Synthesis of novel arylfurfurylchalcones

Article abstract of DOI:10.14233/ajchem.2013.14590A

Various aryl furans-2-carbaldehyde chalcones with different acetophenones were prepared and characterized through their elemental analyses and spectroscopic techniques (FTIR, ¹H NMR, ¹³C NMR and mass spectra).

Full text of DOI:10.14233/ajchem.2013.14590A

Asian Journal of Chemistry; Vol. 28, No. 6 (2016), 1210-1214
A
SIAN
J
OURNAL OF HEMISTRY
C
http://dx.doi.org/10.14233/ajchem.2016.19624
Synthesis of Arylfurfural Oximes and Their Biological Evaluation
2
3
1
1
SAMINA ASLAM1,2,*, SAMIA KHAKWANI , AREESHA NAZEER , MEHRZADI NOUREEN SHAHI , ASMA YAQOOB ,
1
1
1
1
HAMNA SHAFIQ , RAFIA MANAZER , FAIZUL HASSAN NASIM and MISBAHUL AIN KHAN
1Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
2Department of Chemistry, Women University Multan, Multan, Pakistan
3Institute of Chemistry, University of the Punjab, Quaid-e-Azam Campus, Lahore, Pakistan
*Corresponding author: E-mail: saminaaslam2009@gmail.com
Received: 18 September 2015;
Accepted: 14 January 2016;
Published online: 29 February 2016;
AJC-17776
1
Various oximes of arylfurfural were prepared and characterized through elemental analysis and spectroscopic techniques (FTIR, H
NMR, 13C NMR and Mass). Synthesized compounds were tested for their antioxidant, tyrosinase and chemotrypson activities.
Keywords: Arylfurans, Oximes, Meerwein reaction, Antioxident activity.
recrystallization (for solids) or by redistillation (for liquids)
as necessary. Thin layer chromatography was performed using
aluminium sheets (Merck) coated with silica gel 60 F254. IR
spectra were recorded by using an IR Perkin-Elmer Spectrum
1 FTIR spectrophotometer and peaks are reported max (neat)/
cm-1 which refer to the min wave numbers. Proton magnetic
resonance spectra were recorded in CDCl3 with BrukerAM 300
spectrometers (Rheinstetten-Forchheim, Germany) operating
at 300 MHz. 13C NMR spectra were recorded in CDCl3 with
BrukerAM 300 spectrometer operating at 75 MHz. Tetramethyl-
silane was used as an internal standard. Elemental analyses
for C, H and N were recorded with Perkin-Elmer 2400 Series II
CHN analyzer. Melting points were recorded on a GallenKamp
apparatus and are uncorrected.
INTRODUCTION
Conversion of carbonyl functionalities into oximes is an
important reaction in organic chemistry since oximes are highly
crystalline compounds that find applications not only for
protection of aldehyde function but also for the purification
and characterization of carbonyl compounds [1,2]. Conversion
into nitriles [3], nitro compounds [4,5], nitrones [6], amines
[7] and synthesis of azaheterocycles [8] are some of the synthetic
application of the oximes. They are also useful for selective
α-activation [9] and are extensively used as intermediates for
the preparation of amides by the Beckmann rearrangement
[10,11]. In inorganic chemistry, oximes act as a versatile ligand
[12]. These also have applications as fungicides and herbicides
[13].
One such example is 1-pheneyl-3-trifluoromethyl-5-
pheoxypyrazole-4-carbaldehyde oxime (A) [12]. Another
oxime(E)-tiglaldoxime is found to be sweeter than sucrose
[14]. There are some reports that some oxime esters of (A) or
related structures show insecticidal activity and are good plant
growth regulators [15], yet others have good antiviral activity
[16]. Some flavanone oxime N,N-diethylaminoethyl ethers
were found to have good antioxidant properties [17].
Our continuous interest in the chemistry of arylfurans [18-
21] led us to the synthesis of 5-arylfuran-2-carbaldehydes
oximes and their biological screening.
5-Arylfuran 2-carbldehydes: These were prepared as
described in an earlier publication [21].
General procedure for the preparation of oximes: Equi-
molecular quantities (5 mmol) of 5-arylfuran-2-carbaldehyde
and hydroxylamine hydrochloride were refluxed in ethanol
for 30 min in the presence of 2, 3 drops of piperidine as a
catalyst. On cooling precipitates were formed which were
filtered, dried and recrytallized from ethanol.
