Synthesis and biological activity of novel (Z)- and (E)-verbenone oxime esters

Article abstract of DOI:10.3390/molecules22101678

Twenty-seven (Z)- and (E)-verbenone derivatives bearing an oxime ester moiety were designed and synthesized in search of novel bioactive molecules. Their structures were confirmed by UV-Vis, FTIR, NMR, ESI-MS, and elemental analysis. The antifungal and herbicidal activities of the target compounds were preliminarily evaluated. As a result, compound (E)-4n (R = b-pyridyl) exhibited excellent antifungal activity with growth inhibition percentages of 92.2%, 80.0% and 76.3% against Alternaria solani, Physalospora piricola, and Cercospora arachidicola at 50 g/mL, showing comparable or better antifungal activity than the commercial fungicide chlorothalonil with growth inhibition of 96.1%, 75.0% and 73.3%, respectively, and 1.7 5.5-fold more growth inhibition than its stereoisomer (Z)-4n (R = b-pyridyl) with inhibition rates of 22.6%, 28.6% and 43.7%, respectively. In addition, seven compounds displayed significant growth inhibition activity of over 90% against the root of rape (Brassica campestris) at 100 g/mL, exhibiting much better herbicidal activity than the commercial herbicide flumioxazin with a 63.0% growth inhibition. Among these seven compounds, compound (E)-4n (R = b-pyridyl) inhibited growth by 92.1%, which was 1.7-fold more than its stereoisomer (Z)-4n (R = b-pyridyl) which inhibited growth by 54.0%.

Full text of DOI:10.3390/molecules22101678

molecules
Article
Synthesis and Biological Activity of Novel (Z)- and
(E)-Verbenone Oxime Esters
Qiong Hu 1, Gui-Shan Lin 1,*, Wen-Gui Duan 1,*, Min Huang 1 and Fu-Hou Lei 2
1
School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, Guangxi, China;
hq460175625@163.com (Q.H.); gaominhuang@mail.gxu.cn (M.H.)
Guangxi Key Laboratory of Chemistry and Engineering of Forest Products, Nanning 530008, Guangxi,
2
China; dwg105@gxu.edu.cn
*
Correspondence: gxlinguas@sina.com (G.-S.L.); wgduan@gxu.edu.cn (W.-G.D.);
Tel.: +86-771-323-9910 (W.-G.D.); Fax: +86-771-323-3718 (W.-G.D.)
Received: 13 September 2017; Accepted: 7 October 2017; Published: 10 October 2017
Abstract: Twenty-seven (Z)- and (E)-verbenone derivatives bearing an oxime ester moiety were
designed and synthesized in search of novel bioactive molecules. Their structures were confirmed
by UV-Vis, FTIR, NMR, ESI-MS, and elemental analysis. The antifungal and herbicidal activities of
the target compounds were preliminarily evaluated. As a result, compound (E)-4n (R =
exhibited excellent antifungal activity with growth inhibition percentages of 92.2%, 80.0% and 76.3%
against Alternaria solani, Physalospora piricola, and Cercospora arachidicola at 50 g/mL, showing
comparable or better antifungal activity than the commercial fungicide chlorothalonil with growth
inhibition of 96.1%, 75.0% and 73.3%, respectively, and 1.7 5.5-fold more growth inhibition than
its stereoisomer (Z)-4n (R = -pyridyl) with inhibition rates of 22.6%, 28.6% and 43.7%, respectively.
In addition, seven compounds displayed significant growth inhibition activity of over 90% against
the root of rape (Brassica campestris) at 100 g/mL, exhibiting much better herbicidal activity than the
commercial herbicide flumioxazin with a 63.0% growth inhibition. Among these seven compounds,
compound (E)-4n (R = -pyridyl) inhibited growth by 92.1%, which was 1.7-fold more than its
β-pyridyl)
µ
−
β
µ
β
stereoisomer (Z)-4n (R = β-pyridyl) which inhibited growth by 54.0%.
Keywords: α-pinene; verbenone; oxime; (Z)- and (E)-isomer; antifungal activity; herbicidal activity
1. Introduction
Verbenone—a natural bicyclic monoterpene containing a ketone group, a carbon-carbon double
bond, and a four-membered ring—is found in medicinal plants such as Verbena triphvlla and Eucalyptus
globulus Labill [
of -pinene [ ], the main component of turpentine oil, which is an abundant natural product.
Verbenone was found to have good pesticidal properties such as antiaggregation pheromone activity [
and pine bark beetle repellent activity [ ], as well as some pharmacological properties like
bronchodilating, anti-inflammatory, and haemolytic activities [ ]. Also, some verbenone-based
amine derivatives were synthesized and found to show insecticidal and antifungal activities [ ].
1]. It can also be conveniently prepared by the regioselective oxidation reaction
α
2
3]
4–6
7
8
Based on its bioactive properties and chemical reactivity, verbenone deserves further study for
pharmaceutical or agrochemical use. On the other hand, oxime ester derivatives were reported
to possess diverse biological activities, such as anticancer [
9,10], antiviral [11,12], antioxidant [13,14],
insecticidal [15 16], antifungal [17 18], and herbicidal [19 20] properties. Although asymmetric oxime
,
,
,
esters have (E)- and (Z)-isomers, the differences between their biological activities rarely receives
attention. In fact, taking advantage of the distinction in properties between (E)- and (Z)-isomers,
azobenzene derivatives can perform some amazing functions, for example, to be used as control
ion channel molecules [21], molecular devices [22], and photoswitchable antibacterial agents [23],
Molecules 2017, 22, 1678; doi:10.3390/molecules22101678
www.mdpi.com/journal/molecules

Molecules 2017, 22, 1678
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etc., which inspired us to investigate the different biological activities of (E)- and (Z)-oxime esters
with the prospect of potential application. In continuation of our interest in the bioactive properties
of natural product-based compounds [24
were designed and synthesized by integrating the bioactive oxime ester moiety into the skeleton of
verbenone converted from -pinene. Structural characterization, antifungal and herbicidal evaluation
–29], a series of novel (E)- and (Z)-verbenone oxime esters
α
of all the title compounds were carried out as well.
2. Results and Discussion
2.1. Synthesis and Characterization
As illustrated in the Scheme 1, verbenone (
oxidation of -pinene using t-butyl hydroperoxide (TBHP) as oxidant and CuCl2 as catalyst [
it underwent condensation with hydroxylamine to give a mixture of (Z)- and (E)-verbenone oximes
), which were effectively separated in 30.5% and 45.5% yields, respectively, by silica gel column
chromatography with step gradient elution with a mixed eluent (petroleum ether:EtOAc = 10:1 to
2
) was prepared in 76.2% yield by regioselective
α
2], then
(3
4:1, v/v), respectively. Finally, the (Z)- and (E)-verbenone oxime esters 4a–4n were synthesized by
O-acylation reactions of the corresponding oximes with acyl chlorides.
4a: R = n-butyl; 4b: R = n-amyl; 4c: R = cyclopentyl; 4d: R=cyclohexyl; 4e: R=2′-CH3 Ph; 4f: R = 2′-Cl Ph;
4g: R = 2′-F Ph; 4h: R = 3′-CH3 Ph; 4i: R = 3′-Cl Ph; 4j: R = 4′-Br Ph; 4k: R = 2′,3′-Cl Ph; 4l: R = 2′,4′-Cl Ph;
4m: R = α-Cl-β-pyridyl; 4n: R = β-pyridyl
Scheme 1. Synthesis of (Z)- and (E)-verbenone oxime esters 4a–4n.
NOESY experiments were employed to identify the (E)- and (Z)-verbenone oxime isomers 3,
as shown in Figure 1. It was found that there was correlation between the olefinic H-3 proton at
6.48 ppm and the hydroxyl hydrogen H-O (Figure 1a), however, for the other isomer, no correlation
signal between the H0-3 olefinic proton at 5.81 ppm and the hydroxyl hydrogen H0-O was found
(Figure 1b), implying that H-3 was near to H-O in space, identifying the compound with the H-3 signal
0
at 6.48 ppm as the (E)-verbenone oxime (Figure 1a), while the other isomer (H -3 at 5.81 ppm) was the
(Z)-verbenone oxime (Figure 1b).

Molecules 2017, 22, 1678
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Figure 1. Expanded NOESY spectra of the (Z)- and (E)-verbenone oximes
(b) (Z)-verbenone oxime.
3, (a) (E)-verbenone oxime;
The structures of the target compounds were characterized by IR, 1H-NMR, 13C-NMR, ESI-MS,
and elemental analysis. In the IR spectra, the weak absorption bands at about 3045 cm−1 were
attributed to the stretching vibrations of the unsaturated C-H in the verbenone moiety. The absorption
bands at about 1760 cm−1 were due to the vibrations of the carbonyl group C=O.
−1
The weak absorption bands at 1604–1640 cm−1 and the strong absorption bands at 1456–1522 cm
were assigned to the vibrations of C=C in the verbenone moiety and the carbon-nitrogen double bonds
C=N, respectively. In the 1H-NMR spectra of the E-isomers, the olefinic protons of verbenone scaffold
showed signals at about 6.00 ppm, but the Z-isomers showed at about 6.50 ppm, and the other protons
bonded to the saturated carbons of the verbenone moiety displayed signals at about 3.60 ppm in the
E-form of the target compounds, but at about 3.00 ppm in the Z-forms. The 13C-NMR spectra of the
E-form target compounds showed peaks for the olefinic carbons of the verbenone moiety at about
115.0 and 160.0 ppm, but the Z-form target compounds showed them at about 110.0 and 163.0 ppm.
The carbon-nitrogen double bonds of the E-form target compounds appreared at about 168.0 ppm,
but the Z-form target compounds showed them at about 165.0 ppm. The other saturated carbons
displayed signals in the 21.8–49.7 ppm region. Their molecular weights and the C, H, and N element
ratios were confirmed by ESI-MS and elemental analysis, respectively.
2.2. Antifungal Activity
The antifungal activities of the target compounds (Z)- and (E)-4a–4n were evaluated by an in vitro
method against fusarium wilt on cucumber (Fusarium oxysporum f. sp. cucumerinum), speckle on peanut
(C. arachidicola), apple root spot (P. piricola), tomato early blight (A. solani), wheat scab (Gibberella zeae),
rice sheath blight (Rhzioeotnia solani), corn southern leaf blight (Bipolaris maydis), and watermelon
anthracnose (Colleterichum orbicalare) at 50 µg/mL. The results are listed in Table 1.

