Synthesis of 1-triazolyl-4-trimethylsilyl-2-butanol and 1-triazolyl-5-trimethylsilyl-2-pentanol derivatives and an investigation of their fungicidal activities

Article abstract of DOI:10.1248/cpb.51.1113

A new series of azole derivatives of 1-triazolyl-4-trimethylsilyl-2-butanol and 1-triazolyl-5-trimethylsilyl-2-pentanol were synthesized and evaluated for fungicidal activities against rice blast, sheath blight, and powdery mildew on barley. The derivatives of 2,4-difluorobenzene exhibited high antifungal activities when applied by spray, but exhibited no fungicidal activity by submerged application.

Full text of DOI:10.1248/cpb.51.1113

September 2003
Notes
Chem. Pharm. Bull. 51(9) 1113—1116 (2003)
1113
Synthesis of 1-Triazolyl-4-trimethylsilyl-2-butanol and 1-Triazolyl-5-
trimethylsilyl-2-pentanol Derivatives and an Investigation of Their
Fungicidal Activities
Hiroyuki ITOH, ,a Rieko YONEDA,a Junzo TOBITSUKA,a Hiroshi OHTA,a Yukiyoshi TAKAHI,a
*
b
Mikio TSUDA,a and Hideo TAKESHIBA
a Agroscience Research Laboratories, Sankyo Co., Ltd.; Yasu, 1041 Yasu, Yasu-cho, Yasu-gun, Shiga 520–2342, Japan: and
b Medicinal Chemistry Research Laboratories, Sankyo Co., Ltd.; 1–2–58 Hiromachi, Shinagawa-ku, Tokyo 140–8710,
Japan. Received May 19, 2003; accepted June 16, 2003
A new series of azole derivatives of 1-triazolyl-4-trimethylsilyl-2-butanol and 1-triazolyl-5-trimethylsilyl-2-
pentanol were synthesized and evaluated for fungicidal activities against rice blast, sheath blight, and powdery
mildew on barley. The derivatives of 2,4-difluorobenzene exhibited high antifungal activities when applied by
spray, but exhibited no fungicidal activity by submerged application.
Key words fungicidal activity; 1H-1,2,4-triazole; silicon; synthesis
In a previous paper,1) we reported our research targeting a
systemic fungicide and our discovery of silicon-containing
azole compounds showing fungicidal activity against rice
sheath blight by submerged application.
gal activity of the agents against Pyricularia oryzae and Rhi-
zoctonia solani and evaluating their efficacy by submerged
application against rice blast and rice sheath blight, we exam-
ined their efficacy against the powdery mildew of barley, a
fungus against which the azole fungicides are generally ef-
fective.
Before the development of the compounds 3, Chollet et al.
reported6) that compounds in which the number of carbons
increased were synthesized by the addition of trimethylsilyl-
acetylene to triazolylacetophenone. The compounds 3 can be
anticipated to follow by reduction of the triple bond (Fig. 3).
In our experiment, the route required two reductions and af-
forded 3 in low yield.
Azole fungicide acts on the fungus by inhibiting the
biosynthesis of ergosterol,2) an important component of the
cell membrane of the fungus. The effectiveness of the azole
fungicide against rice sheath blight might be due to the prop-
erty of Rhizoctonia solani as a filamentous fungus possessing
an ergosterol-containing cell membrane. However, an agent
is likely to lack a systemic feature if it fails to consistently
show excellent efficacy by submerged application. From this
standpoint, it was very promising to find that a series of sili-
con-containing azole derivatives 1 exhibited excellent effects
in comparison with the existing fungicides by submerged ap-
plication.
In our program, the derivation was performed using the
Grignard reaction with the epoxides 8 in the presence of cup-
per halide7) (Fig. 4).
We speculated that the compounds 4 could be prepared by
a similar method, using the oxetanes 9 of the intermediate to
take the place of the epoxides 8 (Fig. 5). The oxetanes 9
could be generated by reaction with two equivalents of di-
In spite of these promising effects, the compounds 1 are
structured with two carbons between a hydroxyl group and a
trimethylsilyl group, hence they are liable to decompose to
allyl compounds 2 by Peterson elimination3—5) under acidic
or alkaline conditions (Fig. 1). This may pose problems with
the industrialized manufacture and use of these compounds.