5-(4'-Methyl benzoate)furan-2-carbaldehyde (1):
Yield: 0.78 g (85 %) m.p.: 102-104 °C; FTIR (KBr, νmax, cm-1):
1633.68 (C=N oxime), 2359.67 (aromatic ring), 1722 (C=O
1
ester). H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.823-
7.452 (4H, m, arom.), 7.283 (1H, d, J = 3.1, H-3), 6.940 (1H,
d, J = 3.1, H-4), 2.524 (3H, s, CH3). 13C NMR (CDCl3, 75
MHz) δ ppm: 164.95 (C=O ester), 153.78, 151.90, 133.89,
131.45, 130.67, 130.13, 129.83, 127.65, 121.40, 118.79,
EXPERIMENTAL
All the reagents and solvents were used as obtained from
the supplier. However when required these were purified by

Vol. 28, No. 6 (2016)
Synthesis of Arylfurfural Oximes and Their Biological Evaluation 1211
109.34 (Ar-C), 15.43 (CH3); Anal. calcd. for C13H11NO4: C
63.67; H 4.48; N 5.71 Found C 63.46; H 4.39; N 5.45 %.
5-(2'-Nitrophenyl)furan-2-carbaldehyde oxime (2):
Yield: 0.8 g (75 %) m.p.: 194 °C, FTIR (KBr, νmax, cm-1):1639.02
(C=N oxime) 1532.80 and 1350.86 (Asym and sym-NO2), 1H
NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.992-7.267 (4H, m,
arom.), 7.096 (1H, d, J = 3.9, H-3), 6.910 (1H, d, J = 3.9, H-
4).13C NMR (CDCl3, 75 MHz) δ ppm: 151.03, 150.28, 150.25,
147.17, 132.82, 130.27, 129.58, 124.25, 122.20, 119.50,
112.40 (Ar-C); Anal. calcd. for C11H8N2O4: C 56.89; H 3.44;
N 12.06, Found C 56.75; H 3.40; N 11.86 %.
5-(3'-Nitrophenyl)furan-2-carbaldehyde oxime (3):
Yield: 0.75 g (80 %) m.p.: 240 °C; FTIR (KBr, νmax, cm-1):
1637.98 (C=N oxime) 1525.33 and 1351.43 (Asym and sym-
NO2), 2362.91 (aromatic ring). 1H NMR (CDCl3, 300 MHz),
δ ppm (J, Hz): : 8.560-7.518 (4H, m, arom.), 7.444 (1H, d, J =
3.1, H-3), 7.306 (1H, d, J = 3.1, H-4). 13C NMR (CDCl3, 75
MHz) δ ppm: 154.56, 148.90, 147.34, 133.89, 131.45, 128.79,
127.90, 122.56, 121.34, 112.89, 110.98 (Ar-C); Anal. calcd.
for C11H8N2O4: C 56.89; H 3.44; N 12.06, Found C 56.69; H
3.30; N 11.98 %.
5-(4'-Nitrophenyl)furan-2-carbaldehyde oxime (4):
Yield: 0.8 g (85 %) m.p.: 152 °C; FTIR (KBr, νmax, cm-1):
1636.99 (C=N oxime) 1536.54 and 1355.78 (Asym and sym
-NO2), 2363.65 (aromatic ring). 1H NMR (CDCl3, 300 MHz),
δ ppm (J, Hz): 7.901-7.321 (4H, m, arom.), 7.650 (1H, d, J =
3.3, H-3), 6.890 (1H, d, J = 3.3, H-4). 13C NMR (CDCl3, 75
MHz) δ ppm: 154.12, 150.91, 147.67, 129.53, 128.91, 125.17,
124.95, 124.52, 124.41, 111.20, 109.04(Ar-C); Anal. calcd.
for C11H8N2O4: C 56.89; H 3.44; N 12.06, Found C 56.74; H
3.29; N 11.84 %.
5-(4'-Bromophenyl)furan-2-carbaldehyde oxime (8):
Yield: 0.78 g (80 %) m.p.: 186 °C; FTIR (KBr, νmax, cm-1):
1628.62 (C=N oxime), 2360.75 (aromatic ring), 1030.15 (C-
Br). 1H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.890-7.425
(4H, m, arom.), 7.290 (1H, d, J = 2.1, H-3), 6.780 (1H, d, J =
2.1, H-4). 13C NMR (CDCl3, 75 MHz) δ ppm: 154.97, 150.15,
149.06, 132.09, 128.40, 126.16, 121.82, 120.04, 109.54 (Ar-
C); Anal. calcd. for C11H8NO2Br: C 49.81; H 3.01; N 5.28,
Found C 49.68; H 2.88; N 5.33 %.
