| 摘要 |
<p>Compounds of the formula IIa, IIb and IIc < IMG > wherein R represents a carboxyl esterifying group removable by hydrolysis, photolysis, reduction, or enzyme action to give the free acid R1 represents a chlorine or bromine atom, R2a and R2b, which may be the same or different, each represents an alkyl group having from 1 to 4 carbon atoms, an aryl group, and A represents a direct bond or the residue of a dicarboxylic acid and processes for their manufacture, are provided. These compounds are useful intermediates in the production of 7-oxo-4-thia-1-azabicyclo¢3,2,0!-heptane and hept-2-ene derivatives, which in turn have antibacterial properties.</p> |
