HERBICIDALLY ACTIVE PYRIMIDINYL AND TRIAZINYL COMPOUNDS

Abstract: Pyrimidinyl and triazinyl ethers and thioethers of formula (I) wehrein Q is (Q1), (Q2), (Q3); and the other definitions of the substituents are given in patent claim 1, and the salts of compounds of formula (I) have herbicidal activity and are suitable as active ingredients in compositions for controlling weeds.

Description: Herbici dal ly active pyr1ra1d1ny1 and tr1az1nyl compounds The present invention relates to novel, herbicidally active pyrimidinyl and triazinyl ethers and thioethers, to processes for their preparation, to compositions comprising them as active ingredients, and to their use for controlling weeds, especially selectively in crops of useful plants. Pyrimidinyl and triazinyl ethers and thioethers having herbicidal action are generally known. Such compounds are described, for example, in European Patent Applications Nos.0400741 and 0409 369. The compounds disclosed therein are not always capable, however, of fulfilling requirements in terms of strength of action and selectivity. Novel herbicidally active pyrimidinyl and triazinyl ethers and thioethers have now been found. The pyrimidinyl and triazinyl ethers and thioethers according to the invention have the formula I wherein Q is X is oxygen or CHR 26 ; Y is oxygen or sulfur, A is hydrogen, fluorine, chlorine, (C^alkyl-oxetan-S-yl^xy, R 8 or the group *1 N N / " (A4)> \ N s Ri5 (As) or H *13 H E is methine, halo-substituted methine or nitrogen; Ej is methine or nitrogen; Yj is oxygen or sulfur; each of Rj and R 24 , independently of the other, is C^alkyl, cyclopropyl, C-^alkoxy, difluoromethoxy, methylthio, ethylthio, methylamino, ethylamino, dimethylamino or diethylamino; each of R 2 and R- 5 , independendy of the other, is methyl, methoxy, ethoxy or difluoro- methoxy; R 3 is hydrogen, C alkyl, C L salkylthio, halogen, C-^alkoxy, C^alkylamino or C 1-2 dialkylamino or, together with R , is -(CH-*^- or -S(CH 2 ) q S-; R 4 is Ci.salkylthio, formyl, C j ^alkylcarbonyl, carboxy, C_ ^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R 5 is hydrogen, C alkyl, halogen, C^alkoxy or, together with R 6 , is -(CH.^-', R 6 is hydrogen or C j ^alkyl; R 7 is hydrogen, hydroxy, halogen, C^alkoxy, carboxy or C lJt alkoxycarbonyl; R 8 is hydroxy, Cι_galkoxy, sulfinyl-C-^alkoxy, C^dialkylamino-C^alkoxy, C 1 . 3 alkoxycarbonyl-C 1 . alkoxy, C 3 _ 4 alkenyloxy, C^alkyliminooxy, C L galkylt io, C^diaUsylamino-C^alkylthio, C^alkoxycarbonyl- C^alkylthio, phenoxy, phenylthio, or phenoxy or phenylthio substituted by fluorine, chlorine, bromine, methyl, methoxy or by nitro; R 9 is hydrogen, methyl or, together with R 10 , is -(CH- ) q -, -CH 2 CH(OH)CH 2 - or -GH 2 SCH 2 -; each of R 10 and R 22 , independently of the other, is hydrogen, methyl, hydroxymethyl, formyl, cyano or a group COZ, R n is hydrogen, mercapto, Ci^alkylmercapto, vinyl, phenyl, 4-hydroxyphenyl, 4-imidazolyl, 3-indolyl, hydroxy- carbonyl, Cj ^alkoxycarbonyl, 2-propenyloxycarbonyl, cyano or by carbamoyl, or is trifluoromethyl, ethynyl, vinyl, phenyl, cyano or C^alkoxycarbonyl; R 12 , R 19 , R- 23 and R 27 are hydrogen or methyl; R 13 is hydrogen, C^alkyl, phenyl, or phenyl mono- or di-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, methoxy or by nitro; Rj 4 is hydrogen or methyl; Rχ 5 is Cj.βalkyl, C 1-6 haloalkyl, phenyl, benzyl, or phenyl substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, methoxy, nitro, cyano, carboxy or by C 1 . 3 alkoxy- carbonyl; m is 1, 2 or 3; n is O, 1, 2 or 3; p is 4 or 5; q is 2 or 3; W is oxygen, sulfur or NH; Z is hydroxy, C 2 _ 4 dialkyl- am o, or a group (Z_) or (Z2) . each of R 16 and R 18 , independently of the other, is hydroxy, C alkoxy, 2-propenyloxy, benzyloxy, amino or a group each of R 1 and Rj , independently of the other, is hydrogen, C-^alkyl or benzyl; R 20 is Ci.galkyl, carboxy, Ci^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R 21 is hydrogen, C^alkyl, C^alkylthio or, together with R 20 , is -(CH 2 ) p - or -S(CH 2 ) q S-; R- 26 is hydrogen or C*- ^alkyl; R 29 is hydroxy, C^alkoxy, 2-propenyloxy, benzyloxy, or amino; and the salts of those compounds of formula I that have a free carboxy group; with the proviso that R 3 is or -S(CH_ q S- when at the same time A is a group R 8 or a group A 4 and R 4 is C^alkyl, ^alkenyl, C 3 . 6 cycloalkyl, Ci.ghaloalkyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl. If the compounds of formula I have an asymmetric centre, then those compounds may occur in the form of optical isomers. Some compounds of formula I may occur in tautomeric forms (e.g. keto-enol tautomerism). If there is an aliphatic C=C double bond, then geometric isomerism may occur (E form or Z form). This is the case especially for those compounds of formula I wherein Q is Q-* . Formula I thus includes all possible stereoisomers in the form of enantiomers, tautomers, diastereoisomers, E/Z isomers, or mixtures thereof. In formula I, the alkyl, alkenyl and alkynyl radicals may be straight-chain or branched. The same is true of the alkyl moiety or each alkyl moiety of alkoxy, alkylthio, alkoxy¬ carbonyl (and accordingly C^carboxy) groups and other alkyl-containing groups. In the definitions, C^alkyl is, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl and isomeric pentyl and also hexyl and isomeric hexyl. The C^alkenyl and C^alkynyl radicals occurring in the substituents may likewise be straight-chain or branched, such as vinyl, allyl, methallyl, 1 -methyl vinyl, but-2-en-l-yl, 2-propyn-l-yl, l-methyl-2-propyn-l-yl and 2-butyn-l-yl. Halomethyl is, for example, chloromethyl, fluoromethyl or trifluoromethyl. The grouping (C h alky l-oxetan-3-yl)oxy is to be understood as being, for example, (oxetan-3-yl)oxy, (3-methyl-oxetan-3-yl)oxy, (3-ethyl-oxetan-3-yl)oxy and (4-methyl- oxetan-3-yl)oxy. Alkoxycarbonyl is, for example: methoxycarbonyl, ethoxycarbonyl, n-propoxycarbonyl, isopropoxycarbonyl and n-butoxycarbonyl, tert-butoxycarbonyl, preferably methoxy¬ carbonyl and ethoxycarbonyl. Suitable salts of the free carboxy groups are especially alkali metal salts such as lithium, sodium, potassium, alkaline earth metal salts such as magnesium, calcium or salts of organic ammonium bases, such as ammonia, primary, secondary or tertiary alkylamines, such as methylammonium, diethylammonium, triethylammonium, morpholinium or pyridinium. The groupings (A_), (A 2 ) and (A 3 ) are to be understood as being, in addition to the compounds listed in Tables 1 to 3, for example also the following substituents T: T21:NhT CONH 2 ;T22: NH In preferred compounds of formula I: Q is Y is oxygen or sulfur; A is hydrogen, fluorine, chlorine, (C^alkyl-oxetan-S-y oxy, R 8 or the group E is methine or nitrogen; Ej is methine or nitrogen; Y ! is oxygen or sulfur; each of R ! and R2 4 , independently of the other, is C^alkyl, cyclopropyl, C^alkoxy, difluoromethoxy, methylthio, ethylthio, methylamino, ethylamino, dimethylamino or diethylamino; each of R 2 and R**-^, independently of the other, is methyl, methoxy, ethoxy or difluoro¬ methoxy; R 3 is hydrogen, C-* ^alkyl, C^alkylthio or, together with 1^, is -(CH^ p - or -S(CH 2 ) q S-; R is C j .galkyl, C^alkenyl, C 3 _^cycloalkyl, C^ghaloalkyl, C^alkylthio, formyl, Cι_5alkylcarbonyl, carboxy, C j ^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R5 is hydrogen, C^alkyl or, together with R , is -(CH 2 ) p -; R 6 is hydrogen or C^alkyl; R 7 is hydrogen, hydroxy, Cι_ 6 alkoxy, carboxy or R 8 is hydroxy, sulfinyl-C^alkoxy, C^dialkylamino-C^alkoxy, C^alkoxycarbonyl-C^alkoxy, C 3 _ 4 alkenyloxy, C 3 _ 4 alkynyloxy, C 3 _. 6 cycloalkoxy, benzyloxy, C^alkylaminooxy, C 2 . 6 alkyliminooxy, C 1 . 6 alkylthio, C 2 ^dialkylamino-C 1-2 alkylthio, C^alkoxycarbonyl- C j ^alkylthio, phenoxy, phenylthio, or phenoxy or phenylthio substituted by fluorine, chlorine, bromine, methyl, methoxy or by nitro; Rg is hydrogen, methyl or, together with R 10 , is -(CH-^-, -CH 2 CH(OH)CH 2 - or -CH 2 SCH -; each of RJO and R 22 , independently of the other, is hydrogen, methyl, hydroxymethyl, formyl, cyano or a group COZ, R π is hydrogen, substituted by hydroxy, mercapto, Ci^alkylmercapto, vinyl, phenyl, 4-hydroxyphenyl, 4-imidazolyl, 3-indolyl, hydroxy- carbonyl, ^alkoxycarbonyl, 2-propenyloxycarbonyl, cyano or by carbamoyl, or is trifluoromethyl, ethynyl, vinyl, phenyl, cyano or Ci ^alkoxycarbonyl; R 12 , R 19 and R^ are hydrogen or methyl; R 13 is hydrogen, C^alkyl, phenyl, or phenyl mono- or di-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, methoxy or by nitro; R 14 is hydrogen or methyl; R 15 is C^alkyl, C^haloalkyl, phenyl, benzyl, or phenyl substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, methoxy, nitro, cyano, carboxy or by C^alkoxy- carbonyl; m is 1, 2 or 3; n is O, 1, 2 or 3; p is 4 or 5; q is 2 or 3; W is oxygen, sulfur or NH; Z is hydroxy, C^alkoxy, C 3 _ 4 alkenyloxy, benzyloxy, amino, C^alkylamino, C^dialkyl- amino, or a group (Z_) or each of R 16 and R 18 , independently of the other, is hydroxy, C alkoxy, 2-propenyloxy, benzyloxy or amino; R 17 is hydrogen, C^alkyl or benzyl; R* 20 is C^alkyl, C-^alkenyl, C 3 . 