Fluorine containing heterocyclic compounds: Synthesis of 6-substituted-2-substituted-aryl-1,2,4-triazolo[5,1-b] 1,3,5-thiadiazin-7-one derivatives

Article abstract of DOI:10.1016/S0022-1139(00)00287-6

A group of heterocylic compounds of condensed triazole-thiadiazinone derivatives containing fluorine (IIIa-h) were obtained in good yields by the reactions of the corresponding 3-aryl-5-mercapto-1,2,4-triazole (IIa-d) with N-substituted-N-chloromethyl carbamoyl chloride (I) in the presence of potassium carbonate in N,N-dimethylformamide at room temperature. Cyclization of 3-(2,3,5-trifluoro-4-methoxyl)phenyl-5-mercapto-1,2,4-triazole (IIe) with I was difficult due to an intermolecular hydrogen bond of IIe. The structures of the compounds synthesized were confirmed by IR, MS, ¹H NMR and elemental analyses. Fungicidal and insecticidal activities of these compounds were also studied.

Full text of DOI:10.1016/S0022-1139(00)00287-6

Journal of Fluorine Chemistry 105 (2000) 111±115
Fluorine containing heterocyclic compounds: synthesis of
6-substituted-2-substituted-aryl-1,2,4-triazolo[5,1-b]
1,3,5-thiadiazin-7-one derivatives
Suyou Liua, Xuhong Qianb,*, Gonghua Songa,
Jing Chena, Weidong Chena
aInstitute of Pesticides and Pharmaceuticals, East China University of Science and Technology,
P.O. Box 544, 130 Meilong Road, Shanghai 200237, PR China
bState Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, PR China
Received 7 February 2000; accepted 17 April 2000
Abstract
A group of heterocylic compounds of condensed triazole-thiadiazinone derivatives containing ¯uorine (IIIa±h) were obtained in good
yields by the reactions of the corresponding 3-aryl-5-mercapto-1,2,4-triazole (IIa±d) with N-substituted-N-chloromethyl carbamoyl
chloride (I) in the presence of potassium carbonate in N,N-dimethylformamide at room temperature. Cyclization of 3-(2,3,5-tri¯uoro-4-
methoxyl)phenyl-5-mercapto-1,2,4-triazole (IIe) with I was dif®cult due to an intermolecular hydrogen bond of IIe. The structures of the
compounds synthesized were con®rmed by IR, MS, 1H NMR and elemental analyses. Fungicidal and insecticidal activities of these
compounds were also studied. # 2000 Elsevier Science S.A. All rights reserved.
Keywords: Triazole; Triazole-thiadiazinone; Biological activity
1. Introduction
2. Results and discussions
Triazole derivatives have been reported to have pharma-
cological, insecticidal, fungicidal and herbicidal activities
[1±6,20±22]. Some thiadiazinone derivatives are reported as
insect growth regulators [7,8]. In view of these facts and with
hope of developing bioactive compounds with high potency,
a series of novel heterocyclic compounds containing s-
triazole and 1,3,5-thiadiazin-4-one nuclei were synthesized
and a few of them showed moderate insecticidal, fungicidal
and herbicidal activitivies [9]. Organic ¯uorides have good
and extensive biological activities allowing their possible
application in pharmaceuticals and pesticides [10].
However, no report describes the effect of ¯uorine incor-
poration on the synthesis and bioactivity of previous com-
pounds. It prompted us to synthesize some new fused
triazolo-thiadiazinone compounds containing a ¯uoroaryl
moiety, which might be expected to enhance their activities
(Scheme 1).
It was easier to prepare the intermediate (Ia) by the
reaction of N-methylformanilide with sulfuryl chloride
instead of chlorine [11] (Scheme 2).
The intermediate (Ib) was synthesized in 65% yield by the
reaction of 1,3,5-triethyl-perhydro-s-triazine with bis(tri-
chloromethyl)carbonate instead of phosgene (Scheme 3)
[12,23].
