11390 J. Agric. Food Chem., Vol. 56, No. 23, 2008
Sun et al.
typical CsO (1.51 Å), which suggest that the electron density is
localized among the nitro group, phenyl, and CdNsO. We can
conclude that the nitro group, phenyl, and CdN double bond are
close to planar from the selected torsion angles of O(3)sN(2)s
C(7)sC(4), C(5)sC(4)sC(7)sN(2), and O(1)sN(1)sC(1)sC(6)
in Table 9.
their structures characterized by 1H NMR, elemental analysis
(or HRMS), and single-crystal X-ray diffraction analysis. The
larvicidal activities against oriental armyworm and mosquito
and plant growth regulatory activities of these ben-
zoylphenyureas were evaluated. The results of larvicidal
activities showed that most compounds exhibited excellent
larvicidal activities against oriental armyworm and mosquito.
The structure-activity relationship indicated that a bigger
size of O-alkyl of the target compounds increases the
larvicidal activities. In particular, the larvicidal activities
against oriental armyworm of compounds 1 and 23 were
5-10 times better than that of Flucycloxuron. Compound
18 exhibited excellent larvicidal activity against mosquito,
which had 90% mortality even at 0.001 mg L-1. Surprisingly,
some of these benzoylphenylureas exhibited good plant
growth regulatory activities.
Structure-Activity Relationship (SAR). LarVicidal ActiVi-
ties against Oriental Armyworm (Mythimna separata). Table
7 shows the larvicidal activities of the target compounds
1-24 and Flucycloxuron against oriental armyworm and
mosquito. The results indicate that most compounds have
excellent larvicidal activities against oriental armyworm and
that some compounds exhibit higher larvicidal activities than
Flucycloxuron. For example, the larvicidal activities of
compounds 1, 18, 19, 20, and 23 against oriental armyworm
at 1.0 mg L-1 were 100, 90, 80, 90, and 100%, respectively,
as compared with 10% mortality of Flucycloxuron at the same
concentration. However, intermediates 24a and 24b showed
no or poor larvicidal activities against oriental armyworm
and mosquito, which suggest that the O-alkyl oxime ether
group would have great influence on the activities. The result
in Table 7 shows that there exist steric effects and electric
effects on the larvicidal activities. The activity becomes
higher with the size of O-alkyl of compounds increasing,
for example, compounds 23 and 1 exhibit higher larvicidal
activities against oriental armyworm than compounds 5, 12,
13, and 15. The larvicidal activities of compounds 11, 10, 9,
8, 7, and 23 against oriental armyworm increase subsequently
with the electron density of the C atom connecting to the O
atom in the O-alkyl chain decreasing. Although the electron
density of the C atom connecting to the O atom in the O-alkyl
chain of compound 18 is higher than that of compound 1,
compounds 18 and 1 displayed similar larvicidal activities
against oriental armyworm. Compound 23 displayed excellent
larvicidal activity against oriental armyworm, whereas com-
pound 24 exibited poor larvicidal activity against oriental
armyworm when the C atom connecting to the O atom in
the O-alkyl chain was replaced by a Si atom. The larvicidal
activities of several commercial benzoylphenylureas against
oriental armyworm were tested under the same condition,
and the results have been reported (39). The LC50 values of
Chlorfluazuron, Teflubenzuron, Dichlorbenzuron, Chlorben-
zuron, Flucycloxuron, and Hexaflumuron were 1.03, 1.14,
1.82, 2.29, 2.44, and 4.70 mg L-1, respectively. From Table
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In summary, a series of novel benzoylphenylureas contain-
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