6 cycloalkyl, C^haloalkyl, C^alkoxy, C^alkylthio, carboxy, C^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R 21 is hydrogen, C^alkyl, C^alkylthio or, together with R 20 , is -(CH-^ p - or -S(CH 2 ) q S-; and die salts of those compounds of formula I that have a free carboxy group. Further preferred compounds of formula I are those wherein Q is Q , and wherein preferably either Y is oxygen; E is methine; Ri is methoxy; R 2 is methoxy; R 5 is methyl; R 6 is methyl or ethyl; and R 7 is hydrogen, hydroxy, C^alkoxy, carboxy or C^alkoxycarbonyl; or Y is sulfur, E is methine; Ri is methoxy; R 2 is methoxy; R 5 is methyl; R 6 is hydrogen, methyl or ethyl; and R 7 is hydrogen, hydroxy or Also of special interest are those compounds of formula I wherein Q is Q-i and A is (Cι_ 3 alkyl-oxetan-3-yl)oxy or the group R n (Aj , * ιs (A 5 ) Especially preferred compounds of formula I are those wherein Q is the group Q x ; Y is oxygen; E is methine; R j and R 2 are methoxy; R 3 is methyl or ethyl or, together with R 4 , is -(CH^ p -; and R 4 is C^alkyl or phenyl. Of that group of compounds of formula I preference is given to those wherein a) R 3 is methyl or ethyl and A is C^alkoxy, hydroxy, 2-propenyloxy or an inorganic or organic salt of the free acid; or b) A is (C^alkyl-oxetan-S-ylJoxy; or c) A is an <S> chiral group Aj wherein R9 is hydrogen or, together with R π , is -(CH 2 ) 3 -, R 10 is a group COZ wherein Z is as defined for formula I, R n is hydrogen, C j ^alkyl or benzyl, R 12 and R 19 are hydrogen, W is oxygen or sulfur and m is die number 1; or d) A is a group A wherein R 13 is C^alkyl, phenyl, or phenyl mono- or di-substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro; or e) A is a group A5 wherein R 15 is C^alkyl, phenyl, or phenyl mono- or di-substituted by fluorine, chlorine or by methyl; or f) A is an <S> chiral group A-- wherein R^ is hydrogen or, together with R π , is -(CH 2 ) 3 -, R 10 is a group COZ wherein Z is as defined for formula I and R 12 is hydrogen, Z preferably being C j ^alkoxy, C 3 _ 4 alkenyloxy, amino or a group (Zj) and R π being hydrogen, C j ^alkyl or benzyl. Also of special interest are those compounds of formula I wherein Q is the group Qj; Y is oxygen; E is methine; Rj is methoxy; R 2 is methoxy; R 3 is hydrogen, methyl or ethyl or, together with R is -(CH^ p -; R is formyl, carboxy, C 1-2 alkylcarbonyl or C^alkoxycarbonyl; and A is hydroxy, C^alkoxy, 2-propenyloxy or an organic or inorganic salt of the free acid. Special preference is given to compounds of formula I wherein Q is Qi; Y is sulfur, E is methine; Rj is methoxy; and R 2 is methoxy. Prominent among that group of compounds of formula I are those wherein a) R 3 is methyl or ethyl; R 4 is C^alkyl, cyclopropyl or phenyl; and A is hydroxy or an inorganic or organic salt of the free acid; or b) R 3 is hydrogen, metiiyl, ethyl, methylthio or, together with R , is -S(CH 2 ) 2 S-; R 4 is methylthio, formyl, carboxy, C^alkylcarbonyl or C^alkoxycarbonyl; and A is hydroxy, C^alkoxy, 2-propenyloxy or an inorganic or organic salt of the free acid; or c) R 3 is metiiyl or ethyl; R 4 is cyclopropyl or phenyl; and A is (oxetan-3-yl)oxy, 2-propenyloxy or an <S> chiral group A l or A 2 wherein R 9 is hydrogen or, together with R n , is -(CH_ 3 -, R 10 is a group COZ wherein Z is as defined for formula I, and R n is hydrogen, or benzyl. In a further prominent group of compounds of formula I Q is the group Q 2 ; Y is sulfur; E is methine; R j is methoxy; R 2 is methoxy; R 5 is methyl or methoxy; R 6 is hydrogen, methyl or ethyl; and R 7 is hydrogen, hydroxy or In an especially preferred group of compounds of formula I E is nitrogen; R j is methyl, methoxy or dimethylamino and R 2 is methoxy. Prominent compounds of formula I from that group are especially those wherein either a) Y is oxygen; R 3 or R 5 is methyl; R or R_ 6 is methyl or ethyl; and R 7 is hydrogen, hydroxy, or carboxy; or b) Y is oxygen; R 3 is hydrogen or methyl; R is C j ^alkoxy or Cι_ 2 alkoxycarbonyl and A is hydroxy, C^alkoxy or an organic or inorganic salt of the free acid. Especially preferred individual compounds within the scope of formula I that may be mentioned are: 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoic acid, [E and/or Z]-2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-pentenoic acid, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-alanine ethyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-valine ethyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-leucine methyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-glycine methyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-leucine amide, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-leucine allyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-medιyl-2-butenoyl]-L-leucine, 2-[(4,6-dimethoxy-l,3,5-triazin-2-yl)oxy]-3-methyl-2-butenoic acid ethyl ester, 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-4-ethyl-3-methyl-butenolide, 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-4-carboxy-4-ethyl-3-methyl-butenolide, 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-ethyl-2-pentenoic acid, [E]-2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy3-3-methyl-2-pentenoic acid, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-glycine methyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-L-alanine methyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-L-valine methyl ester, N-[2-[(4,6-dύnethoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-L-leucine methyl ester, 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-cyclopentylpropenoic acid, 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-sodium butenate, N-[2-[(4,6-dimethoxy-pyrimidm-2-yl)oxy]-3-methyl-pentenoyl]-L-alanine ethyl ester, 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-(l,3-dithia-cyclopent-2-yl)propenoic acid, 2- [(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-methyl-2-butenoic acid, 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-methyl-2-pentenoic acid and 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-4-hydroxy-4-ethyl-3-methyl-butenolide. Compounds of formula I, especially those wherein Y is oxygen, can be prepared by reacting a pyrimidine of formula π wherein E, Rj and R are as defined for formula I and L is a leaving group such as fluorine, chlorine, bromine, methylsulfonyl, ethanesulfonyl, benzylsulfonyl, 3-C**. 4 alkylsulfonyl-lH-l,2,4-triazol-l-yl (e.g. 3-methylsulfonyl- lH-l,2,4-triazol-l-yl) with a propenoate, 2-oxo-propionate or furanone compound of foimula LU, Ilia or IV, respectively, wherein R 3 , R , R 5 and R 6 arc as defined for formula I and R is hydrogen, carboxy or ^alkoxycarbonyl, A is hydrogen, hydroxy, C^alkoxy, C^alkoxy- C 1-2 alkoxy, alkoxy, benzyloxy or (C*ι_ 3 alkyl-oxetan-3-yl)oxy and Y' is hydroxy or mercapto, but especially hydroxy, in the presence of an acid-binding agent, such as n-butyllithium, sodium hydride, potassium carbonate or triethylamine, and in the presence of an inert solvent, such as tetrahydrofuran, diethoxymethane, dimethoxyethane, acetone, methyl ethyl ketone, acetonitrile, propionitrile, dimethylformamide, N-methylpynolidone or dimethyl sulfoxide. The reaction is advantageously carried out at from O°C to the boiling temperature of the solvent used, preferably from room temperature to approximately 100°C. Compounds of formula I wherein Y is especially sulfur can be prepared by lithiating, under the reaction conditions familiar to a person skilled in the art, a compound of formula V S=C=S/R'X or Ia S=C=NR"/R'X or R 4 C(OCH 3 ) 2 NR"' wherein E, R-* and R 2 are as defined for formula I, R"' is hydroxy or a leaving group and A' is Cj.galkoxy, C^alkoxy-C^alkoxy, C 2-6 alkenyloxy, benzyloxy or (C^alkyl- oxetan-3-yl)oxy, especially C^alkoxy, 2-propenyloxy or benzyloxy, and then reacting the product thereof with the conesponding electrophilic compound of formula VI, wherein R 3 and R 4 are as defined above, or with carbon disulfide or an alkylisothiocyanate, wherein R" is and a subsequent corresponding alkylating agent R'X wherein R' is and X is methoxy- or ethoxy-sulfonyl, chlorine, bromine or iodine, or with a corresponding orthoester or dialkylaminodimethylacetal. Suitable lithiating agents are solutions of lithium diisopropylamide, bis(trimethylsilyl)- lithium amide, n-butyllithium, sec-butyllithium, tert-butyllithium or phenyllithium in hexane, heptane, isooctane or diethyl ether, especially the lithium salt of 1,1,1,3,3,3-hexa- methyldisilazane or n-butyllithium in hexane. In that reaction, especially where R 3 is it is advantageous to isolate the inter- mediate of formula Vm vm if wherein R'" is hydroxy or a leaving group, and then to convert it under the dehydration conditions familiar to a person skilled in the art into the compound of formula If wherein R 1? R 2 , E and A' arc as defined above and R 3 is C^alkyl and 1^ is C-^alkyl, C . 6 alkenyl, C 3 . 