U.S. patent application number 10/686400 was filed with the patent office on 2004-04-22 for process for the preparation of strobilurin intermediates.
Invention is credited to Kelsall, Edward, Waditschatka, Rudolf, Wang, Linhua, Ziegler, Hugo, Zurfluh, Rene.
Application Number | 20040077895 10/686400 |
Document ID | / |
Family ID | 10843959 |
Filed Date | 2004-04-22 |
United States Patent
Application |
20040077895 |
Kind Code |
A1 |
Waditschatka, Rudolf ; et
al. |
April 22, 2004 |
Process for the preparation of strobilurin intermediates
Abstract
The present invention relates to a novel improved process and
intermediates for the process of preparing the oxime intermediates
of formula (II) wherein R.sub.1 is hydrogen, fluoro or chloro, and
R.sub.2 is methyl, ethyl, methoxy, ethoxy, trifluoromethyl,
trifluoromethoxy, cyano, fluoro, chloro or bromo. The novel process
comprises diazotizing an aniline of formula (VI) reacting the
resulting diazonium salt with isopropenylacetate of formula (X) and
reacting the resulting ketone of formula (XI) with an organic
nitrite in the presence of hydrogene chloride, and methylating the
resulting ketooxime of formula (VIII) with a methylating agent and
reacting the resulting O-methyl ketooxime of formula (IX) with
hydroxylamine. The compounds of formula (II) are intermediates for
highly active fungicides from the class of the atrobilurins. 1
Inventors: |
Waditschatka, Rudolf;
(Gipf-Oberfrick, CH) ; Zurfluh, Rene; (Bulach,
CH) ; Kelsall, Edward; (Hessle, GB) ; Ziegler,
Hugo; (Witterswil, CH) ; Wang, Linhua; (Baton
Rouge, LA) |
Correspondence
Address: |
BAYER CROPSCIENCE LP
Patent Department
100 BAYER ROAD
PITTSBURGH
PA
15205-9741
US
|
Family ID: |
10843959 |
Appl. No.: |
10/686400 |
Filed: |
October 15, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10686400 |
Oct 15, 2003 |
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09857391 |
Aug 13, 2001 |
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6664422 |
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09857391 |
Aug 13, 2001 |
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PCT/EP99/09705 |
Dec 9, 1999 |
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Current U.S.
Class: |
558/408 ;
564/259 |
Current CPC
Class: |
C07C 45/00 20130101;
C07C 49/233 20130101; C07C 251/48 20130101; C07C 45/00 20130101;
C07C 249/08 20130101; C07C 49/233 20130101; C07C 249/08
20130101 |
Class at
Publication: |
558/408 ;
564/259 |
International
Class: |
C07C 255/64; C07C
249/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 10, 1998 |
GB |
9827163.8 |
Claims
What is claimed is:
1. A process for preparing the oximes of formula II 24wherein
R.sub.1 is hydrogen, fluoro or chloro, and R.sub.2 is methyl,
ethyl, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy, cyano,
fluoro, chloro or bromo, which process comprises diazotizing an
aniline of formula VI 25reacting the resulting diazonium salt with
isopropenylacetate of formula X 26and reacting the resulting ketone
of formula XI 27with an organic nitrite in the presence of
hydrogene chloride, and and methylating the resulting ketooxime of
formula VIII 28with an methylating agent and reacting the resulting
O-methyl ketooxime of formula IX 29with hydroxylamine.
2. The compound 2,4-difluorophenylacetone 30
3. A process for preparing the oximes of formula II 31wherein
R.sub.1 is hydrogen, fluoro or chloro, and R.sub.2 is methyl,
ethyl, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy, cyano,
fluoro, chloro or bromo, which process comprises diazotizing an
aniline of formula VI 32and reacting the resulting diazonium salt
with methylglyoxal-1-oxime of formula VII 33and methylating the
resulting ketooxime of formula VIII 34with an methylating agent and
reacting the resulting O-methyl ketooxime of formula IX 35with
hydroxylamine.