5-(5'-Chloro-2'-nitrophenyl)furan-2-carbaldehyde
oxime (9): Yield: 0.8 g (85 %) m.p.: 190 °C; FTIR (KBr, νmax
,
cm-1): 1633.98 (C=N oxime), 1523.58 and 1345.71 (Asym
and sym -NO2), 2358.21 (aromatic ring), 1097.83 (C-Cl). 1H
NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 8.044-7.282 (3H, m,
arom.), 7.234 (1H, d, J = 3.6, H-3), 7.222 (1H, d, J = 3.6, H-
4).13C NMR (CDCl3, 75 MHz) δ ppm: 150.44, 150.37, 149.65,
145.53, 137.23, 129.88, 128.92, 126.10, 124.00, 119.44,
113.61 (Ar-C).Anal. calcd. for C11H7N2O4Cl: C 49.62; H 2.63;
N 10.52, Found C 49.41; H 2.57; N 10.27 %.
5-(4'-Chloro-2'-nitrophenyl)furan-2-carbaldehyde
oxime (10): Yield: 1.0 g (85 %) m.p.: 240 °C; FTIR (KBr,
ν
max, cm-1): 2363.16 (aromatic ring), 1633.29, (C=N oxime)
1108.62 (C-Cl), 1555.90 and 1342 (Asym and sym -NO2),1H
NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 8.121-7.336 (3H, m,
arom.), 7.167 (1H, d, J = 3.1, H-3), 6.755 (1H, d, J = 3.1, H-
4).13C NMR (CDCl3, 75 MHz) δ ppm: 153.42, 151.90, 148.79,
133.78, 132.67, 131.65, 130.56, 127.43, 126.30, 122.67,
119.70, 112.62 (Ar-C);Anal. calcd. for C11H7N2O4Cl: C 49.62;
H 2.63; N 10.52, Found C 49.50; H 2.45; N 10.28 %.
5-(2'-Chloro-4'-nitrophenyl)furan-2-carbaldehyde
oxime (11): Yield: 0.78 g (80 %) m.p.: 234 °C; FTIR (KBr,
5-(2'-Chlorophenyl)furan-2-carbaldehyde oxime (5):
ν
max, cm-1): 1581.08 (C=N oxime), 2360.42 (aromatic ring),
Yield: 1 g (88 %) m.p.: 170 °C; FTIR (KBr, νmax, cm-1): 2363.07
1108.91 (C-Cl), 1506.66 and 1330.55 (Asym and sym -NO2)
1H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 8.699-7.361 (3H,
m, arom.), 7.349 (1H, d, J = 3.9, H-3), 7.175 (1H, d, J = 3.9,
H-4). 13C NMR (CDCl3, 75 MHz) δ ppm: 151.98, 150.12,
148.76, 133.90, 131.56, 130.63, 127.89, 122.54, 121.23,
119.87, 112.56 (Ar-C). Anal. calcd. for C11H7N2O4Cl: C 49.62;
H 2.63; N 10.52, Found C 49.38; H 2.44; N 10.65 %.
1
(aromatic ring), 1612.88 (C=N oxime) 1088.40 (C-Cl), H
NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.938-7.353 (4H, m,
arom.), 7.340 (1H, d, J = 2.9, H-3), 7.291 (1H, d, J = 2.9, H-
4).13C NMR (CDCl3, 75 MHz) δ ppm: 152.22, 150.45, 148.86,
130.99, 130.85, 130.12, 129.78, 128.97, 127.86, 127.54,
119.60, 113.06(Ar-C). Anal. calcd. for C11H8NO2Cl: C 59.72;
H 3.61; N 6.33, Found C 59.48; H 3.55; N 6.27 %.
5-(2',4'-Dinitrophenyl)furan-2-carbaldehyde oxime
5-(3'-Chlorophenyl)furan-2-carbaldehyde oxime (6):
Yield: 0.8 g (75 %) m.p.: 96 °C; FTIR (KBr, νmax, cm-1):
1559.37 (C=N oxime), 2360.51 (aromatic ring), 1091 (C-Cl).
1H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.745-7.231 (4H,
m, arom.), 7.108 (1H, d, J = 2.1, H-3), 6.930 (1H, d, J = 2.1,
H-4). 13C NMR (CDCl3, 75 MHz) δ ppm: 155.67, 149.80,
134.56, 133.90, 131.20, 128.90, 127.89, 12765, 122.34,
119.78, 110.67 (Ar-C).Anal. calcd. for C11H8NO2Cl: C 59.72;
H 3.61; N 6.33, Found C 59.64; H 3.48; N 6.15 %.
