Infrared spectroscopic detection of ketene formation from carbene and CO sources: an amide synthesis

Article abstract of DOI:10.1039/c9nj06161d

The synthesis and transformation of ketene into a desired organic molecule is one of the methodologies widely used in synthetic organic chemistry; however, there are only a few reports available for the detection of ketenes (not free ketene but ketene and transition metal complexes) using expensive techniques. Furthermore, there are no reports on the detection of ketene directly. In this regard, we have developed a methodology to make amidesviaketene formation using diazo compounds, [Co₂(CO)₈] as a carbonyl source, and suitable amines, and then detected the ketene formation with the help of IR spectroscopy. The non-gaseous carbonyl source, [Co₂(CO)₈], mediated the carbonylation of ethyl 2-diazo-2-phenylacetate and produced ketene as a key intermediate. The transformation of ketene to amide was achieved by the nucleophilic addition of amine. We also made an effort to detect the formation of a ketene intermediate from the reaction between ethyl 2-diazo-2-phenylacetate and [Co₂(CO)₈] in the absence of a nucleophile. The IR spectroscopy revealed the formation of ketene, followed by the transformation of ketene to an amide by the further addition of amine. The progress of the reaction was monitored over time using IR spectroscopy. Furthermore, all the newly synthesized amides were fully characterized using standard spectroscopic and analytical techniques.

Full text of DOI:10.1039/c9nj06161d

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Infrared spectroscopic detection of ketene formation from carbene and CO source: amide
synthesis
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Packirisamy Kuzhalmozhi Madarasi and Chinnappan Sivasankar*
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*Catalysis and Energy Laboratory, Department of Chemistry, Pondicherry University,
R. V. Nagar, Puducherry 605 014, INDIA
*Corresponding author. Tel.: +91-413-2654709, Fax: +91-413-2655987
E-mail address: siva.che@pondiuni.edu.in (Prof. Dr. C. Sivasankar)

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Abstract:
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Synthesis and transformation of ketene into desired organic molecule is one of the
methodologies widely used in synthetic organic chemistry, however there are only few reports
available for the detection of ketenes (not free ketene but ketene complex of transition metal
complexes) by using expensive techniques. Nevertheless, there is no report available to detect the
ketene directly. In this regard we have developed a methodology to make amides via ketene
formation by using diazo compounds, [Co2(CO)8] as a carbonyl source and suitable amines, and
detected the ketene formation with the help of IR spectroscopy. The non-gaseous carbonyl source,
[Co2(CO)8] mediated carbonylation of ethyl 2-diazo-2-phenylacetate produced ketene as key
intermediate. The transformation of ketene to amide has been achieved by the nucleophilic
addition of amine. We have also taken an effort to detect the formation of ketene intermediate from
the reaction between ethyl 2-diazo-2-phenylacetate and [Co2(CO)8] in the absence of nucleophile.
The IR spectroscopy revealed the formation of ketene followed by the transformation of ketene to
amide by further addition of amine. The progress of the reaction has been monitored with function
of time by using IR spectroscopy. Furthermore, all the newly synthesized amides have been fully
characterized by using standard spectroscopic and analytical techniques.
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Introduction
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The chemistry of ketene is a dynamic area of research in both synthetic and mechanistic
aspects.1 Ketenes are highly reactive, versatile intermediate for many organic transformations such
as esters, amides, β-lactones, β-lactams.1,2 The most prevalent methodology for the synthesis of
ketene are thermolysis,3Wolf rearrangement,4 dehydrogenation of acyl chloride,5 and aza-Wittig
reaction6. However all these methodologies suffer from their own limitations such as, narrow
substrate scope along with the formation of undesired side products.7 One of the prominent way of
generation of ketene is carbonylation of carbene.8 A large number of transition metal mediated
generation of ketene from carbene using carbon monoxide has also been reported.9 Bruin et al.
reported a Rh-PNP complex which showed a stronger affinity towards binding ketene than any
other metals.7 Carbon monoxide mediated generation of ketene from carbene is one of the
promising methods while other known methods suffer from their own drawbacks such as harsh
reaction conditions, poor yield etc.10 Transition metal catalyzed carbonylation of carbene
precursors such as diazo compounds and tosylhydrazones using carbon monoxide is also been
reported.11 Wang et al. reported the generation of ketene through transition metal catalyzed
carbonylation of carbene using CO gas and further reacted with nucleophiles to produce
corresponding organic compounds and it has its own merits.10-12Nevertheless, handling of carbon
monoxide is perilous owing to its toxicity and thus required adequate facilities.13
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Metal carbonyls are good non-gaseous carbonyl source. Ungváry et al. reported dicobalt
octacarbonyl as a non-gaseous CO-source for ketene generation by carbonylation of carbene
generated from diazoacetate and the disadvantage of this method is one has to use equal molar
concentration of metal carbonyl. The in situ generated ketene further can be scavenged by added
nucleophiles or by N-substituted imines in a [2 + 2] cycloaddition reaction.14-16
In spite of its (ketene) greater utility, there is no reliable method to detect the formation of
free ketene. The commonly used gravimetric, titrimetric and gas chromatography methods are not
sound enough for trace analysis and highly decomposing compound like ketene;17,18 Nevertheless
the derivatized ketene could be detected by gas chromatography due to the increased
stability.19The report for the spectrometric detection of the ketene dye, 1-acetyl-4-(4-
nitrobenzylidene)-1,4-dihydropyridine which is formed by the addition of ketene with a 10:1
mixture of 4-(4-nitrobenzyl)-pyridine and 1-hydro-4-(4-nitrobenzyl)-pyridinium perchlorate could
be interfered by the salts produced by the dyes.20 A laser photolysis study with IR and UV-

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detection has been reported for the detection of ketene hydrate derived from diazoquinone.21-
23Albeit, in all the cases ketene is detected in the derivatized form, however the ketene intermediate
is not flourished as intrinsically.
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Similarly, the mechanism involved in the metal catalyzed generation of ketene from diazo
compounds is not clear. In the reaction mechanism, the formation of ketene is just inferred and not
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detected. Grotjahn et al. reported the first coordination of ketenes to trans-ClIr[P(iPr)3]2 ;
Hermann et al.25 reported the synthesis and structures of η2-ketene complexes by carbonylation of
metallocarbenes (Scheme 1). Hoff et al. reported a mechanism involving metalloradical based
conversion of diazo and CO to ketene and studied the carbonylation of diazoalkanes using
Cr2(CO)6(C5R5)2, (R=H, CH3) and spectroscopically detected the formation of ketene along with
two key intermediates in the reaction (Cr(CO)2(ketene)(C5R5) and Cr2(CO)5(C5R5)2).26 Bruin et al.
detected the formation of free phenyl ketene from β-lactam by 1H NMR spectroscopy.7 Ungvary
et al. reported the mechanistic investigation of [Co2(CO)8] catalyzed carbonylation of ethyl
diazoacetate. The reaction mechanism involves the formation of highly reactive ethoxycarbonyl
ketene by intramolecular coupling of a carbonyl ligand with the ethoxycarbonyl carbene ligand.27
Scheme 1. Spectroscopically detected transition metal complex of ketene.
In continuation of our research in carbene related chemistry28 and in aim to explore the
chemistry of ketene, herein we reported the infrared spectroscopy supported detection of ketene.
The transformation of ketene into amide is also been detected by IR spectroscopic technique.
Results and discussion
Recently we have reported the synthesis of amido esters through carbonylation of diazo
compounds followed by nucleophilic addition reaction.28e In order to understand the mechanism
of amide formation and to detect the ketene intermediate, we started our experiments with aliphatic
amines (Scheme 2). The aliphatic amines takes longer reaction time when compared to the
aromatic amines therefore practically one can accomplish the ketene detection. And therefore we
selected aliphatic amine as a nucleophile in order to detect the ketene using IR spectroscopy
technique.