4. A process for preparing the oximes of formula II 36wherein
R.sub.1 is hydrogen, fluoro or chloro, and R.sub.2 is methyl,
ethyl, methoxy, ethoxy, trifluoromethyl, trifluoromethoxy, cyano,
fluoro, chloro or bromo, which process comprises reacting a
propiophenone of formula IV 37wherein R.sub.1 and R.sub.2 are as
defined for formula II in the presence of hydrochloric acid with an
organic nitrite such as pentylnitrite, and converting the resulting
ketooxime of formula V 38wherein R.sub.1 and R.sub.2 are as defined
for formula II, into the compound of formula II by reacting it with
an aqueous solution of O-methyl-hydroxylamine-hydrochloride, and
subsequent isomerisation of the racemate of compound II into
predominantly the E-form thereof.
5. A compound of formula II obtained by the process of any one of
claims 1, 3 or 4.
6. Use of the compounds of formula II according to claim 5 for
preparing fungicidal strobilurins of formula I 39wherein R.sub.1
and R.sub.2 are as defined for formula II in claim 1 and X is NH or
oxygen wherein the compound of formula II in a conventional
etherification step is in the presence of a base with the coupled
with a compound of formula III 40wherein X is as defined for
formula I and Hal is halogen, preferably chlorine or bromine.
Description
[0001] The present invention relates to a novel improved process of
preparing certain intermediates for highly active fungicides from
the class of the strobilurins. Another aspect of the invention are
the novel intermediates per se which have been prepared for the
process of this invention.
[0002] The fungicidal strobilurins have previously been described
in e.g. WO-A-95/18789 or the later WO-A-95/21153 and WO-A-95/21154.
The processes disclosed therein are typical laboratory routes which
for large scale production are not in all steps suitable. The
present invention now provides a new improved process designed for
large scale industrial production which allows the production of
strobilurins and its key intermediates in an industrial production
process.
[0003] The fungicidal strobilurins have the general formula I 2
[0004] wherein
[0005] R.sub.1 is hydrogen, fluoro or chloro,
[0006] R.sub.2 is methyl, ethyl, methoxy, ethoxy, trifluoromethyl,
trifluoromethoxy, cyano, fluoro, chloro or bromo, and
[0007] X is NH or oxygen.
[0008] The known individual strobilurins of formula I are listed in
the following table
1TABLE 1 Comp. No. R.sub.1 R.sub.2 X 01 H Cl O 02 H Cl NH 03 H F O
04 H F NH 05 F H O 06 F H NH 07 Cl H O 08 Cl H NH 09 Cl Cl O 10 Cl
Cl NH 11 F F O 12 F F NH 13 Cl F O 14 Cl F NH 15 F Cl O 16 F Cl NH
17 H Br O 18 H Br NH 19 H CN O 20 H CN NH 21 H CH.sub.3 O 22 H
CH.sub.3 NH 23 H OCH.sub.3 O 24 H OCH.sub.3 NH 25 H C.sub.2H.sub.5
O 26 H C.sub.2H.sub.5 NH 27 H CF.sub.3 O 28 H CF.sub.3 NH 29 H
OC.sub.2H.sub.5 O 30 H OC.sub.2H.sub.5 NH
[0009] The fungicidal strobilurins of formula I are synthesized by
a conventional etherification step from the oxime compound of
formula II 3
[0010] wherein R.sub.1 and R.sub.2 are as defined for formula I in
the presence of a base with the coupling component III 4
[0011] wherein X is as defined for formula I and Hal is halogen,
preferably chlorine or bromine.
[0012] The coupling components III and most of the members of the
oximes of formula II are known.
[0013] According to the process of this invention the oximes of
formula II are obtained by the process comprising reacting a
propiophenone of formula IV 5
[0014] wherein R.sub.1 and R.sub.2 are as defined for the compounds
of formula I in the presence of hydrogen chloride with an organic
nitrite, e.g. alkyl nitrite such as iso- or n-pentyl nitrite, and
converting the resulting ketooxime of formula V 6
[0015] wherein R.sub.1 and R.sub.2 are as defined for the compounds
of formula I into the compound of formula II by reacting it with an
aqueous solution of O-methyl-hydroxylamine-hydrochloride, and
subsequent isomerisation of the (E,E/E,Z)-mixture of compound II
into predominantly the (E/E)-form thereof.