6 cycloalkyl, C^haloalkyl, C^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl. For the dehydration, it is advantageous for the compound of formula VHI wherein OR' ' ' is hydroxy to be converted into a compound of formula VHI having a suitable leaving group OR'", such as an acetate, mesylate or tosylate group, by esterifying the hydroxy compound VI or the lithium salt thereof directly in the presence of acetic anhydride, acetyl chloride or a sulfonic acid chloride or, where appropriate, indirecdy in the presence of a base, such as triethylamine, l,8-diazabicyclo[5.4.0]undec-7-ene or dimethylamino- pyridine, and then, while heating, eliminating the OR"' group. In addition, compounds of formula la wherein R 1? R 2 and E arc as defined above, and A' is especially hydrogen, C^alkoxy, 2-propenyloxy or benzyloxy, R 3 is hydrogen and R is formyl, C^alkylcarbonyl, carboxy or C^alkoxycarbonyl can be prepared by reacting a compound of formula IX XI wherein Q' is hydroxy or mercapto or the lithium, sodium or potassium salt thereof, with a compound of formula X or XI wherein Hal is chlorine or bromine. If a substrate of formula X is used, compounds of formula la wherein R 3 is hydrogen are obtained. That reaction is likewise advantageously carried out in the presence of an acid-binding agent, such as sodium hydride, sodium hydrogen carbonate, potassium carbonate or triethyl- amine, and in the presence of an inert diluent, such as tetrahydrofuran, diethoxymethane, dimethoxyethane, acetone, methyl ethyl ketone, methanol, ethanol, acetonitrile, propio- nitrile, dimethylformamide, N-methylpyrrolidone, l,3-dimethyl-3,4,5,6-tetrahydro- 2(lH)-pyrimidinone (DMPU) or dimethyl sulfoxide. The reaction is advantageously carried out at from O°C to the boiling temperature of the solvent used, preferably from room temperature to approximately 60°C. Compounds of formula I wherein Rj, R 2 , R 5 , Rg, E and Y are as defined above and R 7 is hydroxy (compound of formula Ig') Hal IX Ig' can also be prepared by condensing a compound of formula IX with a compound of formula X or XII wherein R 4 is formyl, C^alkylcarbonyl, carboxy or C^alkoxycarbonyl, A' is hydroxy and Hal is chlorine or bromine. In addition, compounds of formula I wherein E, Y, R lf R 2 , R 3 and R,^ are as defined above, and wherein A is hydroxy (formula lb) can be prepared as follows: a compound of formula la wherein A' is especially C^alkoxy, 2-propenyloxy or benzyloxy is hydrolysed under hydrolysis conditions familiar to a person skilled in the art or is cleaved by hydrogen- olysis, for example with H 2 Pd in the case of benzyloxy, or with tris(triphenylphosphine)- rhodium(I) chloride (Wilkinson catalyst) in the case of 2-propenyloxy, to form the acid. Suitable hydrolysis agents for the former case, especially in the case of compounds wherein Y is oxygen, are sodium or potassium hydroxide and sodium or potassium carbonate. Suitable solvents are, for example, water or mixtures of methanol/water, ethanol/water, tetrahydrofuran/water, diethoxymethane/water, dioxane/water or dimethyl- formamide/water. Suitable solvents for the hydrogenolytic cleavage are especially methanol, ethanol, ethyl acetate, acetic acid, trifluoroacetic acid, dioxane and water, and mixtures thereof. Compounds of formula lb wherein Y is sulfur (formula If) If If are advantageously hydrolysed under strongly acidic conditions, for example in trifluoro¬ acetic acid where the tert-butoxy group is used for A' in formula If or under neutral conditions with tris(triphenylphosphine)-rhodium(I) chloride and water where the 2-propenyloxy group is used for A'. Compounds of formula I wherein Q is Q 2 and R 7 is halogen, hydroxy or C 1-6 alkoxy can be prcpared under customary conversion conditions from compounds of formula I wherein Q is Q 2 and R 7 is hydrogen. Compounds of formula I wherein Q is Q 3 and R 26 is hydrogen or C alkyl can likewise be prepared under customary conversion conditions from compounds of formula I wherein Q is Q 2 and R 7 is halogen or hydroxy. Compounds of formula I wherein Q is Q 4 can also be prepared by heating a compound of formula lb wherein R 3 is hydrogen or C 1-4 alkyl, if desired in the presence of an agent that removes the elements of water, such as a carboxylic acid anhydride, especially acetic anhydride. Compounds of formula I can also be prepared by reacting a compound of formula Ic or an anhydride of formula Id (I) wherein E, Y, Rj, R 2 , R , 4 , R 20 , R 2 ι, R^ and R^ are as defined above, and wherein A'" is a leaving group such as chlorine, fluorine, bromine, 2,4,6-triisopropyl-sulfonyl, imidazolyl, triazolyl, 2-thiono-thiazolidin-3-yl or N,N'-dicyclohexyl-isoureidyl, with a nucleophilic compound of formula VII wherein A is Rg, (C h alky l-oxetan-3-yl)oxy or a group Aj to A 6 , Aj to A_ being as defined for formula I, where appropriate in the presence of a base and of a solvent. The reaction is advantageously carried out in the presence of a base as acid-binding agent. Suitable bases arc especially tertiary amines, such as triethyl- amine, N,N-dimethylaniline, l,8-diazabicyclo[5.4.0]undec-7-ene, imidazole, pyridine or 2,5-dimethylpyridine. They can be used in a catalytic amount, as well as in a stoichio¬ metric amount or in excess; preferably in a stoichiometric amount or in a slight excess. A slight excess of the substrate of formula VII used is also suitable as a base. Suitable solvents are hydrocarbons, such as toluene, halogenated chlorohydrocarbons, such as dichloromethane, 1,2-dichloroethane or chlorobenzene, ethers, such as diethyl ether, dimethoxyethane or tertiary butyl methyl ether, aprotic solvents, such as aceto- nitrile, or protic solvents, such as alcohols, especially ethanol, or water. In addition, it is also possible to carry out the reaction in a two-phase system, such as in a mixture of dichloromethane and water, toluene and water or diethyl ether and water. Compounds of formula Ic wherein A"' is 2,4,6-triisopropyl-sulfonyl, imidazolyl, triazolyl, 2-thiono-thiazolidin-3-yl or N,N'-dicyclohexyl-isoureidyl can also be prepared from compounds of formula la by known conversion processes with l-(2,4,6-triisopropyl- phenylsulfbnyl)-imidazole (Y.A. Berlin et al., Tetrahedron letters 1973, 1353), l-(2,4,6-trϋsopropylphenylsulfonyl)-lH-l*2,4-triazole (N.Katagiri et al., Chem. Commun. 1974. 325), lJ'-carbonyl-diimidazole, l,l'-caτbonyl-di((l,2,4)-triazole) (H.A. Staab, Angew. Chem. 74, 407 (1962)), thiazolylidine-2-thione (Y. Nagao et al., Tetrahedron letters, 21, 841 (1980)) or dicyclohexylcarbodiimide. In that case it is likewise unnecessary to isolate the intermediate of formula Ic in order to convert it "in situ" into the compounds of formula I as described above with a nucleophilic compound of formula VII. Compounds of formula Ic wherein A"' is chlorine can, for example, also be prepared by reacting an acid of formula lb with a chlorinating agent such as phosphorus oxychloride, thionyl chloride, oxalyl chloride or phosgene, especially phosphorus oxychloride, in the presence of a base, such as triethylamine, dimethylaniline or pyridine, and, where appropriate, in a solvent such as a hydrocarbon, for example toluene, a chlorohydrocarbon, for example methylene chloride, or an ether, for example tetrahydrofuran, in a temperature range of from -20° to the reflux temperature of the reaction mixture, preferably at from -5°C to room temperature. If desired, the coπesponding acid chloride (A'" is chlorine) or imidazolide (A"' is imidazole) can also be reacted without being isolated with the corresponding nucleophilic compound of formula VII, where appropriate in the presence of an additional base, such as triethylamine. That reaction likewise takes place in a temperature range of from approx¬ imately -20°C to the reflux temperature of the solvent used, preferably at from -5°C to room temperature. On the other hand, it is advantageous to convert an acid of formula lb first into the cones¬ ponding more stable acid anhydride of formula Id using from 0.50 to 0.55 of an equivalent of phosphorus oxychloride and a slight excess of from 2.0 to 3.0 equivalents of triethyl¬ amine and then to react the acid anhydride with the corresponding nucleophilic compound of formula V. Compounds of formulae HI, πia, IV, V, VI, VII, __K, X, XI and XII are either known or can be prepared by processes known from the literature. The compounds of formula I are used in unmodified form, as obtainable from the synthesis, or, preferably, together with the adjuvants customarily employed in formulation technology and are therefore formulated in known manner e.g. into emulsifiable concen¬ trates, direcdy sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granules, and also encapsulations in e.g. polymer substances. As with the nature of the compositions, the methods of application, such as spraying, atomising, dusting, wetting, scattering or pouring, are chosen in accordance with the intended objectives and the prevailing circumstances. The formulations, i.e. the compositions, preparations or mixtures comprising the compound (active ingredient) of formula I and, where appropriate, one or more solid or liquid adjuvants, are prepared in known manner, e.g. by homogeneously mixing and/or grinding the active ingredients with extenders, e.g. solvents, solid carriers and, where appropriate, surface-active compounds (surfactants). Suitable solvents are: aromatic hydrocarbons, preferably the fractions containing 8 to 12 