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Table 1. Antifungal activity of the target compounds (Z)- and (E)-4a–4n at 50 µg/mL.
Fungal Growth Inhibition (%)
Compounds
F. oxysporum f.
C. arachidicola
P. piricola
A. solani
G. zeae
R. solani
B. maydis
C. orbiculare
Average(I)
sp. cucumerinum
28.6
17.2
34.3
17.2
57.1
28.6
21.5
17.2
21.5
17.2
12.8
8.5
(Z)-4a (R = n-butyl)
(E)-4a (R = n-butyl)
32.8
10.9
10.9
21.8
43.7
32.8
12
45.7
40
37
28.6
28.6
11.4
28.6
22.8
11.4
21.8
16.3
35.4
16.3
8.2
48.7
22.6
48.7
31.3
76.6
48.7
0
24
18
21.1
7.1
33.3
22.7
20.4
25.4
40.7
22.4
24.2
18.4
32.8
30
37
(Z)-4b (R = n-amyl)
17.2
45.7
45.7
17.2
36.4
0
9.2
24
7.1
(E)-4b (R = n-amyl)
27.7
27.7
9.2
24
7.1
(Z)-4c (R = cyclopentyl)
(E)-4c (R = cyclopentyl)
(Z)-4d (R = cyclohexyl)
(E)-4d (R = cyclohexyl)
24
28.2
7.1
24
43.2
43.2
52.8
52.8
24
32
26.6
26.6
57.7
66.7
40
24
0
20
0
(Z)-4e (R = 2 -CH3 Ph)
24
50.9
50.9
43.7
3.6
0
20
0
(E)-4e (R = 2 -CH3 Ph)
24
0
12
0
(Z)-4f (R = 2 -Cl Ph)
24
0
16
21.1
16.8
14.7
21.3
38.8
44.5
41.8
25.4
34.8
25.7
19.3
20.1
21.2
25.5
26
0
(E)-4f (R = 2 -Cl Ph)
18
33.6
24
19.1
5.4
0
16
35.5
22.2
44.4
56.5
70.6
53.3
44.4
44.4
7.1
0
(Z)-4g (R = 2 -F Ph)
12.8
17.2
40
12
25.4
3.6
0
16
0
(E)-4g (R = 2 -F Ph)
24
43.2
9.2
21.8
22.8
28.6
46.3
30
0
16
0
(Z)-4h (R = 3 -CH3 Ph)
54.6
65.4
24
45.7
34.3
32.8
25.4
65.4
11.4
11.4
25.4
32.8
34.3
51.5
28.6
80
57.4
62.6
14.4
0
24
0
(E)-4h (R = 3 -CH3 Ph)
45.7
64.3
25.7
42.8
40
18.5
67.2
33.6
38.4
37
30
0
(Z)-4i (R = 3 -Cl Ph)
32
0
(E)-4i (R = 3 -Cl Ph)
12
32
0
(Z)-4j (R = 4 -Br Ph)
24
32.8
28.6
28.6
8.2
2.9
36.5
31.3
0
28
0
0
(Z)-4k (R = 2 ,3 -Cl Ph)
32.8
10.9
12
12
0
0
(E)-4k (R = 2 ,3 -Cl Ph)
28.6
30
18.5
28.8
52.8
9.2
18
7.1
0
0
(Z)-4l (R = 2 ,4 -Cl Ph)
16
40
0
0
(E)-4l (R = 2 ,4 -Cl Ph)
(Z)-4m (R = α-Cl-β-pyridyl)
(E)-4m (R = α-Cl-β-pyridyl)
(Z)-4n (R = β-pyridyl)
(E)-4n (R = β-pyridyl)
Average(II)
8.5
30
10.9
28.6
11.4
11.4
28.6
21.9
35.3
21.1
58.7
73.1
0
12
22.2
7.1
17.2
17.2
11.4
62.9
27.6
13.3
16
32.8
32.8
43.7
76.3
28.4
10.9
10.9
26.7
73.3
62.6
57.4
22.6
92.2
26.5
42.8
42.8
33.5
96.1
12
18.5
9.2
12
7.1
12
21.1
77.6
31.7
13.3
13.3
27
20
46.2
31.5
52.6
30
42
63.2
-
33.5
38.8
38.8
58.1
75
21
(Z)-oxime 3
22.8
28.6
20.8
90.4
-
(E)-oxime 3
-
verbenone 2
16.4
100
16.3
73.9
-
Chlorothalonil
91.3
-
Chlorothalonil, a current commercial fungicide, was used as a positive control. Values are the average of three replicates.

Molecules 2017, 22, 1678
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It was found that, at 50
µg/mL, most of target compounds exhibited certain antifungal activity
against the eight tested fungi. On the whole, all the target compounds exhibited the best antifungal
activity against P. piricola, with an average inhibition activity of 33.5%. Also, compound (E)-4n
(R = β-pyridyl) showed the best antifungal activity against all the eight tested fungi, with an average
inhibition activity of 63.2%. Compared with that of the commercial fungicide chlorothalonil (positive
control), compound (E)-4n (R = β-pyridyl) exhibited excellent antifungal activity with inhibition rates
of 92.2%, 80.0%, and 76.3% against A. solani, P. piricola, and C. arachidicola, respectively, displaying
better or comparable antifungal activity than that of the positive control with inhibition rates of 96.1%,
75.0%, and 73.3%, respectively. Besides, some compounds displayed moderate activity in the region of
60–80% inhibition rates, although their antifungal activities were inferior to that of the positive control.
For example, compound (E)-4h (R = 30-CH3 Ph) held 70.6%, 65.4%, and 62.6% inhibitory rates against
0
C. orbiculare, C. arachidicola, and R. solani, respectively, as well as compounds (Z)-4j (R = 4 -Br Ph), (Z)-4i
0
(R = 3 -Cl Ph), and (Z)-4m (R =
α
-Cl-
β
-pyridyl) had inhibition rates of 65.4%, 64.3%, and 62.6% against
P. piricola, F. oxysporum, and R. solani, respectively. However, the title compounds showed weak activity
against B. maydis. To our surprise, some compounds showed large antifungal activity differences
between the (Z)- and (E)-isomers, even against the same fungal species. Particularly, compound (E)-4n
(R = β-pyridyl) showed 5.5-, 4.1-, 2.8-, and 1.7-fold higher antifungal activity against F. oxysporum
f. sp. cucumerinum, R. solani, P. piricola, and C. arachidicola, respectively, than its stereoisomer (Z)-4n
(R = β-pyridyl).
2.3. Herbicidal Activity
The herbicidal activities of the target compounds (Z)- and (E)-4a
–4n were evaluated by the
rape petri dish method and the barnyard grass beaker method against the root-growth of rape
(B. campestris) and the seedling-growth of barnyard grass (Echinochloa crusgalli) at 10
100 µg/mL, respectively. The results are listed in Table 2.
µg/mL and
As shown in Table 2, at 100 µg/mL, the target compounds exhibited remarkable herbicidal activity
against the root-growth of rape (B. campestris). Among them, seventeen target compounds displayed
better herbicidal activity with 63.6–99.3% inhibition rates than that of the commercial herbicidal
flumioxazin (positive control) with inhibition rate of 63.0%, in which seven compounds held growth
inhibition rates of over 90%. However, the title compounds showed extremely weak inhibition activity
against the seedling-growth of barnyard grass (E. crusgalli). Interestingly, it was also found that, some
compounds showed certain herbicidal activity difference between (Z)- and (E)-isomers, in which
compound (E)-4n (R =
(Z)-4n (R = β-pyridyl).
β-pyridyl) showed 1.7-fold greater inhibition compared to its stereoisomer

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Table 2. Herbicidal activity of the target compounds (Z)- and (E)-4a–4n at 10 µg/mL and 100 µg/mL.
Growth Inhibition (%)
Compounds
B. campestris
10 µg/mL 100 µg/mL
76.7
E. crusgalli
10 µg/mL 100 µg/mL
(Z)-4a (R = n-butyl)
(E)-4a (R = n-butyl)
(Z)-4b (R = n-amyl)
0
0
0
0
8.1
0
0
0
14.1
31.2
19.1
38.6
42.1
8.6
31.2
63.6
71.7
62.0
41.7
83.8
82.7
49.5
34.8
16.7
5.1
0
0
16.5
0
5.5
0
0
0
5.5
0
0
0
0
0
3.3
5.5
0
0
0
0
0
0
0
0
29.4
0
0
0
11.0
22.0
12.7
97.5
59.3
48.5
27.0
76.3
77.4
74.3
68.1
60.5
63.6
66.6
54.5
95.9
76.0
90.1
92.6
96.9
88.0
79.9
96.6
99.3
52.5
57.8
60.3
57.9
54.0
92.1
62.2
72.8
16.3
63.0
11.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
11.0
0
95.1
(E)-4b (R = n-amyl)
(Z)-4c (R = cyclopentyl)
(E)-4c (R = cyclopentyl)
(Z)-4d (R = cyclohexyl)
(E)-4d (R = cyclohexyl)
0
(Z)-4e (R = 2 -CH3 Ph)
0
(E)-4e (R = 2 -CH3 Ph)
0
(Z)-4f (R = 2 -Cl Ph)
(E)-4f (R = 2 -Cl Ph)
(Z)-4g (R = 2 -F Ph)
0
0
0
(E)-4g (R = 2 -F Ph)
0
(Z)-4h (R = 3 -CH3 Ph)
0
(E)-4h (R = 3 -CH3 Ph)
0
0
(Z)-4i (R = 3 -Cl Ph)
(E)-4i (R = 3 -Cl Ph)
0
(Z)-4j (R = 4 -Br Ph)
0
0
(Z)-4k (R = 2 ,3 -Cl Ph)
0
0
(E)-4k (R = 2 ,3 -Cl Ph)
0
0
0
(Z)-4l (R = 2 ,4 -Cl Ph)
0
(E)-4l (R = 2 ,4 -Cl Ph)
(Z)-4m (R = α-Cl-β-pyridyl)
(E)-4m (R = α-Cl-β-pyridyl)
(Z)-4n (R = β-pyridyl)
(E)-4n (R = β-pyridyl)
(Z)-oxime 3
23.0
58.1
27.7
46.4
0
(E)-oxime 3
verbenone 2
Flumioxazin
57.8
Flumioxazin, a current commercial herbicide was used as a positive control Values are the average of three replicates.
3. Materials and Methods
3.1. General Information
The GC analysis was performed on an Agilent 6890 GC (Agilent Technologies Inc., Santa Clara,
CA, USA) equipped with a HP-1 column (30 m, 0.530 mm, 0.88 µm). IR spectra were recorded on
a Nicolet iS50 FT-IR spectrometer (Thermo Scientific Co., Ltd., Madison, WI, USA) using the KBr pellet
method. NMR spectra (including 1H-NMR, 13C-NMR, NOESY) were recorded in CDCl3 on an Avance
III HD 600 MHz spectrometer (Bruker Co., Ltd., Zurich, Switzerland) and chemical shifts are expressed
in ppm (δ) downfield relative to TMS as an internal standard. MS spectra were obtained by means
of the electrospray ionization (ESI) method on TSQ Quantum Access MAX HPLC-MS instrument
(Thermo Scientific Co., Ltd., Waltham, MA, USA). Elemental analyses were measured using a PE
2400 II elemental analyzer (Perkin-Elmer Instruments Co., Ltd., Waltham, MA, USA). The UV spectra
were measured on a UV-1800 spectrophotometer (Shimadzu Corp., Kyoto, Japan). Melting points
were determined on a MP420 automatic melting point apparatus (Hanon Instruments Co., Ltd., Jinan,
China) and were not corrected. α-Pinene (GC purity 96%) was provided by Wuzhou Pine Chemicals
Co., Ltd. (Wuzhou, Guangxi, China). Other reagents were purchased from commercial suppliers and
used as received.
3.2. Synthesis of Verbenone (2) from α-Pinene
Verbenone (
method [ ]. Yield 76.2%. UV-vis (EtOH)
2975, 2941, 2871 (C-H), 1681 (C=O); 1H-NMR (600 MHz, CDCl3)
2
) was prepared as a pale yellow liquid (GC purity 98.9%), according to the literature
max(log
): 253.8 (4.26) nm; IR (KBr, cm−1): 3040 (=CH),
= 5.72 (s, 1H, H-3), 2.80 (dd, J = 8.5,
2
λ
ε
δ

