Synthesis of novel fused β-lactams by intramolecular 1,3-dipolar cycloadditions. Part 1. Tricyclic triazole

Abstract

4-Azido-1-alk-2-ynylazetidin-2-ones (3), (14), and (19) when heated in refluxing toluene gave smooth intramolecular cycloaddition of the azido-group to the acetylene function to afford the corresponding 4H,7aH-azeto[1,2-a]-v-triazolo[3,4-c]imidazol-6(7H)-ones (4), (15), and (18). These products were antibacterially inactive, but possessed weak β-lactamase inhibitory properties, particularly against the staphylococcal enzyme.

Similar reaction of 4-azido-1-(1-benzyloxycarbonyl-2-hydroxy-2-methylbut-3-ynyl)azetidin-2-one (24) provided benzyl 4,5,7,8-tetrahydro-4-hydroxy-4-methyl-7-oxo-8aH-azeto[1,2-a]-v-triazolo[3,4-c]pyrimidine-5-carboxylate (25), which has been converted into 7,8-dihydro-4-methyl-7-oxo-8aH-azeto[1,2-a]-v-triazolo-[3,4-c]pyrimidine-5-carboxylic acid (21). The latter was devoid of antibacterial activity, and showed no significant activity as an inhibitor of various β-lactamases.