| 摘要 |
The invention provides compounds of the formula <IMAGE> wherein R* is a group of the formula <IMAGE> wherein R and R0 are individually C1-C6 alkyl groups or together form a ring consisting of the nitrogen atom to which they are attached and two to seven carbon atoms, said ring optionally substituted by one or more C1-C6 alkyl and/or C1-C6 substituted alkyl groups; Q and Q' are individually hydrogen, C1-C6 alkyl, or when taken together form a divalent radical of the formula -CH=CH-CH=CH-; A is C1-C6 alkyl, C1-C6 substituted alkyl, -S-(C1-C6 alkyl)CO2R'', or -CH2(C1-C6 alkyl) CO2R'' wherein R''is hydrogen or a carboxy-protecting group; A' is hydrogen, an amide-protecting group, or a group of the formula -CH2CO2R''.
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