In one limited case, however, we were able to prepare and
evaluate a promising compound in which the number of car-
bons between the hydroxyl group and trimethylsilyl group in-
creased. Given their small possibility of Peterson elimina-
tion, the compounds 3 were thought to be favorable from the
viewpoint of synthesis.
Fig. 2. Research Strategy
Although the 4-fluorobenzene derivative 3a exhibited a
low efficacy compared to the 4-fluorobenzene derivative 1a
in testing, we tried to confirm the effect of variation on the
substitution of the benzene ring to boost the activity (Fig. 2).
We also examined the compounds 4 structured with an in-
creased number of carbons. In addition to testing the antifun-
Fig. 3. 1-Triazolyl-4-trimethylsilyl-2-butanol Prepared from Chollet’s
Compound 5
Fig. 4. 1-Triazolyl-4-trimethylsilyl-2-butanol Prepared by the Grignard
Reaction
Fig. 1. Peterson Reaction
To whom correspondence should be addressed. e-mail: hiroit@yasu.sankyo.co.jp
© 2003 Pharmaceutical Society of Japan

1114
Vol. 51, No. 9
Table 1. Synthesis of 1-Triazolyl-4-trimethylsilyl-2-butanols 3
Compd.
X
Yield (%)
3a
3b
3c
3d
3e
3f
4-F
4-Cl
4-Br
H
4-Me
4-MeO
2,4-F2
2,4-Cl2
63a)
61
73
27
76
67
Fig. 5. 1-Triazolyl-5-trimethylsilyl-2-pentanol Prepared by the Grignard
Reaction
methylsulfoxonium methylide8,9) 7 to triazolylacetophenones
6. The target compounds 4 could be prepared from the oxe-
tanes 9 under reaction conditions similar to those used for
the preparation of the compounds 3.
3g
3h
49
b)
a) Data from our previous work.1) b) Prepared from Chollet’s compound 5.
We performed tests on 1-triazolyl-4-trimethylsilyl-2-bu-
tanols and 1-triazolyl-5-trimethylsilyl-2-pentanols obtained
367.071487.
2-Phenyl-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-butanol (3d) mp
by the above-described methods in order to assess their 76—77 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1510, 1494, 1248, 1202,
1136, 1062, 1011. 1H-NMR (200 MHz, CDCl3) d: Ϫ0.06 (9H, s), 0.22 (1H,
fungicidal activities against rice blast, rice sheath blight, and
powdery mildew of barley, as well as to measure their IC50
dt, Jϭ4.5, 13.5 Hz), 0.51 (1H, dt, Jϭ4.5, 13.5 Hz), 1.70 (1H, dt, Jϭ4.5,
13.5 Hz), 1.90 (1H, dt, Jϭ4.5, 13.5 Hz), 4.48 (2H, s), 7.21—7.37 (5H, m),
values against the phytophathogenic fungi Pyricularia oryzae
and Rhizoctonia solani. The results are shown in Table 3.
Among several derivatives on the substituted phenyl, 2,4-
difluorobenzne derivatives 3g and 4d exhibited high antifun-
gal activity against both fungi, and 2,4-disubstituted deriva-
tives of 2-butanols 3g and 3h showed fungicidal activity for
powdery mildew. However in spite of these high effects, none
of these derivatives exhibited any effect whatever by sub-
merged application. Based on the results obtained, we pre-
sume that these derivatives are missing a systemic feature.
In conclusion, a new series of azole derivatives of 1-tria-
zolyl-4-trimethylsilyl-2-butanol and 1-triazolyl-5-trimethylsi-
lyl-2-pentanol were synthesized and evaluated for fungicidal
activities against rice blast, sheath blight, and powdery
mildew on barley. Among them, the derivatives of 2,4-difluo-
robenzene exhibited high antifungal activities but did not
show fungicidal activity by submerged application.
7.90 (1H, s), 8.00 (1H, s). MS m/z: 289 (Mϩ), 274, 207, 188, 83, 73. HR-
MS. Calcd for C15H23N3OSi: 289.161041. Found: 289.161107.