Molecules 2017, 22, 1678
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5.5 Hz, 1H, H-1), 2.66
−
2.62 (t, J = 5.8 Hz, 1H, H-5), 2.41 (t, J = 5.8 Hz, 1H, H-7), 2.07 (d, J = 9.2 Hz, 1H,
H-7), 2.01 (s, 3H, H-10), 1.49 (s, 3H, H-9), 1.01 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3)
δ = 204.0 (C-2),
170.2 (C-4), 121.2 (C-3), 57.6 (C-1), 53.0 (C-6), 49.7 (C-5), 40.8 (C-7), 26.6 (C-8), 23.6 (C-10), 22.0 (C-9);
ESI-MS m/z: 151.24 ([M + H]+).
3.3. Synthesis of (Z)- and (E)-verbenone Oximes 3
A solution of NH2OH HCl (0.835 g, 12.1 mmol) in H2O (5 mL) was added slowly in 1 h to the
·
solution of verbenone (2, 1.500 g, 9.99 mmol) in C2H5OH (10 mL). The reaction mixture was refluxed
for 4 h. Then, the reaction mixture was distilled in vacuum to remove solvent, and dichloromethane
(10 mL) was added. The mixture was washed with deionized water and purified in silica gel column
chromatography by step gradient elution with a mixed eluent (petroleum ether-EtOAc = 25:1, 10:1, v/v)
to give the (Z)- and (E)-verbenone oximes.
(Z)-verbenone oximes ((Z)-
258.2 (4.01) nm; IR (KBr, cm−1): 3189 (-OH), 3062 (=CH), 2936, 2897 (C-H), 1637, 1470, 1434 (C=N,
C=C); 1H-NMR (600 MHz, CDCl3)
: 9.20 (s, 1H, H-11), 5.81 (d, J = 1.4 Hz, 1H, H-3), 3.65 (td, J = 5.9,
3 λmax(log ε):
). Yield 30.5%. melting point: 105.2–106.9 ◦C UV-Vis (EtOH)
δ
1.4 Hz, 1H, H-1), 2.62 (dt, J = 8.9, 5.5 Hz, 1H, H-5), 2.26–2.23 (m, 1H, H-7), 1.88 (d, J = 1.6 Hz, 3H,
H-10), 1.63 (d, J = 8.9 Hz, 1H, H-7), 1.47 (s, 3H, H-9), 0.91 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3)
δ
= (150 MHz, CDCl3) 159.7 (C-2), 158.7 (C-4), 109.6 (C-3), 49.4 (C-1), 48.3 (C-6), 48.0 (C-5), 37.5 (C-7),
26.1 (C-8), 23.6 (C-10), 21.9 (C-9); MS (ESI) m/z: 165.93 ([M + H]+).
◦
(E)-verbenone oxime ((E)-3). Yield 45.5%. melting point: 132.7–135.9 C UV-Vis (EtOH) λmax(log ε):
247.0 (4.08) nm; IR (KBr, cm−1): 3189 (-OH), 3059 (=CH), 2968, 2900 (C-H), 1637, 1480, 1442 (C=N,
1
C=C); H-NMR (600 MHz, CDCl3)
δ: 9.05 (s, 1H, H-11), 6.48 (dd, J = 3.0, 1.5 Hz, 1H, H-3),
2.71 (td, J = 6.0, 1.5 Hz, 1H, H-1), 2.66 (dt, J = 8.9, 5.5 Hz, 1H, H-5), 2.26 (dd, J = 8.4, 3.2 Hz, 1H,
H-7), 1.93 (d, J = 1.5 Hz, 3H, H-10), 1.73 (d, J = 8.9 Hz, 1H, H-7), 1.43 (s, 3H, H-9), 0.92 (s, 3H, H-8);
13C-NMR (150 MHz, CDCl3)
δ = 162.1 (C-2), 154.3 (C-4), 115.6 (C-3), 49.1 (C-1), 47.3 (C-6), 41.5 (C-5),
36.3 (C-7), 26.1 (C-8), 23.1 (C-10), 22.2 (C-9); ESI-MS m/z: 165.94. ([M + H]+).
3.4. General Procedure for the Synthesis of (Z)- and (E)-verbenone Oxime Esters 4
Under an anhydrous atmosphere, acyl chloride (1.1 mmol) was added slowly to a stirred solution
of (Z)- or (E)-verbenone oxime (3, 0.17 g, 1.00 mmol) in dichloromethane (5 mL) and ten drops of
triethylamine in an ice-water bath. The reaction process was monitored by TLC. Upon completion,
5 mL deionized water was added to destroy the unreacted acyl chloride. Then, the organic layer was
separated, washed with deionized water three times, and concentrated in vacuum. The crude product
was further purified by silica gel chromatography to afford the target compounds (Z)- and (E)-4a–4n.
◦
(Z)-verbenone O-n-pentanoyl oxime ((Z)-4a). Light yellow liquid. Yield: 77.0%, melting point: 69.3–70.3 C.
UV-Vis (EtOH)
λmax(log ε
): 255.4 (4.33) nm; IR (KBr, cm−1): 3084 (=C-H), 2958, 2930, 2872 (C-H), 1759
(C=O),1622, 1603 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 6.46–6.23 (m, 1H, H-3), 2.93 (t, J = 5.9 Hz,
1H, H-1, 2.74–2.70 (m, 1H, H-5), 2.43 (t, J = 7.6 Hz, 2H, H-12), 2.31 (t, J = 5.7 Hz, 1H, H-7a), 1.97 (dd,
J = 1.5, 0.7 Hz, 3H, H-10), 1.80 (d, J = 9.2 Hz, 1H, H-7b), 1.73–1.69 (m, 2H, H-13), 1.45 (s, 3H, H-9),
1.42–1.39 (m, 2H, H-14), 0.95–0.92 (m, 6H, H-8,15); 13C-NMR (150 MHz, CDCl3):
δ = 171.5 (C-11), 165.8
(C-2), 163.4 (C-4), 110.0 (C-3), 49.7 (C-1), 49.4 (C-6), 48.3 (C-5), 38.4 (C-12), 32.8 (C-7), 27.1 (C-13), 26.1
(C-8), 23.8 (C-14), 22.3 (C-10), 21.8 (C-9), 13.7 (C-15); ESI-MS m/z: 249.91 [M + H]+. Anal. calcd. For
C15H23NO2: C, 72.25; H, 9.30; N, 5.62; Found: C, 72.22; H, 9.21; N, 5.59.
(E)-verbenone O-n-pentanoyl oxime ((E)-4a) as a yellow liquid, Yield 86.0% melting point: 78.8–81.3 ◦C.
UV-Vis (EtOH)
λ
max(log
ε
): 252.1 (4.37) nm; IR (KBr, cm−1): 3053 (=C-H), 2958, 2933, 2872 (C-H),
1
1760 (C=O),1628, 1595 (C=N, C=C); H-NMR (600 MHz, CDCl3):
δ = 6.00–5.97 (m, 1H, H-3),
3.52 (td, J = 5.8, 1.6 Hz, 1H, H-1), 2.66–2.63 (m, 1H, H-5), 2.42–2.39 (m, 2H, H-12), 2.30–2.27 (m, 1H, H-7a),
1.93 (d, J = 1.5 Hz, 3H, H-10), 1.73 (d, J = 9.1 Hz, 1H, H-7b), 1.69–1.66 (m, 2H, H-13), 1.48 (s, 3H, H-9),