(12): Yield: 0.75 g (78 %) m.p.: 168 °C, FTIR (KBr, νmax,
cm-1): 1595.43 (C=N oxime), 2361.98 (aromatic ring), 1563.21
1
and 1350.56 (Asym and sym -NO2), H NMR (CDCl3, 300
MHz), δ ppm (J, Hz): 7.945-7.455 (3H, m, arom.), 7.198(1H,
d, J = 3.1, H-3), 7.089 (1H, d, J = 3.1, H-4). 13C NMR (CDCl3,
75 MHz) δ ppm: 155.10, 151.32, 148.90, 148.25, 133.78,
131.98, 130.79, 129.45, 127.34, 122.60, 121.62, 119.34,
110.61(Ar-C). Anal. calcd. for C11H7N3O6: C 47.65; H 2.52; N
15.16, Found C 47.52; H 2.40; N 14.87 %.
5-(4'-Chlorophenyl)furan-2-carbaldehyde oxime (7):
Yield: 0.7 g (75 %) m.p.: 202 °C; FTIR (KBr, νmax, cm-1):
1589.21 (C=N oxime), 2362.57 (aromatic ring), 1089.10 (C-
Cl). 1H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.874-7.490
(4H, m, arom.), 7.410 (1H, d, J = 3.1, H-3), 6.843 (1H, d, J =
3.1, H-4).13C NMR (CDCl3, 75 MHz) δ ppm: 154.93, 150.17,
149.03, 133.16, 129.22, 128.09, 125.96, 120.08, 109.08 (Ar-
C); Anal. calcd. for C11H8NO2Cl: C 59.72; H 3.61; N 6.33,
Found C 59.65; H 3.42; N 6.24 %.
5-(2',4'-Dichlorophenyl)furan-2-carbaldehyde oxime
(13): Yield: 0.82 g (85 %) m.p.: 214 °C; FTIR (KBr, νmax
,
cm-1): 1614.35 (C=N oxime), 1563.90 and 1354.67 (Asym
1
and sym -NO2), 2360.72 (aromatic ring). H NMR (CDCl3,
300 MHz), δ ppm (J, Hz): 8.699-7.361 (3H, m, arom.), 7.349
(1H, d, J = 3.1, H-3), 7.175 (1H, d, J = 3.1, H-4). 13C NMR
(CDCl3, 75 MHz) δ ppm: 151.92, 150.65, 133.43, 133.21,
131.87, 130.34, 129.56, 127.65, 123.60, 122.40, 121.72,
118.95, 110.43 (Ar-C).Anal. calcd. for C11H7 NO2Cl2: C 51.76;
H 2.74; N 5.49 Found C 51.63; H 2.58; N 5.24 %.

1212 Aslam et al.
Asian J. Chem.
5-(2',5'-Dichlorophenyl)furan-2-carbaldehyde oxime
5-(2'-Methyl-5'-nitrophenyl)furan-2-carbaldehyde
(14): Yield: 0.76 g (80 %) m.p.: 252 °C; FTIR (KBr, νmax
,
oxime (20): Yield: 0.75 g (80 %) m.p.: 178 °C; FTIR (KBr,
cm-1): 1680.16(C=N), 2359.30 (aromatic ring), 1041.23 cm-1
ν
max, cm-1): 2361.34 (aromatic ring), 1643.67 (C=N oxime),
1
(C-Cl bond). H NMR (CDCl3, 300 MHz), δ ppm (J, Hz):
1523.78 and 1360.65 (Asym and sym -NO2), 1H NMR (CDCl3,
300 MHz), δ ppm (J, Hz): 87.852-7.425 (3H, m, arom.), 7.235
(1H, d, J = 2.3, H-3), 6.980 (1H, d, J = 2.3, H-4), 2.428 (3H,
s, CH3). 13C NMR (CDCl3, 75 MHz) δ ppm: 154.39, 151.23,
133.98, 132.65, 131.06, 130.98, 129.76, 127.54, 122.83, 118.96,
110.67 (Ar-C), 15.67 (CH3); Anal. calcd. for C12H10N2O4: C
58.53; H 4.06; N 11.38, Found C 58.42; H 3.92; N 11.09 %.
3-(5'-Formylfuran-2-yl)benzoic acid oxime (21): Yield:
8.100-7.467 (3H, m, arom.), 7.108 (1H, d, J = 2.9, H-3), 6.923
(1H, d, J = 2.9, H-4). 13C NMR (CDCl3, 75 MHz) δ ppm:
152.34, 151.39, 144.37, 133.87, 131.45, 130.89, 129.34,
127.49, 122.41, 121.65, 118.21, 109.82 (Ar-C). Anal. calcd.
for C11H7 NO2Cl2: C 51.76; H 2.74; N 5.49 Found C 51.48; H
2.55; N 5.29 %.