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Scheme 2 Synthesis of amido esters through carbonylation of diazo compounds followed by
nucleophilic addition reaction.
Table 1 Optimization of catalyst for aliphatic amine reaction with phenyldiazoestera
entry metalcarbonylb
time (h)
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yield (%)c
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3
[Co2(CO)8]
[Fe2(CO)9]
[Mn2(CO)10]
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n.d
aAll the reactions were carried out with 1 mmol of isopropyl amine and 1.1 mmol of
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phenyldiazoester in 5 mL of DCM in a Schlenk tube under dinitrogen atmosphere. 0.5 mmol of
metal carbonyl was used. cPure compound from column chromatography.
Initial screening did begin with metal carbonyls; the treatment of [Co2(CO)8] (0.5 equiv.,
0.5 mmol) with isopropyl amine (1 mmol) and isopropyl 2-diazo-2-phenylacetate (1.1 equiv., 1.10
mmol) using dichloromethane (5 mL) as the solvent yielded desired amido ester in 18 h with 87%
yield (Table 1, entry 1). Replacement of [Co2(CO)8] by [Fe2(CO)9] and [Mn2(CO)10] lead to
longer reaction time and poor yield. The reaction with [Fe2(CO)9] produced 18 % of amido ester
in 32 h (Table 1, entry 2) and the reaction with [Mn2(CO)10] did not produce expected product
even after 48 h (Table 1, entry 3).

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Table 2 Optimization of solvent, temperature and catalyst loada
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entry
solvent
DCM
[Co2(CO)8] (equiv) time (h)
yield(%)b
80
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0.5
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Toluene
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CH3OH
CH3CN
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n.dc
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DCM
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DCM
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DCM
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DCM
61d
aAll the reactions were carried out with 1 mmol of isopropyl amine and 1.1 mmol of
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phenyldiazoester in 5 mL of solvent in a Schlenk tube under dinitrogen atmosphere. Pure
compound from column chromatography. cExpected product not detected. dReaction carried out at
40 ºC.
With a suitable carbonyl source [Co2(CO)8], we have carried out solvent screening.
Toluene produced 56% of amido ester in 24 h (Table 2, entry 2) and THF produced 34% yield in
24 h (Table 2, entry 3). Methanol gave only 19% of desired amido ester along with trace amount
of OH-addition product (Table 2, entry 4). In case of acetonitrile, expected product was not
formed even after 48 h instead, carbene dimerization was taken place (Table 2, entry 5). DCE
produced expected amido ester in 77% yield (Table 2, entry 6). Thus the solvent screening results
revealed that the DCM is a better choice of solvent for the reaction. With DCM as an optimal
solvent decreasing the [Co2(CO)8]load to 0.25 equivalent reduced the yield to 68% (Table 2, entry

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7). Further increasing the catalyst load up to 0.75 and 1.0 equivalents produced the desired product
in 81% and 83% yields, respectively (Table 2, entry 9 and 8). Since there is no significant change
in the yield even by doubling the catalyst load, therefore 0.5 equivalent was decided as the optimal
catalyst load. Raising the reaction temperature up to 40 ºC decreased the product yield along with
increased carbene dimerization; therefore, the optimum reaction temperature was found to be room
temperature.
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The optimized condition was applied for the synthesis of amido esters using aliphatic
amines as ketene scavenger. Keeping the isopropyl 2-diazo-2-phenylacetate as constant, aliphatic
amines have been varied. As expected, all the aliphatic amines took longer time compared to the
aromatic amines for completion of the reaction. Among all the aliphatic amines, methylamine
produced less yield of 58%. n-propyl amine (3d) produced 82% amido ester and iso-propyl amine
(3a) produced 80% of the product; likewise, n-butyl amine (3c) produced 81% yield and tert-butyl
amine (3b) produced 75% yield. This might be attributed to the increase in the negative charge on
the nitrogen atom of amine due to the +I effect of the alkyl group and bulkiness of the tert-butyl
group. Dipropyl amine, cyclohexyl amine and dicyclohexyl amine produced 77, 82 and 85% yield,
respectively (3f – 3h). Phenethylamine yielded 87% of the expected amido ester (3i) and 3,4-
dimethoxy phenethylamine produced 84% yield (3j). 4-Fluorobenzylamine (3k), benzylamine
(3l), 4-methoxy benzylamine (3m) and 4-methyl benzylamine (3m) produced 85, 92, 82 and 88%
yields, respectively.

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Scheme 3 Scope of amines for the synthesis of amido esters
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Then the scope of diazoesters has been explored by changing different diazo esters. Among
all the diazo esters screened, almost all of them produced good to better yields. As mentioned
above, in this case also methylamine produced lesser yield (6a, 59%). n-Butylamine produced 88
and 86% yields with 4-bromo substituted (6b) and ethylphenyldiazoacetate (6c), respectively. iso-

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Propylamine produced 71% and 68% yields with 4-bromo (6d) and 4-methyl substituted
ethylphenyldiazoacetate (6e), respectively. Among all the benzyl amines, 4-bromo substituted
ethylphenyldiazoacetate produced maximum yield of 94% (6f), methylphenyldiazoacetate (6g)
and ethylphenyldiazoacetate (6h), produced 90% and 91% yields respectively. Both 2,4-dichloro
(6i) and 4-fluoro (6j) substituted ethylphenyldiazoacetate yielded 88% of expected amido ester. In
case of 4-methylbenzylamine, ethylphenyldiazoacetate (6k) gave 88% yield and
methylphenyldiazoacetate (6l) produced 81% yield. 4-Methyl (6m) and 4-bromo (6n) substituted
ethylphenyldiazoacetate yielded 89% and 83% of desired amido ester. Ethylphenyldiazoacetate
gave 81% yield with 4-fluoro benzylamine (6o).
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Fig. 1 Molecular structure of 3h (hydrogen atoms are omitted for clarity). Thermal ellipsoids are
set at 50 % probability (CCDC:1948319).

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Scheme 4 Scope of diazo compounds for the synthesis of amido esters
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Detection of ketene intermediate using IR – spectroscopy
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After exploring the substrate scope, in order to obtain more evidence for the formation of
ketene pro-reactive intermediate, we used infrared spectroscopy technique. IR experiment has been
carried out for the reaction of ethyl 2-diazo-2-phenylacetate with isopropylamine in the presence
of [Co2(CO)8] and spectra has been recorded during the course of the reaction at various time
intervals.
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Fig. 2 FTIR spectra recorded during the course of the reaction of [Co2(CO)8] with ethyl-2-diazo-
2-phenylacetate at 25 °C in DCM (in a sealed reaction tube fitted with septa). Band at 2091 cm-1
is assigned to N-N stretching of ethyl-2-diazo-2-phenylacetate; band at 1891cm-1 is assigned to
C=O stretching of ketene and band at 1640 cm-1 assigned to C=O stretching of amide.
To get a clear knowledge about the formation of ketene intermediate, the reaction was
started with ethyl 2-diazo-2-phenylacetate and [Co2(CO)8] without addition of nucleophile
(amine). During the course of the reaction, the ketene formation has been detected by infrared

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spectroscopy. As depicted in Figure 2, at 0 minute, the observed bands at 2070, 2040 and 1858
cm-1 can be attributed to unreacted [Co2(CO)8] (Figure S1) and a band at 2091 cm-1 can be
attributed to unreacted diazo (N2 vibration) compound (Figure S2). Over a period of time the
vibrational band at 2091 cm-1 which is attributed to N=N stretching of diazo compound started
decreasing gradually, with simultaneous increase in intensity of the vibrational band at1891 cm-
1owing to the formation of ketene (R2C=C=O). To confirm the transformation of ketene into
amide, isopropyl amine has been added at this stage. The appearance of a new IR band at 1640
cm-1, which corresponds to the C=O stretching frequency confirmed the formation of amide (amide
band). The IR spectra showed a periodic decrease in the intensity of diazo compound and ketene
band with the simultaneous increase in the intensity of C=O stretching band of amide. After 17 hr,
the IR band corresponding to the diazo almost disappeared and the band corresponding to amide
intensified to the maximum.
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Fig. 3 Transmittance versus time plots for key species in reaction ofethyl-2-diazo-2-phenylacetate
and [Co2(CO)8]. Transmittance bands of ethyl-2-diazo-2-phenylacetate at 2087 cm-1and ketene at
1886 cm-1.