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1.41–1.38 (m, 2H, H-14), 0.92 (t, J = 3.7 Hz, 6H, H-8,15); 13C-NMR (150 MHz, CDCl3):
δ
= 171.7 (C-11),
168.1 (C-2), 159.2 (C-4), 115.1 (C-3), 49.2 (C-1), 49.1 (C-6), 43.7 (C-5), 37.2 (C-12), 32.8 (C-7), 27.0 (C-13),
26.2 (C-8), 23.4 (C-14), 22.3 (C-10), 22.2 (C-9), 13.7 (C-15); ESI-MS m/z: 249.84 [M + H]+. Anal. calcd.
For C15H23NO2: C, 72.25; H, 9.30; N, 5.62; Found: C, 72.20; H, 9.23; N, 5.60.
(Z)-verbenone O-n-hexanoyl oxime ((Z)-4b). Yellow liquid. Yield: 80.0%, melting point: 62.1–63.2 ◦C.
UV-Vis (EtOH)
λ
max(log
ε
): 254.0 (4.38) nm; IR (KBr, cm−1): 3050 (=C-H), 2958, 2933, 2872 (C-H),
1
1760 (C=O),1628, 1600 (C=N, C=C); H-NMR (600 MHz, CDCl3):
δ = 6.37–6.33 (m, 1H, H-3),
2.93 (t, J = 5.9 Hz, 1H, H-1), 2.72 (dt, J = 10.9, 5.5 Hz, 1H, H-5), 2.42 (t, J = 7.6 Hz, 2H, H-12),
2.31 (t, J = 5.7 Hz, 1H, H-7a), 1.96 (d, J = 1.6 Hz, 3H, H-10), 1.80 (d, J = 9.2 Hz, 1H, H-7b), 1.74–1.69
(m, 2H, H-13), 1.45 (s, 3H, H-9), 1.37–1.34 (m, 4H, H-14,15), 0.94 (s, 3H, H-8), 0.91 (t, J = 6.2 Hz, 3H,
H-16); 13C-NMR (150 MHz, CDCl3):
δ = 171.5 (C-11), 165.8 (C-2), 163.4 (C-4), 110.0 (C-3), 49.7 (C-1),
49.4 (C-6), 48.3 (C-5), 38.4 (C-12), 33.1 (C-14), 31.4 (C-7), 26.1 (C-8), 24.7 (C-13), 23.8 (C-15), 22.3 (C-10),
21.8 (C-9), 13.9 (C-16); ESI-MS m/z: 263.80 [M + H]+. Anal. calcd. For C16H25NO2: C, 72.97; H, 9.57; N,
5.32; Found: C, 72.65; H, 9.47; N, 5.29.
◦
(E)-verbenone O-n-hexanoyl oxime ((E)-4b). Light yellow liquid. Yield: 72.0%, melting point: 78.2–79.6 C.
UV-Vis (EtOH)
λmax(log ε
): 252.5 (4.33) nm; IR (KBr, cm−1): 3053 (=C-H), 2957, 2933, 2872 (C-H), 1760
(C=O), 1629, 1600 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 5.99 (d, J = 1.7 Hz, 1H, H-3), 3.52
(td, J = 5.8, 1.6 Hz, 1H, H-1), 2.65 (dt, J = 9.1, 5.5 Hz, 1H, H-5), 2.40 (t, J = 7.6 Hz, 2H, H-12), 2.30–2.27
(m, 1H, H-7a), 1.93 (d, J = 1.6 Hz, 3H, H-10), 1.73 (d, J = 9.1 Hz, 1H, H-7b), 1.71–1.66 (m, 2H, H-13),
1.48 (s, 3H, H-9), 1.34 (q, J = 3.6 Hz, 4H, H-14,15), 0.92 (s, 3H, H-8), 0.91–0.89 (m, 3H, H-16); 13C-NMR
(150 MHz, CDCl3):
δ = 171.7 (C-11), 168.1 (C-2), 159.2 (C-4), 115.1 (C-3), 49.2 (C-1), 49.1 (C-6), 43.7 (C-5),
37.2 (C-12), 33.1 (C-14), 31.3 (C-7), 26.2 (C-8), 24.7 (C-13), 23.4 (C-15), 22.3 (C-10), 22.2 (C-9), 13.9 (C-16);
ESI-MS m/z: 263.88 [M + H]+. Anal. calcd. For C16H25NO2: C, 72.97; H, 9.57; N, 5.32; Found: C, 72.71;
H, 9.49; N, 5.30.
(Z)-verbenone O-cyclopentylcarbonyl oxime ((Z)-4c). Slight brown liquid. Yield: 90.0%, melting point:
90.2–91.3 ◦C. UV-Vis (EtOH)
λ
max(log
2961, 2899, 2876 (C-H), 1755 (C=O), 1621, 1599, 1577 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 6.35 (d, J = 1.5 Hz, 1H, H-3), 2.94 (td, J = 6.0, 1.6 Hz, 1H, H-12), 2.85 (p, J = 8.1 Hz, 1H, H-1),
ε
): 256.9 (4.28) nm; IR (KBr, cm−1): 3082, 3061 (Ar-H, =C-H),
δ
2.72 (dt, J = 9.2, 5.5 Hz, 1H, H-5), 2.33–2.29 (m, 1H, H-7a), 1.97 (d, J = 1.6 Hz, 3H, H-10),
1.94 (d, J = 5.5 Hz, 2H, H-16), 1.93–1.85 (m, 2H, H-13), 1.80 (d, J = 9.2 Hz, 1H, H-7b),
1.78–1.72 (m, 2H, H-15), 1.61 (dt, J = 9.0, 4.2 Hz, 2H, H-9), 1.45 (s, 3H, H-14), 0.94 (s, 3H, H-8); 13C-NMR
(150 MHz, CDCl3):
δ = 174.3 (C-11), 165.8 (C-2), 163.3 (C-4), 110.0 (C-3), 49.7 (C-1), 49.4 (C-6), 48.3 (C-5),
42.8 (C-12), 38.4 (C-16), 30.2 (C-13), 30.1 (C-7), 26.1 (C-15), 25.9 (C-14), 25.9 (C-8), 23.9 (C-10), 21.8 (C-9);
ESI-MS m/z: 261.85 [M + H]+. Anal. calcd. For C16H23NO2: C, 73.53; H, 8.87; N, 5.36; Found: C, 73.25;
H, 8.78; N, 5.33.
(E)-verbenone O-cyclopentylcarbonyl oxime ((E)-4c). Brown liquid. Yield: 90.0%, melting point:
◦
102.11–104.35 C. UV-Vis (EtOH)
λmax(log ε
): 252.6 (4.25) nm; IR (KBr, cm−1): 3066 (= C-H), 2959, 2933,
2873 (C-H), 1741 (C=O), 1619, 1436 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 5.99 (q, J = 1.6 Hz,
1H, H-3), 3.51 (td, J = 5.8, 1.7 Hz, 1H, H-12), 2.82 (p, J = 8.1 Hz, 1H, H-1), 2.64 (dt, J = 9.1, 5.5 Hz,
1H, H-5), 2.28 (td, J = 5.9, 1.4 Hz, 1H, H-7a), 1.92 (d, J = 1.6 Hz, 3H, H-10), 1.90–1.85 (m, 2H, H-16),
1.78–1.74 (m, 1H, H-7b), 1.74–1.72 (m, 2H, H-13), 1.60 (dd, J = 7.2, 4.0 Hz, 2H, H-15), 1.48 (s, 3H, H-9),
1.46–1.24 (m, 2H, H-14), 0.92 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 174.5 (C-11), 168.1 (C-2),
159.1 (C-4), 115.2 (C-3), 49.2 (C-1), 49.1 (C-6), 43.7 (C-5), 42.7 (C-12), 37.2 (C-16), 30.2 (C-13), 30.1 (C-7),
26.2 (C-15), 25.8 (C-14), 25.8 (C-8), 23.4 (C-10), 22.3 (C-9); ESI-MS m/z: 261.86 [M + H]+. Anal. calcd.
For C16H23NO2: C, 73.53; H, 8.87; N, 5.36; Found: C, 73.29; H, 8.80; N, 5.34.
(Z)-verbenone O-cyclohexylcarbonyl oxime ((Z)-4d). Yellow liquid. Yield: 93.0%, melting point:
95.7–98.2 ◦C. UV-Vis (EtOH)
λ
max(log
ε
): 256.5 (4.57) nm; IR (KBr, cm−1): 3071 (=C-H), 2980, 2933,
2856 (C-H), 1756 (C=O), 1621, 1600 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 6.34 (q, J = 1.6 Hz,