2-(4-Methylphenyl)-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-bu-
tanol (3e) mp 93—94 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1736, 1512,
1
1425, 1277, 1250, 1188, 1136, 1075, 1032. H-NMR (200 MHz, CDCl3) d:
Ϫ0.06 (9H, s), 0.23 (1H, dt, Jϭ4.5, 13.5 Hz), 0.50 (1H, dt, Jϭ4.5, 13.5 Hz),
1.69 (1H, dt, Jϭ4.5, 13.5 Hz), 1.89 (1H, dt, Jϭ4.5, 13.5 Hz), 2.32 (3H, s),
4.50 (2H, s), 7.12 (2H, d, Jϭ8.5 Hz), 7.18 (2H, d, Jϭ8.5 Hz), 7.92 (1H, s),
8.26 (1H, s). MS m/z: 303 (Mϩ), 288, 221, 202, 83, 73. HR-MS. Calcd for
C16H25N3OSi: 303.176691. Found: 303.176674.
2-(4-Methoxyphenyl)-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-bu-
tanol (3f) mp 87—88 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1734, 1611,
1
1512, 1423, 1250, 1178, 1134, 1072, 1031. H-NMR (200 MHz, CDCl3) d:
Ϫ0.06 (9H, s), 0.23 (1H, dt, Jϭ4.5, 13.5 Hz), 0.50 (1H, dt, Jϭ4.5, 13.5 Hz),
1.68 (1H, dt, Jϭ4.5, 13.5 Hz), 1.88 (1H, dt, Jϭ4.5, 13.5 Hz), 3.79 (3H, s),
4.49 (2H, s), 6.84 (2H, d, Jϭ8.5 Hz), 7.19 (2H, d, Jϭ8.5 Hz), 7.94 (1H, s),
8.31 (1H, s). MS m/z: 319 (Mϩ), 304, 237, 218, 121, 83, 73. HR-MS. Calcd
for C16H25N3O2Si: 319.171606. Found: 319.171722.
2-(2,4-Difluorophenyl)-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-bu-
tanol (3g) mp 76—77 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1610, 1512,
1
1423, 1250, 1138, 1094, 1032. H-NMR (200 MHz, CDCl3) d: Ϫ0.05 (9H,
s), 0.13 (1H, dt, Jϭ4.5, 13.5 Hz), 0.58 (1H, dt, Jϭ4.5, 13.5 Hz), 1.74 (1H,
Experimental
All melting points (mp) were uncorrected. IR was recorded on a Perkin dt, Jϭ4.5, 13.5 Hz), 1.90 (1H, dt, Jϭ4.5, 13.5 Hz), 4.49 (1H, d, Jϭ14.0 Hz),
1
Elmer 1600 spectrometer and H-NMR spectra were recorded on a Varian 4.81 (1H, d, Jϭ14.0 Hz), 6.69—6.83 (2H, m), 7.37—7.49 (1H, m), 7.85
Gemini 200 spectrometer using tetramethylsilane as an internal standard. (1H, s), 8.12 (1H, s). MS m/z: 325 (Mϩ), 310, 243, 224, 83, 73. HR-MS.
MS values were obtained on a JEOL JMS-D300 spectrometer and a VG Calcd for C15H21F2N3OSi: 325.142197. Found: 325.142052.
Auto Spec M mass spectrometer. TLC was performed on a plate precoated
2-(2,4-Dichlorophenyl)-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-bu-
with a 0.25 mm-thick layer of silica gel (E. Merck), and the spots were made tanol (3h) A solution of sodium bis(2-methoxyethoxy)aluminum hydride
visible by ultraviolet (UV) irradiation or by spraying with a solution made of in toluene (0.59 ml, 2.0 mmol) was diluted with teterahydrofuran (50
25 g ammonium molybdate and 1 g ceric sulfate in 500 ml of 10% sulfuric
ml), and a solution of 2-(2,4-dichlorophenyl)-1-(1H-1,2,4-triazol-1-yl)-4-
acid followed by heating. Silica gel (350—250 mesh, Yamamura Chemical trimethylsilylbut-3-yn-2-ol was added to the mixture at 0 °C. The mixture
Laboratories Co., Ltd.) was used for column chromatography. The following was stirred at room temperature for 3 h, and neutralized with 20% sulfuric
abbreviations are used hereafter: s, singlet; d, doublet; dd, doublet of dou- acid, poured into ice for quenching and extracted with ethyl acetate. The or-
blet; t, triplet; q, quartet; m, multiplet; br, broad.