[0016] The two-step process of the invention
(IV.fwdarw.V.fwdarw.II) may be carried out in large industrial
scale vessels. The first step (IV.fwdarw.V.) is advantageously
conducted in an inert organic solvent, e.g. tetrahydrofurane,
dioxane, toluene, xylenes or a cyclic hydrocarbon like cyclohexane,
methylcyclohexane, or iso or n-pentanol, etc. at temperatures
between -20.degree. C. and +60.degree. C., with -5.degree. C. to
+40.degree. C., and especially +25.degree. C. to +40.degree. C.,
and even more +10.degree. C. to +40.degree. C. being preferred. In
the second step the keto group is replaced by the methoximino
function in a single step reaction. The resulting intermediate may
be isomerised in situ in the work-up solution and it may be
isolated therefrom, if desired. However, for the large scale
production process it is even more advantageous to use the work-up
solution directly for the coupling of intermediate II with the
Intermediate III.
[0017] The product of formula II is preferably used in the from of
the (E,E)-isomer for further coupling with the compound of formula
III for producing the fungicidal stobilurins.
[0018] Alternatively, the compounds of formula II may be obtained
by diazotizing an aniline of formula VI 7
[0019] and reacting the resulting diazonium salt with
methylglyoxal-1-oxime of formula VII 8
[0020] and methylating the resulting ketooxime of formula VIII
9
[0021] with an methylating agent and reacting the resulting
O-methyl ketooxime of formula IX 10
[0022] with hydroxylamine.
[0023] Alternatively, in a variant the compounds of formula VIII
may be obtained by diazotizing an aniline of the formula VI and
reacting the resulting diazonium salt with isopropenylacetate of
formula X 11
[0024] and reacting the resulting ketone of formula XI 12
[0025] with an organic nitrite in the presence of hydrogene
chloride.
[0026] The diazotization reaction is carried out in an organic
solvent with an organic nitrite, e.g. an alkyl nitrite as isoamyl
nitrite, or an aryl nitrite, as phenyl nitrite; or, more
preferably, in aqueous solution with nitrous acid or a salt
thereof, in presence of an acid. Preferred nitrites are sodium
nitrite, potassium nitrite, magnesium nitrite, particularly
preferred is sodium nitrite. Preferred acids are hydrochloric acid,
sulfuric acid and nitrosulf uric acid. Advantageous is a
temperature of -10.degree. C. to +30.degree. C. and a pH 0-3.
[0027] The diazonium compound is preferably reacted in the presence
of CuCl.sub.2 or CuSO.sub.4 at -10.degree. C. to +40.degree. C.,
more preferably -10.degree. C. to +15.degree. C., and at pH 2-7,
more preferably at pH 3-5. The amount of the copper salt is 1 to 20
mol %, more preferably 3 to 6 mol %, in relation to the aniline of
formula VI.
[0028] Methylation of the ketooxime of formula VIII is carried out
with a methylating agent such as methyl iodide, dimethylsulfate or
diazomethane in presence of a base, e.g. potassium carbonate or
sodium hydride in a suitable solvent at suitable reaction
temperatures as described by H. S. Anker and H. T. Clarke in
Organic Synthesis, Coll. Vol. 3,172.
[0029] The introduction of the oxime function into the Intermediate
of formula XI is preferably carried out in an inert organic
solvent, e.g. tetrahydrofurane, dioxane, toluene, xylenes or a
cyclic hydrocarbon like cyclohexane, methylcyclohexane, or iso- or
n-pentanol, etc. at temperatures between -20.degree. C. and
+60.degree. C., with -5.degree. C. to +40.degree. C., and
especially +25.degree. C. to +40.degree. C. and even more
+10.degree. C. to +40.degree. C. in the presence of e.g. hydrogen
chloride by treatment with an organic nitrite, e.g. an alkyl
nitrite as iso- or n-pentyl nitrite, or an aryl nitrite, as phenyl
nitrite
[0030] According to the process of the invention the following
intermediates of formula II may be obtained with high yields. Novel
intermediates of formula II constitute another feature of the
present invention.