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1H, H-3), 2.94 (td, J = 5.9, 1.7 Hz, 1H, H-12), 2.71 (dt, J = 9.2, 5.5 Hz, 1H, H-1), 2.45 (ddt, J = 11.5,
7.8, 3.6 Hz, 1H, H-5), 2.32–2.29 (m, 1H, H-7a), 2.01–1.98 (m, 2H, H-17), 1.97 (d, J = 1.6 Hz, 3H, H-10),
1.80 (d, J = 9.2 Hz, 2H, H-13), 1.67 (d, J = 10.9 Hz, 1H, H-7b), 1.60–1.54 (m, 2H, H-15), 1.45 (s, 3H, H-9),
1.34–1.25 (m, 4H, H-14,16), 0.94 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 173.4 (C-11), 165.9 (C-2),
163.3 (C-4), 110.0 (C-3), 49.7 (C-1), 49.4 (C-6), 48.3 (C-5), 42.5 (C-12), 38.4 (C-17), 29.2 (C-13), 29.1 (C-7),
26.1 (C-15), 25.7 (C-16), 25.5 (C-14), 25.5 (C-8), 23.8 (C-10), 21.8 (C-9); ESI-MS m/z: 275.86 [M + H]+.
Anal. calcd. For C17H25NO2: C, 74.14; H, 9.15; N, 5.09; Found: C, 73.85; H, 9.06; N, 5.06.
(E)-verbenone O-cyclohexylcarbonyl oxime ((E)-4d). Yellow liquid. Yield: 95.0%, melting point:
◦
104.3–105.4 C. UV-Vis (EtOH)
λmax(log ε
): 251.9 (4.33) nm; IR (KBr, cm−1): 3048 (=C-H), 2985,
2933, 2856 (C-H), 1759 (C=O), 1630, 1598 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 5.99 (q, J = 1.6
Hz, 1H, H-3), 3.51 (td, J = 5.8, 1.7 Hz, 1H, H-12), 2.64 (dt, J = 9.1, 5.5 Hz, 1H, H-1), 2.41 (tt, J = 11.4,
3.6 Hz, 1H, H-5), 2.28 (td, J = 5.7, 1.5 Hz, 1H, H-7a), 1.97 (d, J = 1.6 Hz, 2H, H-17), 1.92 (d, J = 1.6 Hz,
3H, H-10), 1.79–1.76 (m, 2H, H-13), 1.67–1.64 (m, 1H, H-7b), 1.56–1.50 (m, 2H, H-15), 1.48 (s, 3H, H-9),
1.32–1.23 (m, 4H, H-14,16), 0.92 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 173.6 (C-11), 168.2 (C-2),
159.1 (C-4), 115.2 (C-3), 49.2 (C-1), 49.1 (C-6), 43.7 (C-5), 42.4 (C-12), 37.2 (C-17), 29.1 (C-13), 29.0 (C-7),
26.3 (C-15), 25.7 (C-16), 25.5 (C-14), 25.5 (C-8), 23.4 (C-10), 22.3 (C-9); ESI-MS m/z: 275.94 [M + H]+.
Anal. calcd. For C17H25NO2: C, 74.14; H, 9.15; N, 5.09; Found: C, 73.89; H, 9.08; N, 5.07.
0
◦
(Z)-verbenone O-(2 -methylbenzoyl) oxime ((Z)-4e). White solid. Yield: 95.0%, melting point: 86.3–87.4 C.
UV-Vis (EtOH) max(log
): 262.9 (4.42), 237.8 (4.28) nm; IR (KBr, cm−1): 3027 (Ar-H), 2962, 2943, 2897
(C-H), 1740 (C=O), 1623, 1600, 1575 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 7.90 (dd,
λ
ε
δ
J = 8.1, 1.2 Hz, 1H, H-17), 7.42 (td, J = 7.5, 1.3 Hz, 1H, H-15), 7.29–7.26 (m, 2H, H-16,14), 6.43 (d, J = 1.5
Hz, 1H, H-3), 3.03 (td, J = 6.0, 1.5 Hz, 1H, H-5), 2.76 (dt, J = 9.3, 5.5 Hz, 1H, H-1), 2.64 (s, 3H, H-18),
2.35–2.32 (m, 1H, H-7a), 1.98 (d, J = 1.5 Hz, 3H, H-10), 1.85 (d, J = 9.2 Hz, 1H, H-7b), 1.48 (s, 3H, H-9),
0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 166.3 (C-11), 165.5 (C-2), 163.7 (C-4), 134.0 (C-13),
131.8 (C-15), 131.6 (C-12), 130.1 (C-14), 129.3 (C-17), 125.7 (C-16), 110.3 (C-3), 49.8 (C-1), 49.5 (C-6), 48.4
(C-5), 38.5 (C-7), 26.2 (C-8), 23.9 (C-10), 21.9 (C-9), 21.4 (C-18); ESI-MS m/z: 283.84 [M + H]+. Anal.
calcd. For C18H21NO2: C, 76.30; H, 7.47; N, 4.94; Found: C, 75.98; H, 7.40; N, 4.92.
(E)-verbenone O-(20-methylbenzoyl) oxime ((E)-4e). White solid. Yield: 90.0%, melting point: 87.8–90.4
◦C. UV-Vis (EtOH)
λ
max(log
ε
): 262.7 (4.33), 238.0 (4.19) nm; IR (KBr, cm−1): 3027 (Ar-H), 2962, 2943,
2868 (C-H), 1740 (C=O), 1623, 1560, 1574 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 7.90
(dd, J = 8.0, 1.5 Hz, 1H, H-17), 7.42 (td, J = 7.5, 1.5 Hz, 1H, H-15), 7.31–7.26 (m, 2H, H-16,14), 6.43 (d,
J = 1.5 Hz, 1H, H-3), 3.03 (td, J = 5.9, 1.7 Hz, 1H, H-5), 2.78–2.74 (m, 1H, H-1), 2.64 (s, 3H, H-18), 2.33
(ddd, J = 6.5, 5.3, 1.4 Hz, 1H, H-7a), 1.98 (d, J = 1.7 Hz, 3H, H-10), 1.85 (d, J = 9.3 Hz, 1H, H-7b), 1.48 (s,
3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 166.3 (C-11), 165.5 (C-2), 163.7 (C-4), 134.0
(C-13), 131.8 (C-15), 131.6 (C-12), 130.1 (C-14), 129.3 (C-17), 125.7 (C-16), 110.3 (C-3), 49.8 (C-1), 49.5
(C-6), 48.4 (C-5), 38.5 (C-7), 26.2 (C-8), 23.9 (C-10), 21.9 (C-9), 21.4 (C-18); ESI-MS m/z: 283.82 [M + H]+.
Anal. calcd. For C18H21NO2: C, 76.30; H, 7.47; N, 4.94; Found: C, 76.05; H, 7.41; N, 4.93.
(Z)-verbenone-based O-(20-chlorobenzoyl) oxime ((Z)-4f). Yellow solid. Yield: 91.2%, melting point:
101.1–104.0 ◦C. UV-Vis (EtOH)
λ
max(log
(Ar-H, =C-H), 2975, 2955, 2867 (C-H), 1736 (C=O), 1620, 1591, 1469 (C=N, Ar-C=C, C=C); 1H-NMR
(600 MHz, CDCl3): = 7.85 (dd, J = 7.7, 1.6 Hz, 1H, H-17), 7.48 (dd, J = 8.0, 1.1 Hz, 1H, H-14),
ε
): 263.1 (3.92), 202.5 (4.36) nm; IR (KBr, cm−1): 3083, 3060
δ
7.44 (td, J = 7.7, 1.7 Hz, 1H, H-15), 7.35 (td, J = 7.6, 1.3 Hz, 1H, H-16), 6.48 (d, J = 1.7 Hz, 1H, H-3),
3.02 (td, J = 6.0, 1.6 Hz, 1H, H-1), 2.76 (dt, J = 9.3, 5.5 Hz, 1H, H-5), 2.36 – 2.31 (m, 1H, H-7a),
1.97 (d, J = 1.6 Hz, 3H, H-10), 1.86 (d, J = 9.2 Hz, 1H, H-7b), 1.48 (s, 3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR
(150 MHz, CDCl3):
δ = 167.0 (C-11), 164.2 (C-2), 164.0 (C-4), 133.3 (C-15), 132.5 (C-13), 131.5 (C-12),
130.9 (C-17), 130.2 (C-14), 126.7 (C-16), 110.5 (C-3), 50.1 (C-1), 49.5 (C-6), 48.3 (C-5), 38.6 (C-7), 26.2
(C-8), 23.9 (C-10), 21.8 (C-9); ESI-MS m/z: 303.72 [M + H]+. Anal. calcd. For C17H18ClNO2: C, 66.95; H,
5.97; N, 4.61; Found: C, 67.21; H, 5.91; N, 4.59.