5-(3',4'-Dichlorophenyl)furan-2-carbaldehyde oxime
(15): Yield: 0.80 g (85 %) m.p.: 182 °C; FTIR (KBr, νmax
,
0.74 g (78 %) m.p.: Decompose < 200 °C; FTIR (KBr, νmax,
cm-1): 2363.72 (aromatic ring), 1634.83 (C=N oxime) 1094.49
cm-1): 1630.45 (C=N oxime), 1686.45 (C=O carboxylic acid),
2362.71 (aromatic ring). 1H NMR (CDCl3, 300 MHz), δ ppm
(J, Hz): 10.783 (1H, s, -OH), 7.789-7.450 (4H, m, arom.),
7.327 (1H, d, J = 2.9, H-3), 6.980 (1H, d, J = 2.9, H-4). 13C
NMR (CDCl3, 75 MHz) δ ppm: 166.10 (C=O of COOH),
155.70, 151.34, 133.89, 132.90, 131.67, 130.67, 129.70, 127.43,
122.70, 118.97, 109.54 (Ar-C). Anal. calcd. for C12H9NO4: C
62.33; H 3.89; N 6.06 Found C 62.19; H 3.72; N 6.25 %.
4-(5'-Formylfuran-2-yl)benzoic acid oxime (22):Yield:
0.72 g (75 %) m.p.: 120 °C; FTIR (KBr, νmax, cm-1): 2545.07
(aromatic ring), 1816.29 (C=O acid), 1568.03 (C=N oxime),
3250.83 (-OH acid). 1H NMR (CDCl3, 300 MHz), δ ppm (J,
Hz): 10.980 (1H, s, -OH), 7.655-7.339 (4H, m, arom.), 7.290
(1H, d, J = 3.1, H-3), 6.845 (1H, d, J = 3.1, H-4). 13C NMR
(CDCl3, 75 MHz) δ ppm: 165.89 (C=O of COOH), 155.70,
151.34, 133.89, 132.90, 131.67, 130.67, 129.70, 127.43, 122.70,
118.97, 109.54 (Ar-C). Anal. calcd. for C12H9NO4: C 62.33; H
3.89; N 6.06 Found C 62.22; H 3.75; N 5.83 %.
1
(C-Cl). H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.931-
7.340 (3H, m, arom.), 7.182 (1H, d, J = 3.1, H-3), 7.021 (1H,
d, J = 3.1, H-4). 13C NMR (CDCl3, 75 MHz) δ ppm: 152.34,
151.39, 144.37, 133.87, 131.45, 130.89, 129.34, 127.49, 122.41,
121.65, 118.21, 109.82 (Ar-C). Anal. calcd. for C11H7NO2Cl2:
C 51.76; H 2.74; N 5.49 Found C 51.68; H 2.54; N 5.20 %.
5-(2',3'-Dichlorophenyl)furan-2-carbaldehyde oxime
(16):Yield: 0.75 g (82 %) m.p.: 210-212 °C; FTIR (KBr, νmax
,
cm-1): 2360.98 (aromatic ring), 1640.89 (C=N oxime), 1091.29
1
(C-Cl). H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 7.930-
7.420 (3H, m, arom.), 7.378 (1H, d, J = 2.9, H-3), 6.993 (1H,
d, J = 2.9, H-4). 13C NMR (CDCl3, 75 MHz) δ ppm: 155.43,
151.89, 133.90, 132.73, 131.56, 130.90, 128.79, 127.65,
121.80, 119.60, 110.65 (Ar-C). Anal. calcd. for C11H7 NO2Cl2:
C 51.76; H 2.74; N 5.49 Found C 51.49; H 2.85; N 5.68 %.
5-(3',5'-Dichlorophenyl)furan-2-carbaldehyde oxime
(17):Yield: 0.8 g (86 %) m.p.: 192 °C; FTIR (KBr, νmax, cm-1):
1558.70 (C=N oxime), 2361.94 (aromatic ring), 1091.25 (C-
Cl). 1H NMR (CDCl3, 300 MHz), δ ppm (J, Hz): 8.023-7.531
(3H, m, arom.), 7.428 (1H, d, J = 2.5, H-3), 6.829 (1H, d, J =
2.5, H-4). 13C NMR (CDCl3, 75 MHz) δ ppm: 153.65, 151.89,
133.72, 132.65, 131.34, 130.98, 130.12, 129.63, 127.33,
122.89, 118.93, 110.98 (Ar-C). Anal. calcd. for C11H7 NO2Cl2:
C 51.76; H 2.74; N 5.49 Found C 51.63; H 2.52; N 5.15 %.