The triazoles (IIa±e) described in this study were pre-
pared according to the method of Hoggarth [13] and Sand-
strom and Wennerberk [14]. Thus, the reaction of aroyl
chlorides (1) and thiosemicarbazide (2) in dried pyridine
gave 1-substituted thiosemicarbazides (3), which, without
puri®cation, were cyclized in re¯uxing diluted aqueous
potassium hydroxide to yield the desired 3-aryl-5-mer-
capto-1,2,4-triazoles (IIa±e) (Scheme 4). The synthesized
compounds IIb±e were characterized by their IR, 1H NMR,
mass spectra and elemental analyses. The IR spectra of
compounds IIb±d showed NH and SH stretching bands at
3100±3300 and 2600±2700 cm 1, respectively. The 1H
NMR spectra of compounds IIb±d showed signals at d
13.7±14.0 ppm attributed to NH and SH of triazole.
* Corresponding author.
E-mail address: xhqian@ecust.edu.cn (X. Qian).
0022-1139/00/$ ± see front matter # 2000 Elsevier Science S.A. All rights reserved.
PII: S 0 0 2 2 - 1 1 3 9 ( 0 0 ) 0 0 2 8 7 - 6

112
S. Liu et al. / Journal of Fluorine Chemistry 105 (2000) 111±115
Scheme 1.
we suggest that the cyclization reaction occurs to give
expected product III as shown in Scheme 5. The 1H
NMR spectra of the compounds IIIa±h showed a singlet
at d 4.81±5.21 ppm for two protons corresponding to the
methylene of thiadiazinone and lacked the NH signal and the
SH signal corresponding to a triazole. The IR spectra of
Scheme 2.
compounds IIIa±h showed no NH band around 3100±
1
3300 cm
1,2,4-Triazolo[5,1-b]1,3,5-thiadiazinone
derivatives
or SH band around 2600±2700 cm 1, but
(IIIa±h) were synthesized by the reactions of N-chloro-
methyl carbamoyl chloride (I) with 3-¯uorophenyl-5-mer-
capto-1,2,4-triazole in N,N-dimethylformamide in the
presence of potassium carbonate (see Scheme 1). Consider-
ing both the difference in reactivity between the chloro-
methyl and the carbamoyl chloride group [15,24] and in
basicity among 1-N, 2-N and 4-N in the s-triazole [16,17],
showed carbamoyl absorption of thiadiazinone around
1715±1735 cm 1. The mass spectrum were consistent with
the expected structures (Table 3).
However, a similar reaction with 3-(2,3,5-tri¯uoro-4-
methoxyl)phenyl-5-mercapto-1,2,4-triazole (IIe) did not
give the expected fused triazolo-thiadiazinone compound.
Further, the IR spectra of the product IIe showed a broad
Scheme 3.
Scheme 4.
Scheme 5.

S. Liu et al. / Journal of Fluorine Chemistry 105 (2000) 111±115
113
days later. Thirty larvae were used for each treatment with
two replications.
2.1.3. Test against northern house mosquitoes larvae
A test compound was dissolved in small amount of DMF
and diluted with pure water to prepare a test solution of 50
g/l. Thirty third-instar larvae of mosquitoes were released
into the test solution (50 ml wide-mouth bottle). Treated
insects were kept at 258C. Mortality was observed 1 day
later. Thirty larvae were used for each treatment with two
replications.