2TABLE 2 Intermediates of formula II Comp. No. R.sub.1 R.sub.2 01 H
Cl 02 H F 03 F H 04 Cl H 05 Cl Cl 06 F F 07 Cl F 08 F Cl 09 H Br 10
H CN 11 H CH.sub.3 12 H OCH.sub.3 13 H C.sub.2H.sub.5 14 H CF.sub.3
15 H OC.sub.2H.sub.5
[0031] The following Examples serve as illustration of the
invention and in no way present any limitation.
EXAMPLE 1
(E,E/E,Z)-1
-(4-Chloro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)-2-oxim-
e
[0032] 13
a) (E)-1-(4-Chlorophenyl)-propan-1,2-dione-2-oxime
[0033] 14
[0034] To a solution of 440 g (2.437 mol) of 4-chloropropiophenone
and 335 g (2.925 mol) t-butylnitrite in 700 g of tetrahydrofurane
97.8 g (2.681 mol) of gaseous hydrochloric acid is dosed over 2
hours at +25.degree. C to +40.degree. C. Following the end of the
addition the batch is stirred for two hours at +15.degree. C. to
+30.degree. C. The reaction mixture is neutralized by adding 630.5
g of 20% sodium carbonate solution at +25.degree. C. Some brine and
methylcyclohexane is added and the phases are separated. The
product crystallizes from the organic phase when concentrated. The
product is isolated by filtration and the filter cake is washed
with 75 g of methylcyclohexane at 0.degree. C.: 438.9 g of
(E)-1-(4-chlorophenyl)-propan-1,2-dione-2-oxime (m.p. 115-115C) are
obtained in 91.1% yield.
[0035] b) To 200 g of chlorobenzene are added 99.8 g (0.50 mol) of
(E)-1-(4-chlorophenyl)-propan-1,2-dione-2-oxime and 192.7 g (0.66
mol) of a 26% aqueous solution of
O-methylhydroxyl-amine-hydrochloride. The pH of the resulting
solution is adjusted to 3.3 by the addition of 100 g (1.26 mol)
pyridine. Following the dosing the reaction mixture is stirred for
7 hours, at the reaction temperature of +75.degree. C. The reaction
mixture is concentrated by evaporation of chlorobenzene and the
residue is stirred with water and ethyl acetate. The organic phase
is washed neutral with HCl 32% andi.water and the combined aqueous
phases are again extracted with ethyl acetate. On evaporation of
the solvent the product is crystallized from methylcyclohexane and
dried. Yield: 95.7 g
(E,E/E,Z)-1-(4-chloro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)-2-oxim-
e (yield 84.0% of the 1:1 isomer mixture), m.p. 162.degree. C.
EXAMPLE 2
(E,E/E,Z)-1-(2,4-Difluoro-phenyl)-propane-1,2-dione
1-(O-methyl-oxime)-2-oxime
[0036] 15
a) 1-(2,4-Difluoro-phenyl)-propane-1,2-dione 1-oxime
[0037] 16
[0038] With stirring 10.0 g (0.1 mol) of sulfuric acid (95-97%) are
diluted with 45 ml of water. At +20.degree. C. 12.9 g (0.1 mol) of
2,4-difluoroaniline are added in one portion. The solution warms up
to +38.degree. C. and the 2,4-difluoroaniline-sulfate precipitates
as a white crystalline powder. The suspension is cooled to
0.degree. C., Within 20 minutes continuously a solution of 7.0 g
(0.101 mol) sodium nitrite in 30 ml of water is added at 0.degree.
C. to 5.degree. C. Close to the end of the addition the diazonium
salt suspension is diluted with 150 ml of water to allow further
stirring. The viscous suspension is allowed to be stirred for
another 15 minutes before 0.6 g of amido-sulfuric acid in 4 ml of
water are added to inactivate the excess nitrite.
