New derivatives of acrylic acid beta-methoxy, method of preparing them and their use as pesticides

Compounds of formula (I) in which R1, R2 and R3 are a) alkyl, alkoxy, alkenyl, alkenyloxy, alkynyl, alkynyloxy or alkanoyloxy, each of which is straight, branched or cyclic, comprising up to 8 carbon atoms, optionally substituted by one or more halogen atoms and optionally interrupted by one or more oxygen atoms; b) phenyl or phenoxy, optionally substituted by one or more halogen atoms, one or more hydroxy radicals, one or more alkyl radicals which are linear or branched and are optionally substituted by one or more halogen atoms, one or more alkoxy or alkylthio radicals, which are optionally substituted by one or more halogen atoms, one or more hydroxy radicals (which may be esterified), or one or more cyano radicals; c) R1 and R2 can together with the carbon atom to which they are attached form a double carbon bond; d) R1 and R2 can together with the carbon to which they are attached form a ring comprising up to 8 chain atoms and which can comprise one or more hetero atoms selected from oxygen, sulfur and nitrogen; R4 is halogen, or an alkyl, alkenyl, alkynyl, alkoxy, alkenyloxy, alkynyloxy, alkylthio, alkenylthio or alkynylthio radical, each of which is optionally substituted by one or more halogen atoms and comprises up to 11 carbon atoms, a phenyl radical optionally substituted as defined under (b), CN, NO2, NH2, N(alk1)alk2, CO2alk3, where alk1, alk2 and alk3, which are the same or different from each other, are alkyl comprising up to 8 carbon atoms, X has the same meaning as R4 or can be hydrogen, or X and R4 together with atoms to which they are attached, can form a ring optionally containing one or more hetero atoms selected from oxygen, nitrogen and sulfur, have pesticidal, especially fungicidal or acaricidal, activity.