The synthesis and reactions of a monocyclic β-lactam tripeptide, 1-[(1R)-carboxy-2-methylpropyl]- (3R -[(5S-5-amino- 5-carboxypentanamido]-(4R)-mercaptoazetidin-2-one, a putative intermediate in penicillin biosynthesis

The disulphide corresponding to the above thiol has been synthesised, but all attempts to reduce this substance to the thiol were unsuccessful, although an alternative procedure via a thiomercury intermediate, enabled the thiol to be generated in situ , the properties of this thiol, however, are not in accord with those previously described for a putative free intermediate in penicillin biosynthesis. 1