Stereoselective synthesis and antifungal activities of (E)-α- (methoxyimino)benzeneacetate derivatives containing 1,3,5-substituted pyrazole ring

Article abstract of DOI:10.1021/jf060074f

Thirteen novel (E)-α-(methoxyimino)benzeneacetate derivatives, the analogues of strobilurins, which contain two pharmacophoric substructures of the methyl (E)-methoxyiminoacetate moiety and 1,3,5-substituted pyrazole ring, were stereoselectively synthesized. It was found that the coupling reaction could give stereoselectively (E:Z ca. 14:1) the key intermediate material (E)-methyl 2-(hydroxyimino)-2-o-tolyl acetate (2). An X-ray crystallographic structure determination was carried out in a representative product. The preliminary bioassays indicated that all of the compounds 1 showed potent fungicidal activity against Rhizoctonia solani, Botrytis cinereapers, Gibberella zeae, Physalospora piricola, and Bipolaris mayclis.

Full text of DOI:10.1021/jf060074f

3636 J. Agric. Food Chem. 2006, 54, 3636−3640
Stereoselective Synthesis and Antifungal Activities of
(E)-
r
-(Methoxyimino)benzeneacetate Derivatives Containing
1,3,5-Substituted Pyrazole Ring
YAN LI,*,†,‡ HONG-QUAN ZHANG,† JIE LIU,† XIANG-PING YANG,† AND
‡
ZHAO-JIE LIU
Key Laboratory of Synthesis and Application of Organic Functional Molecules of the Education
Ministry, Hubei University, Wuhan, Hubei 430062, China and Key Laboratory of Pesticide &
Chemical Biology of the Education Ministry, Central China Normal University, Wuhan, Hubei
430079, China
Thirteen novel (E)-R-(methoxyimino)benzeneacetate derivatives, the analogues of strobilurins, which
contain two pharmacophoric substructures of the methyl (E)-methoxyiminoacetate moiety and 1,3,5-
substituted pyrazole ring, were stereoselectively synthesized. It was found that the coupling reaction
could give stereoselectively (E:Z ca. 14:1) the key intermediate material (E)-methyl 2-(hydroxyimino)-
2-o-tolyl acetate (2). An X-ray crystallographic structure determination was carried out in a
representative product. The preliminary bioassays indicated that all of the compounds 1 showed
potent fungicidal activity against Rhizoctonia solani, Botrytis cinereapers, Gibberella zeae, Phys-
alospora piricola, and Bipolaris mayclis.
KEYWORDS: Strobilurins; (E)-r-(methoxyimino)benzeneacetates; 1,3,5-substituted pyrazoles; fungicidal
INTRODUCTION
Normal University. The solvents and reagents were used as received
or were dried prior to use as needed. Melting points were determined
with a Tech X-6 micromelting points apparatus made in Beijing.
Infrared spectra were recorded on a Perkin-Elmer PE-SPECTRUM ONE
apparatus, for solid compounds in KBr-pressed disks, and the V values
were recorded in wavenumbers (cm-1). 1H NMR and 13C NMR spectra
were obtained on a Varian Unity INOVA-600 MHz spectrometer (600
MHz, 1H; 150 MHz, 13C) in CDCl3 with tetramethylsilane as the internal
reference. The mass spectra were obtained on a Finnigen Trace Mass
spectrometer (70 eV). Elemental analyses (C, H, and N) were performed
with a Perkin-Elmer PE-2400 elemental analyzer.
Strobilurins are a class of highly potent antifungal compounds,
and they have, therefore, been applied to agricultural disinfec-
tants in many countries (1, 2). These compounds act through
inhibition of mitochondrial respiration by blocking electron
transfer at the ubiquinol oxidation center (Qo site) of the
cytochrome bc1-enzyme complex (complex III) (3), and they
have a methyl (E)-methoxyiminoacetate moiety as a common
pharmacophoric substructure (4). On the other hand, substituted
pyrazole ring derivatives also exhibit a broad spectrum of
biological activities such as antimicrobial (5-7), herbicidal (8),
antitumor (9, 10), and antiinflammatory (11) activities. In view
of these facts, we have developed a new and efficient method
for stereoselective synthesis of the key intermediate methyl (E)-
R-(methoxyimino)benzeneacetate and synthesized some novel
analogues of strobilurins, which contain both methyl (E)-
methoxyiminoacetate and 1,3,5-substituted pyrazole ring moi-
eties, viz. methyl (RE,E)-R-(methoxyimino)-2-[(1,3-dimethyl-
5-substituted 1H-pyrazol-4-yl)methyleneaminooxymethyl]-
benzeneacetates (1), in order to obtain better fungicidal activities.
X-ray Diffraction. Colorless blocks of 1g (0.50 mm × 0.25 mm ×
0.20 mm) were mounted on a quartz fiber with protection oil. Cell
dimensions and intensities were measured at 293 K on a Bruker
SMART CCD area detector diffractometer with graphite-monochro-
mated Mo KR radiation (λ ) 0.71073 Å); θmax ) 26.00; 24306
measured reflections; 4578 independent reflections (Rint ) 0.0615) of
which 2596 had |Fo| > 2|Fo|. Data were corrected for Lorentz and
polarization effects and for absorption (Tmin ) 0.9526; Tmax ) 0.9807).
The structure was solved by direct methods using SHELXS-97 (12);
all other calculations were performed with Bruker SAINT system and
Bruker SMART programs (13). Full-matrix least-squares refinement
2
based on F2 using the weight of 1/[σ2(Fo ) + (0.0786P)2 + 0.6674P]
gave final values of R ) 0.0586, ωR ) 0.1723, and GOF(F) ) 1.019
for 332 variables and 2237 contributing reflections. Maximum shift/
error ) 0.0000(3), max/min residual electron density ) 0.292/-0.212
e Å-3. Hydrogen atoms were observed and refined with a fixed value
of their isotropic displacement parameter. The general synthesis of target
compounds is shown in Figure 1.