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A transmittance versus time plot for the key species in the reaction is depicted in Figure
3. The graph shows a periodic decrease in the intensity of diazo and a gradual increase in the
intensity of ketene band followed by decrease in the intensity with a simultaneous increase in the
intensity of amide band (after addition of amine). Attempts have been made to characterize the
metal carbonyl after the reaction however the results were not fruitful.
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Conclusion
There are numerous reports for metal mediated ketene involved organic transformations.
In all the cases, the formation of ketene is just inferred but not directly detected. Here we attempted
to detect the ketene intermediate by using IR spectroscopy that formed during the course of
formation of amide. The formation of amide from the reaction of carbene (generated from
diazoester), amine and [Co2(CO)8] was also been detected by infrared spectroscopy. The IR
spectroscopic technique revealed the formation of ketene intermediate and further transformation
of ketene into amide. The choice of aliphatic amine over aromatic amine made the ketene detection
more viable due to the extended reaction time. All the newly synthesized amides have been fully
characterized by using standard spectroscopic and analytical techniques. More research work
related to carbene and ketene are under progress in our laboratory.
Experimental section
1. General Information. Unless and otherwise specified all the reactions were carried out with
oven dried glassware under nitrogen atmosphere. All the solvents were distilled prior to use by
using standard procedures. Dichloromethane was distilled from the CaH2 and used. Amines were
procured from Aldrich chemicals and used as received without any further purification. All the
diazo compounds were prepared by following the standard literature procedures, characterized and
confirmed by the spectral data.21 TLC was performed on pre-coated silica gel 60 F254 on
aluminum plates and UV light (254 nm). Column chromatography was performed on silica gel
100−200 mesh size. 1H and 13C NMR spectra were recorded on 400 MHz (1H) and 100 MHz (13C),
1
Chemical shifts (δ) are given in ppm. The residual solvent signals were used as references for H
13
NMR and C NMR. HR-MS was recorded on UHD Q-TOF mass spectrometer. CCDC1948319
(for 3h) contains the supplementary crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre.

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2. General procedure for IR control experiment:
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The IR spectrum was recorded on a Perkin-Elmer spectrophotometer. A sealed reaction tube fitted
with rubber septa was charged with [Co2(CO)8] (0.26 mmol), ethyldiazoacetate (0.52 mmol) and
5 mL of dichloromethane. The reaction was carried out at room temperature and IR spectrum was
recorded for reaction mixture for every 30 min. DCM was used as background reference. After the
observation of ketene band, isopropyl amine (0.57 mmol) was added to the reaction tube and the
experiment was continued till the disappearance of N2 stretching band of diazo compound.
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3. General procedure for amine addition into ketene generated from diazo compounds (A).
An oven dried 20 mL Schlenk flask was charged with amine (1 mmol) and [Co2(CO)8] (0.5 equiv.),
then 5 mL of dichloromethane was added to the reaction mixture. Then a dichloromethane solution
of diazo compound (1.1 mmol) was added dropwise to the reaction mixture and the reaction
mixture was stirred at room temperature for 14 h. The completion of the reaction was monitored
by TLC using appropriate mixture of hexane and ethyl acetate as an eluent. After completion of
reaction, the reaction mixture was extracted with 15 mL (5 mL × 3) of diethyl ether. Then diethyl
ether was evaporated under reduced pressure and the crude residue was purified using column
chromatography on silica gel using hexane/ethyl acetate.
Isopropyl 3-(isopropylamino)-3-oxo-2-phenylpropanoate (3a). Prepared according to the
general procedure A. Compound 3a was isolated as a white solid in 80% yield (211 mg). Melting
1
point: 96 °C. H NMR (400 MHz, CDCl3) δ 7.38 (dd, J = 5.2, 3.0 Hz, 1H), 7.37 – 7.34 (m, 2H),
7.34 – 7.28 (m, 2H), 6.76 (t, J = 11.6 Hz, 1H), 5.04 (hept, J = 6.3 Hz, 1H), 4.43 (s, 1H), 4.07 (qt,
J = 13.2, 6.6 Hz, 1H), 1.27 (d, J = 6.3 Hz, 3H), 1.16 (t, J = 6.6 Hz, 6H), 1.12 (d, J = 6.6 Hz, 3H).
13C NMR (100 MHz, CDCl3) δ 170.61, 166.48, 134.57, 129.05, 128.20, 77.48, 77.16, 76.84, 69.62,
58.82, 41.75, 22.59, 21.76, 21.52. IR (KBr) 3350, 3035, 2975, 2927, 2854, 1732, 1655, 1523,
1455, 1356, 1311, 1278, 1229, 1177, 1101, 1021, 972, 806, 742, 703, 605, 504 (cm-1). HRMS
(ESI-MS) calcd for C15H22NO3 m/z [M + H]+: 264.1600; found: 264.1593.
Isopropyl 3-(tert-butylamino)-3-oxo-2-phenylpropanoate (3b). Prepared according to the
general procedure A. Compound 3b was isolated as a white solid in 75% yield (200 mg). Melting

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point: 135.8 °C;1H NMR (400 MHz, CDCl3) δ 7.38 (dd, J = 5.0, 2.9 Hz, 1H), 7.37 (d, J = 1.3 Hz,
1H), 7.35 (d, J = 6.6 Hz, 1H), 7.34 – 7.32 (m, 1H), 7.32 – 7.27 (m, 1H), 6.73 (s, 1H, NH), 5.04
(hept, J = 6.3 Hz, 1H), 4.36 (s, 1H), 1.32 (s, 9H), 1.27 (d, J = 6.3 Hz, 3H), 1.17 (d, J = 6.2 Hz,
3H); 13C NMR (100 MHz, CDCl3) δ 170.75, 166.42, 134.83, 129.02, 128.15, 77.48, 77.16, 76.84,
69.54, 59.70, 51.52, 28.67, 21.78, 21.54; IR (KBr) 3307, 3076, 2980, 2935, 1739, 1648, 1553,
1456, 1362, 1226, 1178, 1105, 966, 809, 711, 582 (cm-1); HRMS calcd for C16H24NO3 (ESI-MS)
m/z [M + H]+: 278.1756; found: 278.1755.
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Isopropyl 3-(butylamino)-3-oxo-2-phenylpropanoate (3c). Prepared according to the general
procedure A. Compound 3c was isolated as a white solid in 81% yield (225 mg). Melting point:
121 °C. 1H NMR (400 MHz, CDCl3) δ 7.38 (dt, J = 3.6, 2.1 Hz, 2H), 7.35 (s, 1H), 7.31 (ddd, J =
11.9, 8.2, 5.4 Hz, 2H), 6.90 (s, 1H, NH), 5.05 (hept, J = 6.3 Hz, 1H), 4.46 (s, 1H), 3.25 (qd, J= 7.0,
1.0 Hz, 2H), 1.51 – 1.43 (m, 2H), 1.32 (dd, J = 15.2, 7.6 Hz, 2H), 1.27 (d, J = 6.3 Hz, 3H), 1.16
(d, J = 6.3 Hz, 3H), 0.89 (t, J = 7.3 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 170.59, 167.34, 134.55,
129.05 , 128.20, 77.48 , 77.16 , 76.84 , 69.62 , 58.86 , 39.54 , 31.48 , 21.75 , 21.51 , 20.09 , 13.79.
IR (KBr) 3297, 3087, 2974, 2956, 2868, 1741, 1645, 1558, 1455, 1368, 1281, 1235, 1172, 1103,
984, 797, 702, 614 (cm-1). HRMS (ESI-MS) calcd for C16H24NO3 m/z [M + H]+: 278.1756; found:
278.1760.
Isopropyl 3-oxo-2-phenyl-3-(propylamino)propanoate (3d). Prepared according to the general
procedure A. Compound 3d was isolated as a white solid in 82% yield (216 mg). Melting point:
1
108°C. H NMR (400 MHz, CDCl3) δ 7.40 – 7.36 (m, 2H), 7.34 (ddd, J = 7.5, 4.8, 1.8 Hz, 2H),
7.31 – 7.27 (m, 1H), 6.92 (s, 1H), 5.04 (hept, J = 6.3 Hz, 1H), 4.46 (s, 1H), 3.20 (dd, J = 13.4, 6.5
Hz, 2H), 1.49 (dt, J = 14.6, 7.3 Hz, 2H), 1.26 (d, J = 6.3 Hz, 3H), 1.16 (d, J = 6.3 Hz, 3H), 0.87 (t,
13
J = 7.4 Hz, 3H). C NMR (100 MHz, CDCl3) δ 170.52, 167.38, 134.50, 129.01, 128.18, 77.48,
77.16, 76.84, 69.58, 58.81, 41.42, 22.66, 21.72, 21.48, 11.34. IR (KBr) 3332, 3017, 2963, 2910,
2841, 1768, 1693, 1541, 1449, 1369, 1303, 1284, 1244, 1201, 1158, 1011, 985, 818, 740, 717,
622, 600, 534 (cm-1). HRMS (ESI-MS) calcd for C15H22NO3, m/z [M + H]+: 264.1600; found:
264.1594.

