The sydnone-dibenzocyclooctyne and norbornene-tetrazine cycloadditions are both bioorthogonal and mutually orthogonal, used for simultaneous labeling of two targets.

A practical, palladium-catalyzed synthesis of aryl fluorides from arylboronic acid derivatives is presented. The reaction is operationally simple and amenable to multi-gram-scale synthesis. Evaluation of the reaction mechanism suggests a single-electron-transfer pathway, involving a Pd(III) intermediate that has been isolated and characterized.