MATERIALS AND METHODS
Materials. Rhizoctonia solani, Botrytis cinereapers, Gibberella zeae,
Physalospora piricola, and Bipolaris mayclis were provided through
the courtesy of the Center for Analysis and Testing, Central China
Preparation of Methyl 2-Hydroxyimino-2-o-tolyl Acetate (2). To
3.92 g (38 mmol) methyl 2-hydroxyiminoacetate and 17 mL of water
placed in a round-bottom flask were added 0.65 g (2.6 mmol) of cupric
sulfate hydrate, 0.1 g (0.79 mmol) of sodium sulfite, and a solution of
* To whom correspondence should be addressed. Tel: 86-27-50865369.
Fax: 86-27-88663043. E-mail: liyanok@hotmail.com.
† Hubei University.
‡ Central China Normal University.
10.1021/jf060074f CCC: $33.50
© 2006 American Chemical Society
Published on Web 04/15/2006

(E)-
R-(Methoxyimino)benzeneacetate Derivatives
J. Agric. Food Chem., Vol. 54, No. 10, 2006 3637
Figure 1. General synthetic route for the target compound 1.
16 g of sodium acetate hydrate in 18 mL of water. The solution was
maintained at 5-10 °C and stirred vigorously. Neutral 2-methylphenyl
diazonium chloride (5.87 g, 38 mmol) solution was then slowly
introduced into the oxime solution. After the addition of the diazonium
salt solution was complete, the stirring was continued for an additional
hour. Then, the mixture was stirred for 2 h at 20 °C, the mixture was
extracted with 3 × 10 mL of ether. The combined ether extracts were
washed with an aqueous 10% sodium bicarbonate solution and then
with brine, dried over anhydrous magnesium sulfate, filtered, and
concentrated. The residue was subjected to column chromatography
using a mixture of n-hexane and ethyl acetate (4:1) as an eluent to
obtain the compound (Z)-2: upper spot, Rf 0.63, as an oil; 0.22 g, 3%.
IR (KBr): 3353, 1728, 1620, 1445, 1314, 1032, 930, 757, 732, 670
1438, 1321, 1220, 1067, 1018, 958, 762 cm-1. 1H NMR: δ 3.86 (3H,
s, -COOMe), 4.04 (3H, s, N-OCH3), 4.31 (2H, s, -CH2-), 7.13 (1H,
dd, J1 ) 7.8 Hz, J2 ) 1.2 Hz, 3-ArH), 7.35-7.40 (2H, m, 2 × Ar-H),
7.46 (1H, dd, J1 ) 7.8 Hz, J2 ) 0.6 Hz, 6-ArH).
Preparation of Methyl (E)-r-(Methoxyimino)-2-(o-phthalimi-
doxymethyl)benzeneacetate (5). A dry 100 mL round-bottom flask
equipped with a magnetic stirrer and nitrogen inlet was charged with
0.98 g (6 mmol) of N-hydroxyphthalimide, 0.24 g (6 mmol) of
powdered sodium hydroxide, and 50 mL of DMF. The dark red solution
was stirred at ambient temperature for 20 min, followed by the addition
of 1.72 g (6 mmol) of (E)-4 in one portion. The reaction was stirred at
ambient temperature overnight, then poured into 50 mL of water, and
stirred for 1 h to afford a solid, which was collected by vacuum filtration
and washed with water and hexane. The tan solid was dried under
vacuum at 40 °C overnight, yielding 2.01 g (91%) of 5 as a light brown
solid. 1H NMR: δ 3.84 (s, 3H, COOMe), 3.98 (s, 3H, NO-CH3), 5.07
(s, 2H, -CH2-), 7.18 (d, J ) 7.2 Hz, 1H, 3-ArH), 7.45-7.51 (m, 2H,
3′ and 4′-ArH), 7.73-7.80 (m, 4H, 2′, 5′, 4 and 5-ArH), 7.83 (d, J )
7.2 Hz, 1H, 3-ArH).
Preparation of Methyl (E)-r-(Methoxyimino)-2-(aminoxymeth-
yl)benzeneacetate (6). To a 50 mL round-bottom flask equipped with
a magnetic stirrer were added 1.47 g (4 mmol) of 5, 20 mL of anhydrous
methanol, and 0.22 g (4.4 mmol) of hydrazine monohydrate. The flask
was stoppered, and the reaction was stirred at ambient temperature for
2 h. The resulting solid was removed by filtration, and the filtrate was
evaporated on a rotavap. The residue was slurried in 30 mL of
anhydrous ether and filtered, and the filtrate was again evaporated to
afford 0.85 g (89%) of 6 as a light yellow liquid. This was unstable
and was used rapidly in the next step of the synthesis.
1
cm-1. H NMR: δ 2.36 (3H, s, Ar-CH3), 3.88 (3H, s, -COOCH3),
7.27-7.22 (3H, m, 3 × Ar-H), 7.32 (1H, d, J ) 7.8 Hz, 6-ArH). Also
obtained was compound (E)-2: down spot, Rf 0.50, as an oil; 3.01 g,
41%. IR (KBr): 3349, 1732, 1622, 1443, 1310, 1034, 930, 757, 730,
696 cm-1. 1H NMR: δ 2.23 (3H, s, Ar-CH3), 3.83 (3H, s, -COOMe),
7.15 (1H, d, J ) 7.8 Hz, 3-ArH), 7.25-7.28 (2H, m, 2 × Ar-H), 7.33
(1H, t, J ) 7.2 Hz, 4-ArH), 10.15 (1H, s, -OH).