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Isopropyl 3-(methylamino)-3-oxo-2-phenylpropanoate (3e). Prepared according to the general
procedure A. Compound 3e was isolated as a white solid in 58% yield (137 mg). Melting point:
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76 °C. H NMR (400 MHz, CDCl3) δ 7.39 – 7.34 (m, 2H), 7.34 – 7.30 (m, 2H), 7.30 – 7.27 (m,
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1H), 6.95 (s, 1H), 5.09 – 4.97 (m, 1H), 4.46 (s, 1H), 2.77 (dd, J = 4.8, 1.4 Hz, 3H), 1.25 (d, J = 6.3
Hz, 3H), 1.15 (d, J = 6.3 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 170.35, 168.11, 134.34, 128.97,
128.19, 77.48 , 77.16, 76.84, 69.55, 58.62, 26.52, 21.67, 21.44. IR (KBr) 3448, 3338, 1738, 1648,
1543, 1454, 1410, 1308, 1410, 1279, 1182, 1106, 974, 718, 576 (cm-1). HRMS (ESI-MS) calcd
for C12H16NO3, m/z [M + H]+: 236.1287; found: 236.1287.
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Isopropyl 3-(dipropylamino)-3-oxo-2-phenylpropanoate (3f). Prepared according to the
general procedure A. Compound 3f was isolated as a white solid in 77% yield (235 mg). Melting
point: 98 °C. 1H NMR (400 MHz, CDCl3) δ 7.31 (d, J = 1.8 Hz, 1H), 7.29 – 7.27 (m, 2H), 7.25 –
7.22 (m, 1H), 7.23 – 7.17 (m, 1H), 5.03 – 4.91 (m, 1H), 4.69 (s, 1H), 3.32 – 3.15 (m, 2H), 3.13 –
13
3.01 (m, 2H), 1.57 – 1.35 (m, 4H), 1.16 (dd, J = 6.2, 2.8 Hz, 6H), 0.77 (t, J = 7.4 Hz, 6H). C
NMR (100 MHz, CDCl3) δ 168.53, 167.57, 133.93, 129.35, 128.54, 127.83, 77.48, 77.16, 76.84,
69.13, 56.35, 47.82, 22.14, 21.75, 21.53, 20.61, 11.22. IR (KBr) 3299, 3070, 2985, 2926, 1734,
1654, 1591, 1553, 1474, 1370, 1342, 1314, 1239, 1186, 1038, 1008, 835, 811, 747, 697, 641, 504
(cm-1). HRMS (ESI-MS) calcd for C18H28NO3, m/z [M + H]+: 306.2069; found: 306.2077.
Isopropyl 3-(cyclohexylamino)-3-oxo-2-phenylpropanoate (3g). Prepared according to the
general procedure A. Compound 3g was isolated as a white solid in 82% yield (252 mg). Melting
1
point: 84 °C. H NMR (400 MHz, CDCl3) δ 7.39 (d, J = 7.6 Hz, 2H), 7.34 (s, 2H), 7.32 (s, 1H),
6.84 (s, 1H), 5.05 (dd, J = 12.6, 6.1 Hz, 1H), 4.44 (s, 1H), 3.78 (d, J = 9.3 Hz, 1H), 1.86 (t, J =
13.9 Hz, 2H), 1.74 (d, J = 14.1 Hz, 2H), 1.64 (s, 4H), 1.38 – 1.31 (m, 2H), 1.28 (d, J = 6.2 Hz,
13
3H), 1.17 (d, J = 6.3 Hz, 3H). C NMR (100 MHz, CDCl3) δ 170.58, 166.37, 153.56, 134.63,
133.55, 128.78, 128.19, 77.47, 77.16, 76.84, 69.56, 58.84, 48.27, 32.72, 25.13, 21.75. IR (KBr)
3420, 2933, 2854, 1741, 1645, 1540, 1452, 1373, 1165, 1110, 1031, 894, 579 (cm-1). HRMS (ESI-
MS) calcd for C18H26NO3, m/z [M + H]+: 304.1913; found: 304.1905.
Isopropyl 3-(dicyclohexylamino)-3-oxo-2-phenylpropanoate (3h). Prepared according to the
general procedure A. Compound 3h was isolated as a white solid in 85% yield (328 mg). Melting

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point: 98 °C. 1H NMR (400 MHz, CDCl3) δ 7.33 (s, 2H), 7.32 (s, 2H), 7.31 – 7.26 (m, 1H), 5.04
(hept, J = 6.3 Hz, 1H), 4.73 (s, 1H), 3.40 (dd, J = 15.8, 7.4 Hz, 1H), 2.80 (s, 1H), 2.52 (s, 2H), 1.83
– 1.76 (m, 2H), 1.74 (s, 2H), 1.53 (dd, J = 19.0, 10.7 Hz, 4H), 1.47 – 1.30 (m, 2H), 1.23 (d, J = 6.3
Hz, 6H), 1.20 (d, J = 9.8 Hz, 4H), 1.13 – 0.92 (m, 2H), 0.92 – 0.75 (m, 2H). 13C NMR (100 MHz,
CDCl3) δ 168.78, 166.96, 134.57, 129.34, 128.58, 127.72, 77.48, 77.16, 76.84, 69.09, 58.68, 56.55,
29.80, 29.26, 26.65, 26.13, 25.85, 25.30, 21.83. IR (KBr) 3462, 2978, 2928, 2854, 1741, 1635,
1450, 1361, 1307, 1176, 1110, 992, 896, 714, 567 (cm-1). HRMS (ESI-MS) C24H36NO3, m/z [M +
H]+: calcd for 386.2695; found: 386.2704.
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Isopropyl 3-oxo-3-(phenethylamino)-2-phenylpropanoate (3i). Prepared according to the
general procedure A. Compound 3i was isolated as a white solid in 87% yield (283 mg). Melting
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point: 83°C. H NMR (400 MHz, CDCl3) δ 7.33 (m, 5H), 7.30 – 7.26 (m, 2H), 7.25 – 7.20 (m,
1H), 7.13 – 7.10 (m, 2H), 6.83 (dd, J = 6.7, 2.2 Hz, 1H), 5.05 (hept, J = 6.3 Hz, 1H), 4.46 (s, 1H),
3.56 – 3.50 (m, 2H), 2.80 (t, J = 6.9 Hz, 2H), 1.28 (d, J = 6.3 Hz, 3H), 1.17 (d, J = 6.3 Hz, 3H).
13C NMR (100 MHz, CDCl3) δ 170.31 (s), 167.44 (s), 138.80 (s), 134.26 (s), 129.09 (s), 128.88
(s), 128.68 (s), 128.25 (d, J = 3.3 Hz), 126.56, 77.48, 77.16, 76.84, 69.64, 58.94, 41.03, 35.51,
21.76, 21.53. IR (KBr) 3307, 3080, 3030, 2871, 1730, 1653, 1521, 1461, 1356, 1279, 1226, 1108,
1087, 1008, 904, 806, 741, 697, 536, 538, 497 (cm-1). HRMS (ESI-MS) calcd for C20H24NO3, m/z
[M + H]+: 326.1756; found: 326.1768.
Isopropyl 3-((3,4-dimethoxyphenethyl)amino)-3-oxo-2-phenylpropanoate (3j). Prepared
according to the general procedure A. Compound 3j was isolated as a white solid in 84% yield
(324 mg). Melting point: 78.7 °C. 1H NMR (400 MHz, CDCl3) δ 7.28 (s, 4H), 6.88 (s, 1H), 6.76
– 6.72 (m, 1H), 6.67 – 6.61 (m, 2H), 5.01 (hept, J = 6.3 Hz, 1H), 4.43 (s, 1H), 3.84 (s, 3H), 3.81
(s, 3H), 3.48 (ddd, J = 12.5, 7.0, 2.3 Hz, 2H), 2.73 (t, J = 7.0 Hz, 2H), 1.24 (d, J = 6.3 Hz, 3H),
1.13 (d, J = 6.3 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 170.27, 167.38, 149.03, 147.68, 134.25,
131.26, 128.96, 128.15, 120.70, 111.97, 111.41, 77.48, 77.16, 76.84, 69.56, 58.80, 55.89, 41.03,
35.00, 21.66, 21.43. IR (KBr) 3313, 3056, 2984, 2936, 2838, 1733, 1652, 1523, 1455, 1235, 1190,
1147, 1102, 1027, 850, 808, 708 (cm-1). HRMS (ESI-MS) calcd for C22H28NO5, m/z [M + H]+:
386.1967; found: 386.1972.