5-(4'-Ethoxycarbonylphenyl)furan-2-carbaldehyde
oxime (18): Yield: 0.76 g (83 %) m.p.: 114-116 °C; FTIR
(KBr, νmax, cm-1): 2370.45 (aromatic ring), 1664.77 (C=N
oxime), 1725.46 (C=O ester), 1H NMR (CDCl3, 300 MHz), δ
ppm (J, Hz): 8.094-7.297 (4H, m, arom.), 7.285 (1H, d, J =
3.3, H-3), 7.117 (1H, d, J = 3.3, H-4), 2.524 (3H, t, J = 4.5,
CH3), 3.560 (2H, d, J = 4.5, CH2). 13C NMR (CDCl3, 75 MHz)
δ ppm: 166.54 (C=O ester), 155.78, 151.75, 134.01, 133.45,
131.90, 130.98, 129.45, 127.56, 122.40, 121.67, 119.09, 110.11
(Ar-C), 64.32 (CH2), 13.90 (CH3);Anal. calcd. for C14H13 NO4:
C 64.86; H 5.01; N 5.40 Found C 64.73; H 5.23; N 5.12 %.
5-(2'-Methyl-3'-nitrophenyl)furan-2-carbaldehyde
oxime (19): Yield: 0.72 g (79 %) m.p.: 136 °C; FTIR (KBr,
5-(2'-Methyl-4'-nitrophenyl)furan-2-carbaldehyde
oxime (23): Yield: 0.75 g (81 %) m.p.: 184-86 °C; FTIR (KBr,
ν
max, cm-1): 2360.21 (aromatic ring), 1630.91 (C=N oxime),
1590.70 and 1365.71 (Asym and sym -NO2), 1H NMR (CDCl3,
300 MHz), δ ppm (J, Hz): 7.765-7.378 (3H, m, arom.), 7.109
(1H, d, J = 2.1, H-3), 6.895 (1H, d, J = 2.1, H-4), 2.541 (3H,
s, CH3). 13C NMR (CDCl3, 75 MHz) δ ppm: 155.45, 151.67,
133.98, 131.65, 130.90, 129.87, 127.83, 126.54, 123.67,
122.32, 118.93, 110.63 (Ar-C), 13.89(CH3); Anal. calcd. for
C12H10N2O4: C 58.53; H 4.06; N 11.38, Found C 58.42; H 4.18;
N 11.02 %.
5-(2'-Chloro-5'-nitrophenyl)furan-2-carbaldehyde
oxime (24): Yield: 0.82 g (90 %) m.p.: 156 °C; FTIR (KBr,
ν
max, cm-1): 2361.34 (aromatic ring), 1643.67 (C=N oxime),
1523.78 and 1360.65 (Asym and sym -NO2), 1H NMR (CDCl3,
300 MHz), δ ppm (J, Hz): 7.980-7.320 (3H, m, arom.), 7.201
(1H, d, J = 3.3, H-3), 6.852 (1H, d, J = 3.3, H-4). 13C NMR
(CDCl3, 75 MHz) δ ppm: 155.80, 151.62, 133.90, 131.63,
130.98, 130.17, 129.65, 128.90, 127.65, 122.78, 121.87,
119.80, 109.97 (Ar-C),Anal. calcd. for C11H7N2O4Cl: C 49.62;
H 2.63; N 10.52, Found C 49.29; H 3.76; N 11.29 %.
ν
max, cm-1): 2363.63(aromatic ring), 1640.75 (C=N oxime),
1518.40 and 1358.08 (Asym and sym -NO2), 1H NMR (CDCl3,
300 MHz), δ ppm (J, Hz): 7.790-7.435 (3H, m, arom.), 7.109
(1H, d, J = 2.3, H-3), 6.845 (1H, d, J = 2.3, H-4), 2.539 (3H,
s, CH3). 13C NMR (CDCl3, 75 MHz) δ ppm: 155.48, 151.23,
133.89, 132.13, 131.78, 127.90, 123.89, 122.45, 119.78,
109.65 (Ar-C), 13.90 (CH3); Anal. calcd. for C12H10N2O4: C
58.53; H 4.06; N 11.38, Found C 58.44; H 3.76; N 11.09 %.
RESULTS AND DISCUSSION
5-Arylfuran-2-carbaldehyde oximes have been prepared
in excellent yield by using a convenient one pot synthesis by
the reaction of the aldehydes with hydroxylamine hydro-
chloride in the presence of piperidine as a catalyst (Scheme-I).