Preparation of Methyl (E)-2-Methoxyimino-2-o-tolyl Acetate (3).
To 0.68 g (17 mmol) of 60% NaH was added 10 mL of dry dimethyl
formamide (DMF) at 0 °C, and 2.9 g (15 mmol) of the compound (E)-2
was added thereto. The resulting solution was stirred for 30 min at
room temperature, and then, 2.52 g (20 mmol) of dimethyl sulfate was
added. After 12 h at room temperature, the mixture was extracted with
ethyl acetate, and the combined organic layers were washed with an
aqueous 5% NaOH solution and then with brine, dried over anhydrous
magnesium sulfate, filtered, and concentrated. The residue was subjected
to column chromatography using a mixture of n-hexane and ethyl
acetate (15:1) as an eluent to obtain compound (E)-3 (2.82 g) in 91%
yield: mp 63 °C [ref (14), 63-64 °C]. IR (KBr): 2949, 1726 (CdO),
Synthesis of the Target Compounds (1). A 25 mL round-bottom
flask equipped with a magnetic stirrer and nitrogen inlet was charged
with 9 (2 mmol) and 0.55 g (2.3 mmol) of 6. The mixture was dissolved
in 10 mL of anhydrous methanol, and one drop of glacial acetic acid
was added as a catalyst. The flask was stirred at ambient temperature
overnight, then poured into 50 mL of water, and extracted with 3 ×
50 mL of ethyl ether. The combined ether extracts were washed with
2 × 50 mL of water and 50 mL of brine, dried over anhydrous
magnesium sulfate, and filtered, and the filtrate was evaporated to afford
an oil, which was chromatographed on silica with ethyl acetate and
hexane monitoring by thin-layer chromatography. The pure fractions
were combined and evaporated to afford the target compounds.
Data for 1a. Yield, 65%; mp 112.2-113.7 °C. IR (KBr): 2924,
1
1439, 1068, 1011, 755 cm-1. H NMR: δ 2.20 (3H, s, Ar-CH3), 3.88
(3H, s, -COOMe), 4.06 (3H, s, N-OCH3), 7.12 (1H, d, J ) 8.4 Hz,
3-Ar-H), 7.22-7.26 (2H, m, 2 × ArH), 7.32 (1H, d, J ) 7.8 Hz,
6-ArH).
Preparation of Methyl (E)-r-(Methoxyimino)-2-(1-bromo-me-
thyl)benzeneacetate (4). To a mixture of 2.07 g (10 mmol) of (E)-3
and 2.14 g (12 mmol) of N-bromosuccinimide in 30 mL of carbon
tetrachloride was added 20 mg of 2,2′-azo-bisisobutyronitrile. The
resulting solution was refluxed for 10 h, then cooled, and filtered to
remove succinimide. The filtrate was evaporated under a reduced
pressure, and the oily residue was subjected to column chromatography
using a mixture of n-hexane and ethyl acetate (20:1) as an eluent to
obtain (E)-4 (2.32 g) in 81% yield. IR (KBr): 2942, 1728 (CdO),
1
1726 (CdO), 1623, 1062, 1014 cm-1. H NMR: δ 2.30 (s, 3H, Ar-
CH3), 2.32 (s, 3H, C-CH3), 3.58 (s, 3H, N-CH3), 3.73 (s, 3H, COOMe),
3.99 (s, 3H, NO-CH3), 4.91 (s, 2H, -CH2-), 6.76 (d, J ) 8.4 Hz, 2H,

3638 J. Agric. Food Chem., Vol. 54, No. 10, 2006
Li et al.
2′ and 6′-ArH), 7.08 (d, J ) 7.8 Hz, 2H, 3′ and 5′-ArH), 7.15 (d, J )
9.0 Hz, 1H, 6-ArH), 7.34-7.39 (m, 3H, 3, 4 and 5-ArH), 7.68 (s, 1H,
CHdN). 13C NMR: δ 15.4 (NdC-CH3), 21.0 (ph-CH3), 34.6 (N-
CH3), 53.3 (COOCH3), 64.2 (CdNOMe), 74.7 (NOCH2), 100.5 (4-
HetC), 115.5, 128.1, 128.7, 129.4, 129.7, 130.3, 130.9, 133.6, 136.5,
141.3 (3-HetC), 147.3 (CdNOMe), 148.6, 150.1 (CHdN), 155.2 (5-
HetC), 163.7 (COOMe). MS (70 eV): m/z (%) 450 (M+, 100), 391
(M - COOMe+, 17), 228 ([M - 222]+, 65), 213 (44), 131 (33), 116
(23), 91 (5), 59 (6). Anal. calcd for C24H26N4O5: C, 63.99; H, 5.82; N,
12.44. Found: C, 64.11; H, 5.73; N, 12.29.
C-CH3), 3.65 (s, 3H, N-CH3), 3.79 (s, 3H, COOMe), 3.99 (s, 3H, NO-
CH3), 4.80 (s, 2H, -CH2-), 7.12 (d, J ) 7.2 Hz, 1H, 6′-ArH), 7.19-
7.22 (m, 2H, 6 and 5-ArH), 7.31-7.33 (m, 2H, 3 and 4-ArH), 7.44 (t,
J ) 8.4 Hz, 1H, 5′-ArH), 7.69 (s, 1H, 2′-ArH), 7.72 (s, 1H, CHdN),
7.92 (d, J ) 7.8 Hz, 1H, 4′-ArH). 13C NMR: δ 14.8 (NdC-CH3),
34.7 (N-CH3), 53.2 (COOCH3), 64.1 (NOCH2), 74.7 (OCH2), 100.6
(4-HetC), 111.1, 111.5, 119.0, 119.8, 122.0, 128.0, 128.8, 129.6, 130.0,
131.0, 131.4, 136.4, 140.4 (3-HetC), 147.9 (CdNOMe), 149.6, 150.0
(CHdN), 151.0 (5-HetC), 163.7 (COOMe). MS (70 eV): m/z (%) 483
([M + 2]+, 4) , 481 (M+, 5), 450 (M - CH3O+, 14), 259 ([M - 222]+,
55), 131 (100), 116 (53), 70 (36), 59 (30). Anal. calcd for
C23H23N5O7: C, 57.38; H, 4.82; N, 14.55. Found: C, 57.50; H, 4.73;
N, 14.52.
