l, or may be alkylaminocarbonyl in which alkyl has up to and including 7, preferably up to and including 4, carbon atoms, and which may carry as substituent in the 2 -position, especially in the 1-position, alkoxycarbonyl in which alkyl contains up to and including 4 carbon atoms and is, for example, methyl or ethyl, especially alkoxycarbonylmethylaminocarbonyl in which alkyl has up to and includi