Vol. 28, No. 6 (2016)
Synthesis of Arylfurfural Oximes and Their Biological Evaluation 1213
interesting results are obtained. The compound containing
4-NO2 (1), 4-Cl substituent (6) at para position of the aryl
group and 11 which has 2,4-dinitro substituent at aryl group
show comparable IC50 value with standard ascorbic acid 50.43.
While compound 4, 8, 9, 13, 16 and 22 show significant
antioxidant activities in comparison with the standard.
It can be concluded that the 5-arylfuran-2-carbaldehydes
oximes having the electron withdrawing group (-NO2, -Cl and
-COOH) were the most active compounds.
Tyrosinase activity: Tyrosinase (EC 1.14.18.1) performs
multiple functions in humans. It is glycosylated and copper
containing oxidase which catalyzes the first two steps of
melanogenesis in mammals. Tyrosinase overproduction causes
hyperpigmentation, ocular retinitis pigmentosa; it also
accelerates the induction of catecholamine quinone derivatives
by its oxidase activity; over expression of tyrosinase results in
increased intracellular dopamine contents in association with
the formation of melanin pigments in neuronal stomata which
causes apoptotic cell death.
Tyrosinase forms neuromelanin in human brain and causes
dopamine neurotoxicity as well as contributes to neurodegene-
ration associated with Parkinson’s disease. Tyrosinase also
causes enzymatic browning reaction in damaged fruits during
post-harvest handling and processing. Hyperpigmentation in
human skin and enzymatic browning in fruits are not desirable.
These phenomena have urged researchers to seek new potent
tyrosinase inhibitors for use in food and cosmetics [15-18].
Enzyme assay: Total volume of reaction mixture contained
100 µL, 60 µL 100 mM phosphate buffer, pH 6.8, 10 µL
NH2OH·HCl
Ar
CHO
Ar
CH N OH
Piperidine,
Reflux, 0.5 h
O
O
Scheme-I
The prepared compounds were characterized, besides
other analytical techniques, through their FTIR spectra when
different compounds displayed absorption peaks in their
respective regions as strong peak of a C=N moiety of oxime
have been observed in the region of 1558.73 to 1643.67 cm-1
while NO2 group showed symmetric and asymmetric peaks at
1532.80 and 1350.86 cm-1, respectively. While in compound
17 and 18 peaks of C=O of ester group were observed in the
region of 1710 and 1722 cm-1, respectively. Compound 21
and 22 showed peaks in the region of 1686.45 and 1681.29
cm-1 for the carbonyl group of acid, these compounds also
showed broad absorption band of –OH in the region of 3057.34
and 3250.83 cm-1. Proton NMR and 13C NMR results have been
presented in the experimental section and these values are in
accordance with their structure.
Antioxidant activity: Garret nitric oxide (NO) scavenging
method was used for the determination of antioxidant activity
[14]. The method is based on the principle that nitrate present
in the sample must be reduced to nitrite. This method involves
the determination of nitrite, instead of nitrate in the presence
of Griss reagent. The results are presented in Table-1.
It is clear that most of the compounds show significant
antioxident activities. When the activities of the different
5-arylfuran-2-carbaldehydes oximes are compared, very
TABLE-1
BIOLOGICAL ACTIVITIES RESULTS OF 5-ARYLFURAN-2-CARBALDEHYDE OXIMES
Antityrosinase activity*
Chymotripson activity**
Antioxidant activity***
Compound
No.
