Novel herbicidal oxime derivatives of aryl glyphosate esters are described and claimed along with a process for producing such oxime derivatives.

BACKGROUND TO THE INVENTION 
The present invention relates to novel glyphosate oxime derivatives with 
herbicidal properties and to a process by which these derivatives may be 
obtained. 
The discovery of the herbicidal properties of "glyphosate", the full 
chemical name of which is N-phosphonomethylglycine, has given rise to the 
discovery of a series of related derivatives with herbicidal properties. 
The basic patent in this area is U.S. Pat. No. 3,799,758 which discloses 
salts, esters and amides of glyphosate. Other patents including U.S. Pat. 
No. 4,053,505 and U.S. Pat. No. 4,120,689 have described the aryl esters 
and still others, such as U.S. Pat. No. 3,970,695, have claimed glyphosate 
derivatives with trifluoroacetyl substituents. There has however been no 
examination of the oxime ester derivatives of glyphosate since a a 
suitable process by which such compounds could be made has not previously 
been defined. The present invention provides such a process and the novel 
compounds made thereby have been found to exhibit herbicidal activity. 
DESCRIPTION OF THE INVENTION 
The novel compounds of the invention have the formula: 
##STR1## 
wherein R.sub.1 and R.sub.2 are each independently hydrogen alkyl, aryl, 
aralkyl or haloalkyl and X.sub.1, X.sub.2 and X.sub.3 are each 
independently hydrogen, halogen, C.sub.1 -C.sub.4 alkyl or alkoxy, or 
nitro groups. 
In preferred compounds of the invention, X.sub.2 and X.sub.3 are hydrogen 
and X.sub.1 is hydrogen, chloro or C.sub.1 to C.sub.4 alkyl. The preferred 
embodiments of R.sub.1 and R.sub.2 are hydrogen, phenyl and methyl with 
compounds in which at least one of R.sub.1 and R.sub.2 is methyl most 
preferred. 
The invention further comprises a process for the preparation of the above 
compounds by the reaction of a compound having the structure: 
##STR2## 
with an oxime having the structure 
##STR3## 
in an aprotic organic solvent and in the presence of a tertiary amine base 
and N,N.sup.1 -dicyclohexylcarbodiimide. In the above formula the terms 
R.sub.1, R.sub.2, X.sub.1, X.sub.2 and X.sub.3 have the same significances 
as are set forth above. 
The starting phosphonate ester in the above reaction can be obtained by the 
process described in U.S. Pat. No. 4,218,235. Alternatively it may be 
obtained by the procedures outlined in Example 1 with appropriate 
modifications. 
The compounds of the invention are found to have post emergent herbicidal 
activity.

DESCRIPTION OF PREFERRED EMBODIMENTS 
The following Examples illustrate preferred compounds according to the 
invention as well as preferred reactions by which they may be made. They 
are of course illustrative in nature and imply no limitations on the scope 
of the invention. 
The process to produce the compounds of the invention takes place in any 
aprotic organic solvent capable of bringing the starting materials into 
solution. Usually dichloromethane, tetrahydrofuran or dimethyl formamide 
are suitable but others can also be used if desired if they remain inert 
to the reactants and starting materials. 
The reaction between the oxime and the carboxylic acid function in the 
starting material is catalyzed by a tertiary amine such as 
4-pyrrolidinopyridine, dimethylaminopyridine, triethylamine or pyridine. 
The preferred tertiary amine is however 4-pyrrolidinopyridine. 
The reaction proceeds at room temperatures though elevated temperatures can 
be used if desired. 
EXAMPLE 1 
This Example illustrates the production of a compound according to the 
invention having the formula: 
##STR4## 
For purposes of illustration the production process starting from readily 
available materials is described. It is understood that this process could 
readily be adopted to produce other compounds according to the invention. 