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(E)-verbenone O-(20-chlorobenzoyl) oxime ((E)-4f). Yellow solid. Yield: 91.0%, melting point:
104.4–107.2 ◦C. UV-Vis (EtOH) ): 262.3 (4.01), 203.2 (4.35) nm; IR (KBr, cm−1): 3081, 3060
max(log
(Ar-H, =C-H), 2979, 2952, 2865 (C-H), 1747 (C=O),1621, 1591, 1466 (C=N, Ar-C=C, C=C); 1H-NMR
(600 MHz, CDCl3): = 7.80 (dd, J = 7.7, 1.6 Hz, 1H, H-17), 7.47 (d, J = 1.5 Hz, 1H, H-14), 7.45–7.41
λ
ε
δ
(m, 1H, H-15), 7.35–7.33 (m, 1H, H-16), 6.07 (d, J = 1.6 Hz, 1H, H-3), 3.67 (td, J = 5.8, 1.8 Hz, 1H, H-1),
2.68–2.64 (m, 1H, H-5), 2.31 (td, J = 5.7, 1.5 Hz, 1H, H-7a), 1.96 (d, J = 1.7 Hz, 3H, H-10), 1.78 (d, J = 9.2 Hz,
1H, H-7b), 1.48 (s, 3H, H-9), 0.96 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 169.3 (C-11), 164.1
(C-2), 160.1 (C-4), 133.2 (C-15), 132.5 (C-13), 131.5 (C-12), 130.9 (C-17), 130.1 (C-14), 126.7 (C-16), 114.8
(C-3), 49.7 (C-1), 49.1 (C-6), 44.4 (C-5), 37.4 (C-7), 26.2 (C-8), 23.5 (C-10), 22.3 (C-9); ESI-MS m/z:
303.72 [M + H]+. Anal. calcd. For C17H18ClNO2: C, 67.21; H, 5.97; N, 4.61; Found: C, 66.97; H, 5.93;
N, 4.60.
0
◦
(Z)-verbenone O-(2 -fluorobenzoyl) oxime ((Z)-4g). Yellow solid. Yield: 89.8%, melting point: 68.9–71.9 C.
UV-Vis (EtOH) max(log
): 265.1 (4.28), 226.6 (4.26) nm; IR (KBr, cm−1): 3064, 3041 (Ar-H, =C-H), 3000,
2964, 2865 (C-H), 1731 (C=O), 1613, 1488, 1456 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 8.05 (td, J = 7.5, 1.8 Hz, 1H, H-17), 7.56–7.53 (m, 1H, H-15), 7.26–7.24 (m, 1H, H-14), 7.17 (dd, J = 10.3,
λ
ε
δ
8.7 Hz, 1H, H-16), 6.55 – 6.50 (m, 1H, H-3), 3.03 (td, J = 6.0, 1.5 Hz, 1H, H-1), 2.76 (dt, J = 9.3, 5.5 Hz, 1H,
H-5), 2.35–2.32 (m, 1H, H-7a), 1.99 (d, J = 1.5 Hz, 3H, H-10), 1.86 (d, J = 9.2 Hz, 1H, H-7b), 1.48 (s, 3H,
H-9), 0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 167.0 (C-11), 164.1 (C-2), 134.6 (C-4), 134.5,
132.6 (C-13), 124.2 (C-15), 124.2 (C-17), 117.0 (C-16), 116.8 (C-12), 110.5 (C-14), 110.5 (C-3), 50.0 (C-1),
49.5 (C-6), 48.2 (C-5), 38.6 (C-7), 26.2 (C-8), 23.9 (C-10), 21.8 (C-9); ESI-MS m/z: 287.80 [M + H]+. Anal.
calcd. For C17H18FNO2: C, 71.06; H, 6.31; N, 4.87; Found: C, 70.71; H, 6.25; N, 4.85.
(E)-verbenone-based O-(20-fluorobenzoyl) oxime ((E)-4g). Faint yellow solid. Yield: 90.5%, melting point:
101.3–103.7 ◦C. UV-Vis (EtOH)
λ
max(log
(Ar-H, =C-H), 2979, 2958, 2870 (C-H), 1741 (C=O), 1626, 1610, 1597 (C=N, Ar-C=C, C=C); 1H-NMR
(600 MHz, CDCl3): = 8.01 (td, J = 7.5, 1.9 Hz, 1H, H-17), 7.54 (ddd, J = 15.4, 4.9, 1.8 Hz, 1H,
ε
): 264.7 (4.34), 227.3 (4.23) nm; IR (KBr, cm−1): 3067, 3043
δ
H-15), 7.24 (td, J = 7.6, 1.1 Hz, 1H, H-14), 7.17–7.13 (m, 1H, H-16), 6.08 (d, J = 1.7 Hz, 1H, H-3),
3.71 (td, J = 5.8, 1.7 Hz, 1H, H-1), 2.69 (dt, J = 9.1, 5.5 Hz, 1H, H-5), 2.36–2.27 (m, 1H, H-7a),
1.96 (d, J = 1.6 Hz, 3H, H-10), 1.79 (d, J = 9.2 Hz, 1H, H-7b), 1.50 (s, 3H, H-9), 0.96 (s, 3H, H-8);
13C-NMR (150 MHz, CDCl3):
δ = 169.2 (C-11), 160.0 (C-2), 134.6 (C-4), 134.6, 132.5 (C-13), 132.5 (C-15),
124.2 (C-17), 124.2 (C-16), 117.0 (C-12), 116.8 (C-14), 114.9 (C-3), 49.6 (C-1), 49.2 (C-6), 44.4 (C-5), 37.4
(C-7), 26.3 (C-8), 23.5 (C-10), 22.3 (C-9); ESI-MS m/z: 287.80 [M + H]+. Anal. calcd. For C17H18FNO2:
C, 71.06; H, 6.31; N, 4.87; Found: C, 70.82; H, 6.26; N, 4.86.
(Z)-verbenone O-(30-methylbenzoyl) oxime ((Z)-4h). brown liquid. Yield: 90.5%, melting point:
85.8–89.4 ◦C. UV-Vis (EtOH)
λ
max(log
2953, 2933, 2865 (C-H), 1740 (C=O), 1619, 1590, 1490 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 7.92 (s, 1H, H-17), 7.90 (d, J = 7.7 Hz, 1H, H-13), 7.39 (d, J = 7.6 Hz, 1H, H-16), 7.36 (d, J = 7.5 Hz,
ε
): 262.8 (4.28), 236.0 (4.29) nm; IR (KBr, cm−1): 3066 (Ar-H),
δ
1H, H-15), 6.49 (q, J = 1.6 Hz, 1H, H-3), 3.04 (td, J = 5.9, 1.7 Hz, 1H, H-1), 2.76 (dt, J = 9.2, 5.5 Hz, 1H,
H-5), 2.43 (s, 3H, H-17), 2.36–2.32 (m, 1H, H-7a), 2.01 (d, J = 1.7 Hz, 3H, H-10), 1.86 (d, J = 9.2 Hz, 1H,
H-7b), 1.48 (s, 3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 166.6 (C-11), 164.5 (C-2),
163.8 (C-4), 138.3 (C-14), 133.8 (C-15), 130.1 (C-13), 129.5 (C-12), 128.3 (C-17), 126.6 (C-16), 110.1 (C-3),
49.9 (C-1), 49.5 (C-6), 48.3 (C-5), 38.5 (C-7), 26.1 (C-8), 23.9 (C-10), 21.9 (C-9), 21.3 (C-18); ESI-MS m/z:
283.83 [M + H]+. Anal. calcd. For C18H21NO2: C, 76.30; H, 7.47; N, 4.94; Found: C, 75.95; H, 7.41;
N, 4.92.
(E)-verbenone O-(30-methylbenzoyl) oxime ((E)-4h). Faint brown liquid. Yield: 90.5%, melting point:
96.8–97.5 ◦C. UV-Vis (EtOH)
λ
max(log
2957, 2928, 2870 (C-H), 1741 (C=O), 1619, 1592, 1508 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 7.92 (s, 1H, H-17), 7.90 (d, J = 7.6 Hz, 1H, H-13), 7.39 (d, J = 7.6 Hz, 1H, H-16), 7.36 (t, J = 7.5 Hz,
1H, H-15), 6.49 (q, J = 1.6 Hz, 1H, H-3), 3.04 (td, J = 5.9, 1.7 Hz, 1H, H-1), 2.76 (dt, J = 9.3, 5.5 Hz, 1H,
ε
): 263.2 (4.28), 237.1 (4.25) nm; IR (KBr, cm−1): 3071 (Ar-H),
δ

Molecules 2017, 22, 1678
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H-5), 2.43 (s, 3H, H-17), 2.36–2.33 (m, 1H, H-7a), 2.01 (d, J = 1.7 Hz, 3H, H-10), 1.86 (d, J = 9.2 Hz, 1H,
H-7b), 1.48 (s, 3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
= 166.6 (C-11), 164.5 (C-2),
δ
163.8 (C-4), 138.3 (C-14), 133.8 (C-15), 130.2 (C-13), 129.5 (C-12), 128.3 (C-17), 126.6 (C-16), 110.1 (C-3),
49.9 (C-1), 49.5 (C-6), 48.3 (C-5), 38.5 (C-7), 26.1 (C-8), 23.9 (C-10), 21.9 (C-9), 21.3 (C-18); ESI-MS m/z:
283.83 [M + H]+. Anal. calcd. For C18H21NO2: C, 76.30; H, 7.47; N, 4.94; Found: C, 76.05; H, 7.42;
N, 4.93.
(Z)-verbenone O-(30-chlorobenzoyl) oxime ((Z)-4i). Pink solid. Yield: 90.5%, melting point: 84.2–87.5 ◦C.
UV-Vis (EtOH)
λmax(log ε
): 265.9 (4.17), 231.4 (4.10) nm; IR (KBr, cm−1): 3075 (Ar-H), 2999, 2937,
2869 (C-H), 1734 (C=O), 1619, 1571, 1469 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 8.07
(t, J = 1.8 Hz, 1H, H-13), 8.00 (dt, J = 7.8, 1.3 Hz, 1H, H-17), 7.56 (ddd, J = 8.0, 2.1, 1.1 Hz, 1H,
H-15), 7.43 (t, J = 7.9 Hz, 1H, H-16), 6.46 (q, J = 1.5 Hz, 1H, H-3), 3.03 (td, J = 6.0, 1.6 Hz, 1H, H-1),
2.77 (dt, J = 9.3, 5.5 Hz, 1H, H-5), 2.37–2.34 (m, 1H, H-7a), 2.02 (d, J = 1.6 Hz, 3H, H-10), 1.87 (d, J = 9.3 Hz,
1H, H-7b), 1.49 (s, 3H, H-9), 0.99 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 167.1 (C-11), 164.5 (C-2),
163.2 (C-4), 134.6 (C-14), 133.1 (C-15), 131.4 (C-12), 129.8 (C-13), 129.6 (C-16), 127.7 (C-17), 109.9
(C-3), 50.1 (C-1), 49.6 (C-6), 48.3 (C-5), 38.6 (C-7), 26.1 (C-8), 24.0 (C-10), 21.9 (C-9); ESI-MS m/z:
303.76 [M + H]+. Anal. calcd. For C17H18ClNO2: C, 67.21; H, 5.97; N, 4.61; Found: C, 66.92; H, 5.91;
N, 4.59.
(E)-verbenone O-(30-chlorobenzoyl) oxime ((E)-4i). Faint pink solid. Yield: 90.5%, melting point:
89.4–94.8 ◦C. UV-Vis (EtOH)
λ
max(log
3048 (Ar-H, =C-H), 2983, 2959, 2871 (C-H), 1743 (C=O), 1632, 1601, 1569 (C=N, Ar-C=C, C=C);
1H-NMR (600 MHz, CDCl3):
= 8.01 (s, 1H, H-13), 7.93 (d, J = 7.8 Hz, 1H, H-17), 7.57 – 7.53
ε
): 265.1 (4.08), 232.5 (3.99) nm; IR (KBr, cm−1): 3077,
δ
(m, 1H, H-15), 7.41 (t, J = 7.9 Hz, 1H, H-16), 6.14–6.03 (m, 1H, H-3), 3.64 (td, J = 5.8, 1.5 Hz, 1H, H-1),
2.72 (dt, J = 9.2, 5.5 Hz, 1H, H-5), 2.36–2.31 (m, 1H, H-7a), 1.97 (d, J = 1.3 Hz, 3H, H-10), 1.82 (d, J = 9.2 Hz,
1H, H-7b), 1.53 (s, 3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 169.3 (C-11), 163.2
(C-2), 156.0 (C-4), 134.6 (C-14), 133.1 (C-15), 131.3 (C-12), 129.8 (C-13), 129.6 (C-16), 127.7 (C-17), 115.0
(C-3), 49.6 (C-1), 49.1 (C-6), 44.1 (C-5), 37.5 (C-7), 26.3 (C-8), 23.5 (C-10), 22.3 (C-9); ESI-MS m/z:
303.73 [M + H]+. Anal. calcd. For C17H18ClNO2: C, 67.21; H, 5.97; N, 4.61; Found: C, 67.10; H, 5.94; N,
4.60.
0
◦
(Z)-verbenone O-(4 -bromobenzoyl) oxime ((Z)-4j). White solid. Yield: 90.5%, melting point: 124.6–128.0 C.
UV-Vis (EtOH) max(log
): 262.6 (4.29), 249.2 (4.30) nm; IR (KBr, cm−1): 3093, 3074 (Ar-H, =C-H), 2963,
2943, 2869 (C-H), 1737 (C=O), 1619, 1586, 1482 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 8.00–7.94 (m, 2H, H-13,17), 7.67–7.59 (m, 2H, H-14,16), 6.45 (q, J = 1.4 Hz, 1H, H-3), 3.03 (td, J = 5.8,
λ
ε
δ
1.7 Hz, 1H, H-1), 2.77 (dt, J = 9.3, 5.4 Hz, 1H, H-5), 2.40–2.30 (m, 1H, H-7a), 2.01 (d, J = 1.6 Hz, 3H,
H-10), 1.86 (d, J = 9.2 Hz, 1H, H-7b), 1.48 (s, 3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ
= 166.9 (C-11), 164.3 (C-2), 163.6 (C-4), 131.8 (C-13,17), 131.1 (C-14,16), 128.5 (C-12), 128.1 (C-15), 109.9
(C-3), 50.0 (C-1), 49.5 (C-6), 48.3 (C-5), 38.6 (C-7), 26.1 (C-8), 24.0 (C-10), 21.8 (C-9); ESI-MS m/z: 347.65
[M + H]+. Anal. calcd. For C17H18BrNO2: C, 58.63; H, 5.21; N, 4.02; Found: C, 58.39; H, 5.17; N, 4.00.
(Z)-verbenone O-(20,30-dichlorobenzoyl) oxime ((Z)-4k). Yellow solid. Yield: 90.5%, melting point:
50.2–52.3 ◦C. UV-Vis (EtOH)
λ
max(log
2953, 2933, 2868 (C-H), 1754 (C=O), 1650, 1622, 1593 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 7.71–7.68 (m, 1H, H-15), 7.64–7.61 (m, 1H, H-17), 7.31 (s, 1H, H-16), 6.44 (d, J = 1.4 Hz, 1H, H-3),
ε
): 262.4 (4.26), 204.9 (4.61) nm; IR (KBr, cm−1): 3074 (Ar-H),
δ
3.02 (td, J = 6.0, 1.5 Hz, 1H, H-1), 2.78 (dt, J = 9.4, 5.5 Hz, 1H, H-5), 2.35 (t, J = 5.3 Hz, 1H, H-7a),
1.99 (d, J = 1.3 Hz, 3H, H-10), 1.88 (d, J = 9.2 Hz, 1H, H-7b), 1.50 (s, 3H, H-9), 0.99 (s, 3H, H-8); 13C-NMR
(150 MHz, CDCl3):
δ = 167.2 (C-11), 164.6 (C-2), 163.7 (C-4), 134.4 (C-14), 133.0 (C-15), 132.8 (C-12),
131.3 (C-13), 129.1 (C-17), 127.3 (C-16), 110.2 (C-3), 50.2 (C-1), 49.5 (C-6), 48.0 (C-5), 38.6 (C-7), 26.1 (C-8),
23.9 (C-10), 21.8 (C-9); ESI-MS m/z: 337.66 [M + H]+. Anal. calcd. For C17H17Cl2NO2: C, 60.37; H, 5.07;
N, 4.14; Found: C, 60.07; H, 5.02; N, 4.12.