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Isopropyl 3-((4-fluorobenzyl)amino)-3-oxo-2-phenylpropanoate (3k). Prepared according to
the general procedure A. Compound 3k was isolated as a white solid in 85% yield (330 mg).
Melting point: 108 °C. 1H NMR (400 MHz, CDCl3) δ 7.47 (d, J = 6.9 Hz, 2H), 7.41 (d, J = 6.4 Hz,
1H), 7.39 (s, 2H), 7.35 (d, J = 6.5 Hz, 2H), 7.33 – 7.27 (m, 2H), 5.19 – 5.05 (m, 1H), 4.61 (s, 1H),
4.49 (d, J = 5.5 Hz, 2H), 1.33 (d, J = 6.0 Hz, 3H), 1.23 (d, J = 6.0 Hz, 3H). 13C NMR (100 MHz,
CDCl3) δ 170.09, 167.47, 137.97, 134.20, 129.49, 129.10, 129.10, 128.00, 127.52, 127.43, 77.48,
77.16, 76.84, 69.59, 58.70, 43.55, 23.19, 20.52. IR (KBr) 3314, 3060, 2982, 2940, 1740, 1650,
1608, 1532, 1453, 1356, 1211, 1228, 1179, 1102, 1020, 973, 829, 750, 704, 581, 487 (cm-1).
HRMS (ESI-MS) calcd for C19H21FNO3, m/z [M + H]+: 330.1505; found: 330.1500.
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Isopropyl 3-(benzylamino)-3-oxo-2-phenylpropanoate (3l). Prepared according to the general
procedure A. Compound 3l was isolated as a white solid in 92% yield (285 mg). Melting point:
107.8 °C. 1H NMR (400 MHz, CDCl3) δ 7.40 (dt, J = 3.9, 2.2 Hz, 2H), 7.38 – 7.34 (m, 2H), 7.33
(dd, J = 3.2, 1.7 Hz, 1H), 7.31 (dd, J = 4.2, 1.2 Hz, 1H), 7.31 – 7.26 (m, 2H), 7.22 (dd, J = 5.2, 2.9
Hz, 2H), 5.06 (hept, J = 6.3 Hz, 1H), 4.54 (s, 1H), 4.46 (d, J = 5.8 Hz, 2H), 1.27 (d, J = 6.3 Hz,
13
3H), 1.17 (d, J = 6.3 Hz, 3H). C NMR (100 MHz, CDCl3) δ 170.42, 138.06, 134.36, 129.17,
128.80, 128.33, 127.62, 77.48, 77.16, 76.84, 69.80, 58.91, 43.77, 21.80, 21.54. IR (KBr) 3348,
3033, 2980, 2938, 1732, 1656, 1521, 1455, 1355, 1309, 1278, 1230, 1178, 1102, 1017, 973, 807,
742, 702, 605, 505, 422 (cm-1). HRMS (ESI-MS) calcd for C19H22NO3, m/z [M + H]+: 312.1600;
found: 312.1602.
Isopropyl 3-((4-methoxybenzyl)amino)-3-oxo-2-phenylpropanoate (3m). Prepared according
to the general procedure A. Compound 3m was isolated as a white solid in 82% yield (280 mg).
1
Melting point: 79 °C. H NMR (400 MHz, CDCl3) δ 7.42 – 7.39 (m, 1H), 7.39 (dq, J = 3.3, 2.2
Hz, 2H), 7.37 (dd, J = 3.4, 1.1 Hz, 1H), 7.38 – 7.34 (m, 2H), 7.36 – 7.32 (m, 2H), 7.34 – 7.29 (m,
1H), 5.06 (dq, J = 12.5, 6.3 Hz, 1H), 4.60 (s, 1H), 3.75 (s, 3H), 1.26 (d, J = 6.3 Hz, 3H), 1.21 (d, J
13
= 6.3 Hz, 3H). C NMR (100 MHz, CDCl3) δ 168.87, 167.68, 132.92, 129.86, 129.35, 128.70,
128.30, 128.07, 77.21, 76.84, 76.84, 69.62, 58.13, 52.83, 21.63. IR (KBr) 3348, 3033, 2980, 2938,
1732, 1656, 1521, 1455, 1355, 1309, 1278, 1230, 1178, 1102, 1017, 973, 807, 742, 702, 605, 505,
422 (cm-1). HRMS (ESI-MS) calcd for C19H22NO3, m/z [M + H]+: 312.1600; found: 312.1602.

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Isopropyl 3-((4-methylbenzyl)amino)-3-oxo-2-phenylpropanoate (3n). Prepared according to
the general procedure A. Compound 3n was isolated as a white solid in 88% yield (287 mg).
Melting point: 79 °C. 1H NMR (400 MHz, CDCl3) δ 7.56 (dt, J = 4.0, 2.2 Hz, 2H), 7.54 – 7.48 (m,
2H), 7.50 – 7.45 (m, 2H), 7.48 – 7.44 (m, 1H), 7.46 – 7.40 (m, 1H), 7.34 – 7.27 (m, 1H), 5.21
(hept, J = 6.3 Hz, 1H), 4.70 (s, 1H), 4.54 (d, J = 5.7 Hz, 2H), 2.47 (s, 3H), 1.43 (d, J = 6.3 Hz,
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3H), 1.33 (d, J = 6.3 Hz, 3H). C NMR (100 MHz, CDCl3) δ 187.01 – 170.10, 170.00, 168.68,
187.01 – 135.06, 152.30, 187.01, 129.32, 187.01, 128.96, 187.01, 128.46, 141.22, 187.01, 127.82,
219.37, 127.34, 113.96, 77.48, 77.16, 76.84, 69.48, 58.67, 43.28, 21.59, 21.38, 21.02. IR (KBr)
3351, 3024, 2994, 2905, 1741, 1662, 1533, 1441, 1325, 1313, 1262, 1209, 1182, 1102, 1007, 981,
800, 736, 698, 627, 514, 438 (cm-1). HRMS (ESI-MS) calcd for C20H24NO4, m/z [M + H]+:
342.1705; found: 342.1711.
Ethyl 3-(methylamino)-3-oxo-2-phenylpropanoate (6a). Prepared according to the general
procedure A. Compound 6a was isolated as a white solid in 59% yield (131 mg). Melting point:
75°C. 1H NMR (400 MHz, CDCl3) δ 7.38 (dt, J = 8.3, 2.2 Hz, 2H), 7.33 (d, J = 7.6 Hz, 2H), 7.14
– 7.10 (m, 1H), 6.84 – 6.74 (m, 1H), 4.51 (s, 1H), 4.17 (ddd, J = 7.4, 5.1, 4.7 Hz, 2H), 2.78 (dd, J
= 4.8, 0.7 Hz, 3H), 1.23 (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 170.73, 168.00, 134.19,
128.99, 128.28, 127.78, 114.02, 77.48, 77.16, 76.84, 61.84, 58.50, 26.54, 13.98. IR (KBr) 3453,
3324, 1758, 1653, 1555, 1474, 1410, 1399, 1321, 1283, 1179, 1096, 981, 743, 601, 581 cm-1.
HRMS (ESI-MS) calcd for C12H16NO3, m/z [M + H]+: 222.1130; found: 222.1125.
Ethyl 2-(4-bromophenyl)-3-(butylamino)-3-oxopropanoate (6b). Prepared according to the
general procedure A. Compound 6b was isolated as a white solid in 88% yield (302 mg). Melting
point: 72 °C. 1H NMR (400 MHz, CDCl3) δ 7.46 (d, J = 8.5 Hz, 2H), 7.30 – 7.21 (m, 2H), 6.95 (s,
1H), 4.43 (s, 1H), 4.26 – 4.11 (m, 2H), 3.23 (dd, J = 13.4, 6.6 Hz, 2H), 1.49 – 1.41 (m, 2H), 1.34
13
– 1.26 (m, 2H), 1.23 (dd, J = 7.4, 6.9 Hz, 3H), 0.89 (d, J = 7.3 Hz, 3H). C NMR (100 MHz,
CDCl3) δ 170.59, 166.67, 133.38, 132.12, 130.06, 122.46, 77.47, 77.16, 76.84, 62.11, 57.85, 39.62,
31.36, 20.06, 14.02, 13.74. IR (KBr) 3242, 3081, 2995, 2953, 2879, 1744, 1650, 1559, 1441, 1378,
1275, 1221, 1173, 1052, 982, 748, 690, 602, 596 (cm-1). HRMS (ESI-MS) calcd for C15H21BrNO3,
m/z [M + H]+: 342.0705; found: 342.0699.