[0039] In a separate beaker to a mixture of 8.3 g sulfuric acid
(95-97%) and 60 ml of water 8.7 g of anti-methylglyoxal-1-oxime is
added. To this mixture 5.0 g of copper sulfate pentahydrate and 5 g
of sodium sulfite are added. The dark-greenish solution is cooled
to 0.degree. C. and stored.
[0040] With vigorous stirring and cooling the diazonium salt
solution is added within 10 minutes to the anti-methylglyoxal-oxime
solution at 0.degree. C. The viscous suspension is stirred for 5
hours at 0.degree. C. and then with continued stirring for 16 hours
allowed to warm up to room temperature. After this period the
yellow suspension can be stirred easily.
[0041] The mixture is saturated with solid NaCl and filtered. The
brownish residue is washed with 50 ml of water. This crude product
is taken up with 100 ml of 1N sodium hydroxide solution and again
filtered. The residue is discarded. The orange filtrate is added to
40 g of ice and adjusted to pH 1 by adding 2N HCl. The solid
residue is separated and washed with water. For further
purification the residue is solved in 300 ml of ethyl
acetate/hexane (1:1) and filtered through 20 g of silicagel.
Evaporating of the solvent and drying yields 7.52 g of
1-(2,4-difluoro-phenyl)-propane-1,2-dione-1-oxime, m.p.
126-129.degree. C. After recrystallisation from methylcyclohexanone
the melting point is 133-135.degree. C.
b)
(E)-1-(2,4-Difluoro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)
[0042] 17
[0043] 258 g potassium carbonate is added to a solution of 310 g
1-(2,4-difluoro-phenyl)-propane-1,2-dione-1-oxime in 2 l
acetonitrile. After stirring for a half hour 265 g methyl iodide is
added dropwise at +35.degree. C. to +40.degree. C. The reaction
mixture is stirred for 5 hours and then diluted with 2 l water.
After extraction with 5 l ethyl acetate the organic layer is washed
two fold with 2 l sodium chloride solution (25%) and dried with
sodium sulfate. After evaporation of the volatile parts 323 g of a
brown oil remain, which is purified by heating at +70.degree. C. in
1.2 l toluene containing 100 g Hyflo and 13 g activated carbon for
10 minutes followed by filtration of the cold solution through
silicagel. Evaporating of the solvent and drying yields 317 g of an
orange oil containing 80% of (E)-1-(2,4-difluoro-phenyl)-prop-
ane-1,2-dione-1-(O-methyl-oxime).
c)
(E,E)-1-(2,4-Difluoro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)-2-ox-
ime
[0044] A solution of 4.26 g
(E)-1-(2,4-Difluoro-phenyl)propane-1,2-dione-1- -(O-methyl-oxime)
and 1.5 g hydroxylamine hydrochloride in 20 ml pyridine is heated
to +90.degree. C. for 2 hours. After addition of 50 ml ice-cold
water a yellow oil precipitates, which crystallizes within several
hours. Filtration, washing with water and drying yields 4.4 g of a
yellow solid. Purification by recrystallization in ethyl
acetate/hexane gives 4.0 g
(E,E)-1-(2,4-difluoro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)
2-oxime as white crystals, m.p 115-117.degree. C.
EXAMPLE 3
(E,E/E,Z)-1-(2,4-Difluoro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)-2-o-
xime
[0045] 18
a) (E)-1-(2,4-Difluoro-phenyl)-propane-1,2-dione-2-oxime
[0046] 19
[0047] To a solution of 170 g (1.00 mol) of
2,4-difluoropropiophenone in 200 g methylcyclohexane 37 g (1.01
mol) of gaseous hydrochloric acid is dosed over 3 hours at
0.degree. C. Thereafter 120 g (1.04 mol) of pentylnitrite are added
over a period 3 to 4 hours to the reaction mixture at +10.degree.
