CHAPTER 3 PREPARATION OF SYNTHETIC TARGETS

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CHAPTER 3

PREPARATION OF SYNTHETIC TARGETS

3.1 INTRODUCTION

Heterocyclic chalcones were synthesized using the Claisen-Schmidt condensation reaction. This reaction involves the condensation of an aromatic aldehyde with an aromatic aldehyde or ketone, yielding an α,-unsaturated aldehyde or ketone, and it is usually carried out in the presence of a basic catalyst (Nielsen & Houlihan, 1968).

In this study, heteroaromatic groups such as pyrrole, methylthiophene, 5-chlorothiophene and methoxypyridine were included and substitution on the phenyl ring was also varied to investigate the effect of the different combinations. (2E)-3-(4-Chlorophenyl)-1-(2-hydroxy-4-methoxyphenyl)prop-2-en-1-one (8), a chalcone with known MAO inhibitory properties (Chimenti et al., 2009), was also synthesized for comparative purposes.

3.2 CHEMISTRY

Ar

O

CH

_H

O

Ar

Ar

Ar

O

+

a

KETONE ALDEHYDE CHALCONE

Scheme 3.1: General synthetic route for chalcones. Reactants and conditions: (a) 99% EtOH, 40%

NaOH, room temperature, 2 hours. Ar1 _{= aromatic/heteroaromatic ring, Ar}2 _{= aromatic/heteroaromatic}

ring.

Commercially available ketones were reacted with appropriate aldehydes in the presence of a base. After completion of the reactions (as monitored by thin layer chromatography [TLC]), the resulting residues were filtered, washed with ice cold ethanol, and dried. The crude products were recrystallized from absolute ethanol (Cocconcelli et al., 2008). Table 3.1 illustrates the chalcones that were synthesized in this study.

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Table 3.1: Synthesized chalcones.

No. Chalcone No. Chalcone

R

R

O

R

R

O

S

Cl

CF

N

H

CF

N

H

_Cl

N

H

CF

N

O

CH

Cl

S

Cl

Br

F

OH

O

CH

S

_Cl

S

H

C

Br

F

N

H

_Br

F

O

OH

CH

Cl

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3.3 MATERIALS AND INSTRUMENTATION

Starting materials and reagents were purchased from Sigma-Aldrich, and were used without further purification. Solvents from Rochelle were used for reactions and chromatography, while deuterated solvents used for NMR spectroscopy were obtained from Merck.

Thin layer chromatography (TLC)

Reactions were monitored using TLC silica gel 60 F254 aluminium coated sheets (Merck). The TLC plates were visualized under ultraviolet (UV) light at a wavelength of 254 nm. The mobile phase used for the TLC of the chalcones was petroleum ether: ethyl acetate (8:2), in most cases. For compounds 10d and 8, petroleum ether: ethyl acetate (95:5) served as mobile phase.

Nuclear magnetic resonance (NMR) spectroscopy

Proton (1_{H) and carbon (}13_{C) NMR spectra were recorded on a Bruker Avance III spectrometer at} frequencies of 600 and 150 MHz for 1_{H and} 13_{C spectra, respectively. Samples were dissolved in} either deuterochloroform (CDCl3) or deuterated dimethyl sulfoxide (DMSO-d6) with chemical shifts

referenced to the residual solvent signal; at 7.26 and 77.0 ppm for 1_{H and} 13_{C NMR spectra,} respectively, in CDCl3, and at 2.5 and 39.5 ppm for 1H and 13C NMR spectra, respectively, in DMSO-d6. MestReNova8 was used to process and analyze the data. Chemical shifts (δ) are given

in parts per million (ppm), and coupling constants (J) are given in Hz. 1_{H NMR data is reported by} providing the chemical shift (), the integration (e.g.1H) and the multiplicity. Abbreviations used to describe multiplicity include the following: singlet (s), broad singlet (br s), doublet (d), broad doublet (br d), doublet of doublets (dd), doublet of doublet of doublets (ddd), triplet (t), broad triplet (br t), quartet (q), pentet (p), and a multiplet (m).

Mass spectrometry (MS)

All mass spectra were acquired on a Bruker micrOTOF-QII mass spectrometer operating in atmospheric-pressure chemical ionization (APCI), positive ion mode.

Infrared (IR)

An Alpha Bruker Platinum-ATR instrument with the Opus 7.0.129 software was used to record IR spectra.

