Paula Louise Sharpe

The discovery of indoxacarb: oxadiazines as a new class of pyrazoline-type insecticides†

The evolution of the insecticidal pyrazoline moiety that was originally discovered in 1972 has led to the discovery of a new crop insecticide, indoxacarb, which is the first commercialized pyrazoline-type sodium-channel blocker. Both monocyclic and fused-tricyclic pyrazolines and pyridazines, as well as structurally related semicarbazones were examined prior to the discovery of analogous tricyclic oxadiazines which had similarly high activity as well as favorable environmental dissipation rates and low toxicity to non-target organisms. The eventual leading candidate, DPX-JW062, was originally obtained as a racemic molecule, but a chiral synthesis was developed which produces material that is 50% ee in the insecticidal (+)-S-enantiomer (DPX-MP062, indoxacarb).

Tubulin modulating antifungal and antiproliferative pyrazinone derivatives

A novel class of synthetic tubulin polymerization disruptors, based on a substituted pyrazin-2-one core, has been discovered. These molecules have proven to be potent broad spectrum fungicides, with activity on agriculturally important ascomycete and basidiomycete pathogens. They have also been found to be particularly potent against human rhabdomyosarcoma cells. Using an efficient synthetic route, the agricultural and medicinal activity was explored.