Data for 1g. Yield, 69%; mp 118.9-119.3 °C. IR (KBr): 2927,
1708 (CdO), 1615, 1058, 1018 cm-1. 1H NMR: δ 2.30 (s, 3H, C-CH3),
3.64 (s, 3H, N-CH3), 3.77 (s, 3H, COOMe), 4.00 (s, 3H, NO-CH3),
4.87 (s, 2H, -CH2-), 6.75 (t, J ) 7.8 Hz, 1H, 4′-ArH), 7.01 (t, 1H,
5′-ArH), 7.05 (d, 1H, 6′-ArH), 7.15-7.18 (m, 2H, 6 and 3′-ArH), 7.34-
7.36 (m, 3H, 3, 4 and 5-ArH), 7.70 (s, 1H, CHdN). 13C NMR: δ 15.1
(NdC-CH3), 34.7 (N-CH3), 53.3 (COOCH3), 64.2 (NOCH2), 74.7
(OCH2), 100.3 (4-HetC), 117.2, 117.5, 117.7, 125.0, 125.1, 128.1, 128.8,
129.3, 130.3, 136.4, 140.8 (3-HetC), 147.5 (CdNOMe), 147.5, 150.1
(CHdN), 151.5, 153.2 (5-HetC), 163.7 (COOMe). MS (70 eV): m/z
(%) 454 (M+, 100), 423 (M - CH3O+, 43), 395 (M - COOMe+, 54),
232 ([M - 222]+, 65), 217 (36), 131 (30), 116 (25), 59 (17). Anal.
calcd for C23H23FN4O5: C, 60.79; H, 5.10; N, 12.33. Found: C, 60.91;
H, 5.19; N, 12.46. Crystal data, colorless block, (C23H23FN4O5), Mr )
454.45; µ ) 0.098 mm-1, dx ) 1.294 g/cm3, P 21/c, Z ) 8, a ) 14.2781-
(10), b ) 16.1865(12), c ) 20.1828(15) Å, R ) 90°, â ) 90°, γ )
90°, V ) 4664.5(6) Å3.
Data for 1b. Yield, 69%; mp 98.0-98.5 °C. IR (KBr): 2920, 1721
1
(CdO), 1622, 1060, 1017 cm-1. H NMR: δ 2.31 (s, 3H, Ar-CH3),
2.33 (s, 3H, C-CH3), 3.57 (s, 3H, N-CH3), 3.73 (s, 3H, COOMe), 3.98
(s, 3H, NO-CH3), 4.91 (s, 2H, -CH2-), 6.66 (d, J ) 7.8 Hz, 1H, 6′-
ArH), 6.67 (s, 2H, 2′-ArH), 6.89 (d, J ) 7.8 Hz, 1H, 4′-ArH), 7.15 (t,
J ) 7.8 Hz, 1H, 5′-ArH), 7.17 (d, J ) 7.2 Hz, 1H, 3-ArH), 7.33-7.35
(m, 2H, 4-ArH and 5-ArH), 7.36 (d, J ) 7.2 Hz, 1H, 6-ArH), 7.70 (s,
1H, CHdN). 13C NMR: δ 15.4 (NdC-CH3), 16.5 (ph-CH3), 34.5 (N-
CH3), 53.2 (COOCH3), 64.1 (NOCH2), 74.6 (OCH2), 100.3 (4-HetC),
113.8, 124.0, 126.9, 127.7, 128.1, 128.7, 129.3, 129.7, 130.3, 131.9,
136.4, 141.1 (3-HetC), 147.4 (CdNOMe), 148.6, 150.1 (CHdN), 155.4
(5-HetC), 163.7 (COOMe). MS (70 eV): m/z (%) 450 (M+, 100), 419
(M - CH3O+, 12), 391 (M - COOMe+, 21), 228 ([M - 222]+, 99),
226 (31), 213 (43), 131 (52), 116 (32), 59 (13). Anal. calcd for
C24H26N4O5: C, 63.99; H, 5.82; N, 12.44. Found: C, 64.13; H, 5.66;
N, 12.51.
Data for 1c. Yield, 71%; mp 104.5-104.9 °C. IR (KBr): 2921,
1723 (CdO), 1629, 1067, 1010 cm-1. 1H NMR: δ 2.32 (s, 3H, ArMe),
2.36 (s, 3H, NdCMe), 3.58(s, 3H, CdNMe), 3.72 (s, 3H, COOMe),
4.00 (s, 3H, N-OCH3), 4.88 (s, 2H, -CH2-), 6.50 (d, J ) 8.4 Hz, 1H,
3′-ArH), 6.99 (t, J ) 7.5 Hz, 1H, 5′-ArH), 7.06 (t, J ) 7.5 Hz, 1H,
4′-ArH), 7.14 (d, J ) 7.8 Hz, 1H, 6′-ArH), 7.20 (d, J ) 7.8 Hz, 1H,
6 -ArH), 7.33-7.36 (m, 3H, 3, 4 and 5-ArH), 7.64 (s, 1H, -CHdN).
