FORMAL TOTAL SYNTHESES OF THE BETA-LACTAM ANTIBIOTICS THIENAMYCIN ANDPS-5

Chiral nonracemic acetylenic acids of general structure 11, prepared u sing the Schreiber modification of the Nicholas reaction, have been co nverted to beta-amino acid derivatives of type 12 by a two-step sequen ce involving Curtius rearrangement followed by oxidative cleavage of t he acetylenic bond. Amino acid derivatives 12 are excellent precursors for beta-lactams of the carbapenem class, including the important ant ibiotics thienamycin (1) and PS-5 (4).