High performance liquid chromatography (HPLC)

To determine the purity of the synthesized compounds, HPLC analyses was conducted using an Agilent 1100 HPLC system. This system was equipped with a quaternary pump and Agilent 1100 series diode array detector. Acetonitrile (Merck), HPLC grade, and Milli-Q water was used for the chromatography. A Venusil XBP C18 column (4.60 x 150 mM, 5 μM) was used with 30%

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acetonitrile and 70% Milli-Q water, as the initial mobile phase at a flow rate of 1 ml/min. At the start of each HPLC run, a solvent gradient program was initiated, while the acetonitrile in the mobile phase was linearly increased up to 85% over a period of 5 min. Each HPLC run lasted 15 min, having 5 min for equilibration between runs. Volumes of 2 μl of the analytes dissolved in acetonitrile (0.1 mM) were injected into the HPLC system, and the eluent was monitored at the following wavelengths: 210, 254 and 300 nM.

Melting points

Melting points were determined with a Buchi B-545 melting point apparatus and are uncorrected.

3.4 SYNTHETIC PROCEDURES

The method as described by Cocconcelli and co-workers (2008) was used and modified as follows:

General procedure for the synthesis of chalcones 10a and 10f

The ketone (1 equivalent) and aldehyde (1 equivalent) were dissolved in a minimum amount of absolute ethanol. NaOH (40%; 0.5 equivalents) was added drop wise. The reaction was stirred for 1 (10a) or 2 hours (10f) at room temperature under nitrogen, as the aldehyde, 4-(trifluoromethyl)benzaldehyde, was air sensitive. The resulting residue was filtered, washed with ice cold absolute ethanol, dried and subsequently recrystallized from absolute ethanol.

General procedure for the synthesis of chalcones 10b, 10c, 10e, 10g, 10h and 10i.

The ketone (1 equivalent) and aldehyde (1 equivalent) were dissolved in a minimum amount of absolute ethanol. NaOH (40%; 0.5 equivalents) was added drop wise. The reaction mixture was stirred for 2 hours at room temperature (with the exception of 10h which stirred overnight), and the resulting residue was filtered, washed with ice cold absolute ethanol dried and subsequently recrystallized from absolute ethanol.

General procedure for the synthesis of (2E)-3-(5-chlorothiophen-2-yl)-1-(2-hydroxy-4-methoxyphenyl)prop-2-en-1-one (10d)

2’-Hydroxy-4’-methoxyacetophenone (3.37 mmol; 1 equivalent) and 5-chloro-2-thiophene-carboxaldehyde (3.37 mmol; 1 equivalent) were dissolved in 6 ml absolute ethanol. NaOH (40%; 1.70 mmol; 0.5 equivalents) was added drop wise. The reaction was stirred for 2 hours at room temperature, and the ethanol was evaporated to yield an oily residue. This reaction was repeated and the residues were combined. After evaporation of the ethanol, the residue was purified with column chromatography using firstly petroleum ether: ethyl acetate (9:1) and then petroleum ether: ethyl acetate (8:2) as eluent.

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2

General procedure for the synthesis of (2E)-3-(4-chlorophenyl)-1-(2-hydroxy-4-methoxyphenyl)prop-2-en-1-one (8)

2’-Hydroxy-4’-methoxyacetophenone (7.67 mmol; 1 equivalent) and 4-chlorobenzaldehyde (7.67 mmol; 1 equivalent) was dissolved in 2 ml absolute ethanol. NaOH (40%; 3.83 mmol; 0.5 equivalent) was added drop wise. Since the 4-chlorobenzaldehyde was air sensitive the reaction was carried out in an atmosphere of nitrogen. The reaction was stirred for 48 hours at room temperature, and the ethanol was evaporated to yield an oily residue. The residue was purified by column chromatography using petroleum ether: ethyl acetate (95:5) as eluent.

3.5 RESULTS AND DISCUSSION

The characterization of all compounds was firstly done with NMR spectroscopy. 1_{H and} 13_{C NMR} spectra were recorded for all compounds, while DEPT, HSQC, HMBC and COSY spectra were obtained for selected compounds. The 1_{H and} 13_{C NMR assignments of the synthesized} compounds are given in table 3.2. The most characteristic signals observed in the proton NMR spectra, were those of the double bond protons, that were present as two doublets with coupling constants of approximately 16 Hz, indicating a trans double bond. In the 13_{C spectra, the most} downfield signal, at approximately 180 – 190 ppm, signified the presence of the ketone group.

Assignment of proton signals was based on observed chemical shifts, integration, multiplicities and coupling constants. The corresponding carbon signals were then identified using HSQC correlations (if a HSQC spectrum was obtained) and assignments were further verified by HMBC correlations. Assignments of quaternary carbons were done by inspection of the 13_{C NMR spectra} in conjunction with DEPT spectra and further analysis of HMBC spectra, if available.