carbon atoms, such as mixtures of alkylbenzenes, e.g. xylene mixtures or alkylated naphthalenes; aliphatic and cycloaliphatic hydrocarbons, such as paraffins, cyclohexane or tetrahydronaphthalene; alcohols, such as ethanol, propanol or butanol; glycols and their ethers and esters, such as propylene glycol or dipropylene glycol ether; ketones, such as cyclohexanone, isophorone or diacetone alcohol; strongly polar solvents, such as N- methyl-2-pyrrolidone, dimethyl sulfoxide or water, vegetable oils and esters thereof, such as rape oil, castor oil or soybean oil; and, where appropriate, also silicone oils. The solid carriers used, e.g. for dusts and dispersible powders, are normally natural mineral fillers, such as calcite, talcum, kaolin, montmorillonite or attapulgite. In order to improve the physical properties it is also possible to add highly dispersed silicic acid or highly dispersed absorbent polymers. Suitable granulated adsorptive carriers are porous types, for example pumice, broken brick, sepiolite or bentonite; and suitable nonsorbent carriers arc, for example, calcite or sand. In addition, a great number of prcgranulated materials of inorganic or organic nature can be used, e.g. especially dolomite or pulverised plant residues. Depending upon the nature of the compound of formula I to be formulated, suitable surface-active compounds are non-ionic, canonic and/or anionic surfactants having good emulsifying, dispersing and wetting properties. The term "surfactants" will also be under¬ stood as comprising mixtures of surfactants. Both so-called water-soluble soaps and water-soluble synthetic surface-active compounds are suitable anionic surfactants. Suitable soaps are the alkali metal salts, alkaline earth metal salts or unsubstituted or substituted ammonium salts of higher fatty acids (C 1 Q-C 22 ), e.g. the sodium or potassium salts of oleic or stearic acid, or of natural fatty acid mixtures which can be obtained e.g. from coconut oil or tallow oi Mention may also be made of fatty acid methyltaurin salts. More frequently, however, so-called synthetic surfactants are used, especially fatty alcohol sulfonates, fatty alcohol sulfates, sulfonated benzimidazole derivatives or alkylaryl- sulfonates. The fatty alcohol sulfonates or sulfates are usually in the form of alkali metal salts, alkaline earth metal salts or unsubstituted or substituted ammonium salts and contain a Cg-C-^alkyl radical, which also includes the alkyl moiety of acyl radicals, e.g. the sodium or calcium salt of lignosulfonic acid, of dodecyl sulfate or of a mixture of fatty alcohol sulfates obtained from natural fatty acids. These compounds also comprise the salts of sulfated and sulfonated fatty alcohol ethylene oxide adducts. The sulfonated benz¬ imidazole derivatives preferably contain two sulfonic acid groups and one fatty acid radical containing 8 to 22 carbon atoms. Examples of alkylarylsulfonates are the sodium, calcium or triethanolamine salts of dodecylbenzenesulfonic acid, dibutylnaphthalene- sulfonic acid, or of a condensate of naphthalenesulfonic acid and formaldehyde. Also suitable are corresponding phosphates, e.g. salts of the phosphoric acid ester of an adduct of p-nonylphenol with 4 to 14 mol of ethylene oxide, or phospholipids. Non-ionic surfactants are preferably polyglycol ether derivatives of aliphatic or cyclo- aliphatic alcohols, saturated or unsaturated fatty acids and alkylphenols, said derivatives containing 3 to 30 glycol ether groups and 8 to 20 carbon atoms in the (aliphatic) hydro¬ carbon moiety and 6 to 18 carbon atoms in the alkyl moiety of the alkylphenols. Further suitable non-ionic surfactants are the water-soluble adducts of polyethylene oxide with polypropylene glycol, ethylenediaminopolypropylene glycol and alkylpolypropylene glycol containing 1 to 10 carbon atoms in the alkyl chain, which adducts contain 20 to 250 ethylene glycol ether groups and 10 to 100 propylene glycol ether groups. These compounds usually contain 1 to 5 ethylene glycol units per propylene glycol unit. Representative examples of non-ionic surfactants are nonylphenol polyethoxyethanols, castor oil polyglycol ethers, polypropylene polyethylene oxide adducts, tributylphenoxy- polyethoxyethanol, polyethylene glycol and octylphenoxypolyethoxyethanol. Fatty acid esters of polyoxyethylene sorbitan, e.g. polyoxyethylene sorbitan trioleate, are also suitable non-ionic surfactants. Cationic surfactants are preferably quaternary ammonium salts which contain, as N-substituent, at least one Cg-C^alkyl radical and, as further substituents, unsubstituted or halogenated lower alkyl, benzyl or hydroxy-lower alkyl radicals. The salts are preferably in the form of halides, methyl sulfates or ethyl sulfates, e.g. stearyltrimethylammonium chloride or benzyldi(2-chloroethyl)ethylammonium bromide. The surfactants customarily employed in formulation technology are described inter alia in the following publications: - "Mc Cutcheon's Detergents and Emulsifiers Annual", Mc Publishing Corp., Glen Rock, New Jersey, 1988. - M. and J. Ash, "Encyclopedia of Surfactants", Vol. I-m, Chemical Publishing Co., New York, 1980-1981. - Dr. Helmut Stache "Tensid-Taschenbuch" (Surfactant Handbook), Carl Hanser Verlag, Munich/Vienna 1981. The herbicidal compositions usually comprise 0.1 to 99 %, preferably 0.1 to 95 %, of a compound of formula 1, 1 to 99 % of a solid or liquid adjuvant, and 0 to 25 %, preferably 0.1 to 25 %, of a surfactant. Whereas commercial products will preferably be formulated as concentrates, the end user will normally employ dilute formulations. The compositions may also comprise further auxiliaries, such as stabilisers, e.g. vegetable oils or epoxidised vegetable oils (epoxidised coconut oil, rape oil or soybean oil), anti- foams, e.g. silicone oil, preservatives, viscosity regulators, binders and tackifiers, as well as fertilisers or other active ingredients for obtaining special effects. Prefened formulations have especially the following composition (throughout, percentages are by weight) Emulsifiable concentrates: active ingredient: 1 to 90 %, preferably 5 to 20 % surface-active agent: 1 to 30 %, preferably 10 to 20 % liquid carrier: 5 to 94 %, preferably 70 to 85 % Dusts: active ingredient: 0.1 to 10 %, preferably 0J to 1 % solid carrier 99.9 to 90 %, preferably 99.9 to 99 % Suspension concentrates: active ingredient: 5 to 75 %, preferably 10 to 50 % water 94 to 24 %, preferably 88 to 30 % surface-active agent: 1 to 40 %, preferably 2 to 30 % Wettable powders: active ingredient: 0.5 to 90 %, preferably 1 to 80 % surface-active agent: 0.5 to 20 %, preferably 1 to 15 % solid carrier 5 to 95 %, preferably 15 to 90 % Granules: active ingredient: 0.5 to 30 %, preferably 3 to 15 % solid carrier: 99.5 to 70 %, preferably 97 to 85 % The compounds of formula I are generally used successfully at rates of application of from 0.001 to 3 kg ha, especially from 0.005 to 1 kg ha. The concentration required to achieve the desired effect can be determined by experiment It is dependent upon the type of action, the stage of development of the cultivated plant and of the weed, and also upon the application (place, time, method) and, in dependence on those parameters, can vary within wide limits. When used at relatively low rates of application, the compounds of formula I are distin¬ guished by growth-inhibiting and herbicidal properties, which render them excellently suitable for use in crops of useful plants, especially in cereals, cotton, soybeans, rape, maize, sugar beet and rice. The invention relates also to herbicidal compositions comprising a novel compound of formula I, and to methods of inhibiting plant growth. Preparation Examples: Example PI: Preparation of 2-r(4.6-dimethoxy-pyrimidin-2-yl)oxy1-3-methyl-2-butenoic acid ethyl ester (Compound No. 1.001): In the course of 4 minutes, 52J g of dimethylpyruvic acid ethyl ester are introduced into a suspension of 10.4 g of sodium hydride (99 %) in 400 ml of absolute tetrahydrofuran and die reaction mixture is then heated at 50°C until the evolution of hydrogen has ceased. 