13C NMR: δ 15.4 (NdC-CH3), 16.5 (ph-CH3), 34.5 (N-CH3), 53.2
(COOCH3), 64.1 (NOCH2), 74.6 (OCH2), 100.3 (4-HetC), 113.8, 124.0,
126.9, 127.7, 128.1, 128.7, 129.3, 129.7, 130.3, 131.9, 136.4, 141.1
(3-HetC), 147.4 (CdNOMe), 148.6, 150.1 (CHdN), 155.4 (5-HetC),
163.7 (COOMe). MS (70 eV): m/z (%) 451 ([M + 1]+, 37), 450 (M+,
78) , 419 (6), 391 (M - COOMe+, 13), 228 ([M - 222]+, 100), 213
(28), 131 (59), 116 (33), 59 (14). Anal. calcd for C24H26N4O5: C, 63.99;
H, 5.82; N, 12.44. Found: C, 64.04; H, 5.89; N, 12.25.
Data for 1d. Yield, 67%; mp 64.8-65.5 °C. IR (KBr): 2917, 1734
(CdO), 1630, 1058, 1010 cm-1. 1H NMR: δ 2.34 (s, 3H, NdC-CH3),
3.64 (s, 3H, N-CH3), 3.76 (s, 3H, COOMe), 4.00 (s, 3H, NO-CH3),
4.88 (s, 2H, -CH2-), 6.81 (d, J ) 8.4 Hz, 2H, 2′ and 6′-ArH), 7.15
(d, J ) 9.0 Hz, 1H, 6-ArH), 7.25 (m, 3H, 3′, 5′, and 5-ArH), 7.31 (t,
J ) 4.2 Hz, 1H, 4-ArH), 7.36 (d, J ) 4.5 Hz, 1H, 3-ArH), 7.67 (s, 1H,
CHdN). 13C NMR: δ 15.0 (NdC-CH3), 34.7 (N-CH3), 53.3 (COOCH3),
64.2 (NOCH2), 74.8 (OCH2), 100.7 (4-HetC), 117.1, 128.2, 128.8,
129.3, 130.0, 130.3, 130.3, 130.4, 136.4, 140.7 (3-HetC), 147.4 (Cd
NOMe), 147.7, 150.1 (CHdN), 155.6 (5-HetC), 163.7 (COOMe). MS
(70 eV): m/z (%) 472 ([M + 2]+, 79), 470 (M+, 100), 439 (M -
CH3O+, 20), 411 (M - COOMe+, 31), 248 ([M - 222]+, 91), 233
(50), 205 (25), 131 (76), 116 (64), 59 (25). Anal. calcd for C23H23-
ClN4O5: C, 58.66; H, 4.92; N, 11.90. Found: C, 5.81; H, 4.74; N,
11.75.
Data for 1h. Yield, 67%; mp 83.5-84.6 °C. IR (KBr): 2929, 1718
1
(CdO), 1610, 1053, 1019 cm-1. H NMR: δ 2.31 (s, 3H, C-CH3),
3.60 (s, 3H, N-CH3), 3.74 (s, 3H, COOMe), 3.99 (s, 3H, NO-CH3),
4.89 (s, 2H, -CH2-), 6.83 (t, J ) 8.4 Hz, 2H, 2′ and 4′-ArH), 6.97 (d,
J ) 9.0 Hz, 2H, 3′ and 5′-ArH), 7.15 (d, J ) 7.8 Hz, 1H, 6-ArH),
7.33-7.37 (m, 3H, 3, 4 and 5-ArH), 7.69 (s, 1H, CHdN). 13C NMR:
δ 15.07 (NdC-CH3), 34.6 (N-CH3), 53.3 (COOCH3), 64.2 (NOCH2),
74.7 (OCH2), 100.5 (4-HetC), 116.9, 117.0, 128.1, 128.8, 129.2, 129.7,
130.2, 136.4, 140.4 (3-HetC), 147.5 (CdNOMe), 148.2, 150.1 (CHd
N), 153.0 (5-HetC), 160.0, 163.7 (COOMe). MS (70 eV): m/z (%)
454 (M+, 100), 423 (M - CH3O+, 22), 395 (M - COOMe+, 30), 232
([M - 222]+, 11), 217 (35), 146 (15), 131 (21), 116 (27), 59 (21).
Anal. calcd for C23H23FN4O5: C, 60.79; H, 5.10; N, 12.33. Found: C,
60.90; H, 5.05; N, 12.41.
Data for 1i. Yield, 54%; mp 85.6-86.9 °C. IR (KBr): 2918, 1709
1
(CdO), 1620, 1048, 1017 cm-1. H NMR: δ 2.32 (s, 3H, C-CH3),
3.61 (s, 3H, N-CH3), 3.75 (s, 3H, COOMe), 3.98 (s, 3H, NO-CH3),
4.84 (s, 2H, -CH2-), 7.00 (t, J ) 8.4 Hz, 1H, 6′-ArH), 7.14 (d, J )
8.4 Hz, 1H, 6-ArH), 7.17 (s, 1H, 2′-ArH), 7.30 (d, 1H, J ) 9.0 Hz,
4′-ArH), 7.33-7.37 (m, 3H, 4, 5 and 5′-ArH), 7.40 (d, J ) 8.4 Hz,
1H, 3-ArH), 7.70 (s, 1H, CHdN). 13C NMR: δ 14.9 (NdC-CH3),
34.7 (N-CH3), 53.2 (COOCH3), 64.2 (NOCH2), 74.8 (OCH2), 100.8
(4-HetC), 118.8, 120.9, 128.1, 128.8, 129.2, 129.7, 130.3, 131.1, 136.3,
140.6 (3-HetC), 147.1 (CdNOMe), 147.7, 150.1 (CHdN), 151.2, 157.1
(5-HetC), 163.7 (COOMe). MS (70 eV): m/z (%) 504 (M+, 12), 473
(M - CH3O+, 27), 445 (M - COOMe+, 24), 282 ([M - 222]+, 78),
245 (M - OphCF3+, 100), 186 (63), 161 (CF3phO+, 16), 145 (CF3-
ph+, 48), 131 (61), 116 (64), 59 (28). Anal. calcd for C24H23F3N4O5:
C, 57.14; H, 4.60; N, 11.11. Found: C, 57.03; H, 4.55; N, 11.24.