IR and mass spectra were further acquired to aid in structure conformation. For all compounds, experimental mass values corresponded well with calculated values. Melting points were also determined, while the purities of all compounds were determined by HPLC analysis.

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Table 3.2: 1_{H and} 13_{C NMR assignments of synthesized chalcones.}

Nr. Structure 1_{H NMR signal assignment} 13_{C NMR signal assignment}

10a

S

Cl

O

CF

a. The protons of the double bond, H-2 and H-3, are

present as doublets, with the 15.6 Hz coupling

constants indicative of a trans double bond, at δH 7.82

and 7.38.

b. The protons of the p-disubstituted phenyl ring, H-2' &

6', as well as, H-3' & H-5', are present as a doublet at

δH 7.72 and as part of the multiplet at δH 7.70-7.63

c. The protons of the thiophene ring, H-3'' and H-4'', are

present as part of the multiplet at δH 7.70-7.63 and as

a doublet at δH 7.02.

a. The ketone signal is present at δC 180.5.

b. Both the CF3 and C-4' carbon signals are present as

quartets at δC 123.7 and δC 132.0, respectively.

c. The remaining carbon signals of the phenyl and

thiophene rings, as well as the carbon signals from the double bond, occur between 143.8 and 122.5 ppm. 10b

_O

Cl

N

H

a. The NH proton occurs as a singlet at δH 12.02.

b. The protons of the double bond, H-2 and H-3, are

present as part of the multiplet at δH 7.81-7.74 and as

a doublet at δH 7.62

c. The protons of the pyrrole ring are present at δH 7.49 –

7.41 (H-3'' or H-5''), 7.18 (H-3'' or H-5'') and δH 6.28

(H-4'').

d. The protons of the phenyl ring are present at δH 8.01

(H-2'), 7.81-7.74 and 7.49-7.41 (H-6', H-4', H-5').

a. The ketone signal is present at δC 177.5.

b. The signals of the double bond, pyrrole and phenyl

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N

O

O

Cl

CH

a. The double bond protons, H-2 and H-3, are present at

δH 7.73 as a doublet and as part of the multiplet at δH

7.51-7.42.

b. The proton signals at δH 8.88 (H-2"), 8.22 (H-4") and

6.83 (H-5") were assigned to the protons of the pyridine ring.

c. The protons of the phenyl ring are present in the

aromatic region at δH 7.61 (H-2′), 7.51-7.42 and

7.42-7.32 (H-6′, H-4′ and H-5′).

d. The protons of the OCH3 group are present at δH 4.02.

a. The ketone signal is present at δC 187.3.

b. The signals of the double bond, pyridine and phenyl

rings are present between 166.7 and 111.4 ppm.

c. The OCH3 carbon is present at δC 54.1.

10d

S

_Cl

O

OH

O

CH

a. The OH proton is present at δH 13.4

b. The double bond protons, H-2 and H-3, are present as

two doublets at δH 7.85 and 7.21

c. The proton signals of the thiophene ring occur at δH

7.14 (H-3') and 6.92 (H-4').

d. The proton signals of the phenyl ring are present at δH

7.74 (H-6''), 6.49 (H-5'') and 6.46 (H-3'').

e. The proton signal at δH 3.86 was assigned to the OCH3

group.

a. The ketone signal is present at δC 190.8

b. The carbon signals of the double bond, thiophene and

phenyl rings are present between 166.7 and 101.0 ppm.

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N

O

Br

F

H

a. The NH proton is present at δH 12.01.

b. The double bond protons, H-2 and H-3, are present as

two doublets at δH 7.73 and 7.60.

c. The proton signals of the pyrrole ring occur as part of

the multiplet at δH 7.47-7.40 (H-5'' or H-3''), a triplet at

δH 7.17 (H-5'' or H-3'') and as a doublet of doublets at

δH 6.27 (H-4ʺ).

d. The proton signals of the phenyl ring are present at δH

8.30 (H-2ʹ), 7.88 (H-6ʹ) and 7.47-7.40 (H-5ʹ).

a. The ketone signal is present at δC 177.5

b. The other quaternary carbons were assigned as

follows: δC 159.0 (C-4'), 133.4 (C-1'), 133.1 (C-2''),

and 108.9 (C-3').

c. The double bond carbon signals are present at δC

138.10 and 124.4.

d. The carbons of the phenyl ring are present at δC 133.0

(C-2ʹ), 130.4 (C-6ʹ), 117.1 (C-5').