Scheme 6.
absorption at 2500±3400 cm 1 corresponding to a hydrogen
bond. The H NMR of compound IIe exhibited two broad
1
signals at d 14.26 and 14.35 ppm for one proton attributed to
SH and the chemical shift of corresponding NH has under-
gone a up®eld shift to d 11.0±11.35 ppm with two singlets
(see data given in Section 3). The spectral data of compound
IIe indicated that two types of hydrogen bond between
¯uorine in the 2-position of the aromatic ring and hydrogen
attached to 2-N or 4-N of the triazole ring were formed in a
ratio about 6:4. Many possible three-dimensional molecular
conformations and their energies of compound IIe were
studied using PCMODEL method (Fourth Edition, June
1990). The calculation results indicated that the structural
conformation a (Eˆ27.07 kcal/mol) and b (Eˆ25.48 kcal/
mol) were the most stable with the lowest energies, and
conformation b most probably the higher concentration of
the two isomers. This was consistent with the experiment.
Thus, we assume that, due to the strong electron-withdraw-
ing effect of the poly¯uorophenyl group, the acidity of NH in
the triazole ring would increase and a hydrogen bond is
formed between ¯uorine in the 2-position of aromatic ring
and hydrogen attached to 2-N or 4-N of the triazole ring
(Scheme 6). This would make cyclization very dif®cult.
Some of the synthesized III type compounds were
screened for their antifungal and pesticidal activities. The
compounds IIIe, IIIg and IIIh showed weak activities at
50 g/l against Actinomucor elegans M-211, Botrytis cinerea,
Aspergillus niger, Alternaria solani and Fusarium oxy-
sporum, F. vasinfectum using the plate technique in an agar
medium by measuring the inhibition zone in millimeter [18].
Compound IIIh showed 90% insecticidal activity at 300 g/l
against house mosquito larvae (Cluex pipiens molestus
Forskae). None of IIIa±h showed activities against Aphis
laburnl Kaltenbach and Cirphis unipuncta Haworth.
3. Experimental details
Melting points were taken on a digital melting point
apparatus made in Shanghai and were uncorrected. Infrared
spectra were measured using a Nicolet 20sx FT-IR instru-
ment. Mass spectra were measured on a Hitachi M80
1
instrument. H NMR spectra were obtained using a Bruker
AC-500 (500 MHz) spectrometer with CDCl3 or DMSO-d6,
using TMS as internal standard. Analysis was undertaken
with an Italian MOD 1106 analyzer at the Analysis Center of
the East China University of Science and Technology.
3.1. Preparation of N-chloromethyl-N-ethyl-carbamoyl
chloride (Ia)
To a solution of 39.75 g (0.015 mol) of bis(trichloro-
methyl)carbonate in 100 ml of chloroform cooled down
from 10 to 08C in a ice-salt bath, 26.65 g (0.015 mol)
of 1,3,5-triethyl-hexahydro-s-triazine in 20 ml of chloro-
form was added dropwise below 08C. The mixture was
agitated at room temperature for 1 h, then re¯uxed for
1 h. Solvent was removed under reduced pressure, and
the residue was distilled in vacuo. The product, a colorless
liquid, bp: 83±858C/12 mmHg (bp: 838C/12 mmHg [12]),
was obtained in 65% yield.
Anal. calcd. for C4H7Cl2NO: C, 30.80; H, 4.52; N, 8.98%;
found: C, 30.92; H, 4.50; N, 8.83%.
3.2. Preparation of N-chloromethyl-N-phenylcarbamoyl
chloride (Ib)
2.1. Pests and test methods
A solution of 112 g (0.83 mol) of sulfuryl chloride in
70 ml of carbon tetrachloride was added dropwise to a
solution of 44.8 g (0.33 mol) N-methylformanilide and
4 g of 2,20-azo-bis-iso-butyronitrile in 230 ml of carbon
tetrachloride at 70±758C over 3±4 h. After addition, the
reaction mixture was re¯uxed for 1±2 h followed by tlc.
The reaction was terminated when only trace amount of
starting material was left unchanged. The solvent and excess
sulfuryl chloride was removed at reduced pressure leaving a
syrupy crude material which crystallized on standing.
Recrystallization from boiling hexane gave 43 g (64%) of
Ib; mp: 47.9±50.48C (mp: 45±468C [11]).
