A mixture of 21a (0.5 g, 0.0017 mol) and 2a (0.5 g, 0.004 mol) was heated at 100'for 3 hr. Then the resulting mixture was chilled by ether, and filteration gave 0.6 g (86%) of loa. Reaction of Ethylphthalaldehydate (23) with 4a. A mixture of 23 (5.34 g, 0.03 mol) and 4a (2.8 g, 0.03 mol) in benzene (50 ml) was refluxed for 6 hr using a Dean-Stark trap. After removal of solvent, the residue was distilled under reduced pressure to afford 6.30 g (83% ...
![methyl 3,3-dimethyl-7-oxo-6-[(2-phenoxyacetyl)amino]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate Structure](https://image.chemsrc.com/caspic/137/2315-05-1.png)