C. to +15.degree. C. Following the end of the addition the batch is
stirred for an hour at +10.degree. C. to +15.degree. C. during
which time a suspension is formed. The reaction mixture Is then
cooled to 0.degree. C. and stirred for a further hour. The product
is isolated by filtration and the filter cake is washed with 75 g
of methylcyclohexane at 0.degree. C.: 176 g of
(E)-1-(2,4-difluoro-phenyl)-propane-1,2-dione-2-oxime (m.p.
99-101.degree. C.) are obtained in 88.6% yield.
[0048] b) To 400 g of toluene are added 200 g (1.00 mol) of
(E)-1-(2,4-difluoro-phenyl)-propane-1,2-dione-2-oxime and 338 g
(1.21 mol) of a 30% aqueous solution of
O-methylhydroxyl-amine-hydrochloride. The resulting mixture is
heated to +65.degree. C. and 178 g (1.76 mol) of triethylamine is
dosed over 1.5 to 2 hours. During the dosing the internal
temperature Is allowed to rise to +85.degree. C. Following the
dosing the reaction mixture is stirred for a further 10 hours at
the reaction temperature of +85.degree. C. The pH of the reaction
mixture is then adjusted at +30.degree. C. to +35.degree. C. to
less than pH 0.7 by the addition of approximately 30 g (0.26 mol)
of 32% hydrochloric acid. Subsequent phase separation removes with
the aqueous stream the waste containing
triethylamine-hydrochloride. The (E,E/E,Z)-1-(2,4-difluoro-phe-
nyl)-propane-1,2-dione-1-(O-methyl-oxime)-2-oxime product is
separated from its side products by the addition of 200 g of water
and 171 g (1.29 mol) of a 30% sodium hydroxide solution at
+20.degree. C. to +25.degree. C. A second extraction with 50 g of
water and 41 g (0.31 mol) of a 30% sodium hydroxide solution is
performed. The toluene stream containing the by-product waste is
removed by phase separation. The
(E,E/E,Z)-1-(2,4-difluoro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)-2--
oxime product is set free from its sodium salt form by the addition
of approximately 200 g (1.75 mol) of 32% hydrochloric acid at
+20.degree. C. to +25.degree. C. and 338 g of fresh toluene is
added in order to extract the organic product. The pH of the
mixture is adjusted to less than pH 0.7 by the addition of a
further small quantity of 32% hydrochloric acid. Phase separation
removes the aqueous phase containing the salt waste. Isomerisation
of the product to a isomer ratio (E,E/E,Z: 92:8) is obtained (if
desired) by the addition of 7 g (0. 06 mol) of 32% hydrochloric
acid at +63.degree. C. to +65.degree. C. followed by a 2 hour
period of stirring. The addition of 78g of water at +63.degree. C.
to +65.degree. C. and a subsequent phase separation removes final
traces of acid. Any remaining traces of water are removed with an
azeotropic vacuum distillation. Finally 82 g of
1-methyl-2-pyrrolidone are added to the product solution to prevent
product precipitation during storage at room temperature. The yield
of the reaction (all isomers) is 64%, giving a 100% content of 146
g (0.64 mol) for the product solution.
EXAMPLE 4
{2-[2-(4-Chloro-phenyl)-2-methoxyimino-1-methyl-ethylidene-aminooxymethyl]-
-phenyl)-methoxyimino-acetic acid methyl ester
[0049] 20
[0050] To 150 ml of acetonitrile are added 17.0 g (75.0 mmol)
1-(4-chloro-phenyl)-propane-1,2-dione 1-(O-methyl-oxime) 2-oxime,
21.5 g (75.0 mmol) of (2-bromnomethyl-phenyl)-methoxyimino-acetic
acid methyl ester and 16.6 g (120 mmol) of potassium carbonate. The
resulting suspension: is heated at +80.degree. C. for 3 hours. At
room temperature 400 ml of water is added to the suspension
followed by an extraction with 3.times.200 ml ethyl acetate. The
organic product phase is washed with 2.times.200 ml water and then
dried over magnesium sulfate and filtered. To the crude product oil
obtained by solvent evaporation hexane is added whereafter the pure
(2-[2-(4-chloro-phenyl)-2-methoxyimino-1-methyl-ethyl-
ideneaminooxymethyl]-phenyl}-methoxyimino-acetic acid methyl ester
crystallizes from hexane: 25.5 g, 78.7% of theory, m.p.