71.0 g of 4,6-dimethoxy-pyrimidine-2-methylsulfone are then stirred in and the reaction mixture is stirred for a further 90 minutes at boiling temperature, poured onto ice- water and extracted twice with ethyl acetate. The reaction mixture is washed with water and sodium chloride solution and dried over magnesium sulfate and the solvent is evaporated. The resulting crude product is taken up hot in special boiling point spirit freed of insoluble portions by means of filtration and then crystallised with cold pentane to yield 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoic acid ethyl ester (Compound No. 1.001) having a melting point of 66.5 - 68°C. Example P2: Preparation of 2-r(4,6-dimethoxy-pyrimidin-2-yl)oxy1-3-methyl-2-butenoic acid (Compound No. 1.002): 57.3 g of 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoic acid ethyl ester prepared in accordance with Example PI are added to a mixture of 47.3 g of potassium hydroxide in 270 ml of water and 270 ml of methanol and the reaction mixture is st red for 18 hours at room temperature. After the addition of ice- water and extracting twice when cold with ethyl acetate, the aqueous phase is acidified to pH 1 with concentrated hydrochloric acid and extracted twice more with fresh ethyl acetate. The ethyl acetate extract is dried over sodium sulfate and is then concentrated by evaporation almost to dryness. Crystallisation from ethyl acetate and hexane yields 2-[(4,6-dimethoxy- pyrimidin-2-yl)oxy]-3-methyl-2-butenoic acid having a melting point of 140-142°C. Example P3: Preparation of 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy1-3-methyl-2-butenoic acid anhydride (Compound No. 1.006): In the course of 3 minutes, at a temperature of -5°C, 1.89 g of phosphorus oxychloride dissolved in 6 ml of dichloromethane arc added dropwise to 6.00 g of 2-[(4,6-dimethoxy- pyrimidin-2-yl)oxy]-3-methyl-2-butenoic acid prepared in accordance with Example P2 and 5.92 g of triethylamine in 125 ml of dichloromethane. After stirring for 10 minutes, the solution is washed twice with 100 ml of ice-water, dried over magnesium sulfate and concentrated by evaporation. Recrystallisation from diethyl ether and hexane yields 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoic acid anhydride having a melting point of 120-122°C. Example P4: Preparation of N-r2-r(4.6-dimemoxy-pyrimidin-2-vI)oxy1-3-methyl- 2-butenovn-L-leucine methyl ester (Compound No. 1.010): While stirring at a temperature of -5°C, a solution of 1.04 g of L-leucine methyl ester hydrochloride in 7 ml of water is added to 2.33 g of 2-[(4,6-dimethoxy-pyrimidin-2-yl)- oxy]-3-methyl-2-butenoic acid anhydride prepared in accordance with Example P3, 1J6 g of triethylamine and 50 ml of dichloromethane. After stirring for 90 minutes at room temperature, the aqueous phase is separated off and the organic phase is washed with sodium bicarbonate solution and water, then dried over magnesium sulfate and concen¬ trated. Flash chromatography (eluant 20 % ethyl acetate in hexane) yields N-[2-[(4,6- dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-leucine methyl ester in the form of a yellow oil; ^-NMRfCDCla): 1.79, s, CH 3 ; 2.22, s, CH 3 ; 3.66, s, COOCH 3 ; 3.90, s, 2 x OCH 3 ; 4.62, m, CH; 5.79, s, CH; 6.34, d, J=8Hz, NH; [α] D 20 = -54.17° (EtOH). Example P5: Preparation of N-r2-F(4,6-dimethoxy-pyrimidin-2-yl)oxy1-3-methyl- 2-butenovn-L-alanine tert-butyl ester (Compound No. 1.011): At a temperature of -5°C, 8.87 g.of triethylamine and then, dropwise, 2.21 g of phosphorus oxychloride in 15 ml of dichloromethane are added in succession to 3.43 g of 2-[(4,6-dimethoxy-pvrimidin-2-yl)oxy]-3-methyl-2-butenoic acid prepared in accordance with Example P2 in 150 ml of dichloromethane. After stirring for 5 minutes at a temperature of -5°C, a solution of 4.90 g of L-alanine tert-butyl ester hydrochloride in 20 ml of water, followed by a further 2.73 g of triethylamine, is added, with stirring, to the reaction mixture. After stirring for 15 minutes at room temperature, the organic phase is separated off and washed witii fresh water, dried over magnesium sulfate and concentrated by evaporation. The oil that remains is purified by flash chromatography over silica gel with 20 % ethyl acetate in hexane to yield in the form of a yellow oil N-[2-[(4,6-di- methoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-alanine tert-butyl ester (Compound No. 1.011): 1 H-NMR(CDC1 3 ): 1.28, d, J=7Hz, CH 3 ; 1.41, s, C(CH 3 ) 3 ; 1.78, s, CH 3 ; 2.22, s, CH 3 ; 3.90, s, 2 x OCH 3 ; 4.80, m, CH; 5.75, s, CH; 6.58, d, J=7Hz, NH; [α] D 20 = -10.86° (EtOH). Example P6: Preparation of N-[2-r(4,6-dimethoxy-pyrimidin-2-yl)oxy1-3-methyl- 2-butenoyll-L-alanine (Compound No. 1.015): 10 ml of trifluoroacetic acid are allowed to act for 1 hour at room temperature on 1.14 g of N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-I__-alanine tert-butyl ester prepared in accordance witii Example P5. The trifluoroacetic acid is then removed under reduced pressure and the product that remains is washed with a small amount of ethyl acetate against IN hydrochloric acid, dried over sodium sulfate and concentrated by evaporation, and the oily product is filtered through silica gel (eluant 0.5 % acetic acid in ethyl acetate) to yield in the form of a yellow honey-like substance N-[2-[(4,6-di- methoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-alanine; 1 H-NMR(CDC1 3 ): 1.37, d, J=7Hz, CH 3 ; 1.78, s, CH 3 ; 2.22, s, CH 3 ; 3.89, s, 2 x OCH 3 ; 4.55, m, CH; 5.78, s, CH; 6.69, d, J=7Hz, NH; [α] D 20 = +4.97° (EtOH). Example P7: Preparation of 2-r(4,6-dimethoxy-pyrimidin-2-yl)thio1-3,3-dimethylthio- acrylic acid ethyl ester (Compound No. 2.004): In the course of 4 minutes, 5J7 g of 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-acetic acid ethyl ester dissolved in 10 ml of tetrahydrofuran are added to a solution, cooled to -60°C, of 13.8 ml of 1.6M n-butyllithium solution in hexane and 2.56 g of N,N,N',N'-tetra- methylethylenediamine in 25 ml of absolute tetrahydrofuran. After stirring for 25 minutes, 1.3 ml of carbon disulfide are added dropwise to the reaction mixture at a temperature of 0°C. After stirring for a further 60 minutes at a temperature of 0°C, 2.8 ml of methyl iodide are added. The reaction mixture is then stirred for a further 60 minutes at room temperature, introduced into ice-water and extracted twice with ethyl acetate. It is then washed once with dilute hydrochloric acid and once with sodium chloride solution, dried over magnesium sulfate and concentrated by evaporation. Purification by chromato¬ graphy (eluant 15 % ethyl acetate/hexane) yields in the form of a yellowish oil 2-[(4,6-dimethoxy-pyrimidin-2-yl)tWo]-3,3-dimethylthio-acrylic acid ethyl ester, Η-NMR^DC^): 2.47, s, SCH 3 ; 2.49, s, SCH 3 ; 3.89, 2xOCH 3 ; 4.38, q, J=7Hz, OCHiCTk, 5.73, s, CH. Example P8: Preparation of 2-f(4.6-dimethoxy-pyrimichn-2-yl)thio1-3-methyl-2-pentenoic acid ethyl ester (Example 2.028): At a temperature of -50°C, 16.6 ml of a 1.6 molar n-butyllithium solution in hexane are introduced into a mixture of 3J g of N,N,N',N'-tetramethylethylenediamine and 25 ml of absolute tetrahydrofuran. Then, at a temperature of -65°C, 6.2 g of 2-[(4,6-dimethoxy- pyrimidin-2-yl)thio]-acetic acid ethyl ester dissolved in 15 ml of tetrahydrofuran are added dropwise thereto and the reaction mixture is stirred for 20 minutes. At a temperature below -60°C, 2.4 ml of ethyl methyl ketone are then added and the reaction mixture is heated to room temperature in the course of one hour. Ice- water is then added to die reaction mixture, which is extracted twice with ethyl acetate, washed witii saturated sodium chloride solution, dried and concentrated by evaporation. Column chromato¬ graphy on silica gel, eluant ethyl acetate/hexane 1:4, yields in die form of a yellow oil pure 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-hydroxy-3-methyl-pentanoic acid ethyl ester, i H-NMR(CDCl 3 ): 1.36/1.40, 2s, CH 3 ; 3J7/3.31, OH; 3.93, s, OCH 3 ; 4.2, m, OCH 2 CH 3 ; 4.79/4.80, 2s, CH; 5.76, s, CH; (70/30 E/Z isomeric mixture). With GC monitoring, 2.0 g of that product are refluxed for 7 hours in the presence of 2.9 g of triethylamine, 3.4 g of dimethylaminopyridine and 3.2 g of methanesulfonic acid chloride in 12 ml of toluene. The reaction mixture is then taken up in ethyl acetate and washed once with dilute hydrochloric acid, once witii dilute sodium hydrogen carbonate solution and once with sodium chloride solution, dried over magnesium sulfate and concentrated by evaporation under reduced pressure. Separation by chromatography (eluant ethyl acetate/hexane 1:9) yields in the form of a 1:1 E Z isomeric mixture 2-[(4,6-dimetiιoxy-pyrimidin-2-yl)thio]-3-methyl-2-pentenoic acid ethyl ester (Example 2.028); 1 H-NMR(CDC1 3 ): 2.162.22, 2s, CH 3 ; 2.55/2.57, 2q, CH ? CH ? ; 3.88, s, OCH 3 ; 4J5, q, OCH-.CHV, 5.71, s, CH. Example P9: Preparation of 2-r(4,6-dimethoxy-pyrimidin-2-yl)thio1-3-methyl-butenoic acid (Example 2.008): At a temperature of -70°C, 10 ml of a 1 molar solution of the lithium salt of 1,1,1,3,3,3- hexamethyldisilazane in hexane are placed in absolute tetrahydrofuran and treated dropwise with 2.86 g of [(4,6-dimethoxy-pyrimidin-2-yl)thio]-acetic acid tertiary butyl ester. ter stirring for 20 minutes, 0.64 g of acetone is added thereto. After a further one hour, 1.26 g of methanesulfonic acid chloride are added and the reaction mixture is allowed to warm slowly to room temperature. After 3 hours it is poured onto ice-cold sodium carbonate solution and extracted with diethyl ether, dried and concentrated by evaporation. The residue is dissolved again in fresh tetrahydrofuran and a slight excess of l,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is added. The reaction mixture is then stined for 90 minutes, extracted again with diethyl ether and washed with dilute hydrochloric acid and sodium chloride solution. Purification by chromatography yields pure 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-methyl-butenoic acid tertiary butyl ester (Example 2.027). At room temperature, 0.8 g of the above product is dissolved in a small amount of trifluoroacetic acid until the educt can no longer be detected. The reaction mixture is then introduced