This research describes the scope of 1,3-dipolar cycloaddition between selected 1,3-dipoles (nitrile oxide/nitrone) and dipolarophiles (PFP ethenesulfonate/PFP-1-bromoethenesulfonate). Nitrile oxide cycloaddition with PFP-1-bromoethenesulfonate furnished 3,5-isoxazoles in a regiospecific fashion; where solvent polarity, reaction temperature and the amount of base are the determining factors for efficient cycloaddition. Subsequent aminolysis with various amines were also carried out. Aminolysis with secondary and aromatic amines produced low yields, nevertheless a wide range of the corresponding sulfonamides were synthesized.
A collection of the isoxazolidinyl PFP sulfonate esters, and the corresponding sulfonamides, were found to exhibit anti HIV-1 activity in micromolar scale. Synthesis of the isoxazolidinyl sulfonamides was also diversified in order to investigate the structure-activity relationships. Furthermore, synthesis of the candidate for immobilized medium for affinity chromatography was established, via a multi-step reaction sequence.
Biological testing of the synthesized isoxazolidinyl PFP sulfonate esters, and sulfonamides show that the candidate molecules act on the host factors required for viral infection, rather than the virus itself. Furthermore, they show specific activity toward viral targets and do not exhibit toxicity toward live cells
