1,3-Dipolar Cycloaddition Reactions of Pyrazolidinium Ylides with Vinyl Sulfones. A Regioselective Synthesis of Bicyclic Pyrazolidinone Antibacterial Agents.

Abstract The 1, 3-dipolar cycloaddition reaction of pyrazolidinium ylide 1 with substituted vinyl sulfones 5 was studied. Elimination of benzenesulfinic acid from the resulting cycloadducts gave rise to bicyclic pyrazolidinones 3 . The (E)-olefin isomers were found to undergo cycloaddition in a highly regioselective fashion. These pyrazolidinones 3 represent the nuclei of an exciting new class of potent antibacterial agents that mimic β-lactams.