Data for 1j. Yield, 71%; mp 102.6-103.1 °C. IR (KBr): 2916,
1707 (CdO), 1615, 1041, 1010 cm-1. 1H NMR: δ 2.25 (s, 3H, dC-
CH3), 3.60 (s, 3H, N-Me), 3.83 (s, 3H, COOMe), 3.90 (s, 3H, OMe),
4.02 (s, 3H, N-OCH3), 5.02 (s, 2H, -CH2-), 7.18 (d, J ) 7.2 Hz, 1H,
6-ArH), 7.36 (t, J ) 7.2 Hz, 1H, 5-ArH), 7.41 (t, J ) 7.2 Hz, 1H,
4-ArH), 7.47 (d, J ) 7.8 Hz, 1H, 3-ArH), 7.95 (s, 1H, CHdN). 13C
NMR: δ 14.3 (3-HetCH3), 34.1 (1-HetCH3), 53.3 (COOCH3), 62.0
(5- HetOCH3), 64.2 (NOCH3), 74.7 (OCH2), 97.6 (4-HetC), 128.1 (5-
C), 128.9 (6-C), 129.2 (3-C), 129.8(4-C), 130.3 (1-C), 137.0 (2-C),
142.0 (3-HetC), 147.3 (CdNOMe), 150.2 (CHdN), 153.4 (5-HetC),
163.8 (COOMe). MS (70 eV): m/z (%) 504 (M+, 12), 473 (M -
CH3O+, 27), 445 (M - COOMe+, 24), 282 ([M - 222]+, 78), 245 (M
Data for 1e. Yield, 78%; mp 82.7-83.7 °C. IR (KBr): 2918, 1730
1
(CdO), 1620, 1051, 1019 cm-1. H NMR: δ 2.29 (s, 3H, C-CH3),
3.63 (s, 3H, N-CH3), 3.79 (s, 3H, COOMe), 4.00 (s, 3H, NO-CH3),
4.88 (s, 2H, -CH2-), 6.58 (d, J ) 9.6 Hz, 1H, 6′-ArH), 7.07 (d, J )
9.6 Hz, 1H, 5′-ArH), 7.15 (d, 1H, 6-ArH), 7.31 (t, J ) 4.5 Hz, 1H,
5-ArH), 7.35-3.37 (m, 2H, 3 and 4-ArH), 7.43 (s, 1H, 3′-ArH), 7.68
(s, 1H, CHdN). 13C NMR: δ 14.8 (NdC-CH3), 34.7 (N-CH3), 53.3
(COOCH3), 64.2 (NOCH2), 74.8 (OCH2), 100.6 (4-HetC), 116.8, 123.9,
128.2, 128.4, 128.8, 129.2, 129.5, 129.7, 130.2, 130.9, 136.4, 140.4
(3-HetC), 147.0 (CdNOMe), 147.6, 150.1 (CHdN), 151.3 (5-HetC),
163.7 (COOMe). MS (70 eV): m/z (%) 506 ([M + 2]+, 65), 504 (M+,
100), 469 ([M - Cl]+, 52), 282 ([M - 222]+, 44), 233 (50), 205 (25),
131 (29), 116 (24), 59 (30). Anal. calcd for C23H22Cl2N4O5: C, 54.66;
H, 4.39; N, 11.09. Found: C, 54.80; H, 4.25; N, 11.21.
Data for 1f. Yield, 81%; mp 135.3-135.8 °C. IR (KBr): 2914,
1727 (CdO), 1615, 1335, 1046, 1018 cm-1. 1H NMR: δ 2.33 (s, 3H,

(E)-
R-(Methoxyimino)benzeneacetate Derivatives
J. Agric. Food Chem., Vol. 54, No. 10, 2006 3639
Table 1. Fungicidal Activities of (E)-
R
-(Methoxyimino)benzeneacetate Derivatives 1 (50
µ
g/mL, Relative Inhibitory Rate %)a
inhibitory rate %
compds
R. solani
B. cinereapers
G. zeae
P. piricola
B. mayclis
1a
1b
1c
1d
1e
1f
1g
1h
1i
4-methylphenyl
2-methylphenyl
3-methylphenyl
4-chlorophenyl
2,4-dichlorophenyl
3-nitrophenyl
2-fluorophenyl
4-fluorophenyl
3-trifluoromethyl-phenyl
methyl
90.2
83.7
88.0
100
80.8
80.8
80.8
100
50.0
53.1
96.9
80.0
88.6
62.9
50.0
59.4
68.8
79.4
90.5
78.4
80.0
96.8
88.2
76.5
100
92.6
96.3
77.8
88.2
100
88.2
100
100
93.8
95.5
98.5
72.7
72.7
81.8
92.9
92.9
64.3
68.2
86.4
68.2
86.7
92.6
85.0
90.9
90.6
99.0
91.6
83.7
90.2
83.7
82.7
92.5
87.8
91.8
66.1
100
98.8
84.6
88.5
92.3
85.4
96.8
87.1
100.0
97.2
1j
1k
1l
ethyl
n-propyl
2,2,2-trifluoroethyl
kresoxim-methyl
1m
a Growth inhibition expressed as a percentage of the control (mean
±
SD, n
)
3).
