Beth Lorsbach

Parallel Synthesis of bis-heterocyclic isoxazolylmethyl- and isoxazolinylmethylpyrazoles.

The solution-phase parallel synthesis of a 136-member library of isoxazol(in)e-CH(2)-pyrazoles is described. X-ray crystallographic structure determination verified the regioselectivities of the N-alkylation and nitrile oxide 1,3-dipolar cycloaddition steps. The construction of these pharmaceutically relevant heterocycles on solid support under microwave irradiation is also demonstrated. The resulting library of drug-like compounds has been added to the National Institutes of Health repository (approximately 10 mg of each with >or=90% purity) for pilot-scale biomedical studies with bioassay data available at the National Center for Biotechnology Information PubChem database. A subset of these compounds has been broadly screened by Dow AgroSciences for herbicidal, fungicidal, and insecticidal activity.

3-(Arylthiomethyl)isoxazole-4,5-dicarboxamides: Chemoselective Nucleophilic Chemistry and Insecticidal Activity

A collection of 91 3-(arylthiomethyl)isoxazole-4,5-dicarboxamides was prepared starting from dimethyl 3-(chloromethyl)isoxazole-4,5-dicarboxylate. The thioether moieties in these compounds were subsequently oxidized to give the corresponding 3-(arylsulfonylmethyl)isoxazole-4,5-dicarboxamides. By carefully controlling stoichiometry and reaction conditions, the C4 and C5 carbomethoxy groups could be differentially derivatized to carboxamides. A total of 182 trisubstituted isoxazoles are reported and deposited in the National Institutes of Health Molecular Repository; an 80 compound subset was evaluated for insecticidal activity.

Synthesis of Spiro-fused Pyrazolidoylisoxazolines

Routes to structurally unique spiro-fused pyrazolidoylisoxazolines are reported. These methods start with monosubstituted hydrazines or hydrazides and utilize the nitrile oxide 1,3-dipolar cycloaddition reaction to generate the targeted spiro-fused bis-heterocycles. Molecular shape space diversity analyses were performed on these pyrazolidoylisoxazolines showing that manipulation of the appended R groups significantly changes the molecular shape.

Physicochemical property guidelines for modern agrochemicals: Physicochemical properties for agrochemicals

The relentless need for the discovery and development of new agrochemicals continues as a result of driving forces such as loss of existing products through the development of resistance, the necessity for products with more favorable environmental and toxicological profiles, shifting pest spectra, and the changing agricultural needs and practices of the farming community. These new challenges underscore the demand for novel, high-quality starting points to accelerate the discovery of new agrochemicals that address market challenges. This article discusses the efforts to identify the optimum ranges of physicochemical properties of agrochemicals through analysis of modern commercial products. Specifically, we reviewed literature studies examining physicochemical property effects and analyzed the properties typical of successful fungicides, herbicides, and insecticides (chewing and sap-feeding pests). From the analysis, a new set of physicochemical property guidelines for each discipline, as well as building block class, are proposed. These new guidelines should significantly aid in the discovery of next-generation agrochemicals.