Molecules 2017, 22, 1678
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(E)-verbenone O-(20,30-dichlorobenzoyl) oxime ((E)-4k). Faint yellow solid. Yield: 90.5%, melting point:
◦
62.5–63.8 C. UV-Vis (EtOH)
=C-H), 2954, 2932, 2868 (C-H), 1754 (C=O), 1625, 1595, 1558 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz,
CDCl3): = 7.64 (d, J = 7.7 Hz, 1H, H-15), 7.60 (d, J = 8.0 Hz, 1H, H-17), 7.29 (d, J = 7.9 Hz, 1H, H-16),
λmax(log ε
): 261.4 (4.22), 204.8 (4.58) nm; IR (KBr, cm−1): 3078, 3045 (Ar-H,
δ
6.05 (s, 1H, H-3), 3.62 (td, J = 5.8, 1.7 Hz, 1H, H-1), 2.66 (dt, J = 9.0, 5.5 Hz, 1H, H-5), 2.32 (t, J = 5.6 Hz,
1H, H-7a), 1.96 (s, 3H, H-10), 1.79 (s, 1H, H-7b), 1.48 (s, 3H, H-9), 0.96 (s, 3H, H-8); 13C-NMR (150 MHz,
CDCl3):
δ = 169.6 (C-11), 163.8 (C-2), 160.5 (C-4), 134.4 (C-14), 133.1 (C-15), 132.7 (C-12), 131.2 (C-13),
129.1 (C-17), 127.4 (C-16), 114.6 (C-3), 49.8 (C-1), 49.2 (C-6), 44.3 (C-5), 37.4 (C-7), 26.2 (C-8), 23.5 (C-10),
22.3 (C-9); ESI-MS m/z: 337.65 [M + H]+. Anal. calcd. For C17H17Cl2NO2: C, 60.37; H, 5.07; N, 4.14;
Found: C, 60.12; H, 5.04; N, 4.13.
(Z)-verbenone O-(20,40-dichlorobenzoyl) oxime ((Z)-4l). White solid. Yield: 90.5%, melting point:
◦
78.9–80.3 C. UV-Vis (EtOH)
(Ar-H, =C-H), 2934, 2902, 2870 (C-H), 1755 (C=O), 1622, 1581, 1553 (C=N, Ar-C=C, C=C); 1H-NMR
(600 MHz, CDCl3): = 7.83 (d, J = 8.4 Hz, 1H, H-17), 7.50 (d, J = 2.0 Hz, 1H, H-14), 7.34 (dd, J = 8.4,
λmax(log ε
): 262.8 (4.16), 206.7 (4.45) nm; IR (KBr, cm−1): 3060, 3022
δ
2.0 Hz, 1H, H-16), 6.50–6.39 (m, 1H, H-3), 3.01 (td, J = 6.0, 1.4 Hz, 1H, H-1), 2.76 (dt, J = 9.3, 5.5 Hz,
1H, H-5), 2.34 (t, J = 5.7 Hz, 1H, H-7a), 1.98 (d, J = 1.5 Hz, 3H, H-10), 1.86 (d, J = 9.3 Hz, 1H, H-7b),
1.48 (s, 3H, H-9), 0.97 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 167.1 (C-11), 164.5 (C-2), 163.2 (C-4),
138.2 (C-15), 134.4 (C-13), 132.6 (C-17), 130.8 (C-12), 128.4 (C-14), 127.1 (C-16), 110.4 (C-3), 50.1 (C-1),
49.5 (C-6), 48.2 (C-5), 38.6 (C-7), 26.1 (C-8), 24.0 (C-10), 21.8 (C-9); ESI-MS m/z: 337.74 [M + H]+. Anal.
calcd. For C17H17Cl2NO2: C, 60.37; H, 5.07; N, 4.14; Found: C, 60.09; H, 5.03; N, 4.12.
(E)-verbenone O-(20,40-dichlorobenzoyl) oxime ((E)-4l). Faint yellow liquid. Yield: 90.5%, melting point:
112.7–121.9 ◦C. UV-Vis (EtOH)
λ
max(log
2956, 2927, 2870 (C-H), 1752 (C=O), 1629, 1586, 1557 (C=N, Ar-C=C, C=C); 1H-NMR (600 MHz, CDCl3):
= 7.78 (d, J = 8.4 Hz, 1H, H-17), 7.48 (d, J = 2.0 Hz, 1H, H-14), 7.33 (dd, J = 8.4, 2.0 Hz, 1H, H-16), 6.06
ε
): 262.1 (4.26), 207.1 (4.57) nm; IR (KBr, cm−1): 3084 (Ar-H),
δ
(q, J = 1.6 Hz, 1H, H-3), 3.64 (td, J = 5.8, 1.7 Hz, 1H, H-1), 2.67 (dt, J = 9.2, 5.5 Hz, 1H, H-5), 2.32 (td,
J = 5.9, 1.4 Hz, 1H, H-7a), 1.96 (d, J = 1.6 Hz, 3H, H-10), 1.78 (d, J = 9.2 Hz, 1H, H-7b), 1.48 (s, 3H, H-9),
0.96 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 169.5 (C-11), 163.3 (C-2), 160.3 (C-4), 138.3 (C-15),
134.3 (C-13), 132.6 (C-17), 130.8 (C-12), 128.4 (C-14), 127.2 (C-16), 114.7 (C-3), 49.7 (C-1), 49.1 (C-6),
44.5 (C-5), 37.4 (C-7), 26.3 (C-8), 23.5 (C-10), 22.3 (C-9); ESI-MS m/z: 337.67 [M + H]+. Anal. calcd.
For C17H17Cl2NO2: C, 60.37; H, 5.07; N, 4.14; Found: C, 60.12; H, 5.04; N, 4.13.
(Z)-verbenone O-2-chloropyridylcarbonyl oxime ((Z)-4m). White solid. Yield: 90.5%, melting point:
◦
84.1–87.1 C. UV-Vis (EtOH)
λmax(log ε
): 261.5 (4.39), 219.7 (4.34) nm; IR (KBr, cm−1): 3077 (=C-H), 2955,
2871 (C-H), 1758 (C=O), 1621, 1600 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 8.55 (dd, J = 4.8, 2.0 Hz,
1H, H-14), 8.20 (dd, J = 7.6, 2.0 Hz, 1H, H-16), 7.38 (dd, J = 7.7, 4.8 Hz, 1H, H-15), 6.48 (q, J = 1.5 Hz,
1H, H-3), 3.01 (td, J = 6.0, 1.6 Hz, 1H, H-1), 2.78 (dt, J = 9.3, 5.5 Hz, 1H, H-5), 2.37–2.33 (m, 1H, H-7a),
1.99 (d, J = 1.6 Hz, 3H, H-10), 1.87 (d, J = 9.3 Hz, 1H, H-7b), 1.49 (s, 3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR
(150 MHz, CDCl3):
δ = 167.4 (C-11), 164.9 (C-2), 163.0 (C-4), 151.8 (C-14), 149.5 (C-13), 140.5 (C-15),
127.1 (C-12), 122.2 (C-16), 110.3 (C-3), 50.3 (C-1), 49.5 (C-6), 48.2 (C-5), 38.7 (C-7), 26.1 (C-8), 24.0 (C-10),
21.8 (C-9); ESI-MS m/z: 313.24 [M + H]+. Anal. calcd. For C16H17ClN2O2: C, 63.06; H, 5.62; N, 9.19;
Found: C, 62.81; H, 5.57; N, 9.14.
(E)-verbenone O-2-chloropyridylcarbonyl oxime ((E)-4m). Faint yellow solid. Yield: 90.5%, melting point:
123.7–126.5 ◦C. UV-Vis (EtOH)
λ
max(log
ε
): 266.1(4.30), 218.8 (4.13) nm; IR (KBr, cm−1): 3074 (=C-H),
2964, 2943, 2866 (C-H), 1756 (C=O), 1622, 1578 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
δ
= 8.55 (dd,
J = 4.8, 2.0 Hz, 1H, H-14), 8.20 (dd, J = 7.6, 2.0 Hz, 1H, H-16), 7.38 (dd, J = 7.7, 4.8 Hz, 1H, H-15), 6.48 (q,
J = 1.5 Hz, 1H, H-3), 3.01 (td, J = 5.9, 1.7 Hz, 1H, H-1), 2.78 (dt, J = 9.3, 5.5 Hz, 1H, H-5), 2.38–2.33 (m,
1H, H-7a), 1.99 (d, J = 1.6 Hz, 3H, H-10), 1.87 (d, J = 9.3 Hz, 1H, H-7b), 1.49 (s, 3H, H-9), 0.98 (s, 3H, H-8);
13C-NMR (150 MHz, CDCl3):
δ
= 167.4 (C-11), 164.9 (C-2), 163.0 (C-4), 151.8 (C-14), 149.5 (C-13), 140.5
(C-15), 127.1 (C-12), 122.2 (C-16), 110.3 (C-3), 50.3 (C-1), 49.5 (C-6), 48.2 (C-5), 38.7 (C-7), 26.1 (C-8), 24.0