e. The carbons of the pyrrole ring are present at δC 126.7

(C-3ʺ or C-5ʺ), 117.9 (C-3ʺ or C-5ʺ) and 110.3 (C-4ʺ). 10f

N

O

CF

H

a. The NH proton is present at δH 10.26.

b. The double bond protons, H-2 and H-3, occur at δH

7.84 and 7.42.

c. The protons of the p-disubstituted phenyl ring are

present as two doublets at δH 7.73 (H-2ʹ & H-6ʹ) and

7.66. (H-3' & H-5').

d. The protons of the pyrrole ring are present as

multiplets at δH 7.19-7.16 3ʺ or H-5ʺ), 7.15-7.10

(H-3ʺ or H-5ʺ) and 6.40-6.35 (H-4ʺ).

a. The ketone signal is present at δC 178.3

b. The carbons of the CF3 group and C-4' are present at

δC 123.8 and 131.5, respectively.

c. The other quaternary carbon signals occur at δC 138.4

(C-1ʹ) and 132.9.1' (C-2'').

d. The carbons of the double bond are present at δC

140.3 and 124.2.

e. The CH carbons of the phenyl ring are present at δC

128.3 (C-2ʹ & C-6ʹ) and at δC 125.8 (H-3' & H-5').

f. The CH carbons of the pyrrole ring are present at δC

126.2 (C-3ʺ or C-5ʺ), 117.1 (C-3ʺ or C-5ʺ) and 111.2 (C-4ʺ).

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N

O

CF

H

a. The NH proton is present at δH 12.05.

b. The double bond proton, H-2 and H-3, signals occur at

δH 7.87 and as part of the multiplet at δH 7.77-7.71.

c. The proton signals of the phenyl ring are presnt at δH

8.26 2ʹ), 8.14 6ʹ), 7.77-7.71 4ʹ) and 7.66 (H-5ʹ).

d. The proton signals of the pyrrole ring are present at δH

7.47 3ʺ or H-5ʺ), 7.19 3ʺ or H-5ʺ) and 6.29 (H-4ʺ).

a. The ketone signal is present at δC 177.5.

b. The carbon signals of the CF3 group and C-3' are

present at δC 124.1 and 129.8, respectively.

c. The signals of the other quaternary carbons C-1' and

C-2'' are present at δC 136.1 and 133.0, respectively.

d. The carbon signals of the double bond occur at δC

138.9 and 125.0.

e. The CH carbon signals of the phenyl ring are

present at δC 132.4 (C-6ʹ), 129.9 (C-5'), 126.2 (C-4ʹ)

and 124.8 (C-2ʹ).

f. The CH carbon signals of the pyrrole ring are

present at δC 126.8 (3ʺ or 5ʺ), 118.0 (3ʺ or C-5ʺ) and 110.2 (C-4ʺ). 10h

S

O

Cl

Br

F

a. The protons of the double bond, H-2 and H-3, are

present at δH 7.71 and 7.23.

b. The protons of the phenyl ring occur at δH 7.84 (H-2ʹ),

7.53 (H-6ʹ) and 7.17 (H-5ʹ).

c. The protons of the thiophene ring are present at δH

7.65 (H-3'') and 7.02 (H-4'').

a. The ketone signal is present at δC 180.4.

b. The signal at δC 160.3 was assigned as C-4ʹ.

c. The remaining quaternary carbons occur at δC 143.9

(C-2ʺ or C-5''), 140.2 (C-2ʺ or C-5''), 132.2 (C-1') and 110.0 (C-3').

d. The carbon signals of the double bond occur at δC

141.6 and 121.1.

e. The carbon signals of the phenyl ring are present at

δC 133.1 (C-2ʹ), 129.4 (C-6ʹ), 117.1 (C-5ʹ) and 110.0

(C-3ʹ).

f. The remaining CH carbons of the thiophene ring

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S

O

H

C

Br

F

a. The double bond protons, H-2 and H-3, are present as

part of the multiplet at δH 7.71-7.65 and as a doublet at

δH 7.29.

b. The protons of the phenyl ring are present by δH 7.83

(H-2ʹ), 7.52 (H-6ʹ) and 7.15 (H-5ʹ).

c. The protons of the thiophene ring are present as part

of the multiplet at δH 7.71-7.65 (H-3ʺ) and as a doublet

at δH 6.86 (H-4ʺ).

d. The proton signal of the CH3 group occurs at δH 2.57.

a. The ketone signal is present at δC 181.0

b. The carbon signal at δC 160.0 was assigned as C-4ʹ.

c. The remaining quaternary carbons occur at δC 150.6

(C-2ʺ or C-5''), 143.1 (C-2ʺ or C-5''), 133.0 (C-1') and 109.8 (C-3').

d. The carbon signals of the double bond occur at δC

140.5 and 122.3.

e. The CH carbons of the phenyl ring are present at δC

132.6 (C-2ʹ), 129.2 (C-6ʹ) and 117.0 (C-5ʹ).

f. The remaining CH carbons of the thiophene ring

occurs at δC 132.7 (C-3ʺ) and 127.0 (C-4ʺ).

g. The carbon signal of the CH3 is present at δC 16.2.