2.1.1. Test against Aphis laburnl Kaltenbach
Pea seedlings were immersed in test solution for 20 s,
dried and infested with a mixed population. Samples were
checked for mortality 24 h after introduction.
2.1.2. Test against Cirphis unipuncta Haworth
Corn leaf-cuts were immersed in test solution for 20 s.
Each treated leaf-cut was placed in a Petri dish and two-
instar larvae of C. unipuncta Haworth were released into
each dish. Treated insects were kept at 258C, 70% relative
humidity under lights condition. Mortality was observed 5

114
S. Liu et al. / Journal of Fluorine Chemistry 105 (2000) 111±115
Anal. calcd. for C8H7Cl2NO: C, 46.86; H, 3.44; N, 6.83%;
found: C, 46.74; H, 3.48; N, 6.93%.
1H); electron impact ms: m/e (relative intensity) 195 (100)
‡
M , 136 (41), 122 (36), 95 (12), 95 (23), 75 (15).
Anal. Calcd. for C8H6FN3S: C, 49.22; H, 3.10; N,
21.53%; found: C, 49.31; H, 3.12; N, 21.44%.
3.3. General procedures for the preparation of 3-aryl-5-
mercapto-1,2,4-triazole (IIa±e)
3.3.4. 3-(2,4-Dichloro-5-fluoro)phenyl-5-mercapto-1,2,4-
triazole (IId)
To a stirred, ice-bath solution of the thiosemicarbazide (2)
(0.02 mol) and pyridine (20 ml) was added dropwise the
aroylchloride (1) (0.022 mol). The reaction mixture was
stirred overnight at room temperature. The excess pyridine
was evaporated at reduced pressure, leaving a mixture of the
crude aroylthiosemicarbazide (3) and pyridine hydrochlor-
ide. The mixture was washed with water, removing the
pyridine hydrochloride, and the crude aroylthiosemicarba-
zide (3) was collected by ®ltration. This was heated to re¯ux
in 8% potassium hydroxide or sodium hydroxide solution for
approximately 4±5 h. The ®ltrate was cooled to 08C. Careful
acidi®cation by the dropwise addition of acetic acid afforded
the crude solid products, which were recrystallized from
ethanol.
White powder, 3.8 g (72%), dec.: 284±2858C; IR (KBr):
3100, 3050, 2850, 2750, 1610, 1590, 1480, 1240, 980,
1
960 cm ; 1H NMR (DMSO-d6): d 7.88 (d, 1H, Jˆ9.5 Hz),
8.08 (d, 1H, Jˆ5.8 Hz), 13.88 (s, 1H), 13.95 (s, 1H); electron
‡
impact ms: m/e (relative intensity) 263 (100) M , 265 (68)
‡
‡
M ‡2, 267 (12) M ‡4, 192 (12), 189 (17).
Anal. Calcd. for C8H4Cl2FN3S: C, 36.38; H, 1.53; N,
15.91%; found: C, 36.20; H, 1.52; N, 15.99%.
3.3.5. 3-(2,3,5-Trifluoro-4-methoxyl)phenyl-5-mercapto-
1,2,4-triazole (IIe)
Yellow needles, 2.97 g (58%), mp: 216±2178C; IR (KBr):
2500±3400, 1630, 1530, 1480, 1360, 1280, 1070, 980,
1
1
830 cm ; H NMR (DMSO-d6): d 2.65 (s, 3H), 7.38 (s,
1H), 11.0 (s, NH), 11.35 (s, NH), 14.22 (s, SH), 14.35 (s,
SH); electron impact ms: m/e (relative intensity) 261 (100)
3.3.1. 3-(4-Fluoro)phenyl-5-mercapto-1,2,4-triazole (IIa)
White powder, 2.88 g (74%), dec.: 272±2738C (dec.: 269±
2728C [19]).