The initial reaction product (V) is produced in the following manner: 
______________________________________ 
##STR5## 
##STR6## 
##STR7## 
Reaction Quantities 
Compound Quantity (g) 
Moles 
______________________________________ 
I 5.91 g 0.05 
II 10.62 g 0.05 
III 10.42 g 0.05 
IV 0.25 g 0.0002 
______________________________________ 
Compounds I, II and IV were dissolved in 200 ml of 1,2-dichloroethane and 
the mixture was stirred magnetically under nitrogen. Compound III was then 
added and stirring at room temperature was continued overnight. After 
filtration, washing and finally concentration the reaction mixture yielded 
15.5 g of Compound V. 
Compound V (3.09 g or 10 mmol) was mixed with 20 ml of ethanol, 785 mg of 
acetyl chloride and 50 mg of 10% Pd/C catalyst. This mixture was stirred 
under hydrogen overnight. The catalyst was then filtered off through a 
Celite pad and the filtrate was concentrated to an oil which was further 
purified, concentrated and then dried to give 1.65 g of a product that 
proved to have the formula: 
EQU Cl.sup.-.H.sub.3.sup.+ NCH.sub.2 COOC.sub.2 H.sub.4 Si(CH.sub.3).sub.3 (VI) 
Compound VI (1.06 g or 5 mmole) was dissolved in 425 mg of 
tert-butylazomethine and 25 ml of diethyl ether. This mixture was stirred 
overnight at room temperature then filtered and the residue was washed 
with ether. The filtrate was concentrated to a colorless oil which 
crystallized to a white solid with a melting point of 
42.degree.-44.degree. C. Elemental analysis which was consistent with 
structure VII below, showed: C--51.2%, H--9.15% and N--7.44%. The 
structure contains the theoretical proportions: C--51.3%, H--9.15% and 
N--7.48%. 
##STR8## 
Compound (VII) (27 mmol, 5.06 g) was mixed with 50 ml of toluene and 6.76 g 
(27 mmol+7%) of diphenylphosphite and the mixture was heated at 80.degree. 
C. for 3 hours after which .sup.31 P NMR analysis indicated reaction was 
complete. The mixture was concentrated to leave a pale yellow oil which 
was dried under vacuum overnight. Elemental analysis showed the 
proportions C--57.2%, H--6.89% and N--3.10%. The expected structure (VIII 
below) contains: C--56.99%, H--6.7% and N--3.32% 
##STR9## 
Compound (VIII) (7.0 g of the unpurified product) was dissolved in 15 ml of 
ethyl diisopropylamine and this solution was cooled to 0.degree. C. A 
solution of 4.2 g of trifluoroacetic anhydride in 10 ml of diethyl ether 
was added dropwise with stirring which was continued overnight. After 16 
hours a .sup.31 P NMR spectrum of the reaction mixture indicated a 40:60 
ratio of starting materials to finished product. The mixture was then 
heated to 80.degree. C. for 5 hours. The mixture was cooled to room 
temperature, diluted with ether, washed with 5% sulfuric acid, water and 
brine, and then dried over anhydrous sodium sulphate. Evaporation gave a 
yellow oil in which the major component was a compound with elemental 
analysis: C--51.05%, H--5.30% and N--2.64%. The expected compound, (IX 
below), has the theoretical proportions: C--51.06%; H--5.26% and N13 
2.71%. 
##STR10## 
Compound (IX) (3.84 g) was stirred with 5 ml of trifluoroacetic acid for 3 
hours. The mixture was then concentrated and dried under vacuum to yield a 
white solid. The solid was purified by reprecipitation from a 50/50 
ether-cyclohexane mixture. The solid was dried overnight and an element 
analysis showed C--48.96%, H--3.65% and N--3.33%. Formula X below has the 
proportions C--48.93%, H--3.65% and N--3.30%. 
##STR11## 
Compound X (834 mg or 2 mmol) was dissolved in 15 ml of dichloromethane and 
454 mg (2.2 mmol) of Compound III were added. The mixture was stirred at 
room temperature. In a few minutes a precipitate of dicyclohexyl urea had 
formed. Acetone oxime (160.82 mg or 2.2 mmol) and 30 mg (0.2 mmol) of 
4-pyrrolidinopyridine were then added and stirring at room temperature was 
continued overnight. 