8

_O

O

OH

Cl

CH

a. The OH proton is present at δH 13.38.

b. The double bond protons, H-2 and H-3, are present at

δH 7.84-7.79 and 7.54.

c. The protons of the p-disubstituted phenyl ring, H-2' &

H-6', as well as, H-3' and H-5', are present as two

doublets at δH 7.58 and 7.40.

d. The remaining aromatic protons correspond with the

signals at δH 7.84-7.79 (6ʺ) and 6.52-6.45 (3ʺ &

H-5ʺ).

e. The protons of the OCH3 group are represented by the

signal at δH 3.86.

a. The ketone signal is present at δC 191.5.

b. The carbons of the double bond and phenyl rings are

present between δC 166.7 101.0.

c. The carbon signal of the OCH3 group is present at δC

55.6.

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The presence of a fluorine substituent e.g. compounds 10g and 10h, resulted in more complex NMR spectra, due to fluorine-carbon and fluorine-proton coupling. The NMR data for these examples will thus be discussed in further detail below.

The nine signals observed in the 1_{H NMR spectrum of compound 10g integrated for 10 protons} and were assigned as indicated in table 3.2. In the 13_{C NMR spectrum of this compound, 14 carbon} signals were present, as expected. However, it is important to note that the carbon signals of C-3' (129.8 ppm), C-4' (126.2 ppm), C-2' (124.8 ppm) as well as the carbon of the CF3 group(124.1 ppm) were present as quartets due to fluorine-carbon coupling. Assignments of carbon signals, as present in table 3.2, were based on chemical shifts, HSQC and HMBC correlations and multiplicity.

The 1_{H NMR spectrum of compound 10h indicated the presence of 7 protons, as expected. In this} spectrum fluorine proton-coupling is clear in particular for the signals assigned to H-2ʹ (7.84 ppm) and H-6ʹ (7.53 ppm). In the 13_{C NMR spectrum 13 carbon signals were present and in this case} the carbon signals of C-4' (160.3 ppm), C-1' (132.2 ppm), C-6' (129.4 ppm), C-5' (117.1 ppm), and C-3' (110.0 ppm) presented as doublets due to fluorine-carbon coupling.

10e 10h

10i 8

Figure 3.1: IR spectra of selected compounds.

N O Br F H 5 4 3 6' 5' 2' 3 2 1 " " " S O Cl Br F 4 3 6' 5' 2' 3 2 1 " " S O H3C Br F 1 2 3 2' 5' 6' 3 4" " O O OH Cl H3C 6' 5' 3' 2' 3 2 1 6 5 3" " "

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The IR spectroscopy results of compounds 10e, 10h, 10i and 8 will be discussed (figure 3.1) as representative examples. The characteristic stretching vibrations observed are consistent with the functional groups present in the structures of the synthesized chalcone analogues, although they occurred at wavenumbers lower than expected, probably due to the presence of the conjugated system (Devi et al., 2008, Hergert & Kurth, 1953). The strong band at 3252 cm-1 _{in the IR spectrum} of compound 10e is assigned as the (NH) stretching vibration , while the bands at 1648, 1648, 1588 and 1574 cm-1 _{are assigned as the carbonyl (C=O) for compounds 10e, 10h, 10i and 8,} respectively. The results indicate that replacing the (10i) electron donating group (CH3) on the thiophene ring with an (10h) electron drawing group (Cl) results in a shift to lower frequencies. In general the strong bands at 1591-1496 cm-1 _{represent the stretching vibrations of the double bond} as well as the aromatic (C=C) stretching vibrations. Bands observed at 1600-2000 cm-1 _{are also} due to the presence of the aromatic rings. Interestingly the alcohol (OH) absorption band of compound 8 was not seen in the IR spectrum; this might be due to an intramolecular hydrogen bond with the carbonyl oxygen as seen in literature (Devi et al., 2008, Hergert & Kurth, 1953).