- OphCF3+, 100), 186 (63), 161 (CF3phO+, 16), 145 (CF3ph+, 48),
131 (61), 116 (64), 59 (28). Anal. calcd for C18H22N4O5: C, 57.75; H,
5.92; N, 14.96. Found: C, 57.71; H, 5.86; N, 14.73.
Bioassays of Fungicidal Activities. The fungistatic activity mea-
surement method was adapted from the method described by Molina
Torres et al. (15). The synthesized target compounds were dissolved
in 0.5-1.0 mL of DMF to the concentration of 500 mg/L. The solutions
(1 mL) were mixed rapidly with thawed potato glucose agar culture
medium (9 mL) under 50 °C. The mixtures were poured into Petri
dishes. After the dishes were cooled, the solidified plates were incubated
with 4 mm mycelium disk, inverted, and incubated at 28 °C for 48 h.
Water was used as the blank control. Three replicates of each test were
carried out. The mycelial elongation radius (mm) of fungi settlements
was measured after 48 h of culture. The growth inhibition rates were
calculated with the following equation: I ) [(C - T)/C] × 100%.
Here, I is the growth inhibition rate (%), C is the control settlement
radius (mm), and T is the treatment group fungi settlement radius (mm).
The results are given in Table 1.
Data for 1k. Yield, 68%; mp 75.9-76.7 °C. IR (KBr): 2911, 1717
(CdO), 1625, 1035, 1019 cm-1. 1H NMR: δ 1.25 (t, J ) 7.2 Hz, 3H,
-CH2CH3), 2.22 (s, 3H, dC-CH3), 3.59 (s, 3H, N-Me), 3.83 (s, 3H,
COOMe), 4.03 (s, 3H, N-OCH3), 4.08 (m, J ) 7.2 Hz, 2H, -OCH2-
CH3), 5.02 (s, 2H, -CH2-), 7.18 (d, J ) 7.2 Hz, 1H, 6-ArH), 7.36 (t,
J ) 7.2 Hz, 1H, 5-ArH), 7.41 (t, J ) 7.2 Hz, 1H, 4-ArH), 7.47 (d, J
) 7.8 Hz, 1H, 3-ArH), 7.92 (s, 1H, CHdN). 13C NMR: δ 14.3 (3-
HetCH3), 15.8 (-CH2CH3), 34.1 (1-HetCH3), 53.3 (COOCH3), 64.2
(5-HetOCH2), 71.0 (NOCH3), 74.7 (OCH2), 98.1 (4-Het), 128.0 (5-C),
128.9 (6-C), 129.1 (3-C), 129.7 (4-C), 130.2 (1-C), 137.0 (2-C), 142.0
(3-HetC), 147.3 (CdNOMe), 150.2 (CHdN), 153.4 (5-HetC), 163.8
(COOMe). MS (70 eV): m/z (%) 388 (M+, 97), 357 (M - CH3O+,
31), 329 (M - COOMe+, 57), 206 (86), 166 ([M - 222]+, 99), 151
(100), 137 (99), 116 (99), 89 (70), 66 (99), 59 (95). Anal. calcd for
C19H24N4O5: C, 58.75; H, 6.23; N, 14.42. Found: C, 58.81; H, 6.14;
N, 14.50.
RESULTS AND DISCUSSION
Based on previous literature (16, 17), we found that the
coupling reaction between the aryldiazonium salt derived from
2-methylaniline and the methyl 2-(hydroxyimino)acetate gave
stereoselectively the oxime 2 in 44% yield. The E/Z ratio in
the crude mixture was determined by 1H NMR spectroscopy as
ca. 14:1. After further column chromatography purification, the
purity of E-2 obtained in 41% yield exceeded 99%. The
compound E-2 was methylated by sodium hydride-dimethyl
sulfate in 91% yield and successively brominated with NBS to
afford the oxime ether 4 in 81% yield.
Data for 1l. Yield, 66%; mp 95.6-96.4 °C. IR (KBr): 2921, 1724
(CdO), 1634, 1026, 1011 cm-1. 1H NMR: δ 0.95 (t, J ) 7.5 Hz, 3H,
-CH3), 1.67 (m, 2H, -CH2-), 2.22 (s, 3H, dC-CH3), 3.60 (s, 3H,
N-Me), 3.83 (s, 3H, COOMe), 3.97 (t, J ) 7.5 Hz, 2H, -CH2-), 4.02
(s, 3H, N-OCH3), 5.01 (s, 2H, -CH2-), 7.18 (d, J ) 7.2 Hz, 1H,
6-ArH), 7.36 (t, J ) 7.2 Hz, 1H, 5-ArH), 7.40 (t, J ) 7.2 Hz, 1H,
4-ArH), 7.47 (d, J ) 7.2 Hz, 1H, 3-ArH), 7.93 (s, 1H, CHdN). 13C
NMR: δ 10.6 (-CH2CH3), 14.4 (3-HetCH3), 23.5 (-CH2CH3), 34.1
(N-CH3), 53.3 (COOCH3), 64.2 (NOCH3), 74.7 (NOCH2-), 76.8 (5-
HetOCH2-), 98.0 (4-HetC), 128.1 (5-C), 129.0 (6-C), 129.1 (3-C),
129.7 (4-C), 130.3 (1-C), 137.0 (2-C), 142.1 (3-HetC), 147.3(Cd
NOMe), 150.3 (CHdN), 152.8 (5-HetC), 163.8 (COOMe). MS (70
eV): m/z (%) 402 (M+, 97), 371 (M - CH3O+, 31), 343 (M -
COOMe+, 55), 222 (37), 206 (97), 180 (Het-CHdNO+, 90), 165 (90),
147 (86),131 (97), 116 (100), 99 (97), 59 (98). Anal. calcd for
C20H26N4O5: C, 59.69; H, 6.51; N, 13.92. Found: C, 59.51; H, 6.39;
N, 13.87.
