A new synthesis of 4-isoxazolines and their thermal conversion into pyrroles

A Torquoselective Extrusion of Isoxazoline N-Oxides. Application to the Synthesis of Aryl Vinyl and Divinyl Ketones for Nazarov Cyclization

A mild, convenient reaction sequence for the synthesis of Nazarov cyclization substrates is described. The [3+2] dipolar cycloaddition of a nitrone and an electron-deficient alkyne gives an isolable isoxazoline intermediate, which upon oxidation undergoes stereoselective extrusion of nitrosomethane to give aryl vinyl or divinyl ketones.

Nonsteroidal antiinflammatory agents, XVII: Inhibition of bovine cyclooxygenase and 5-lipoxygenase by N-alkyldiphenyl-pyrrolyl acetic and propionic acid derivatives

A series of 19 N-alkyl-diarylpyrrolyl-acetic and-propionic acid derivatives was synthesized and tested. Using bovine blood as enzyme source the inhibition of cyclooxygenase and 5-lipoxygenase, respectively, was applied to determine the antiinflammatory activity. In general all compounds tested inhibit 5-lipoxygenase more effectively than cyclooxygenase. A structure-activity relationship is discussed.