ganic layer was washed with water and dried over magnesium sulfate, and
2-Phenyl-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-butanol (3) The the solvent was evaporated to give 2-(2,4-dichlorophenyl)-1-(1H-1,2,4-tria-
following compounds 3b—g were prepared using the same procedure em- zol-1-yl)-4-trimethylsilylbut-3-en-2-ol (98 mg, 55%) as colorless crystals
ploying in our previous work.1) The yields are shown in Table 1.
(recrystallized from diisopropyl ether), mp 118—120 °C. 1H-NMR (200
2-(4-Chlorophenyl)-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-bu- MHz, CDCl3) d: 4.65 (1H, d, Jϭ14.1 Hz), 5.12 (1H, d, Jϭ14.1 Hz), 6.05
tanol (3b) mp 83—84 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1736, 1595,
(1H, d, Jϭ18.8 Hz), 6.55 (1H, d, Jϭ18.8 Hz), 7.19 (1H, dd, Jϭ2.2, 8.4 Hz),
1
1510, 1491, 1425, 1248, 1190, 1072, 1015. H-NMR (200 MHz, CDCl3) d: 7.36 (1H, d, Jϭ2.2 Hz), 7.67 (1H, d, Jϭ8.4 Hz), 7.84 (1H, s), 7.99 (1H, s).
Ϫ0.06 (9H, s), 0.18 (1H, dt, Jϭ4.5, 13.5 Hz), 0.50 (1H, dt, Jϭ4.5, 13.5 Hz), MS m/z: 357 (Mϩϩ2), 355 (Mϩ), 342, 340, 275, 273, 258, 256, 216, 214,
1.65 (1H, dt, Jϭ4.5, 13.5 Hz), 1.85 (1H, dt, Jϭ4.5, 13.5 Hz), 4.47 (2H, s), 83, 73. This product (126 mg, 0.35 mmol) was dissolved in ethanol (5 ml)
7.23 (2H, d, Jϭ9.0 Hz), 7.29 (2H, d, Jϭ9.0 Hz), 7.91 (1H, s), 8.11 (1H, s). and subjected to hydrogenation with a hydrogen balloon in the presence of
MS m/z: 323 (Mϩ), 308, 241, 222, 83, 73. High resolution (HR)-MS. Calcd
10% palladium on carbon for 5 h at room temperature. The catalyst was then
for C15H22ClN3OSi: 323.122069. Found: 323.122179.
filtered off and the solvent was removed in vacuo to afford 3h (115 mg,
2-(4-Bromophenyl)-1-(1H-1,2,4-triazol-1-yl)-4-trimethylsilyl-2-bu- 90%) as colorless crystals (recrystallized from diisopropyl ether), mp 91—
tanol (3c) mp 112—113 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1725, 93 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1586, 1518, 1370, 1248, 1188,
1585, 1510, 1490, 1425, 1248, 1190, 1072, 1015. 1H-NMR (200 MHz, 1136, 1092, 1026. 1H-NMR (200 MHz, CDCl3) d: Ϫ0.06 (9H, s), 0.04 (1H,
CDCl3) d: Ϫ0.06 (9H, s), 0.17 (1H, dt, Jϭ4.5, 13.5 Hz), 0.50 (1H, dt,
Jϭ4.5, 13.5 Hz), 1.65 (1H, dt, Jϭ4.5, 13.5 Hz), 1.85 (1H, dt, Jϭ4.5,
dt, Jϭ4.5, 13.5 Hz), 0.57 (1H, dt, Jϭ4.5, 13.5 Hz), 1.77 (1H, dt, Jϭ4.5,
13.5 Hz), 2.36 (1H, dt, Jϭ4.5, 13.5 Hz), 4.48 (1H, d, Jϭ14.0 Hz), 5.25 (1H,
13.5 Hz), 4.47 (2H, s), 7.18 (2H, d, Jϭ8.5 Hz), 7.49 (2H, d, Jϭ8.5 Hz), 7.91 d, Jϭ14.0 Hz), 7.14 (1H, dd, Jϭ2.0, 8.5 Hz), 7.32 (1H, d, Jϭ2.0 Hz), 7.58
(1H, s), 8.10 (1H, s). MS m/z: 369 (Mϩϩ2), 367 (Mϩ), 354, 352, 287, 285, (1H, d, Jϭ8.5 Hz), 7.82 (1H, s), 7.92 (1H, s). MS m/z: 359 (Mϩϩ2), 357
268, 266, 83, 73. HR-MS. Calcd for C15H22BrN3OSi: 367.071552. Found: (Mϩ), 344, 342, 258, 256, 83, 73. HR-MS. Calcd for C15H21Cl2N3OSi:

September 2003
1115
Table 3. Fungicidal Activities of Azole Derivatives
Table 2. Synthesis of 1-Triazolyl-4-trimethylsilyl-2-pentanols 4
Compd.