Percentage
inhibition
(0.5 mM)
Percentage
inhibition
(0.5 mM)
Percentage
inhibition
(0.5 mM)
Percentage
inhibition
(0.1 mM)
IC50
(µM)
IC50
(µM)
IC50
(µM)
1
2
3
4
5
6
7
8
9
26.27 0.35
-10.59 0.71
60.39 0.25
29.80 0.11
30.59 0.25
90.69 0.14
-10.20 0.25
26.08 0.54
1.57 0.71
85.52 0.41
15.88 0.15
7.45 0.11
49.80 0.31
21.18 0.31
5.88 0.88
0.39 0.35
35.88 0.26
15.49 0.33
14.90 0.82
10.20 0.35
10.98 0.64
–
–
–
38.13 0.12
15.30 0.11
33.73 0.11
17.24 0.04
17.42 0.01
30.36 0.11
50.67 0.10
18.25 0.09
43.18 0.11
30.92 0.05
12.45 0.12
15.23 0.11
12.26 0.13
42.36 0.07
34.54 0.11
43.18 0.08
45.60 0.12
13.45 0.04
18.08 0.10
12.30 0.06
11.42 0.08
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
58.91
NA
NA
96.9
–
55.5
–
85.7
95
NA
58
–
84.01
–
–
97.9
NA
NA
–
NA
91.25
NA
–
42.4 0.8
4.7 0.25
9.6 0.8
21.9 0.7
–
84.94 0.52
-37.9 0.7
27.70 0.98
51.85 0.59
–
< 300
–
–
52.00 0.12
–
–
–
45.2 0.4
–
88.54 0.89
–
26.4 0.42
24.1 0.2
11.2 0.2
45.6 0.41
–
59.4 0.72
52.83 0.82
24.9 0.26
72.9 0.18
–
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Standard
62.2 0.91
–
–
–
–
–
–
–
–
–
–
–
–
–
–
32.1 0.94
–
58.35 0.13
–
–
–
25.3 0.35
4.3 0.23
20.2 0.76
–
12.3 0.39
25.8 0.30
-125 0.23
–
51.08 0.9
-45.82 0.4
41.1 0.47
–
36.9 0.69
54.95 0.56
-44.42 0.72
–
11.18 0.64
18.04 0.82
93.50 0.21
22.28 0.04
36.49 0.04
93.50 0.91
6.04 0.11
8.24 0.11
38.5 0.16
84.1 0.12
50.43
Standard *Kojic acid, Standard **Chemostatin, Standard ***Ascorbic acid

1214 Aslam et al.
Asian J. Chem.
mushroom tyrosinase enzyme (5 units) and 10 µL 0.5 mM
test compound mixed in 96-well plate [19]. Contents were
preincubated for 5 min at 37 °C. After incubation, 20 µL of 10
mM L-dopamine was added as a substrate. Contents were
mixed and incubated for further 0.5 h. Absorbance was taken
at 490 nm using Synergy HT BioTek 96-well plate reader. The
enzyme inhibition (%) was calculated by the bellow formula:
Conclusion
A good and efficient method of 5-arylfuran-2-carbaldehydes
oximes from the reaction of 5-arylfuran-2-carbaldehyde is
presented. Although some of these oximes show reasonable
antioxidant and tyrosinase activity however none of the oximes
were active against chymotrypsin activity. These 5-arylfuran-
2-carbaldehydes oximes can serve as starting materials for the
synthesis of a variety of heterocyclic compounds.
Absorbance of test sample
Absorbance of control


Inhibition (%) = 100 −
×100




ACKNOWLEDGEMENTS
IC50 values (concentration at which there is 50 % in
enzyme catalyzed reaction) compounds were calculated using
EZ-Fit Enzyme Kinetics Software (Perrella Scientific Inc.
Amherst, USA).
When tyrosinase activity of 5-arylfuran-2-carbaldehyde
oximes were compared, most of the compounds showed less
significant results (Table-1) while compounds 5 and 9 having
(3-Cl and 4-Cl-2-NO2, respectively) showed significant activity.
So, it can be concluded from these results that 5-arylfuran-2-
carbaldehydes oximes having electron withdrawing group
(-NO2 and -Cl) were the active compounds.
Chymotrypsin assay: The α-chymotrypsin inhibition
activity is performed according to slightly modified method
of Athar et al. [20]. A total volume of 100 µL assay mixture
contained 60 µL Tris-HCl buffer (50 mM pH 7.7), 10 µL test
compound and 20 µL (1.8 units) purified α-chymotrypsin
enzyme (Sigma, USA).The contents were mixed and incubated
for 20 min at 37 °C and pre-read at 410 nm. The reaction was
initiated by the addition of 10 µL (1.3 mM) substrate (N-succinyl
phenyl-alanine-p-nitroanilide). The change in absorbance was
observed after 0.5 h at 410 nm. Synergy HT (BioTek, USA)
96-well plate reader was used in all experiments. All reactions
were performed in triplicates. The positive and negative controls
were included in the assay. Chymostatin (0.5 mM well-1) was
used as a positive control. The percentage inhibition was
calculated by formula given below.
The authors (SA and AN) would like to acknowledge the
financial support by HEC Pakistan in the form of an indigenous
PhD scholarships and IRSIP Fellowships. One of the authors,
(MAK) thanks HEC for the Instrumental analysis support.
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

IC50 values of compounds were calculated using EZ-Fit
Enzyme Kinetics Software (Perrella Scientific Inc. Amherst,
USA).
5-Arylfuran-2-carbaldehyde oximes were tested for their
chymotrypson activity, but all synthesized compound showed
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