115-117.degree. C.
EXAMPLE 5
{2-[2-(2,4-Difluoro-phenyl)-2-methoxyimino-1-methyl-ethylidene-aminooxymet-
hyl]-phenyl}-methoxyimino-acetic acid methyl ester
[0051] 21
[0052] To 150 ml of acetonitrile are added 17.1 g (75.0 mmol) The
(E,E/E,Z)-1-(2,4-difluoro-phenyl)-propane-1,2-dione-1-(O-methyl-oxime)
2-oxime, 21.5 g (75.0 mmol) of
(2-bromomethyl-phenyl)-methoxyimino-acetic acid methyl ester and
16.6 g (120 mmol) of potassium carbonate. The resulting suspension
Is heated at +80.degree. C. for 3 hours. At room temperature 400 ml
of water is added to the suspension followed by an extraction with
3.times.200 ml ethyl acetate. The organic product phase is washed
with 2.times.200 ml water and then dried over magnesium sulfate and
filtered. To the crude product oil obtained by solvent evaporation
hexane is added whereafter the pure
{2-[2-(2,4-difluoro-phenyl)-2-methoxy-
imino-1-methyl-ethylideneaminooxymethyl]-phenyl}-methoxyimino-acetic
acid methyl ester crystallizes from hexane: 24.9 g, 76.6% of
theory. The product is a mixture of two isomers, E,E,E and E,E,Z,
at a ratio of 87:13, m.p. 110-119.degree. C.
EXAMPLE 6
(E)-1-(2,4-Difluoro-phenyl)-propane-2-one
[0053] 22
[0054] With stirring and cooling 132.0 g (1.32 mol) of concentrated
sulfuric acid are diluted with 375 ml of water. At 10-15.degree. C.
78.7 g (0.60 mol) of 2,4-difluoroaniline are added and the
resulting suspension is treated with 104.6 g (0.606 mol) of a 40%
solution of sodium nitrite in water at 0-3.degree. C. over 45
minutes.
[0055] In a separate reactor a mixture is prepared from 6.0 g
copper sulfate pentahydrate, 180 ml of water, 0.9 g of concentrated
sulfuric acid and 91.2 g (0.90 mol) of isopropenyl acetate. To this
mixture the diazonium salt solution and 50.4 g of an aqueous 20%
sodium sulfite solution is concurrently added over a period of 2
hours at 10-15.degree. C. The mixture is stirred for another hour
before it is extracted with two portions of toluene. The combined
organic layers are washed with a diluted bicarbonate solution and
brine. The solvent is removed under reduced pressure and the
residual crude oil is distilled at 75-80.degree. C./5 mbar: 85.8 g
of pale yellow 1-(2,4-difluoro-phenyl)-propan-2-one are obtained in
82.9% yield.
EXAMPLE 7
(E)-1-(2,4-Difluoro-phenyl)-propane-1,2-dione 1-oxime
[0056] 23
[0057] A solution of 140.2 g (0.80 mol) of
1-(2,4-difluoro-phenyl)-propane- -2-one in 550 g of
methylcyclohexane is warmed up to 30-35.degree. C. Over a period of
2 hours 96.6 g (0.80 mol) of isoamyl nitrite is added while a slow
stream of dry hydrogen chloride is fed subsurface into the reactor.
Following the end of the addition the batch is stirred for 15
minutes at 30-35.degree. C. before the suspension is cooled to
0.degree. C. The product Is isolated by filtration and the filter
cake is washed with 150 g of methylcyclohexane at 0.degree. C.:
146.9 g of (E)-1-(2,4-difluoro-phenyl)-propane-1,2-dione 1-oxime
(mp.133-135.degree. C.) are obtained in 89.5% yield.
* * * * *