P.O.
R.B.
R.S.
S.B.
P.M.
Compd.
X
Yield (%)
IC50 (ppm) MIC (g/10a) IC50 (ppm) MIC (g/10a) MIC (ppm)
4a
4b
4c
4d
4e
4-F
4-Cl
H
2,4-F2
3,4-Cl2
49
26
21
37
36
3a
3b
3c
3d
3e
3f
3g
3h
4a
4b
4c
4d
4e
1a
10
Ͼ10
Ͼ10
Ͼ10
Ͼ10
Ͼ10
3.10
2.57
Ͼ3
Ͼ3
Ͼ10
0.89
Ͼ10
1.09b)
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ1.0
Ͼ1.0
Ͼ1.0
Ͼ1.0
Ͼ1.0
Ͼ1.0
Ͼ100a)
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
Ͼ100
3
3
3
3
Ͼ3
Ͼ3
0.3
0.3
3
1
3
0.12
357.083096. Found: 357.083022.
0.05
0.42
0.61
Ͼ1.0
0.01
2-(4-Fluorophenyl)-1-(1H-1,2,4-triazol-1-yl)-5-trimethylsilyl-2-pen-
tanol (4a) A solution of sodium hydride (60% mineral oil dispersion,
880 mg, 22.0 mmol) in dimethyl sulfoxide (20 ml) was heated at 70 °C for
1 h. When the hydrogen gas ceased to evolve, the mixture was cooled to
room temperature and trimethylsulfoxonium iodide (4.8 g, 21.8 mmol) was
added. After stirring at room temperature for 0.5 h, 1-(4-fluorophenyl)-2-
(1H-1,2,4-triazol-1-yl)ethanone 5a (2.05 g, 10.0 mmol) was added and the
mixture was stirred for 4 h at the same temperature. The reaction mixture
was partitioned between ethyl acetate and brine, the organic layer was dried
over magnesium sulfate and concentrated to give a solid, and the solid ob-
tained was chromatographed on silica gel (ethyl acetate–hexane, 1 : 1, v/v) to
afford 1-{[2-(4-fluorophenyl)oxetane-2-yl]methyl}-1H-1,2,4-triazole 9a
1
1.94
Ͼ3
3b)
0.04b)
12.5a)
0.3b)
P.O., Pyricularia oryzae; R.B., Rice blast; R.S., Rhizoctonia solani; S.B., Sheath
blight; P.M., Powdery mildew; a) data from our previous work1); b) data from our previ-
ous work.10)
1
1610, 1550, 1510, 1375, 1248, 1135, 1030. H-NMR (200 MHz, CDCl3) d:
1
(1.29 g, 55%) as an oil. H-NMR (200 MHz, CDCl3) d: 2.66 (1H, m), 3.00
Ϫ0.10 (9H, s), 0.36—0.46 (2H, m), 0.90—1.16 (1H, m), 1.25—1.50 (1H,
m), 1.69 (1H, dt, Jϭ5.0, 12.0 Hz), 1.85 (1H, dt, Jϭ5.0, 12.0 Hz), 4.38 (2H,
s), 7.14 (1H, dd, Jϭ2.0, 8.5 Hz), 7.38 (1H, d, Jϭ8.5 Hz), 7.47 (1H, d,
Jϭ2.0 Hz), 7.89 (1H, s), 7.91 (1H, s). MS m/z: 373 (Mϩϩ2), 371 (Mϩ), 358,
356, 330, 328, 289, 256, 83, 73. HR-MS. Calcd for C16H23Cl2N3OSi:
371.098746. Found: 371.098628.
(1H, m), 4.28 (1H, m), 4.31 (1H, d, Jϭ14.7 Hz), 4.44 (1H, m), 4.54 (1H, d,
Jϭ14.7 Hz), 7.09 (2H, t, Jϭ8.8 Hz), 7.30 (2H, dd, Jϭ5.3, 8.8 Hz), 8.00 (1H,
s), 8.30 (1H, s). This product was used for the next reaction without further
purification. Cuprous iodide (95 mg, 0.5 mmol) was added to a solution of
9a (117 mg, 0.5 mmol) in teterahydrofuran (2 ml) at room temperature. A so-
lution of trimethylsilylmethylmagnesium chloride in diethyl ether (1.9 ml,
1.5 mmol) was added dropwise to the mixture at room temperature for 1 h.
The reaction mixture was poured into ice, and quenched with a saturated
aqueous solution of ammonium chloride, and extracted with ethyl acetate.
The organic layer was washed with water and dried over magnesium sulfate.
The solvent was evaporated to give a solid, which was purified by column
chromatography (ethyl acetate–hexane, 1 : 1, v/v) to afford 4a (143 mg, 89%)
as colorless crystals (recrystallized from diisopropyl ether), mp 133—
135 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1913, 1775, 1736, 1605, 1510,
Antifungal Activity Four-millimeter mycelial agar discs were placed on
potato dextrose agar plates containing test compounds. The plates were incu-
bated at 25 °C for 7 d as for the test of efficacy against Pyricularia oryzae,
and at 25 °C for 3 d for the test of efficacy against Rhizoctonia solani. The
diameters of the mycelium colonies were then measured to examine the ef-
fects of the chemicals on fungal growth. The results are shown in Table 3.
Curative Activity against Rice Blast Rice seedlings (variety
Sachikaze) at the 4—5 leaf stage were sprayed with a spore suspension of
the fungus Pyricularia oryzae and kept in a moist chamber (relative humid-
ity: 100%) at 20—22 °C. After 24 h, the rice seedlings were sprayed with
aqueous suspensions of the test compound at different concentrations, and
placed back in the moist chamber. The concentration with the highest effi-
cacy against rice blast was identified after 6 d. The results are shown in Table
3.
Preventive Activity against Rice Sheath Blight by Submerged Appli-
cation Rice seedlings (variety Nipponbare) at the 3—4 leaf stage were
flooded to a depth of 1 cm with water in pots, then the test compound was
dispensed into the water. After keeping the seedlings in a greenhouse for 7 d,
4—5 oat grains cultured with Rhizoctonia solani were placed around the
base of each seedling. The seedlings were then kept in a moist chamber (rel-
ative humidity: 100%) for 5 d at 25—27 °C. The number of grams per 10
acres required to eradicate rice sheath blight was determined after 5 d. The
results are shown in Table 3.
1
1425, 1370, 1248, 1188, 1136, 1092, 1026. H-NMR (200 MHz, CDCl3) d:
Ϫ0.10 (9H, s), 0.36—0.46 (2H, m), 1.01—1.23 (1H, m), 1.26—1.42 (1H,
m), 1.71 (1H, dt, Jϭ5.0, 12.0 Hz), 1.88 (1H, dt, Jϭ5.0, 12.0 Hz), 4.39 (2H,
s), 6.99 (2H, t, Jϭ8.5 Hz), 7.28 (2H, dd, Jϭ5.0, 8.5 Hz), 7.83 (1H, s), 7.88
(1H, s). MS m/z: 321 (Mϩ), 306, 239, 206, 83, 73. HR-MS Calcd for
C16H24FN3OSi: 321.167269. Found: 321.167289.