Physical data of chalcones

(2E)-1-(5-chlorothiophen-2-yl)-3-[4-(trifluoromethyl)phenyl]-prop-2-en-1-one (10a)

S

Cl

O

CF

The title compound was prepared from 4-(trifluoromethyl)benzaldehyde and 2-acetyl-5-cholorothiophene in a yield of 18%: mp 126.6-126.9 °C, white crystals. 1_{H NMR (600 MHz, CDCl}

3) δ 7.82 (d, J = 15.6 Hz, 1H), 7.72 (d, J = 8.3 Hz, 2H), 7.70 – 7.63 (m, 3H), 7.38 (d, J = 15.6 Hz, 1H), 7.02 (d, J = 4.0 Hz, 1H). 13_{C NMR (151 MHz, CDCl}

3) δ 180.5, 143.8, 142.4, 140.4, 137.8, 132.0 (q, JC-F = 32.5 Hz), 131.6, 128.6 (2C), 127.8, 125.9 (2C, q, JC-F = 3.8 Hz), 123.7 (q, JC-F = 272.3 Hz), 122.5. APCI-HRMS m/z: 315.9931 [M]+ _{calcd for C}

14H8ClF3OS,found 315.9928; purity (HPLC): 99%. IR νmax (cm-1): 1645, 1594, 1418, 1320, 1161, 1111, 1068, 800.

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O

Cl

N

H

The title compound was prepared from 3-chlorobenzaldehyde and 2-acetylpyrrole in a yield of 58%: mp 163.2-163.5 °C, pale yellow crystals. 1_{H NMR (600 MHz, DMSO-d6) δ 12.02 (s, 1H),} 8.01 (br s, 1H), 7.81 – 7.74 (m, 2H), 7.62 (d, J = 15.7 Hz, 1H), 7.49 – 7.41 (m, 3H), 7.18 (br s, 1H), 6.28 (dd, J = 2.3, 3.8 Hz, 1H). 13_{C NMR (151 MHz, DMSO-d6) δ 177.5, 139.1, 137.2, 133.8, 133.1,} 130.7, 127.7, 127.5, 126.8, 124.7, 118.0, 110.3. APCI-HRMS m/z: 231.0445 [M]+ _{calcd for} C13H10ClNO, found 231.0439; purity (HPLC): 100%. IR νmax (cm-1): 3252, 1646, 1588, 1559, 1409, 976, 785, 746, 676. (2E)-3-(3-chlorophenyl)-1-(6-methoxypyridin-3-yl)prop-2-en-1-one (10c)

N

O

H

C

O

Cl

The title compound was prepared from 3-chlorobenzaldehyde and 5-acetyl-2-methoxypyridine in a yield of 47%: mp 127.9-128.9 °C, cream coloured crystals. 1_{H NMR (600 MHz, CDCl}

3) δ 8.88 (d, J = 2.4 Hz, 1H), 8.22 (dd, J = 2.5, 8.7 Hz, 1H), 7.73 (d, J = 15.5 Hz, 1H), 7.61 (br s, 1H), 7.51 – 7.42 (m, 2H), 7.42 – 7.32 (m, 2H), 6.83 (d, J = 8.8 Hz, 1H), 4.02 (s, 3H). 13_{C NMR (151 MHz,} CDCl3) δ 187.3, 166.7, 149.2, 142.9, 138.7, 136.5, 135.0, 130.4, 130.2, 127.9, 127.4, 126.7, 122.4, 111.4, 54.1. APCI-HRMS m/z: 273.0551 [M]+ _{calcd for C}

15H12ClNO2, found 273.0551; purity (HPLC): 97%. IR νmax (cm-1): 2946, 1655, 1607, 1579, 1560, 1219, 1016, 795.

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S

_Cl

O

OH

O

H

C

The title compound was prepared from 5-choloro-2-thiophenecarboxaldehyde and 2'-hydroxy-4'-methoxyacetophenone in a yield of 1.8%: mp 145.7-146.3 °C, bright yellow crystals. 1_{H NMR (600} MHz, CDCl3) δ 13.4 (s, 1H), 7.85 (d, 15.1 Hz, 1H), 7.74 (d, J = 8.9 Hz, 1H), 7.21 (d, J = 15.1 Hz, 1H), 7.14 (d, J = 3.9 Hz, 1H), 6.92 (d, J = 3.9 Hz, 1H), 6.49 (dd, J = 8.9, 2.5 Hz, 1H), 6.46 (d, J = 2.5 Hz, 1H), 3.86 (s, 3H). 13_{C NMR (151 MHz, CDCl}

