摘要:
A subject of the invention is the products of formula (I): ##STR1## in which: R.sub.1, R.sub.2 and R.sub.3, identical or different, represent a linear, branched or cyclic alkyl radical, an alkenyl or alkynyl radical, containing up to 8 carbon atoms, optionally substituted by one or more halogen atoms, an aryl radical optionally substituted by one or more halogen atoms, one or more hydroxyl radicals, one or more linear or branched alkyl radicals, optionally substituted by one or more halogen atoms, one or more O-alkyl or S-alkyl radicals optionally substituted by one or more halogen atoms,X represents a hydrogen atom, a halogen atom, an alkyl, alkenyl, alkynyl, O-alkyl, O-alkenyl, O-alkynyl, S-alkyl, S-alkenyl or S-alkynyl radical, optionally substituted by one or more halogen atoms and containing up to 11 carbon atoms, an aryl radical containing up to 14 carbon atoms, a C.tbd.N, NO.sub.2, NH.sub.2, ##STR2## CO.sub.2 alk.sub.3 radical, alk.sub.1, alk.sub.2 and alk.sub.3, identical to or different from each other, representing an alkyl radical containing up to 8 carbon atoms,R.sub.4 represents one of the values indicated above for X with the exception of hydrogen.