into water and extracted with ethyl acetate, dried over sodium sulfate and concentrated by evaporation. Recrystallisation from acetone/hexane yields pure 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-methyl-butenoic acid (Example 2.008): m.p.: 125-126°C. Example P10: Preparation of 2-r(4,6-dimethoxy-pyrimidin-2-yl)oxyl-3-ethoxycarbonyl- 3-methyl-acrylic acid ethyl ester (Compound No. 1.077): 3.0 g of 2-oxal-propionic acid diethyl ester and 2.2 g of 4,6-dimethoxy-pyrimidine- 2-methylsulfone are heated in the presence of 3.5 g of ground potassium carbonate and a spatula tip of 18-crown-6 in 30 ml of dimethylformamide at a temperature of 100°C for 3.5 hours. The reaction mixture is then extracted with cold water against ethyl acetate, dried over magnesium sulfate and concentrated by evaporation. Purification by chromato¬ graphy yields in the form of a 3070 E Z isomeric mixture pure 2-[(4,6-dimethoxy- pyrimidin-2-yl)oxy]-3-ethoxycarbonyl-3-methyl-acrylic acid ethyl ester, ^-NMR CDC^): 1.60 + 2.04, 2s, CH 3 ; 3.88 + 3.90, 2s, OCH 3 ; 4J7, q, OCH^CHg; 4.28, q, OCH 2 CH 3 ; 5.79 + 5.90, 2s, CH. Example Pl l: Preparation of 2-r(4.6-dimethoxy-pyrimidin-2-yl)oxy1-3-methoxycarbonyl- acrylic acid methyl ester (Compound No. 1.043 and 1.044): 10.1 g of 4,6-dimethoxy-2-hydroxy-pyrimidine are placed in 200 ml of 1,3-dimethyl- 3,4,5,6-tetrahydro-2(lH)-pyrimidinone (DMPU).0J3 g of sodium hydride in the form of a 60 % dispersion in oil is then added thereto. When the evolution of hydrogen has ceased, 11.0 g of acetylene dicarboxylic acid dimethyl ester dissolved in 50 ml of dimethoxyethane are added dropwise. After 90 minutes the reaction mixture is introduced into water and extracted three times with ethyl acetate. The organic extract is washed twice with water, dried over sodium sulfate and concentrated by evaporation. The residue is taken up in diethyl ether and the product that precipitates is filtered off to yield in the form of beige crystals isomer I of 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methoxy- carbonyl-acrylic acid methyl ester (Compound No. 1.043); m.p.: 128-130°C; 1 H-NMR(CDC1 3 ): 6J8, s, CH. The mother liquor is separated by chromatography (eluants: diethyl ether hexane 1:1 and diethyl ether). The more polar fraction, isomer π of 2-[(4,6-dimethoxy-pyrimidin-2-yl)- oxy]-3-methoxycarbonyl-acrylic acid methyl ester (Compound No. 1.044), is isolated; m.p.: 108-112°; Η-NMR CDC^): 6.58, s, CH. Example PI 2: Preparation of 2-r(4.6-dimethoxy-pyrimidin-2-yl)oxyl-4-methoxy-4-ethyl- 3-methyl-butenolide (Compound No. 3.009): With inadiation by a 250 watt tungsten lamp, 2.8 g of 2-[(4,6-dimethoxy-pyrimidin-2-yl)- oxy]-4-ethyl-3-methyl-butenolide (Compound No. 3.001) are refluxed for one hour in the presence of 1.9 g of N-bromosuccinimide and a spatula tip of dibenzoyl peroxide in 50 ml of carbon tetrachloride. The succinimide remaining as solid is then filtered off and the reaction solution is concentrated by evaporation under reduced pressure. Separation by chromatography (eluant 15 % ethyl acetate/hexane) yields as the first fraction 3-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-5-<E>-ethylidene-4-methyl-butenolide; ^-NMR CDC^): 2J3, d, CH 3 ; 2.17, s, CH 3 ; 3.90, s, OCH 3 ; 4.52, q, CH; 5.85, s, CH. As second fraction (eluant 20 % ethyl acetate/hexane), and main component there is eluted 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-4-bromo-4-ethyl-3-methyl-butenolide (Example 3.014): 2J6, s, CH 3 ; ^-NMRfCDC^): 2.12, s, CH 3 ; 2.22 + 2.57, 2m, CΑ_CH 3 ; 3.89, s, OCH 3 ; 5.85, s, CH. As third fraction (eluant 25 % ethyl acetate/hexane) there is eluted 3-[(4,6-dimethoxy- pyrimidin-2-yl)oxy]-5-<Z>-ethylidene-4-methyl-butenolide; 1 H-NMR(CDC1 3 ): 1.97, d, CH 3 ; 2.06, s, 3.89, s, OCH 3 ; 4.38, q, CH; 5.83, s, CH; m.p.: 140-142°C. There may be obtained as fourth fraction 2-[(5-bromo-4,6-dimethoxy-pyrimidin-2-yl)- oxy]-4-ethyl-3-methyl-butenolide; 1 H-NMR(CDα 3 ): 1.68 + 2J0, 2m, CH^C^; 1.99, s, CH 3 ; 3.88, s, OCH 3 ; 4.94, m, CH; 5.82, s, CH. 1.5 g of the above 5-bromo product (Compound 3.014) are stirred at room temperature in a mixture of 15 ml of tetrahydrofuran and 15 ml of water in the presence of a spatula tip of iron(πi) chloride. After 18 hours the reaction solution is extracted with ethyl acetate and washed with saturated sodium chloride solution. Column chromatography (eluant 25 % ethyl acetate hexane) yields 2-[(4,6-d_ϋrnethoxy-pyrimidin-2-yl)oxy]-4-hydroxy-4-ethyl- 3-methyl-butenolide (Compound No. 3.010); m.p. 156-159°C; IR(CHC1 3 ): 1778 cm "1 . 0.2 g of the above 5-hydroxy product (Compound No. 3.010) is introduced into a solution of hydrochloric acid in methanol. After 18 hours the reaction mixture is extracted with ethyl acetate against water, dried over magnesium sulfate and concentrated by evapor¬ ation. Chromatography with 15 % ethyl acetate/hexane yields chromatographically pure 2- [(4,6-dimethoxy-pyrimidin-2-yl)oxy] -4-methoxy-4-ethyl-3-methyl-butenolide (Compound No. 3.009); Η-NMR CDCl-j): 1.88 + 2.12, 2m, CH 2 CH 3 ; 1.92, s, CH 3 ; 3.27, s, OCH 3 ; 3.87, s, OCH 3 ; 5.84, s, CH. Example P13: Preparation of 3,4-dimethoxy-2-r(4,6-dimethoxy-pyrimidin-2-yl)thio1- butenolide (Compound No. 3.017): A suspension of 14J g of mucochloric acid in 250 ml of water is neutralised at room temperature with 7.0 g of sodium hydrogen carbonate. In a separate vessel, a suspension of 14.4 g of 4,6-dimethoxy-2-mercaptopyrimidine is treated with a solution of 3.3 g of sodium hydroxide in water and then in the form of a yellowish solution is added dropwise to the above solution in the course of 40 minutes at a temperature of 0°C. The reaction mixture is stirred for a further hour at 0°C and then is adjusted to pH 3 with 2N hydro¬ chloric acid. The reaction mixture is extracted with diethyl ether, washed with sodium chloride solution, dried over sodium sulfate and concentrated by evaporation to yield in the form of a beige powder 3-chloro-2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-4-hydroxy- butenolide (Compound No. 3.015); 1 H-NMR(CDC1 3 ): 3.83, s, OCH 3 ; 6.07, s, CH; 6.37, d, CH; 8.71, d, OH. 9.0 g of the above product in 100 ml of methanol and 0.3 g of p-toluenesulfonic acid are heated at boiling temperature for 6 hours and then concentrated by evaporation. The crude product is chromatographed over silica gel (eluant: diethyl ether/hexane 3:1) to yield as first fraction 3-chloro-2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-4-methoxybutenolide (Compound No. 3.016); 3.63, s, OCH 3 ; 3.84, s, OCH 3 ; 5.80, s, CH; 5.83, s, CH. There is eluted as second fraction 3,4-dimethoxy-2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]- butenolide (Compound No. 3.017); 1 H-NMR(CDC1 3 ): 3.61, s, OCH 3 ; 3.87, s, 2xOCH 3 ; 4.32, s, OCH 3 ; 5.66, s, CH; 5.77, s, CH. Example P14: Preparation of 2-r(4,6-dimethoxy-pyrimidin-2-yl)thio1-3-methoxy- carbonyl-propenoic acid methyl ester (Compound No. 2.001): 9.5 g of 3-cMoιo-2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-4-hydroxy-butenolide (Compound No. 3.015) in 100 ml of benzene arc heated together with 14.8 g of thionyl chloride at boiling temperaturc until the evolution of gas has ceased. The cooled reaction solution is filtered to remove insoluble portions and concentrated by evaporation under reduced pressure at 50°C. The residue is filtered over 100 g of silica gel (eluant: diethyl ether/hexane 1:1) to yield 3,4-dichloro-2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-butenolide (Compound No. 3.018); 1 H-NMR(CDC1 3 ): 3.87, s, OCH 3 ; 5.82, s, CH, 6.60, s, CH. 3.2 g of that product are treated in 50 ml of methanol with 2.0 g of pyridine. After standing for 20 hours at room temperature, the reaction mixture is concentrated by evapor¬ ation. The residue is taken up in dichloromethane and filtered over silica gel. Recrystal- lisation from diethyl ether/hexane yields in the form of isomerically pure, yellowish crystals 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-methoxycarbonyl-propenoic acid methyl ester (Compound No. 2.001); m.p.: 97-98°C; 1 H-NMR(CDC1 3 ): 3.71, s, OCH 3 ; 3.82, s, OCH 3 ; 3.99, s, 2xOCH 3 ; 5.78, s, CH; 6.94, s, CH. The compounds of Tables 1 to 3 can be prepared analogously to the above Examples and the preparation processes mentioned in the description: Table 1: Compounds of formula le (le) Table 2: Compounds of formula If Table 3: Compounds of formula Ig: Biological Examples Example Bl: Pre-emergence herbicidal action In a greenhouse, immediately after die test plants (a number of weeds, bodi monocotyled- onous and dicotyledonous) have been sown in seed trays, the surface of the soil is treated witii an aqueous spray mixture corresponding to a rate of 3 kg of active ingredient/hectare. The test compounds are preferably formulated as emulsifiable concentrates (EC) and are diluted wi± water to the desired concentration immediately before application. Insoluble compounds are formulated as wettable powders (WP) using kaolin as inert carrier. The wettable powder is suspended in water immediately before application. The concentrations in g of active ingredient hectare relate to the surface of the soil