3) δ 190.8, 166.7, 166.3, 139.0, 136.1, 133.9, 131.9, 131.0, 127.7, 119.0, 113.9, 107.9, 101.0, 55.6. APCI-HRMS m/z: 294.0112 [M]+ _{calcd for} C14H11ClO3S, found 294.0109; purity (HPLC): 94%. IR νmax (cm-1): 1634, 1570, 1523, 1368, 1262, 1208, 957, 779. (2E)-3-(3-bromo-4-fluorophenyl)-1-(1H-pyrrol-2-yl)prop-2-en-1-one (10e)

N

O

Br

F

H

The title compound was prepared from 3-bromo-4-fluorobenzaldehyde and 2-acetylpyrole in a yield of 60%: mp 190.5-191.3 °C, yellow powder. 1_{H NMR (600 MHz, DMSO-d}

6) δ 12.01 (s, 1H), 8.30 (dd, J = 6.9, 2.2 Hz, 1H), 7.88 (ddd, J = 8.6, 4.8, 2.1 Hz, 1H), 7.73 (d, J = 15.7 Hz, 1H), 7.60 (d, J = 15.7 Hz, 1H), 7.47 – 7.40 (m, 2H), 7.17 (t, J = 1.8 Hz, 1H), 6.27 (dd, J = 3.8, 2.4 Hz, 1H).13_C NMR (151 MHz, DMSO-d6) δ 177.5, 159.0 (d, JC-F = 253.6 Hz), 138.1, 133.4 (d, JC-F = 3.7 Hz), 133.1, 133.0, 130.4 (d, JC-F = 7.8 Hz), 126.7, 124.4, 117.9, 117.1 (d, JC-F = 22.5 Hz), 110.3, 108.9 (d, JC-F = 21.2 Hz). APCI-HRMS m/z: 292.9846 [M]+ calcd for C13H9BrFNO, found 292.9847; purity (HPLC): 98%. IR νmax (cm-1): 3252, 1648, 1591, 1493, 1403, 1251, 1114, 975, 816, 747.

P ag e

62

N

O

CF

H

The title compound was prepared from 4-(trifluoromethyl)benzaldehyde and 2-acetylpyrole in a yield of 21%: mp 156.0-157.3 °C, yellow crystals. 1_{H NMR (600 MHz, CDCl}

3) δ 10.26 (br s, 1H), 7.84 (d, J = 15.7 Hz, 1H), 7.73 (d, J = 8.2 Hz, 2H), 7.66 (d, J = 8.2 Hz, 2H), 7.42 (d, J = 15.8 Hz, 1H), 7.19 – 7.16 (m, 1H), 7.15 – 7.10 (m, 1H), 6.40 – 6.35 (m, 1H). 13_{C NMR (151 MHz, CDCl}

3) δ 178.3, 140.3, 138.4, 132.9, 131.5 (q, JC-F = 32.8 Hz), 128.3 (2C), 126.2, 125.8 (2C, q, JC-F = 3.8 Hz), 124.2, 123.8 (q, JC-F = 273.0 Hz), 117.1, 111.2. APCI-HRMS m/z: 265.0709 [M]+ calcd for C14H10F3NO, found 265.0705; purity (HPLC): 100%. IR νmax (cm-1): 3265, 1647, 1587, 1541, 1398, 1317, 1170, 1131, 118, 833, 738. (2E)-1-(1H-pyrrol-2-yl)-3-[3-(trifluoromethyl)phenyl]prop-2-en-1-one (10g)

N

O

CF

H

The title compound was prepared from 3-(trifluoromethyl)benzaldehyde and 2-acetylpyrole in a yield of 11%: mp 166.6-167.8 °C,yellow crystals 1_{H NMR (600 MHz, DMSO-d}

6) δ 12.05 (s, 1H),

8.26 (s, 1H), 8.14 (d, J = 7.8 Hz, 1H), 7.87 (d, J = 15.8 Hz, 1H), 7.77 – 7.71 (m, 2H), 7.66 (t, J = 7.8 Hz, 1H), 7.47 (br d, J = 3.9 Hz, 1H), 7.19 (br s, 1H), 6.29 (dd, J = 2.3, 3.8 Hz, 1H). 13_{C NMR} (151 MHz, DMSO-d6) δ 177.5, 138.9, 136.1, 133.0, 132.4, 129.9, 129.8 (q, JC-F = 31.7 Hz), 126.8, 126.2 (q, JC-F = 3.8 Hz), 125.0, 124.8 (q, JC-F = 3.7 Hz), 124.1, (q, JC-F = 272.8 Hz), 118.0, 110.2. APCI-HRMS m/z: 265.0709 [M]+ _{calcd for C}

14H10F3NO, found 265.0714; purity (HPLC): 100%. IR νmax (cm-1): 3252, 1645, 1573, 1544, 1329, 1108, 1099, 1053, 975, 748, 690.

