Asymmetric Synthesis and Antimicrobial Activity of Some New Mono and Bicyclic β-Lactams

• Published in: Molecules (Basel, Switzerland) Vol. 9; no. 11; pp. 939 - 948
• Main Authors: A. Taslimi, M. Shekarriz, A. A. Jarrahpour
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.11.2004
• Subjects: antimicrobial; asymmetric induction; chiral Schiff base; D-Phenylalanine; DBU
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/91100939

Reaction of the amino acid D-phenylalanine ethyl ester (4) with cinnamaldehyde gave chiral Schiff base 5, which underwent an asymmetric Staudinger [2+2] cycloaddition reaction with phthalimidoacetyl chloride to give the monocyclic β-lactam 6 as a single stereoisomer. Ozonolysis of 6 followed by reduction with lithium aluminum tri(tert-butoxy) hydride afforded the hydroxymethyl β-lactam 8. Treatment of 8 with methansulfonyl chloride gave the mesylated monocyclic β-lactam 9, which was converted to the bicyclic β-lactam 10 upon treatment with 1,8-diazabicyclo[5,4.0] undec- 7-ene (DBU). Deprotection of the phthalimido group in β-lactams 6 and 10 by methylhydrazine and subsequent acylation of the free amino β-lactams with different acyl chlorides in the presence of pyridine afforded mono and bicyclic β-lactams 14a-d and 15a-d respectively. The compounds prepared were tested against Escherichia coli, Staphilococcus citrus, Klebsiella pneumanie and Bacillus subtillis. Some of these compounds showed potential antimicrobial activities.