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Ethyl 3-(butylamino)-3-oxo-2-phenylpropanoate (6c). Prepared according to the general
procedure A. Compound 6c was isolated as a white solid in 86% yield (227 mg). Melting point:
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82 °C. H NMR (400 MHz, CDCl3) δ 7.36 – 7.32 (m, 2H), 7.30 (d, J = 2.3 Hz, 1H), 7.28 – 7.22
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(m, 2H), 6.89 (s, 1H), 4.45 (s, 1H), 4.20 – 4.06 (m, 2H), 3.18 (td, J = 7.1, 5.8 Hz, 2H), 1.40 (dt, J
= 12.4, 7.2 Hz, 2H), 1.25 (dd, J = 15.2, 7.6 Hz, 2H), 1.18 (t, J = 7.1 Hz, 3H), 0.82 (t, J = 7.3 Hz,
3H). 13C NMR (100 MHz, CDCl3) δ 170.83, 167.23, 134.32, 128.96, 128.22,77.48, 77.16, 76.85,
61.80, 58.56, 39.48, 31.36, 19.99, 13.97, 13.69. IR (KBr) 3237, 3074, 2981, 2961, 2884, 1753,
1662, 1571, 1461, 1382, 1267, 1241, 1192, 1092, 971, 771, 695, 596 (cm-1). HRMS (ESI-MS)
calcd for C15H22NO3, m/z [M + H]+: 264.1600; found: 264.1599.
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Ethyl 2-(4-bromophenyl)-3-(isopropylamino)-3-oxopropanoate (6d). Prepared according to
the general procedure A. Compound 6d was isolated as a white solid in 71% yield (233 mg).
Melting point: 88 °C. 1H NMR (400 MHz, CDCl3) δ 7.47 (d, J = 8.4 Hz, 2H), 7.26 (d, J = 8.4 Hz,
2H), 6.76 (s, 1H), 4.40 (s, 1H), 4.24 – 4.13 (m, 2H), 4.04 (dd, J = 13.7, 6.9 Hz, 1H), 1.25 (d, J =
13
7.1 Hz, 3H), 1.13 (t, J = 6.4 Hz, 6H). C NMR (100 MHz, CDCl3) δ 170.56, 165.80, 133.39,
132.10, 130.05, 122.42, 77.48, 77.00, 62.09, 57.81, 41.86, 22.51, 14.02. IR (KBr) 3272, 3088,
2972, 2929, 2873, 1737, 1644, 1555, 1514, 1460, 1365, 1275, 1234, 1172, 1031, 757, 681, 507
(cm-1). HRMS (ESI-MS) calcd for C14H19BrNO3, m/z [M + H]+: 328.0548; found: 328.0551.
Ethyl 3-(isopropylamino)-3-oxo-2-(p-tolyl)propanoate (6e). Prepared according to the general
procedure A. Compound 6e was isolated as a white solid in 68% yield (179 mg).` Melting point:
98 °C. 1H NMR (400 MHz, CDCl3) δ 7.29 (d, J = 8.0 Hz, 2H), 7.17 (d, J = 7.7 Hz, 2H), 6.70 (s,
1H), 4.45 (s, 1H), 4.25 – 4.14 (m, 2H), 4.12 – 4.02 (m, 1H), 2.34 (s, 3H), 1.26 (td, J = 7.1, 1.2 Hz,
13
3H), 1.14 (dd, J = 10.4, 6.6 Hz, 6H). C NMR (100 MHz, CDCl3) δ 174.33, 139.58, 128.63,
128.03, 127.19, 60.74, 51.92, 33.46, 29.87, 22.59, 14.26, 14.02. IR (KBr) 3373, 3041, 2974, 2917,
1744, 1695, 1544, 1463, 1430, 1372, 1309, 1230, 1180, 1077, 1025, 847, 740, 699, 606, 563, 502
(cm-1). HRMS (ESI-MS) calcd for C14H19BrNO3, m/z [M + H]+: 328.0548; found: 328.0535.
Ethyl 3-(benzylamino)-2-(4-bromophenyl)-3-oxopropanoate (6f). Prepared according to the
general procedure A. Compound 6f was isolated as a white solid in 94% yield (356 mg). Melting
point: 84°C. 1H NMR (400 MHz, CDCl3) δ 7.49 (d, J = 8.4 Hz, 2H), 7.39 – 7.34 (m, 1H), 7.33 (d,
J = 4.8 Hz, 2H), 7.31 (d, J = 2.1 Hz, 2H), 7.27 (d, J = 4.4 Hz, 2H), 5.24 – 5.14 (m, 2H), 4.62 (s,

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1H), 4.26 – 4.12 (m, 2H), 1.21 (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 167.05, 131.27,
130.54, 128.02, 127.70, 76.85, 76.54, 76.22, 67.09, 61.60, 56.80, 13.44. IR (KBr) 3329, 3030,
2962, 2923, 2871, 1627, 1570, 1452, 1365, 1260, 1090, 1021, 866, 802, 751, 697, 589, 483 (cm-
1). HRMS (ESI-MS) calcd for C18H19BrNO3, m/z [M + H]+: 376.0548; found: 376.0546.
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Methyl 3-(benzylamino)-3-oxo-2-phenylpropanoate (6g). Prepared according to the general
procedure A. Compound 6g was isolated as a white solid in 90% yield (255 mg). Melting point:
78 °C. 1H NMR (400 MHz, CDCl3) δ 7.45 – 7.41 (m, 2H), 7.39 (s, 1H), 7.37 (d, J = 1.9 Hz, 1H),
7.35 – 7.31 (m, 2H), 7.26 – 7.22 (m, 2H), 7.19 – 7.10 (m, 2H), 6.86 – 6.82 (m, 1H), 4.62 (s, 1H),
13
4.49 (d, J = 5.8 Hz, 2H), 3.78 (s, 3H). C NMR (100 MHz, CDCl3) δ 171.22, 167.28, 133.96,
129.21, 128.78, 128.46, 127.87, 127.60, 114.05, 77.4, 77.16, 76.84, 58.45, 52.94, 43.76. IR (KBr)
3315, 3049, 3001, 2957, 2824, 1720, 1663, 1504, 1442, 1256, 1187, 1112, 1100, 1077, 987, 845,
804, 757 (cm-1). HRMS (ESI-MS) calcd for C17H18NO3, m/z [M + H]+: 284.1287; found:
284.1290.
Ethyl 3-(benzylamino)-3-oxo-2-phenylpropanoate (6h). Prepared according to the general
procedure A. Compound 6h was isolated as a white solid in 91 % yield (271 mg). Melting point:
1
91 °C. H NMR (400 MHz, CDCl3) δ 7.47 – 7.43 (m, 2H), 7.42 – 7.38 (m, 2H), 7.38 – 7.36 (m,
1H), 7.34 (dd, J = 5.8, 1.5 Hz, 2H), 7.32 – 7.29 (m, 1H), 7.25 (d, J = 6.5 Hz, 2H), 4.61 (s, 1H),
4.49 (d, J = 5.8 Hz, 2H), 4.24 (qd, J = 10.8, 7.1 Hz, 2H), 1.29 (t, J = 7.1 Hz, 3H). 13C NMR (100
MHz, CDCl3) δ 170.81, 167.39, 137.97, 134.17, 129.17, 128.77, 128.39, 127.59, 77.48, 77.16,
76.84, 62.03, 58.66, 43.75, 14.06. IR (KBr) 3386, 3030, 2983, 2937, 1723, 1672, 1527, 1453,
1428, 1366, 1310, 1227, 1178, 1078, 1021, 925, 808, 740, 699, 606, 563, 502, 473 (cm-1). HRMS
(ESI-MS) calcd for C18H20NO3, m/z [M + H]+: 298.1443; found: 298.1438.
Ethyl 3-(benzylamino)-2-(2,4-dichlorophenyl)-3-oxopropanoate (6i). Prepared according to
the general procedure A. Compound 6i was isolated as a white solid in 88% yield (324 mg).
Melting point: 86 °C. 1H NMR (400 MHz, CDCl3) δ 7.50 (d, J = 8.4 Hz, 1H), 7.43 (d, J = 2.2 Hz,
1H), 7.33 (ddd, J = 7.3, 4.5, 1.6 Hz, 2H), 7.30 – 7.27 (m, 2H), 7.25 (s, 1H), 6.86 (s, 1H), 4.97 (s,
1H), 4.48 (qd, J = 14.9, 5.8 Hz, 2H), 4.22 (qd, J = 7.1, 0.8 Hz, 2H), 1.58 (s, 3H), 1.25 (t, J = 7.1
Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 131.52, 130.87, 129.66, 128.89, 127.93, 127.66, 77.48,

