Yuji Sendo

Synthetic studies on β-lactam antibiotics. VII. Mild removal of the benzyl ester protecting group with aluminum trichloride☆

The benzyl ester protecting group in β-lactam derivatives can be cleanly removed by treatment with aluminum trichloride under mild conditions, preferably in the presence of anisole, to give the corresponding free acids in high yields.

Practical procedure for epimerization of 7α-amino-1-oxacephems to 7β-amino epimers

Abstract 7α-Amino-1-oxacephems can be epimerized to their 7β-amino epimers by treatment with chloral to give Schiff bases, followed by dehydrochlorination with Hunig base, borohydride reduction, and hydrolysis.

Nucleophilic displacement of 7α-methoxy-7β-amino-1-oxacephem derivatives: synthesis of 7α-substituted 1-oxacephem antibiotics

Acid-catalysed displacement of 7α-methoxy-7β-amino-l-oxacephem (1) with nucleophiles gave the 7α-substituted-7β-amino compounds (5–8), which were converted into the antibiotics (13–16).

Synthetic studies on β-lactam antibiotics. 18. Convenient, stereocontrolled synthesis of 3-methyl 7α-methoxy-1-oxacephems

Abstract Alcohols 4 and 8 , prepared from 3 , underwent completely stereospecific etherification to give 1-oxacephams 5 and 10 , which were converted into the 1-oxacephem nucleus 1b via 6 and 1c . Functionalization at C-3′ in 6 and 1c was unsuccessful.