adical or an amino radical; and it is preferred that the R10 and R11 each is a hydrogen atom and the R12 is an alkoxycarbonyl, acyalamido or alkylsulfonamido radical; and X is as defined in Formula (I), and preferably a radical having Formula (III) or (IV), and the more preferred one of Formula (III) is one having Formula (V) or (VI).