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(C-10), 21.8 (C-9); ESI-MS m/z: 312.88 [M + H]+. Anal. calcd. For C16H17ClN2O2: C, 63.06; H, 5.62; N,
9.19; Found: C, 62.85; H, 5.58; N, 9.16.
◦
(Z)-verbenone O-
UV-Vis (EtOH)
(C-H), 1745 (C=O), 1619, 1589, 1482 (C=N, C=C); 1H-NMR (600 MHz, CDCl3):
β
-pyridylcarbonyl oxime ((Z)-4n). Brown solid. Yield: 90.5%, melting point: 75.2–76.9 C.
λmax(log
ε
): 266.1 (4.45), 220.2 (4.34) nm; IR (KBr, cm−1): 3053 (=C-H), 2980, 2952, 2876
δ
= 9.31 (d, J = 1.7 Hz,
1H, H-13), 8.83 (dd, J = 4.9, 1.6 Hz, 1H, H-14), 8.44 (dt, J = 7.9, 1.9 Hz, 1H, H-16), 7.50 (dd, J = 7.9, 4.9 Hz,
1H, H-14), 6.61–6.36 (m, 1H, H-3), 3.03 (td, J = 6.0, 1.5 Hz, 1H, H-1), 2.78 (dt, J = 9.3, 5.5 Hz, 1H, H-5),
2.38–2.36 (m, 1H, H-7a), 2.03 (d, J = 1.5 Hz, 3H, H-10), 1.88 (d, J = 9.3 Hz, 1H, H-7b), 1.50 (s, 3H, H-9),
0.99 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ = 167.3 (C-11), 164.9 (C-2), 162.7 (C-4), 152.8 (C-14),
150.0 (C-13), 137.8 (C-16), 126.0 (C-12), 123.8 (C-15), 109.8 (C-3), 50.2 (C-1), 49.6 (C-6), 48.3 (C-5), 38.7
(C-7), 26.1 (C-8), 24.0 (C-10), 21.8 (C-9); ESI-MS m/z: 270.83 [M + H]+. Anal. calcd. For C16H18N2O2: C,
71.09; H, 6.71; N, 10.36; Found: C, 70.80; H, 6.64; N, 10.31.
(E)-verbenone O-
β-pyridylcarbonyl oxime ((E)-4n). Faint yellow solid. Yield: 90.5%, melting point:
77.5–82.4 ◦C. UV-Vis (EtOH)
λmax(log
ε
): 261.5(4.39), 219.7 (4.34) nm; IR (KBr, cm−1): 3060
1
(=C-H), 2991, 2965, 2871 (C-H), 1748 (C=O), 1621, 1586 (C=N, C=C); H-NMR (600 MHz, CDCl3):
δ
= 9.23 (d, J = 1.5 Hz, 1H, H-13), 8.80 (dd, J = 4.8, 1.6 Hz, 1H, H-14), 8.34 (dt, J = 7.9, 1.9 Hz, 1H,
H-16), 7.44 (ddd, J = 7.9, 4.9, 0.8 Hz, 1H, H-14), 6.13–6.04 (m, 1H, H-3), 3.66 (td, J = 5.8, 1.6 Hz, 1H,
H-1), 2.72 (dt, J = 9.2, 5.5 Hz, 1H, H-5), 2.34 (td, J = 5.7, 1.6 Hz, 1H, H-7a), 1.97 (d, J = 1.5 Hz, 3H,
H-10), 1.82 (d, J = 9.2 Hz, 1H, H-7b), 1.52 (s, 3H, H-9), 0.98 (s, 3H, H-8); 13C-NMR (150 MHz, CDCl3):
δ
= 169.5 (C-11), 163.0 (C-2), 160.3 (C-4), 153.5 (C-14), 150.6 (C-13), 137.2 (C-16), 125.6 (C-12), 123.5 (C-15),
114.8 (C-3), 49.7 (C-1), 49.1 (C-6), 44.1 (C-5), 37.6 (C-7), 26.3 (C-8), 23.5 (C-10), 22.3 (C-9); ESI-MS m/z:
270.75 [M + H]+. Anal. calcd. For C16H18N2O2: C, 71.09; H, 6.71; N, 10.36; Found: C, 70.83; H, 6.66;
N, 10.33.
3.5. Antifungal Activity Test
This test was performed according to the literature [30]. The tested compound was dissolved in
acetone. Sorporl-144 (200
solution of the tested compound was poured into a culture plate, and then 9 mL Potato-Sugar-Agar
(PSA) culture medium was added to obtain flats containing 50 g/mL of test compound. A bacterium
µg/mL) emulsifier was added to dilute the solution to 500 µg/mL. Then, 1 mL
µ
tray of 5-mm diameter cut along the external edge of the mycelium was transferred to the flat containing
the tested compound and put in equilateral triangular style in triplicate. Later, the culture plate was
cultured at 24
±
1 ◦C and the expanded diameter of the bacterium tray was measured after 48 h and
compared with that treated with aseptic distilled water to calculate the relative inhibition percentage.
The current commercial fungicide chlorothalonil was used as a positive control.
3.6. Herbicidal Activity Test
3.6.1. Inhibition of the Root-growth of Rape (B. campestris)
This test was carried out according to the literature [30]. The compounds to be tested were
made into emulsions by using Tween-80 as emulsifying agent to aid dissolution at concentrations of
10
paper that was in 6-cm Petri dishes containing 2 mL of compound solutions. Equal volume of distilled
water was used as control. Petri dishes were placed in darkness at 28
1 ◦C for 72 h. The radicle
µg/mL and 100 µg/mL. Groups of 15 seeds of rape (B. campestris) were placed on a 5.6-cm filter
±
lengths of seedlings were measured. All experiments had three replicates. The inhibition percent of
average length to control was used to describe the activity of compounds. And the current commercial
herbicide flumioxazin was used as a positive control.

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3.6.2. Inhibition of the Seedling Growth of Barnyard Grass (E. crusgalli)
This test was performed according to the literature [30]. The compounds to be evaluated were
made into emulsions by using TW-80 as emulsifying agent to aid dissolution, at concentrations of
10 µg/mL and 100 µg/mL. Groups of 10 germinated seeds of barnyard grass E. crusgalli were placed
on a filter paper that was in a 50 mL beaker containing 6 mL of compound solutions. Equal volume of
distilled water was used as control. Beakers were placed at 28 ± 1 ◦C (3000 lux) for 72 h. The heights
of seedlings were measured. All experiments had three replicates. The inhibition percent of average
height to control was used to describe the activity of compounds, and the current commercial herbicide
flumioxazin was used as a positive control.
4. Conclusions
Twenty-seven novel (Z)- and (E)-verbenone oxime esters were designed, synthesized,
characterized, and evaluated for their antifungal and herbicidal activities. Compound (E)-4n exhibited
excellent antifungal activity, with growth inhibitions of 92.2%, 80.0% and 76.3% against A. solani, P.
piricola and C. arachidicola, respectively, displaying better or comparable antifungal activity than that of
the positive control with inhibition rates of 96.1%, 75.0%, and 73.3%, respectively. Meanwhile, this
compound (E)-4n also showed 5.5-, 4.1-, 2.8-, and 1.7-fold higher antifungal activity against F. oxysporum
f. sp. cucumerinum, R. solani, P. piricola, and C. arachidicola, respectively, than its stereoisomer (Z)-4n
.
Seventeen target compounds displayed better herbicidal activity with 63.6–99.3% inhibition rates
against the root-growth of rape (B. campestris) than that of the commercial herbicidal flumioxazin
(positive control) with inhibition rate of 63.0%. And compound (E)-4n showed 1.7-fold herbicidal
activity to its stereoisomer (Z)-4n. Thus, the target compound (E)-4n with excellent antifungal and
herbicidal activities, as well as obvious bioactive difference between (Z)- and (E)-isomers, can serve as
lead compounds worthy of further study.
Supplementary Materials: The following are available online. Figure S1: UV-vis spectrum of verbenone
in EtOH.
2
Acknowledgments: This work was supported by the National Natural Science Foundation of China
(No. 31560194), the open fund of Guangxi Key Laboratory of Chemistry and Engineering of Forest Products
(No. GXFC14-01). The authors are grateful to the State Key Laboratory of Element-organic Chemistry,
Nankai University, China, for the bioassay test.
Author Contributions: Qiong Hu carried out the experimental work, participated in the discussion of biological
activities, and wrote the paper; Gui-Shan Lin and Wen-Gui Duan constructed the target compound structure,
designed the experimental scheme, directed, and supervised the whole experimentation, discussed the biological
activities, and revised the paper; Min Huang participated in the work of synthesis and characterization; Fu-Hou Lei
participated in the discussion of biological tests.
Conflicts of Interest: The authors declare no conflict of interest.
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Sample Availability: Samples of the compounds 2, (Z)-3a, (E)-3b, (Z)- and (E)-4a–4n are available from
the authors.
©
2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).