| abstract |
Compounds of the formula <IMAGE> wherein either Q<1> is H and Q<2> is H or alkyl or Q<1> and Q<2> together are -CH2-, n is 1 or 2, R15 is H or F, R18 is H or optionally blocked OH or CH2OH, R32 is H or a blocking group, Z1 is alkylene or phenylenealkylene and X1 is optionally esterified or salified carboxyl, CH2OH, aminomethyl or aminocarbonyl. |