Data for 1m. As an oil, yield, 59%. IR (KBr): 2910, 1711 (CdO),
1626, 1037, 1025 cm-1. 1H NMR: δ 2.20 (s, 3H, dC-CH3), 3.60 (s,
3H, N-Me), 3.82 (s, 3H, COOMe), 4.00 (s, 3H, N-OCH3), 4.09 (s, 2H,
-OCH2CF3), 5.02 (s, 2H, -CH2-), 7.18 (d, J ) 7.2 Hz, 1H, 6-ArH),
7.35 (t, J ) 7.2 Hz, 1H, 5-ArH), 7.40 (t, J ) 7.2 Hz, 1H, 4-ArH), 7.42
(d, J ) 7.8 Hz, 1H, 3-ArH), 7.85 (s, 1H, CHdN). 13C NMR: δ 13.3
(3-HetCH3), 34.3 (1-HetCH3), 53.3 (COOCH3), 64.2 (NOCH3), 69.9
(OCH2), 74.9 (5-HetOCH2), 97.6 (4-HetC), 128.2 (5-C), 129.0 (6-C
and CF3), 129.3 (3-C), 129.7 (4-C), 130.2 (1-C), 137.4 (2-C), 141.6
(3-HetC), 147.5 (CdNOMe), 150.2 (CHdN), 150.7 (5-HetC), 163.7
(COOMe). MS (70 eV): m/z (%): 444 ([M + 2]+, 12), 442 (M+, 71),
411 (M - CH3O+, 80), 338 (M - COOMe+, 71), 222 (76), 220 (77),
206 (45), 190 (67), 137 (86), 131 (45), 116 (100), 59 (38). Anal. calcd
for C19H21F3N4O5: C, 51.58; H, 4.78; N, 12.66. Found: C, 51.47; H,
4.69; N, 12.73.
The aldehyde 5-chloro-1,3-dimethyl-1H-pyrazole-4-carbal-
dehyde (8) was obtained by heating of 1,3-dimethyl-1-H-
pyrazol-5(4H)one with phosphoryl trichloride in DMF. Reaction
of aldehyde 8 with substituted phenols or alcohols yielded the
5-substituted-1,3-dimethyl-1H-pyrazole-4-carbaldehydes (9). For
the detailed reaction conditions used to prepare compounds 7-9,
refer to the literature (18, 19).
Initially, we employed some oximes, derived from corre-
sponding 5-substituded-1,3-dimethyl-1H-pyrazole-4-carbalde-
hydes (9) and hydroxylamine hydrochloride, to react with 4
using MeONa as a base. However, the products were mixtures
of stereoisomers and the yields were low. However, the synthetic
route depicted in Figure 1 gave good results. Thus, oxime ether
4 was reacted with N-hydroxyphthalimide to give methyl (E)-
R-(methoxyimino)-2-(o-phthalimidoxymethyl)benzeneacetate (5),
which was then treated with hydrazine monohydrate to obtain
methyl (E)-R-(methoxyimino)-2-(aminoxymethyl)benzeneac-
etate (6). The reaction of carbaldehydes 9 with 6 proceeded
smoothly, and stereospecificity afforded the (E)-configurated

3640 J. Agric. Food Chem., Vol. 54, No. 10, 2006
Li et al.
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Figure 2. Molecular structure of 1g.
target compounds in satisfactory yields. The structures of 1a-m
were confirmed by elemental analyses, IR, 1H NMR, 13C NMR,
and EI-MS spectral data. The (RE,E)-configurations of com-
pounds 1 were assigned on the basis of their 1H two-dimensional
(2D) NOESY spectra. The 2D-NOESY experiments all showed
the presence of a cross-peak between the resonance of the
NOCH3 protons and that of 6-ArH and the other cross-peak
between the resonance of the CHdNO proton and that of
ArCH2. In addition, the E-configuration of compounds 1g was
proven on the basis of single-crystal structure (Figure 2). The
bond angles of C(22)-C(20)-N(4)-O(3) and C(8)-C(12)-
N(3)-O(2) are 177.4(2) and 179.0(2)°, respectively, which
indicates that both of the CdN double bonds are E-configura-
tions.
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piricola, and B. mayclis, belong to the group of field fungi and
were isolated from corresponding crops. The results of prelimi-
nary bioassays were compared with that of a commercial
agricultural fungicide, kresoxim-methyl. As indicated in Table
1, all of the compounds 1a-m showed potent fungicidal
activities against all of the fungi tested and had more potent
fungicidal activities against R. solani than kresoxim-methyl.
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substituted pyrazole rings to the strobilurin fungicides might
improve their fungicidal activities. On the other hand, the
chlorinated compounds such as 1d and 1e showed higher activity
among 5-phenoxy-substituted compounds while the 5-ethoxyl-
substituted compounds such as 1k and 1m had more significant
potency among 5-alkoxyl-substituted ones.
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Supporting Information Available: Tables of crystal data
and structure refinement, equivalent isotropic displacement
parameters, bond lengths and angles, anisotropic displacement
parameters, hydrogen coordinates and isotropic displacement
parameters, torsion angles, and hydrogen bonds. This material
is available free of charge via the Internet at http://pubs.acs.org.
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Received for review January 10, 2006. Revised manuscript received
February 28, 2006. Accepted March 1, 2006. This work was financially
supported by the Natural Science Foundation of Hubei Provincial
Department of Science and Technology (2002AB091).
JF060074F