‡
M , 188 (11), 174 (36), 125 (11), 99 (14), 88 (36).
Anal. Calcd. for C9H6F3N3OS: C, 41.38; H, 2.32; N,
16.09%; found: C, 41.47; H, 2.30; N, 15.92%.
3.3.2. 3-(2-Fluoro)phenyl-5-mercapto-1,2,4-triazole (IIb)
Colorless plates, 3.15 g (81%), mp: 276±2778C; IR
(KBr): 3100, 3050, 2900, 2850, 1620, 1595, 1575, 1495,
3.4. General procedures for the preparation of 6-
substituted-2-substituted aryl-1,2,4-triazolo-[5,1-b]1,3,5-
thiadiazin-7-ones (IIIa±h)
1
1
1230, 970 cm ; H NMR (DMSO-d6): d 7.35±7.82 (m,
4H), 13.78 (s, 1H), 13.84 (s, 1H); electron impact ms: m/e
‡
(relative intensity) 195 (100) M , 123 (70), 102 (29), 95
(12), 75 (22).
A mixture of N-substituted-N-chloromethyl carbamoyl
chloride I (0.01 mol), 3-aryl-5-mercapto-1,2,4-triazole II
(0.01 mol), anhydrous potassium carbonate (0.022 mol) in
N,N-dimethylformamide (10 ml) was stirred at room tem-
perature for 1±2 h, then diluted with water, the resulting
precipitate was collected and washed with water. After
drying, the crude product was crystallized from ethanol to
obtain the desired products IIIa±h. Analytical data are
recorded in Table 1. The spectroscopic data are given in
Tables 2 and 3.
Anal. Calcd. for C8H6FN3S: C, 49.22; H, 3.10; N,
21.53%; found: C, 49.02; H, 3.13; N, 21.60%.
3.3.3. 3-(3-Fluoro)phenyl-5-mercapto-1,2,4-triazole (IIc)
White powder, 3.00 g (77%), mp: 265±2678C; IR (KBr):
3100, 3050, 2900, 1600, 1570, 1500, 1480, 1240, 980,
1
960 cm ; 1H NMR (DMSO-d6): d 7.38 (td, 1H, Jˆ8.5 Hz,
Jˆ2.2 Hz), 7.59 (m, 1H), 7.72 (dt, 1H, Jˆ6.1 Hz, Jˆ
2.2 Hz), 7.77 (d, 1H, Jˆ7.9 Hz), 13.76 (s, 1H), 13.81 (s,
Table 1
Physical data of compounds IIIa±h
Compound
mp (8C)
Yield (%)
Formula
Calculated (found (%))
III
R
R0
C
H
N
a
b
c
d
e
f
C2H5
C2H5
C2H5
C2H5
C6H5
C6H5
C6H5
C6H5
2-FC6H4
145±146
160±161
204±205
169±171
218±219
204±205
241±242
197±198
85
81
86
80
87
83
85
82
C12H11FN4OS
C12H11FN4OS
C12H11FN4OS
C12H9Cl2FN4OS
C16H11FN4OS
C16H11FN4OS
C16H11FN4OS
C16H9Cl2FN4OS
51.79 (51.57)
51.79 (51.63)
51.79 (51.93)
41.51 (41.64)
58.89 (58.98)
58.89 (58.72)
58.89 (58.71)
48.65 (48.74)
3.98 (3.89)
3.98 (4.06)
3.98 (3.95)
2.61 (2.60)
3.40 (3.37)
3.40 (3.46)
3.40 (3.39)
2.28 (2.30)
20.13 (20.24)
20.13 (20.04)
20.13 (19.99)
16.14 (16.08)
17.17 (17.10)
17.17 (17.31)
17.17 (17.06)
14.20 (14.12)
3-FC6H4
4-FC6H4
2,4-diCl-5-F-C6H2
2-FC6H4
3-FC6H4
g
h
4-FC6H4
2,4-diCl-5-F-C6H2

S. Liu et al. / Journal of Fluorine Chemistry 105 (2000) 111±115
115
Table 2
1H NMR data of compounds IIIa±h
Compound III
1H NMR (CDCl3) d ppm
a
b
c
d
