| 摘要 |
<p>Compounds of the formula IIIa, IIIb and IIIc IIIa IIIb IIIc wherein R represents a carboxyl esterlfying group removable by hydrolysis, photolysis, reduction, or enzyme action to give the free acid R? and Rb, which may be the same or different, each represents an alkyl group having frorn 1 to 4 carbon atoms, an aryl group, A represents a direct bond or the residue of a dicarboxylic acid, and R3 represents an alkyl group having from 1 to 8 carbon atoms, or an alkenyl group having up to 6 carbon atoms and processes for their preparation, 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> |