The mixture was diluted with diethyl ether and this solution was washed 
with water and brine and then dried. Evaporation of the solvent left a 
pale yellow oil. This product was purified by HPLC, using a 25% ethyl 
acetate/cyclohexane eluant. Fractions of 25 ml were collected at 25 
ml/minute. The product appeared in fractions 17 to 30, and after 
evaporation 80 mg of a pale yellow oil were obtained. 
NMR spectroscopy confirmed formation of the product: 
##STR12## 
Elemental analysis yielded the following results: Theory: C 50.85%; H 
4.27%; N 5-93% Found: C 50.79%; H 4.31%; N 5-96%. 
EXAMPLE 2 
This Example illustrates the production of a compound according to the 
invention having the formula: 
##STR13## 
from a starting material with the formula: 
##STR14## 
The above starting material (1.0 g or 0.0022 mole) was dissolved in about 5 
ml of dichloromethane and 0.51 g (0.0024 mole) of 
N,N'dicyclohexylcarbodiimide dissolved in about 2 ml of dichloromethane 
was added with stirring, under nitrogen, at room temperature. A solid 
(dicyclohexyl urea) precipitated almost at once. Stirring was continued 
for 10 minutes. Phenyl methyl ketone oxime (0.33 g or 0.0024 mole) and 
0.03 g (0.0002 mole) of 4-pyrrolidinopyridine were combined with 4 ml of 
dichloromethane and this clear yellow solution was added to the reaction 
mixture. After stirring overnight, more solvent was added to the mixture 
to replace evaporated solvent and agitation was continued. after three 
days the reaction mixture was filtered and then concentrated on a rotovap 
evaporator to a residue of 1.5 g. This was taken up in a small amount of 
dichloromethane and purified by an HPLC procedure. The eluant employed was 
23% ethyl acetate/77% cyclohexane and the flow rate was 15 ml/minute. 
The product obtained was shown to have structure VIII by proton and .sup.31 
P NMR spectroscopy. 
Elemental analysis showed: Theory: C 57.65%; H 4.66%; N 4.98% Found: C 
57.48%; H 4.93%; N 4.93% 
EXAMPLE 3 
This Example describes the production of a compound according to the 
invention having the formula: 
##STR15## 
from a starting material having the formula: 
##STR16## 
The starting material (2.0 g, 0.00449 mole) was dissolved in approximately 
10 ml. of dichloromethane. To this mixture were added 1.02 g (0.00489 
mole), of 99% N,N'dicyclohexylcarboiimide and about 4 ml. of 
dichloromethane. The mixture was stirred at room temperature under 
nitrogen. Almost immediately, dicyclohexylurea was precipitated. Stirring 
under nitrogen was continued for about 20 minutes. 
Acetone oxime (0.36 g, 0.00492 mole) and 0.07 g (0.00047 mole) of 
4-pyrrolidinopyridine were then mixed in about 3 ml. of dichloromethane 
and added to the reaction mixture which was stirred overnight at room 
temperature. 
The reaction mixture was then filtered and the filtrate concentrated on a 
rotovap evaporator in a water bath at 25.degree. C. The residue obtained 
(2.6 g) was purified by HPLC using a 500 ml. column, a flow rate of 500 
ml/minute and a 40% ethyl acetate/60% cyclohexane eluant system. 
The product obtained was subjected to elemental analysis and the following 
results were obtained: 
C--52.71%; H--4.88%; N--5.59% 
This is consistent with the formula of XIV (above) which has the 
theoretical proportions (based on the formula) of: 
C--52.8%; H--4.83%; N--5.6%. 
The Structure XIV was confirmed using proton .sup.31 P and .sup.19 F NMR 
spectroscopy. 
EXAMPLE 4 
This Example illustrates the herbicidal activity of the compounds prepared 
by the process described in Examples 1 and 2. 
The active ingredients are applied in spray form, at a rate equivalent to 
200 gallons per acre, to 14 day old specimens of various plant species. 