e
f
1.36 (t, 3H, CH3, Jˆ7.2 Hz), 3.77 (q, 2H, CH2, Jˆ7.2 Hz), 4.81 (s, 2H, SCH2), 7.22±8.10 (m, 4H)
1.37 (t, 3H, CH3, Jˆ7.2 Hz), 3.77 (q, 2H, CH2, Jˆ7.2 Hz), 4.80 (s, 2H, SCH2), 7.17±7.99 (m, 4H)
1.31 (t, 3H, CH3, Jˆ7.2 Hz), 3.72 (q, 2H, CH2, Jˆ7.2 Hz), 4.75 (s, 2H, SCH2), 7.11 (m, 2H), 8.14 (m, 2H)
1.33 (t, 3H, CH3, Jˆ7.2 Hz), 3.73 (q, 2H, CH2, Jˆ7.2 Hz), 4.78 (s, 2H, SCH2), 7.54 (d, 1H, Jˆ6.6 Hz), 7.78 (d, 1H, Jˆ9.4 Hz)
5.19 (s, 2H, SCH2), 7.20±7.50 (m, 8H), 8.12 (td, 1H, Jˆ7.5 Hz, Jˆ1.4 Hz)
5.21 (s, 2H, SCH2), 7.20 (m, 1H), 7.41±7.53 (m, 6H), 7.94 (m, 1H) 8.30 (dt, 1H, Jˆ7.7 Hz, Jˆ1.5 Hz)
5.18 (s, 2H, SCH2), 7.14 (t, 2H, Jˆ8.6 Hz), 7.40±7.49 (m, 5H), 8.21 (dd, 2H, Jˆ8.6 Hz, Jˆ5.5 Hz)
5.20 (s, 2H, SCH2), 7.38±7.50 (m, 5H), 7.58 (d, 1H, Jˆ6.7 Hz), 7.83 (d, 1H, Jˆ9.3 Hz)
g
h
Table 3
IR and MS spectral data of compounds IIIa±h
1
)
Compound III IR (KBr) (cm
EI MS m/e (%)
‡
a
b
c
d
e
f
3020, 2990, 1715, 1615, 1585, 1520, 1500, 1410, 1320, 1190,
1065, 795
278 (86, M ), 207 (58), 165 (39), 149 (12), 121 (81), 86 (100),
57 (65)
‡
2990, 1715, 1615, 1590, 1525, 1500, 1470, 1415, 1310,
1265, 1205, 1180, 875, 790, 740
278 (100, M ), 207 (46), 165 (43), 149 (26), 121 (73), 86 (47),
57 (49), 56 (14)
‡
3010, 2990, 1710, 1605, 1495, 1475, 1415, 1320, 1275, 1215,
845, 745
278 (100, M ), 207 (48), 165 (43), 149 (28), 121 (82), 86 (40),
57 (42)
‡
‡
‡
3010, 2990, 1715, 1600, 1505, 1490, 1470, 1455, 1405, 1335,
1090, 890, 725
350 (5, M ‡4), 348 (23, M ‡2), 346 (38, M ), 277 (11),
275 (16), 240 (12), 191 (23), 189 (34), 86 (100), 57 (58), 56 (16)
‡
3020, 2950, 1730, 1620, 1580, 1520, 1490, 1440, 1390, 1210, 1060, 326 (60, M ), 207 (48), 165 (4), 149 (10), 121 (19), 105 (100),
770, 760, 740
3020, 1732, 1590, 1520, 1495, 1425, 1350, 1210, 1060, 870, 740
104 (40), 86 (40), 77 (17), 57 (45)
‡
326 (52, M ), 207 (30), 165 (3), 149 (16), 121 (30), 105 (100),
104 (39), 86 (28), 77 (35), 57 (54)
‡
g
h
3040, 1730, 1605, 1490, 1430, 1380, 1220, 1070, 850, 750
326 (95,M ), 205 (39), 165 (5), 149 (26), 121 (38), 105 (100),
104 (39), 86 (20), 77 (43), 57 (57)
‡
3050, 1735, 1595, 1495, 1450, 1390, 1315, 1270, 1210, 1090, 1060, 395 (68, M 1), 397 (44), 276 (11), 241 (13), 191 (10),
950, 890, 725
189 (15), 105 (100), 104 (46), 86 (27), 57 (29), 50 (14)
[9] S.Y. Liu, X.H. Qian, J. Chen and G.H. Song, Novel fused
heterocycles: synthesis and activities of 5,6-dihydro-7-thia-1,3,3a,5-
tetraaza-inden-4-ones and 1-thia-3,4a,9-triaza-fluoren-4-ones deriva-
tives, Monatshefte fur Chemie, in press.
