| 摘要 |
<p>The novel compounds of the formula <IMAGE> I wherein R1 is hydrogen, a residue readily removable by reduction, lower 1-hydroxyalkyl or lower alkanoyl and R2 is hydrogen, or each of R1 and R2 is a residue readily removable by reduction; R3 is hydrogen or lower alkyl; R4 is hydrogen or a readily removable protecting group; and A is lower alkylidene or (C5-7)-cycloalkylidene, are valuable intermediates for the manufacture of antimicrobially-active beta -lactams.</p> |
