Novel C-2 Substituted Carbapenem Derivatives. Part II. Synthesis and Structure-activity Relationships of Isoxazolin-2-yl, Isoxazolidin-2-yl and 2-Pyrazolin-2-yl Carbapenems Generated Using 1,3-Dipolar Cycloaddition Chemistry.

Abstract

A series of carbapenems containing novel C-2 semisaturated heterocyclic substituents were synthesised by 1,3 dipolar cycloaddition reactions of nitrile oxides, nitrile imines and a nitrone to 2-vinylcarbapenem. The isoxazoline and isoxazolidine compounds showed potent antibacterial activity but moderate stability to human dehydropeptidase 1 (DHP-1). Stability to DHP-1 was improved by methyl substitution in the isoxazoline ring, but at the expense of antibacterial activity. The pyrazolines exhibited excellent stability to DHP-1, but reduced potency against Gram-negative organisms.