P ag e

63

S

O

Cl

Br

F

The title compound was prepared from 3-bromo-4-fluorobenzaldehyde and 2-acetyl-5-chlorothiophene in a yield of 14%: mp 151.3-151.9 °C, yellow crystals. 1_{H NMR (600 MHz, CDCl}

3) δ 7.84 (dd, J = 2.1, 6.6 Hz, 1H), 7.71 (d, J = 15.6 Hz, 1H), 7.65 (d, J = 4.1 Hz, 1H), 7.53 (ddd, J = 2.1, 4.7, 8.5 Hz, 1H), 7.23 (d, J = 15.5 Hz, 1H), 7.17 (t, J = 8.3 Hz, 1H), 7.02 (d, J = 4.0 Hz, 1H). 13_{C NMR (151 MHz, CDCl} 3) δ 180.4, 160.3 (d, JC-F = 253.8 Hz), 143.9, 141.6, 140.2, 133.1, 132.2 (d, JC-F = 3.9 Hz), 131.4, 129.4 (d, JC-F = 7.7 Hz), 127.8, 121.1, 117.1 (d, JC-F = 22.9 Hz), 110.0 (d, JC-F =21.7 Hz). APCI-HRMS m/z: 343.9068 [M]+ calcd for C13H7BrClFOS, found 343.9067; purity (HPLC): 100%. IR νmax (cm-1): 1648, 1586, 1490, 1416, 1402, 1194, 969, 818, 800. (2E)-3-(3-bromo-4-fluorophenyl)-1-(5-methylthiophen-2-yl)prop-2-en-1-one (10i)

S

O

H

C

Br

F

The title compound was prepared from 3-bromo-4-fluorobenzaldehyde and 2-acetyl-5-methylthiophene in a yield of 58%: mp 155.6 -156.2 °C, cream coloured crystals. 1_{H NMR (600} MHz, CDCl3) δ 7.83 (dd, J = 6.5, 2.1 Hz, 1H), 7.71 – 7.65 (m, 2H), 7.52 (ddd, J = 8.5, 4.7, 2.2 Hz, 1H), 7.29 (d, J = 15.6 Hz, 1H), 7.15 (t, J = 8.3 Hz, 1H), 6.86 (d, J = 3.7 Hz, 1H), 2.57 (s, 3H). 13_C NMR (151 MHz, CDCl3) δ 181.0, 160.0 (d, JC-F = 251.4 Hz), 150.6, 143.1, 140.5, 133.0, 132.7, 132.6 (d, JC-F = 4.0 Hz), 129.2 (d, JC-F = 7.7 Hz), 127.0, 122.3, 117.0 (d, JC-F = 22.9 Hz), 109.8 (d, JC-F = 21.6 Hz), 16.15. APCI-HRMS m/z: 323.9614 [M]+ calcd for C14H10BrFOS, found 323.9609; purity (HPLC): 99.5%. IR νmax (cm-1): 1588, 1496, 1438, 1218, 973, 960, 810.

P ag e

64

O

O

OH

Cl

H

C

The title compound was prepared from 4-chlorobenzaldehyde and 2'-hydroxy-4'-methyoxyacetophenone in a yield of 1.7%: mp 124.8-126.6 °C, bright yellow crystals. 1_{H NMR (600} MHz, CDCl3) δ 13.38 (s, 1H), 7.84 – 7.79 (m, 2H), 7.58 (d, J = 8.5 Hz, 2H), 7.54 (d, J = 15.5 Hz, 1H), 7.40 (d, J = 8.2 Hz, 2H), 6.52 – 6.45 (m, 2H), 3.86 (s, 3H).13_{C NMR (151 MHz, CDCl}

3) δ 191.5, 166.7, 166.3, 142.8, 136.5, 133.2, 131.2, 129.6 (2C), 129.3 (2C), 120.7, 114.0, 107.9, 101.0, 55.6. APCI-HRMS m/z: 288.0548 [M]+ _{calcd for C}

16H13ClO3, found 288.0543; purity (HPLC): 100%. IR νmax (cm-1): 1574, 1559, 1505, 1273, 1200, 1085, 956, 826, 788.

3.6 SUMMARY

All compounds were successfully synthesized using a standard literature procedure (Cocconcelli et al., 2008), and fully characterized by NMR and IR spectroscopy, as well as mass spectrometry. Melting points were determined and purity was evaluated by HPLC analyses. Compound (8), a known MAO inhibitor was also resynthesized for comparative purposes.