The following compounds were prepared by a similar method. The yields
are shown in Table 2.
2-(4-Chlorophenyl)-1-(1H-1,2,4-triazol-1-yl)-5-trimethylsilyl-2-pen-
tanol (4b) mp 121—122 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1913,
1775, 1720, 1595, 1505, 1425, 1270, 1249, 1090, 1025, 1010. 1H-NMR
(200 MHz, CDCl3) d: Ϫ0.09 (9H, s), 0.35—0.46 (2H, m), 1.01—1.15 (1H,
m), 1.25—1.42 (1H, m), 1.71 (1H, dt, Jϭ4.5, 13.5 Hz), 1.88 (1H, dt, Jϭ4.5,
13.5 Hz), 4.40 (2H, s), 7.26 (4H, m), 7.85 (1H, s), 7.89 (1H, s). MS m/z: 339
(Mϩϩ2), 353 (Mϩ), 324, 322, 255, 222, 83, 73. HR-MS. Calcd for
C16H24ClN3OSi: 337.137719. Found: 337.137675.
Curative Activity against Powdery Mildew of Barley Barley
seedlings (variety Sekishinriki) at the first leaf stage were inoculated with
conidia of Erysiphe graminis f. sp. hordei by sprinkling spores of the fungus
on the seedlings. After being kept in a greenhouse at 15—50 °C for 1 d, the
seedlings were sprayed with an aqueous suspension of the test compound
and kept in the greenhouse at the same temperature for 10 more days. On the
10th day, the most effective concentration against powdery mildew of barley
was determined. The results are shown in Table 3.
2-Phenyl-1-(1H-1,2,4-triazol-1-yl)-5-trimethylsilyl-2-pentanol
(4c)
mp 120—121 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1960, 1775, 1740,
1
1595, 1505, 1450, 1249, 1190, 1025, 1010. H-NMR (200 MHz, CDCl3) d:
Ϫ0.10 (9H, s), 0.37—0.47 (2H, m), 1.05—1.16 (1H, m), 1.25—1.42 (1H,
m), 1.73 (1H, dt, Jϭ5.0, 12.0 Hz), 1.93 (1H, dt, Jϭ5.0, 12.0 Hz), 4.42 (2H,
s), 7.04—7.32 (5H, m), 7.82 (1H, s), 7.88 (1H, s). MS m/z: 303 (Mϩ), 288,
221, 188, 146, 83, 73. HR-MS. Calcd for C16H25N3OSi: 303.176691. Found:
303.176738.
Acknowledgements We are grateful to Dr. S. Sugai, the board member
of our company, Dr. K. Tanaka, the director of our laboratories, and to Dr. T.
Jojima, our former director, for their encouragement throughout this work.
2-(2,4-Difluorophenyl)-1-(1H-1,2,4-triazol-1-yl)-5-trimethylsilyl-2-
pentanol (4d) mp 97—98 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1775,
1
1620, 1510, 1425, 1240, 1190, 1094, 1025. H-NMR (200 MHz, CDCl3) d:
Ϫ0.09 (9H, s), 0.40—0.48 (2H, m), 0.99—1.15 (1H, m), 1.34—1.48 (1H,
m), 1.77 (1H, dt, Jϭ5.0, 12.0 Hz), 1.98 (1H, dt, Jϭ5.0, 12.0 Hz), 4.44 (1H,
d, Jϭ14.0 Hz), 4.77 (1H, d, Jϭ14.0 Hz), 6.68—6.82 (2H, m), 7.39—7.51
(1H, m), 7.83 (1H, s), 7.89 (1H, s). MS m/z: 339 (Mϩ), 324, 257, 224, 83,
73. HR-MS. Calcd for C16H23F2N3OSi: 339.157847. Found: 339.157849.
2-(2,4-Dichlorophenyl)-1-(1H-1,2,4-triazol-1-yl)-5-trimethylsilyl-2-
pentanol (4e) mp 96—97 °C. IR (KBr) cmϪ1: 3250, 2950, 2880, 1755,
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