the Pd@POP-2 catalyst in the
synthesis of α-ketoamides with different reported catalytic systems
Catalyst reusability
The superb catalytic activity of the catalyst encouraged us to
examine its thermal stability, recoverability and reusability which
are the main important feature in a heterogeneous catalytic
Reaction
Entry Catalyst
Reaction
Yield Ref.
(%)
Conditions
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system. In order to investigate the recyclability, this porous material dated 06/12/2016), New Delhi, Govt. of India for providing
was successfully recycled and used to obtain α-ketoamidesusing CO financial support. SSI also acknowledges UDGOCI,:f1o0r.1p03rVo9iev/wCid9AiNnrtiJgc0les5eO0nn8li9ionBer
surrogate chloroform, which are shown in the Figure 10. Once the research fellowship (MANF-2015-17-WES-56540). NY acknowledges
reaction was complete, 8 ml ethyl acetate and 16 ml H2O was added Aliah University for providing support. RAM thankful to S. N. Bose
to the final reaction mixture. Then workup the reaction mixture by Govt. Polytechnic College for support. SSI is also thankful to Mr.
separating funnel and the product was obtained by evaporating the Naveen Tiwari for his valuable support. We acknowledge
organic layer under reduced pressure.The catalyst was Department of Science and Technology (DST) and University Grant
recoveredfrom the remaining aqueous phase through centrifuge, Commission (UGC) New Delhi, India for providing support to the
°
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followed by washing with methanol and then dried at 50 C to 60 Department of Chemistry, the University of Kalyani under FIST and
°C.After drying, the recycled catalyst Pd@POP-2 was further utilized SAP program. We are grateful to the Department of Science and
under optimal conditions in carbonylation reaction. The Pd@POP-2 Technology (DST) New Delhi, India for providing support to the
catalyst shows excellent catalytic efficiency upto six cycles. The University of Kalyani under PURSE program.
catalytic yield becomes nearly half after twelve cycle. We got only
45% yield after becomes twelve cycle. After eleven cycles, AAS data
showed that the Pd@POP-2 catalyst contains 1.24 % of Palladium.
This decrease of catalytic efficiency is due to the leaching of metal
from support and catalysis poison. After twelve run the catalyst
showed very low yield.
Notes and references
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We successfully established a new Pd(II) grafted onto Porous
organic polymer (POP-2) catalyst. The recyclable heterogeneous
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SMI acknowledges the Department of Science and Technology,
DST-SERB (project reference no. EMR/2016/004956), New
Delhi, Govt. of India, Board of Research in Nuclear Sciences
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View Article Online
DOI: 10.1039/C9NJ05089B
Graphical Abstract
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POP-Pd(II) catalyzed easy and safe in-situ carbonylation towards the
synthesis of α-ketoamides from secondary cyclic amines utilizing CHCl3 as
the carbon monoxide surrogate
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Sk Safikul Islam,a,b Sk Riyajuddin,c Rostam Ali Molla,d Nasima Yasmin,*,b Kaushik
Ghosh,c Sk. Manirul Islam*,a
aDepartment of Chemistry,University of Kalyani, Kalyani, Nadia 741235, W.B., India.
bDepartment of Chemistry, Aliah University, Kolkata-700156,W.B, India.
cInstitute of Nano Science and Technology, Mohali, Punjab-160062, India.
dDr. R. A. Molla, Department of Chemistry, S. N. Bose Govt. Polytechnic College,Ratua, Malda, WB,
India .
*Corresponding authors, E-mail: manir65@rediffmail.com and yasminnasima@gmail.com