Some aspects of the chemistry of penicillin.

Some recent advances in the chemistry of penicillin are presented. The group of antibiotics known as the penicillins have a unique position in chemistry. Not only were they the first type of antibiotic to be widely accepted in medical practice, but their chemistry proved to be of unusual interest and complexity. Modem fermentation plants have reduced the cost of the penicillins such that one should now regard these compounds as a potentially useful raw material, suitable as starting point for further transformations. As an example one may quote the use of penicillins as precursors for the synthesis of the related, and important, antibiotics, the cephalosporins. The parent penam (I) and cephem (II) systems have similar chemical structures notably the identical f3-lactam grouping (III) and the same C5 isoprenoid-like unit to the right of the dotted lines in (I) and (II). The systems differ in that the cephalosporins have a higher oxidation level than the penicillins and a different substitution patem on the C5 unit. HHH'. HHH' N2 PhCH2CO NIJOAc (I) C021-I (IT)