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77.16, 76.84, 62.44, 54.70, 44.09, 14.09. IR (KBr) 3031, 2975, 2918, 2864, 1633, 1581, 1448,
1379, 1271, 1088, 1017, 859, 817, 756, 700, 588, 472 (cm-1). HRMS (ESI-MS) calcd for
C18H18Cl2NO3, m/z [M + H]+: 366.0664; found: 366.0667.
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Ethyl 3-(benzylamino)-2-(4-fluorophenyl)-3-oxopropanoate (6j). Prepared according to the
general procedure A. Compound 6j was isolated as a white solid in 88% yield (278 mg). Melting
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point: 108 °C. H NMR (400 MHz, CDCl3) δ 7.47 (d, J = 6.9 Hz, 2H), 7.40 (d, J = 7.3 Hz, 2H),
7.35 (d, J = 6.5 Hz, 2H), 7.32 (d, J = 6.3 Hz, 1H), 7.27 (d, J = 7.1 Hz, 2H), 5.18 – 5.05 (m, 1H),
4.61 (s, 1H), 4.49 (d, J = 5.5 Hz, 2H), 1.33 (d, J = 6.0 Hz, 3H), 1.23 (d, J = 6.0 Hz, 3H). 13C NMR
(100 MHz, CDCl3) δ 170.09, 167.47, 137.97, 134.20, 129.49, 129.10, 129.10, 128.00, 127.43,
77.48, 77.16, 76.84, 69.59, 58.70, 43.55, 21.38. IR (KBr) 3389, 3031, 2981, 2936, 1730, 1658,
1518, 1454, 1428, 1365, 1310, 1280, 1231, 1180, 1106, 1079, 1013, 976, 914, 809, 743, 700, 606,
561, 505, 479, 421 (cm-1). HRMS (ESI-MS) calcd for C18H19FNO3, m/z [M + H]+: 316.1349;
found: 316.1345.
Ethyl 3-((4-methylbenzyl)amino)-3-oxo-2-phenylpropanoate (6k). Prepared according to the
general procedure A. Compound 6k was isolated as a white solid in 89 % yield (277 mg). Melting
point: 94 °C. 1H NMR (400 MHz, CDCl3) δ 7.50 – 7.46 (m, 2H), 7.31 – 7.27 (m, 2H), 7.16 (d, J =
4.5 Hz, 1H), 7.12 (s, 1H), 7.12 (s, 2H), 4.48 (s, 1H), 4.40 (dd, J = 5.7, 2.6 Hz, 2H), 4.19 (dddd, J
= 17.9, 10.8, 7.1, 3.7 Hz, 2H), 2.33 (s, 3H), 1.25 (dd, J = 9.5, 4.8 Hz, 3H). 13C NMR (100 MHz,
CDCl3) δ 170.50, 166.67, 133.20, 132.25, 130.13, 129.52, 127.75, 77.48, 77.16, 76.84, 62.26,
57.89, 43.66, 21.23, 14.07. IR (KBr)3348, 3033, 2980, 2938, 1732, 1656, 1521, 1455, 1355, 1309,
1578, 1230, 1178, 1102, 1017,973, 807, 742, 702, 605, 505, 422 cm-1. HRMS (ESI-MS) calcd for
C19H22NO3, m/z [M + H]+: 312.1600; found: 312.1613.
Methyl 3-((4-methylbenzyl)amino)-3-oxo-2-phenylpropanoate (6l). Prepared according to the
general procedure A. Compound 6l was isolated as a white solid in 81 % yield (241 mg). Melting
point: 92 °C. 1H NMR (400 MHz, CDCl3) δ 7.59 – 7.55 (m, 4H), 7.53 (dd, J = 8.0, 5.1 Hz, 4H),
7.49 – 7.47 (m, 2H), 7.34 – 7.30 (m, 4H), 7.28 (s, 4H), 7.01 – 6.93 (m, 1H), 4.74 (s, 2H), 4.55 (d,
J = 5.7 Hz, 4H), 3.89 (s, 6H), 2.48 (s, 6H). 13C NMR (100 MHz, CDCl3) δ 171.14, 167.17, 137.20,
134.84, 133.99, 129.40, 129.14, 128.43, 127.62, 114.05, 77.48, 77.16, 76.84, 58.46, 52.86, 43.52,

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21.17. IR (KBr) 3300, 3023, 2991, 2945, 2837, 1731, 1641, 1510, 1439, 1251, 1178, 1137, 1114,
1077, 968, 839, 822, 743 (cm-1). HRMS (ESI-MS) calcd for C18H20NO3, m/z [M + H]+: 298.1443;
found: 298.1447.
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Ethyl 3-((4-methylbenzyl)amino)-3-oxo-2-(p-tolyl)propanoate (6m). Prepared according to the
general procedure A. Compound 6m was isolated as a white solid in 89% yield (290 mg). Melting
point: 83°C. 1H NMR (400 MHz, CDCl3) δ 7.44 (d, J = 8.1 Hz, 2H), 7.42 (d, J = 8.4 Hz, 2H), 7.31
(s, 2H), 7.30 (d, J = 2.9 Hz, 2H), 7.19 (s, 1H), 4.67 (s, 1H), 4.55 (dd, J = 5.7, 1.9 Hz, 2H), 4.34
(dd, J = 15.7, 7.2 Hz, 2H), 2.48 (s, 3H), 2.47 (s, 3H), 1.39 (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz,
CDCl3) δ 170.95, 167.52, 138.24, 137.22, 134.98, 131.17, 129.88, 129.51, 128.27, 127.98, 127.66,
77.48, 77.16, 76.84, 61.94, 58.39, 43.53, 21.21, 14.09. IR (KBr) 3386, 3030, 2983, 2937, 1723,
1672, 1527, 1453, 1428, 1366, 1310, 1227, 1178, 1078, 1021, 740, 699, 606, 563, 502 (cm-1).
HRMS (ESI-MS) calcd for C20H24NO3, m/z [M + H]+: 326.1756; found: 326.1748.
Ethyl 2-(4-bromophenyl)-3-((4-methylbenzyl)amino)-3-oxopropanoate (6n). Prepared according to
the general procedure A. Compound 3b was isolated as a white solid in 83% yield (325 mg).
Melting point: 112 °C. 1H NMR (400 MHz, CDCl3) δ 7.52 – 7.43 (m, 2H), 7.30 – 7.26 (m, 2H),
7.18 – 7.12 (m, 2H), 7.12 (s, 2H), 4.48 (s, 1H), 4.40 (dd, J = 5.7, 2.6 Hz, 2H), 4.19 (dd, J = 10.7,
7.1 Hz, 2H), 2.33 (s, 3H), 1.23 (d, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 170.50, 166.67,
133.20, 132.25, 130.13, 129.52, 127.75, 77.48, 77.16, 76.84, 62.26, 57.89, 43.66, 21.23, 14.07. IR
(KBr) 3456, 3283, 3064, 2978, 2924, 1739, 1646, 1544, 1488, 1448, 1366, 1327, 1268, 1232,
1178, 1073, 1019, 890, 805, 737, 600, 502 (cm-1). HRMS (ESI-MS) calcd for C19H21BrNO3, m/z
[M + H]+: 390.0705; found: 390.0683.
Ethyl 3-((4-fluorobenzyl)amino)-3-oxo-2-phenylpropanoate (6o). Prepared according to the
general procedure A. Compound 3b was isolated as a white solid in 81% yield (256 mg). Melting
1
point: 66 °C. H NMR (400 MHz, CDCl3) δ 7.40 (dd, J = 4.2, 2.1 Hz, 1H), 7.39 – 7.36 (m, 2H),
7.35 (dd, J = 4.8, 2.4 Hz, 2H), 7.18 (dd, J = 8.7, 5.4 Hz, 3H), 6.98 (t, J = 8.7 Hz, 2H), 4.56 (s, 1H),
4.42 (d, J = 5.8 Hz, 2H), 4.27 – 4.13 (m, 2H), 1.25 (t, J = 7.1 Hz, 3H). 13C NMR (100 MHz, CDCl3)
δ 170.94, 167.43, 134.15, 129.55, 129.16, 128.50, 128.30, 115.75, 115.54, 77.48, 77.16, 76.84,
62.12, 58.61, 43.05, 14.08. IR (KBr) 3303, 3065, 2982, 2937, 1740, 1652, 1610, 1536, 1510, 1438,