in the containers, unless otiierwise indicated. The spray volume is 10001/ha (corresponding to 100 ml/m 2 ). The seeds of d e plants are sown in plastics plant pots of various sizes containing heat- sterilised (steam-treated) soil (earth 2.6 % peat, 20 % clay, 30 % coarse clay, 47 % sand). The plants arc kept in a greenhouse at a moderate temperature (17 - 25 °C in winter, 18 - 35°C in summer) (humidity 30 - 90 %). The length of the illumination period is from 13 to 16 hours/day; if necessary artificial light is provided (15 000 to 18000 lux). The artificial illumination is also activated automatically when there is insufficient daylight intensity. After 3 weeks, the herbicidal action is evaluated using a linear scale of eleven ratings (necrosis, chlorosis, reduction, deformation) in comparison with an untreated control group (2 = 80-100 % damage, 1 = 30-79 % damage, 0 = 0-29 % damage). In mat test the compounds of formula I described in Tables 1-3 exhibit a surong herbicidal action. Examples of die good herbicidal action of die compounds of formula I described in Tables 1-3 of the present Application are listed in Table Bl: le Bl: Pre-emerence herbicidal action: Biological Example B2 was carried out to test the herbicidal activity of die compounds of die present Application in comparision with that of compounds from the prior art (EP-A-0409741 and EP-A-0400741): Example B2: Post-emergence herbicidal action (contact herbicide) A number of weeds, botii monocotyledonous and dicotyledonous, are treated post- emergence (in die 2- to 6-leaf stage) with an aqueous active ingredient dispersion at a rate of 3 kg of active ingredient per hectare. The test compounds are preferably formulated as emulsifiable concentrates (EC) and are diluted witii water to the desired concentration immediately before application. Insoluble compounds are formulated as wettable powders (WP) using kaolin as inert carrier. The wettable powder is suspended in water immediately before application. The concentrations in g of active ingredient/hectare relate to the surface of the soil in the containers, unless otherwise indicated. The spray volume is 5001 ha. The seeds of die plants are sown in plastics plant pots of various sizes containing heat- sterilised (steam-treated) soil (Optima' earth 80 % peat, 20 % loess). The plants are kept in a greenhouse at a moderate temperature (17 - 25°C in winter, 18 - 35°C in summer) (humidity 30 - 90 %). The length of the illumination period is from 13 to 16 hours/day; if necessary artificial light is provided (15000 to 18000 lux). The artificial illumination is also activated automatically when there is insufficient daylight intensity. After 3 weeks, the herbicidal action (necrosis, chlorosis, reduction, deformation) is evaluated in accordance witii a linear scale of eleven ratings (2 = 80-100 % damage, 1 = 30-79 % damage, 0 = 0-29 % damage) in comparison with an untreated control group. Examples of the good herbicidal action of the compounds of formula I described in the Tables of the present Application are listed in Table B2: Table B2: Post-emer ence herbicidal action Compounds of die prior art: Comp. A 2- [(4,6-dimethoxy-pyrimidin-2-yl)oxy] -3-phenyl-acrylic acid, Compound No. 57 from EP-A-0409 369 Comp. B 2-[(4,6-dimedιoxy-pyrimidin-2-yl)oxy]-3-medιyl-acry lie acid, Compound No. 24 from EP-A-0409 369 Comp. C 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-acrylic acid methyl ester, Compound No. 164 from EP-A-0400741 In that test the compounds of me present Application exhibit a herbicidal action clearly superior to that of the compounds of die prior ait

Claims: What is claimed is: 1. A pyrimidinyl or triazinyl ether or thioether of formula I wherein Q is X is oxygen or CHR 26 ; Y is oxygen or sulfur; A is hydrogen, fluorine, chlorine, (C^alkyl-oxetan-S-ylJoxy, Rg or the group E is methine, halo-substituted metiiine or nitrogen; Eι is methine or nitrogen; Y j is oxygen or sulfur, each of Rj and R 24 , independently of die other, is C^alkyl, cyclopropyl, C-^alkoxy, difluoromethoxy, mediyltiiio, ediyldiio, methylamino, ethylamino, dimethylamino or dietiiylamino; each of R 2 and R 25 , independently of die odier, is methyl, methoxy, edioxy or difluoro¬ methoxy; R 3 is hydrogen, Ci^alkyl, C 1 . 3 alkylthio, halogen, C^alkoxy, C^alkylamino or C^dialkylamino or, together witii R 4 , is -(CH^ p - or -S(CH 2 ) q S-; R 4 is C 3 _ 6 cycloalkyl, .ghaloalkyl, formyl, C^alkylcarbonyl, carboxy, C^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R 5 is hydrogen, halogen, C 1 . 3 alkoxy or, togedier witii R 6 , is -(CH 2 ) p -; R 6 is hydrogen or C^alkyl; R 7 is hydrogen, hydroxy, halogen, C^alkoxy, carboxy or C^alkoxycarbonyl; R 8 is hydroxy, C^alkoxy, C 1 . 2 alkoxy-C 1 . 2 alkoxy, C 1 . 2 alkylthio-C 1 . 2 alkoxy, C j ^alkyl- sulfinyl-Cι_ 2 alkoxy, _ 4 dia_U__ylamino-C**_ 2 alkoxy, C^alkoxycarbonyl-C^alkoxy, C 3 _ 4 alkenyloxy, C 2 . 6 alkyliminooxy, Cι_ 3 alkoxycarbonyl- C^alkylthio, phenoxy, phenylthio, or phenoxy or phenylthio substituted by fluorine, chlorine, bromine, methyl, methoxy or by nitro; Rξ) is hydrogen, methyl or, together with R 10 , is -(CH^ q -, -CH CH(OH)CH - or - CH S CH 2 - ; each of R^ j and R 22 , independently of die other, is hydrogen, methyl, hydroxymetiiyl, formyl, cyano or a group COZ, R π is hydrogen, C^alkyl, or C^alkyl substituted by hydroxy, C^alkoxy, mercapto, Cι_ 4 alkylmercapto, vinyl, phenyl, 4-hydroxyphenyl, 4-imidazolyl, 3-indolyl, hydroxy- carbonyl, C^alkoxycarbonyl, 2-propenyloxycarbonyl, cyano or by carbamoyl, or is trifluoromethyl, ethynyl, vinyl, phenyl, cyano or R 12 , R i , R 23 and R 27 are hydrogen or metiiyl; R 13 is hydrogen, C^alkyl, phenyl, or phenyl mono- or di-substituted by fluorine, chlorine, bromine, metiiyl, trifluoromethyl, methoxy or by nitro; R 14 is hydrogen or methyl; R 15 is phenyl, benzyl, or phenyl substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, methoxy, nitro, cyano, carboxy or by carbonyl; m is 1, 2 or 3; n is 0, 1, 2 or 3; p is 4 or 5; q is 2 or 3; W is oxygen, sulfur or NH; Z is hydroxy, C 1 _ 4 alkoxy, C 3 ^alkenyloxy, benzyloxy, amino, C^alkylamino, C^dialkyl- am o, or a group (Z_) or each of R 16 and R 18 , independently of the other, is hydroxy, C^alkoxy, 2-propenyloxy, benzyloxy, amino or a group each of R 17 and R 28 , independendy of die other, is hydrogen, C^alkyl or benzyl; R 20 is C^aUcyl, C^alkenyl, C 3 . 6 cycloalkyl, C^haloalkyl, C 1-3 alkoxy, Cualkylthio, carboxy, C^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R 21 is hydrogen, C^alkyl, C^alkylthio or, together with R 20 , is -(CH 2 ) p - or -S(CH 2 ) q S-; R 26 is hydrogen or C^alkyl; R 29 is hydroxy, C^alkoxy, 2-propenyloxy, benzyloxy, or amino; or a salt of such a compound of formula I that has a free carboxy group; with the proviso that R 3 is C^alkyl, C^alkylthio or, together with R 4 , is -(CΑ^)_- or -S(CH 2 ) q S- when at the same time A is a group Rg or a group A 4 and R is C^alkyl, C^alkenyl, C 3 _ 6 Cycloalkyl, Cι. 6 haloalkyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl. 2. A compound according to claim 1 wherein Q is Y is oxygen or sulfur, A is hydrogen, fluorine, chlorine, (C^alkyl-oxetan-S-yl^xy, R 8 or the group R 14 N N / " (A4 ), \ N S R 15 (A 5 ) or H R 13 H E is methine or nitrogen; E j is methine or nitrogen; Y j is oxygen or sulfur, each of R j and R 24 , independentiy of the other, is C^alkyl, cyclopropyl, C^alkoxy, difluoromethoxy, methylthio, ethylthio, methylamino, ethylamino, dimethylamino or diediylamino; each of R 2 and R 2 , independently of die other, is methyl, methoxy, ethoxy or difluoro¬ methoxy; R 3 is hydrogen, C 1-4 alkyl, C 1 . 3 alkylthio or, together with R 4 , is -(CΑ^ p - or -S(CH 2 ) q S-; R 4 is C j ^alkyl, C^alkenyl, C 3 _ 6 cycloalkyl, .ghaloalkyl, C^alkylthio, formyl, C^alkylcarbonyl, carboxy, C } ^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R 5 is hydrogen, C j ^alkyl or, together with R , is -(CH^ p -; R 6 is hydrogen or C^alkyl; R 7 is hydrogen, hydroxy, Cι_ 6 alkoxy, carboxy or C^alkoxycarbonyl; Rg is hydroxy, C j .galkoxy, C^alkoxy-C^alkoxy, C^alkylthio-C^alkoxy, C^alkyl- sulfinyl-C 1 . 2 alkoxy, C 1 . 3 alkoxycarbonyl-C 1 . 2 alkoxy, C 3 ^alkenyloxy, C-^alkynyloxy, C 3 . 6 cycloalkoxy, benzyloxy, C^alkylaminooxy, C 2 . 6 alkyliminooxy, C 1 . 3 alkoxycarbonyl- C 1 . 2 alkylthio, phenoxy, phenylthio, or phenoxy or phenylthio substituted by fluorine, chlorine, bromine, methyl, methoxy or by nitro; R 9 is hydrogen, metiiyl or, together with R 10 , is -( Α_) q -, -CH 2 CH(OH)CH 2 - or -CH SCH 2 -; each of R 10 and R 22 , independentiy of the other, is hydrogen, methyl, hydroxymethyl, formyl, cyano or a group COZ, R π is hydrogen, C^alkyl, or C alkyl substituted by hydroxy, C^alkoxy, mercapto, C^alkylmercapto, vinyl, phenyl, 4-hydroxyphenyl, 4-imidazolyl, 3-indolyl, hydroxy- carbonyl, C_ ^alkoxycarbonyl, 2-propenyloxycarbonyl, cyano or by carbamoyl, or is trifluoromethyl, ethynyl, vinyl, phenyl, cyano or C^alkoxycarbonyl; R 12 , Rχ and R 23 are hydrogen or metiiyl; R 13 is hydrogen, C j ^alkyl, phenyl, or phenyl mono- or di-substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, methoxy or by nitro; R 14 is hydrogen or methyl; R 15 is C j .galkyl, C^haloalkyl, phenyl, benzyl, or phenyl substituted by fluorine, chlorine, bromine, methyl, trifluoromethyl, methoxy, nitro, cyano, carboxy or by C 1-3 alkoxy- carbonyl; m is 1, 2 or 3; n is O, 1, 2 or 3; p is 4 or 5; q is 2 or 3; W is oxygen, sulfur or NH; Z is hydroxy, C^alkoxy, C 3 _ 4 alkenyloxy, benzyloxy, amino, C h alky lamino, C 2 ^dialkyl- amino, or a group (Z_) or (Z 2 ); each of R 16 and R 18 , independentiy of the other, is hydroxy, C^alkoxy, 2-propenyloxy, benzyloxy or amino; R 17 is hydrogen, C h alky! or benzyl; R 2 o is C^alkyl, C^alkenyl, C 3 . 