The spray, a water or organic solvent-water solution containing active 
ingredient and a surfactant (35 parts butylamine salt of 
dodecylbenzenesulfonic acid and 65 parts tall oil condensed with ethylene 
oxide in the ratio of 11 moles ethylene oxide to 1 mole tall oil), is 
applied to the plants in different sets of pans at several rates (pounds 
per acre) of active ingredient. The treated plants are placed in a 
greenhouse and the effects are observed and recorded after approximately 2 
weeks or approximately 4 weeks, as is indicated in the last column of 
Table I. 
The post-emergence herbicidal activity index used in Table 1 is as follows: 
______________________________________ 
Plant Plant 
Response Index Response Index 
______________________________________ 
Less than 25% 
0 75-99% inhibition 
3 
inhibition 
25 to less than 
1 100% Inhibition 
4 
50% inhibition 
50 to less than 
2 Not tested -- 
75% inhibition 
The plant species utilized in these tests are identified by letter in 
accordance with the following legend: 
A -- Soybean K -- Smartweed (Penn) 
B -- Sugar Beet L -- Velvetleaf 
C -- Wheat M -- Downy Brome 
D -- Rice N -- Proso Millet 
E -- Sorghum (grain) 
O -- Barnyardgrass 
F -- Cocklebur P -- Crabgrass (Large) 
G -- Wild Buckwheat 
Q -- Nutsedge (Yellow)* 
H -- Morningglory R -- Quackgrass* 
I -- Hemp Sesbania S -- Johnsongrass* 
J -- Lambsquarters (Common) 
T -- Canada thistle* 
______________________________________ 
*Established from vegetative propagules. 
The results obtained are set forth in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Application Days After 
Rate Kg/Ha 
A B C D E F G H I J K L M N O P Q R S 
T Treatment 
__________________________________________________________________________ 
Ex. 1 
11.2 -- 
-- 
-- 
-- 
-- 
2 -- 
2 -- 
1 1 1 0 -- 
2 -- 
1 0 0 
2 11 
11.2 -- 
-- 
-- 
-- 
-- 
2 -- 
2 -- 
2 3 2 2 -- 
3 -- 
1 0 2 
2 34 
5.6 -- 
-- 
-- 
-- 
-- 
2 -- 
2 -- 
3 1 1 0 -- 
2 -- 
1 0 0 
2 11 
5.6 -- 
-- 
-- 
-- 
-- 
2 -- 
2 -- 
3 3 1 0 -- 
3 -- 
2 0 2 
2 34 
5.6 2 3 3 3 3 3 3 2 4 4 -- 
3 3 4 4 4 -- 
-- -- 
-- 15 
1.12 0 1 0 0 0 0 0 0 0 1 -- 
0 0 1 1 2 -- 
-- -- 
-- 15 
Ex. 2 
11.2 -- 
-- 
-- 
-- 
-- 
1 -- 
0 -- 
0 0 0 0 -- 
1 -- 
0 0 0 
0 14 
11.2 -- 
-- 
-- 
-- 
-- 
1 -- 
1 -- 
0 0 0 0 -- 
2 -- 
1 0 0 
0 28 
5.6 -- 
-- 
-- 
-- 
-- 
1 -- 
1 -- 
0 1 1 0 -- 
2 -- 
1 0 0 
0 14 
5.6 -- 
-- 
-- 
-- 
-- 
1 -- 
1 -- 
1 0 1 0 -- 
3 -- 
1 0 0 
0 28 
5.6 2 2 3 0 2 2 2 3 3 3 2 3 1 3 3 3 -- 
-- -- 
-- 14 
5.6 3 3 2 0 3 3 0 3 3 3 3 3 2 3 3 3 -- 
-- -- 
-- 28 
1.12 1 1 1 0 1 2 1 1 2 3 1 0 2 2 3 2 -- 
-- -- 
-- 14 
1.12 1 2 1 0 1 1 1 1 1 3 1 0 1 1 2 0 -- 
-- -- 
-- 28 
.28 0 1 1 0 0 1 1 0 0 1 0 0 1 0 0 1 -- 
-- -- 
-- 14 
.28 0 1 0 0 0 1 1 0 0 2 0 0 1 0 0 0 -- 
-- -- 
-- 28 
__________________________________________________________________________