-C.sub.4)alkylamino(C.sub.1 -C.sub.4)alkyl radical, R.sub.14 represents a hydrogen atom, a halogen atom, such as fluorine, or a C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 monohydroxyalkyl, C.sub.2 -C.sub.4 polyhydroxyalkyl, C.sub.l -C.sub.4 aminoalkyl,