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1364, 1311, 1228, 1184, 1095, 1022, 827, 751, 701, 585, 491 (cm-1). HRMS (ESI-MS) calcd for
C18H19FNO3, m/z [M + H]+: 316.1349; found: 316.1358.
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Corresponding Author
*E-mail: siva.che@pondiuni.edu.in. Tel: +91 413 2654709. Fax: +91 413 2655987.
Acknowledgement
C.S. gratefully acknowledges the Science and Engineering Research Board, New Delhi, India, for
financial support (EEQ/2018/000156). We thank the Central Instrumentation Facility,
Pondicherry University, for NMR and IR spectra; DST-FIST for the ESI-MS and SC-XRD.
Notes and references
1. (a) A. D. Allen and T. T. Tidwell, Eur. J. Org. Chem. 2012, 1081; (b) A. D. Allen and T.
T. Tidwell, Chem. Rev. 2013, 113, 7287.
2. (a) H. Staudinger, Ber. Dtsch. Chem. Ges. 1905, 38, 1735; (b) T. T. Tidwell, Eur. J. Org.
Chem. 2006, 563; (c) D. H. Paull, A. Weatherwax and T. Lectka, Tetrahedron, 2009, 65,
6771.
3. H. W. Moore and D. S. Wilbur, J. Org. Chem.1980, 45, 4483.
4. (a) Y. Chiang, A. J. Kresge and V. V. Popik, J. Am. Chem. Soc.1999, 121, 5930; (b) B. D.
Wagner, B. R. Arnold, G. S. Brown and J. Lusztyk, J. Am. Chem. Soc. 1998, 120, 1827.
5. L. Hegedus, S. J. Montgomery, Y. D. Narukawa and C. A Snustad, J. Am. Chem. Soc.1991,
113, 5784.
6. Y. Yang, W. Shou, D. Hong and Y. Wang, J. Org. Chem. 2008, 73, 3574.
7. Z. Tang, S. Mandal, N. D. Paul, M. Lutz, P. Li, J. I. van der Vlugta and B. de Bruin, Org.
Chem. Front. 2015, 2, 1561.
8. H.; Staudinger and O. Kupfer, Ber. Dtsch. Chem. Ges.1912, 45, 501.
9. (a) K. H. Dötz and J. Mühlemeier, Angew. Chem., Int. Ed. Engl. 1982, 21, 929; (b) P. T.;
Barger, B. D.; Santarsiero, J. Armantrout and J. E. Bercaw, J. Am. Chem. Soc. 1984, 106,
5178; (c) N. Ungvári, E. Fördős, J. Balogh, T. Kégl, L. Párkányi and F. Ungváry,
Organometallics, 2010, 29, 3837.
10. Z. Zhang, Y. Zhang and J. Wang, ACS Catal. 2011, 1, 1621.

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11. (a) Z. Zhang, Y. Liu, L. Ling, Y. Li, Y. Dong, M. Gong, X. Zhao, Y. Zhang and J. Wang,
J. Am. Chem. Soc. 2011, 133, 4330; (b) Z. Zhang, Y. Liu, M. Gong, X. Zhao, Y. Zhang
and J. Wang, Angew. Chem. Int. Ed. 2010, 49, 1139; (c) N. D. Paul, A. Chirila, H. Lu, X.
P. Zhang and B. de Bruin, Chem. Eur. J. 2013, 19, 12953; (d) A. Chirila, K. M. van Vliet,
N. D. Paul, and B. de Bruin, Eur. J. Inorg. Chem. 2018, 2251.
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22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
12. (a) C. Peng, J. Cheng, J. Wang, J. Am. Chem. Soc. 2007, 129, 8708; (b) Y. Xia, Y. Zhang
and J. Wang, ACS Catal. 2013, 3, 2586; (c) Q. Xiao, Y. Zhang and J. Wang, Acc. Chem.
Res. 2013, 46, 236.
13. R. Tuba and F. Ungváry, J. Mol. Catal. A: Chem. 2003, 203, 59.
14. N. Ungvári, T. Kégl and F. Ungváry, J. Mol. Catal. A: Chem. 2004, 219, 7.
15. R. Tuba, E. Fördos and F. Ungváry, J. Mol. Catal. A: Chem. 2005, 236, 113.
16. T. T. Tidwell, 2nd ed., Wiley, Hoboken, 2006.
17. Methoden der Organischen Chemie (Houben-Weyl), 4th Edition, Volume/Ic,
Reduktion, Part 1 Organometallics. 1982, 1, 677.
18. G. M. Breuer, F. J. Grieman and E. K. C; Lee, J. Phys. Chem.1975, 795, 542.
19. Y. Kikuchi, T. Kikkawa and R. Kato, J. Chromatogr. Sci.1967, 5, 261.
20. M.; Kapernaum, G. Kuth, F. Bachmaier and Z. Fresenius, Anal. Chem. 1986, 323, 487.
21. D. V. Avila, K. U. Ingold, J. Lusztyk, W. R. Dolbier and H. Q. Pan, J. Am. Chem. Soc.
1993, 115, 1577.
22. B. D. Wagner, M. Z. Zgierski and J. Lusztyk, J. Am. Chem. Soc. 1994, 116, 6433.
23. K. G. Ashim, J. Am. Chem. Soc.1981, 103, 71765.
24. (a) D. B. Grotjahn, L. S. B. Collins, M. Wolpert, G. A. Bikzhanova, H. C. Lo, D. Combs
and J. L. Hubbard, J. Am. Chem. Soc. 2001, 123, 8260; (b) D. B. Grotjahn and H. C. Lo, J.
Am. Chem. Soc.1996, 118, 2097; (c) H. Urtel, G. A. Bikzhanova, D. B. Grotjahn and P.
Hofmann, Organometallics. 2001, 20, 3938; (d) D. B. Grotjahn, G. A. Bikzhanova, L. S.
B. Collins, T. Concolino, K. C. Lam and A. L. Rheingold, J. Am. Chem. Soc. 2000, 122,
5222.
25. (a) W. A. Herrmann and J. Plank, Angew. Chem., Int. Ed. Engl. 1978, 17, 525; (b) W. A.
Herrmann, J. Plank, M. L. Ziegler and K. Weidenhammer, J. Am. Chem. Soc. 1979, 101,
3133.

New Journal of Chemistry
Page 26 of 27
View Article Online
DOI: 10.1039/C9NJ06161D
1
2
3
4
5
6
7
8
9
26. G. C. Fortman, K. Tamás, L. Qian-Shu, Z. Xiuhui, H. F. Schaefer III, X. Yaoming, R.
Bruce King, T. Joshua and C. D. Hoff, J. Am. Chem. Soc. 2007, 129, 14388.
27. N. Ungvári, E. Fördos, T. Kégl, F. Ungváry, Inorganica. Chim. Acta. 2010, 363, 2016.
28. (a) K. Ramakrishna, M. Murali and C. Sivasankar, Org. Lett. 2015, 17, 3814; (b) K.
Ramakrishna and C. Sivasankar, J. Org. Chem. 2016, 81, 6609; (c) K. Ramakrishna and
C. Sivasankar, J. Organomet. Chem. 2016, 805, 122; (d) K. Ramakrishna, J. M. Thomas
and C. Sivasankar, J. Org. Chem. 2016, 81, 9826; (e) K. Ramakrishna and C. Sivasankar,
Eur. J. Org. Chem. 2017, 4035; (e) P. K. Madarasi, V. Kavya, S. Anjaly and C. Sivasankar,
ChemistrySelect. 2019, 4, 7555.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
29. (a) I. P. Romanova, E. I. Musina, A. A. Nafikova, V. V. Zverev, D. G. Yakhvarov and O.
G. Sinyash, Russ. Chem. Bull. 2003, 52, 1750; (b) X. Bin, Z. Shou-Fei, X. Xiu-Lan, S. Jun-
Jie and Z. Qi-Lin, Angew. Chem. Int. Ed. 2011, 50, 11483; (c) C. L. Elaine and C. F.
Gregory, J. Am. Chem. Soc. 2007, 129, 12066.

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2
3
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21
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An effective methodology to detect the highly reactive ketene intermediate which is formed
insitu during the course of organic transformation.