6 cycloalkyl, C^haloalkyl, C^alkoxy, C-^alkylthio, carboxy, C^alkoxycarbonyl, phenyl, or phenyl substituted by fluorine, chlorine, methyl, trifluoromethyl, methoxy or by nitro, or is 2-, 3- or 4-pyridyl, 2- or 3-furyl or 2- or 3-thienyl; R 2 ι is hydrogen, C^alkyl, Cι_ 3 alkylthio or, together with R 2 o, is -(CΑ ) V - or -S(CH 2 ) q S-; or a salt of such a compound of formula I that has a free carboxy group. 3. A compound of formula I according to claim 1 wherein Q is Q 2 . 4. A compound of formula I according to claim 1 wherein Q is Qj and A is (C j.3 alkyl- oxetan-3-yl)oxy or the group — S R 15 (A 5 ) 5. A compound of formula I according to claim 1 wherein Q is the group Q-,; Y is oxygen; E is methine; Rj and R2 are methoxy; R 3 is methyl or ethyl or, together with R4, is -(CH 2 ) p -; and R 4 is C 1 . 3 alkyl or phenyl. 6. A compound of formula I according to claim 5 wherein R 3 is methyl or ethyl and A is C^alkoxy, hydroxy, 2-propenyloxy or an inorganic or organic salt of the free acid. 7. A compound of formula I according to claim 4 wherein A is 8. A compound of formula I according to claim 4 wherein A is an <S> chiral group A j wherein Rg is hydrogen or, togetiier with R π , is -(CH 2 ) 3 -, Rio is a group COZ wherein Z is as defined for formula I and R^ is hydrogen. 9. A compound of formula I according to claim 8 wherein Z is C^alkoxy, C 3 _4alkenyl- oxy, amino or a group (Z**) and Rn is hydrogen, Chalky 1 or benzyl. 10. A compound of formula I according to claim 1 wherein Q is the group Q_; Y is oxygen; E is methine; Rj is methoxy; R 2 is methoxy; R 3 is hydrogen, methyl or ethyl or, together with R 4 , is -(CH^ p -; R is formyl, carboxy, C h alky lcaibonyl or Cjjalkoxycarbonyl; and A is hydroxy, C^alkoxy, 2-propenyloxy or an organic or inorganic salt of the free acid. 11. A compound of formula I according to claim 2 wherein Y is oxygen; E is methine; R ! is methoxy; R 2 is methoxy; R 5 is methyl; Rg is methyl or ethyl; and R 7 is hydrogen, hydroxy, 12. A compound of formula I according to claim 1 wherein Q is Q ! and Y is sulfur, E is methine; Ri is methoxy; and R 2 is methoxy. 13. A compound of formula I according to claim 12 wherein R 3 is methyl or ethyl; R 4 is Cι. 3 alkyl, cyclopropyl or phenyl; and A is C 1-3 alkoxy, hydroxy or an inorganic or organic salt of the free acid. 14. A compound of formula I according to claim 12 wherein R 3 is hydrogen, methyl, etivyl, methylthio or, together with R 4 , is -S(CH 2 ) 2 S-; R is methylthio, formyl, carboxy, C^alkylcarbonyl or C^alkoxycarbonyl; and A is hydroxy, C^alkoxy, 2-propenyloxy or an inorganic or organic salt of die free acid. 15. A compound of formula I according to claim 12 wherein R 3 is methyl or ethyl; R 4 is C^alkyl, cyclopropyl or phenyl; and A is (oxetan-3-yl)oxy, 2-propenyloxy or an <S> chiral group A ! wherein R 9 is hydrogen or, togetiier with R π , is -(CH 2 ) 3 -, Rio s a group COZ wherein Z is as defined for formula I, and Rπ is hydrogen, C^alkyl or benzyl. 16. A compound of formula I according to claim 3 wherein Y is sulfur, E is methine; R-* is methoxy; R 2 is methoxy; R 5 is methyl or methoxy; R 6 is hydrogen, metiiyl or ethyl; and R 7 is hydrogen, hydroxy or C^alkoxy. 17. A compound of formula I according to claim 1 selected from the group 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-metiιyl-2-butenoic acid, [E and or Z]-2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-pentenoic acid, N-[2-[(4,6-dimemoxy-pvriιnidin-2-yl)oxy]-3-me yl-2-butenoyl]-Lralanine ethyl ester, N-[2-[(4,6-dimetiioxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-valine ethyl ester, N-[2-[(4,6-dimemoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-leucine methyl ester, N-[2-[(4,6-dimethoxy-pvrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-glycine methyl ester, N-[2-[(4,6-dime oxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-leucine amide, N-[2-[(4,6-dimeΛoxy-pyrimidin-2-yl)oxy]-3-methyl-2-butenoyl]-L-leucine allyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-medιyl-2-butenoyl]-L-leucine, 2-[(4,6-dimethoxy-l,3,5-triazin-2-yl)oxy]-3-methyl-2-butenoic acid etiiyl ester, 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-4-ethyl-3-metiιyl-butenolide, 2-[(4,6-dimedιoxy-pyrimidin-2-yl)oxy]-4-carboxy-4-ethyl-3-metiιyl-butenolide, 2- [(4,6-dimethoxy-pyrimidin-2-yl)oxy] -3-ethyl-2-pentenoic acid, |Ε]-2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-2-pentenoic acid, N-[2-[(4,6-dimetiιoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-glycine methyl ester, N-[2-[(4,6-dimemoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-L-alanine methyl ester, N-[2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-L-valine methyl ester, N-[2-[(4,6-dimetiιoxy-pyrimidin-2-yl)oxy]-3-methyl-pentenoyl]-L-leucine methyl ester, 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-3-cyclopentylpropenoic acid, 2-[(4, <iimethoxy-pyrimidin-2-yl)oxy]-3-methyl-sodium butenate, N-[2-[(4,6-dimethoxy-pvrimidin-2-yl)oxy]-3-methyl-pentenoyl]-L-alanine ethyl ester, 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-(l,3-dithia-cyclopent-2-yl)propenoic acid, 2-[(4,6-dimemoxy-pyrimidin-2-yl)thio]-3-methyl-2-butenoic acid, 2-[(4,6-dimethoxy-pyrimidin-2-yl)thio]-3-methyl-2-pentenoic acid and 2-[(4,6-dimethoxy-pyrimidin-2-yl)oxy]-4-hydroxy-4-ethyl-3-methyl-butenolide. 18. A process for the preparation of a compound of formula I wherein a) a pyrimidine of formula II wherein E, Rj and R 2 are as defined for formula I in claim 1 and L is a leaving group is reacted witii a propenoate, 2-oxo-propionate or furanone compound of formula HI, Ilia or IV, respectively, in πia IV wherein R 3 , R R 5 and R 6 are as defined for formula I and R 7 is hydrogen, C^alkoxy, carboxy or ^alkoxycarbonyl, A is hydrogen, hydroxy, C^alkoxy, C 1 . alkoxy- C^alkoxy, C^alkylthio-C^alkoxy, C 1 _ 2 alkylsulfinyl-C 1 . 2 alkoxy, C^dialkylamino- C^alkoxy, C 1 _ 3 alkylcarbonyloxy-C 1 _. 2 alkoxy, C 3 ^alkenyloxy, C 3jt alkynyloxy, C 3.6 cyclo- alkoxy, benzyloxy or (C^alkyl-oxetan-S-ytyoxy and Y' is hydroxy or mercapto, but especially hydroxy, in the presence of an acid-binding agent and in the presence of an inert solvent, or b) a compound of formula V la wherein E, Ri and R 2 are as defined for formula I and A' is C^alkoxy, C^alkoxy- C^alkoxy, C 2 _. 6 alkenyloxy, benzyloxy or (C**. 3 alkyl-oxetan-3-yl)oxy, especially C-^alkoxy, 2-propenyloxy or benzyloxy, is lithiated and tiien the product tiiereof is reacted with the corresponding electrophilic compound of formula VI, wherein R 3 and R 4 arc as defined above, or with carbon disulfide or an alkylisothiocyanate, wherein R" is C^alkyl, and a subsequent corresponding alkylating agent R'X wherein R' is C^alkyl or -(CH-^ q - and X is methoxy- or ethoxy-sulfonyl, chlorine, bromine or iodine, or witii a corresponding orthoester or dialkylaminodimethylacetal; or c) in the case of a compound of formula I wherein A is hydroxy, a compound of formula la wherein A' is C-^alkoxy, 2-propenyloxy or benzyloxy is hydrolysed or reduced by hydrogenolysis; or d) a compound of formula Ic or an anhydride of formula Id (I) wherein E, Y, R_, R 2 , R 3 , R 4 , R 20 ' R 2I ' R 24 an ^ R 25 are as defined above, and wherein A'" is a leaving group, is reacted witii a nucleophilic compound of formula VU wherein A is Rg, ( ^alkyl-oxetan-S-y oxy or a group Aj to A 6 , where appropriate in the presence of a base and of a solvent. 19. A herbicidal and plant-growth-inhibiting composition comprising one or more of the pyrimidinyl and triazinyl ethers and thioethers of formula I, according to claim 1. 20. A composition according to claim 19 comprising from 0.001 % to 95 % by weight compound of formula I according to claim 1. 21. A method of controlling undesired plant growth, wherein an effective amount of a compound of formula I according to claim 1, or of a composition according to claim 19 comprising such a compound, is applied to the plants or to the locus thereof. 22. A method according to claim 21, wherein the compound is applied at a rate of from 0.001 to 3 kg per hectare. 23. A method according to claim 21 for the selective pre- or post-emergence control of weeds in crops of useful plants.

Inventors: LUETHY CHRISTOPH, LUTZ WILLIAM RUDOLF, WINTERNITZ PAUL, LUETHY, CHRISTOPH, LUTZ, WILLIAM, RUDOLF, WINTERNITZ, PAUL
Applicants: CIBA GEIGY AG, LUETHY CHRISTOPH, LUTZ WILLIAM RUDOLF, WINTERNITZ PAUL, CIBA-GEIGY AG, LUETHY, CHRISTOPH, LUTZ, WILLIAM, RUDOLF, WINTERNITZ, PAUL
Application year: 1992
Main classification: C07D239
IPC codes: A01N43, C07D239, C07D251, C07D405, C07D409, C07D419