Acknowledgements
This study was ®nancially supported by Shanghai Foun-
dation of Science and Technology.
[10] X. Qian, J. Tang, W. Chen, R. Zhang, Chem. J. China Univ. 15 (1994)
224.
[11] H. Ulrich, R. Richter, P.J. Whitman, A.A.R. Sayigh, J. Org. Chem. 39
(1974) 2897.
References
[12] H. Kritzler, K. Wagner, H. Holtschmidt, Belg. 621378 (1962).
[13] E. Hoggarth, J. Chem. Soc. (1949) 1163.
[1] J.E. Franis, W.D. Cashi, S. Psychoyos, G. Ghaij, P. Wenk, R.C.
Friedmann, C. Atkins, W. Warren, P. Furness, J.L. Hyun, G.A. Stone,
M. Desai, M. Williams, J. Med. Chem. 31 (1988) 1014.
[2] Y.C. Kim, X.D. Ji, K.A. Jacobson, J. Med. Chem. 39 (1996) 4142.
[3] K.C. Joshi, S. Giri, S.C. Bahel, J. Sci. Ind. Res., Sect. C 21 (1962)
315.
[14] R. Sandstrom, I. Wennerberk, Acta Chem. Scand. 20 (1966) 57.
[15] K.H. Koenig, H. Pommer, Belg. 660727 (1966).
[16] K.T. Potts, S. Husain, J. Org. Chem. 36 (1971) 10.
[17] Z. Szabo, F. Korodi, Synth. Commun. 20 (1990) 2473.
[18] J.G. Hosrall, Bot. Rev. 11 (1945) 357.
[19] J.M. Kane, M.W. Dudley, S.M. Sorensen, F.P. Miller, J. Med. Chem.
31 (1988) 1253.
[4] R.M. Jacobson, N.L. Tu, EP 338685 (1989).
[5] M.J. Costales, W.A. Kleschick, R.J. Her, M.R. Weimer, US 5763359
(1998).
[20] R.M. Jacobson, N.L. Tu, Chem. Abstr. 112 (1990) 178991.
[21] M.J. Costales, W.A. Kleschick, R.J. Her, M.R. Weimer, Chem. Abstr.
129 (1999) 67792.
[6] C.P. Tseng, US 5510320 (1996).
[7] K. Ikeda, M. Yasui, H. Kanno, S. Maekawa, J. Pest. Sci. 11 (1986)
287.
[22] C.P. Tseng, Chem. Abstr. 125 (1996) 58525.
[23] H. Kritzler, K. Wagner, H. Holtschmidt, Chem. Abstr. 59 (1963) 9816.
[24] K.H. Koenig, H. Pommer, Chem. Abstr. 64 (1967) 1972.
[8] H. Kanno, Pure and Appl. Chem. 59 (1987) 1027.