Synthesis of thioxanthone 10,10-dioxides and sulfone-fluoresceins via Pd-catalyzed sulfonylative homocoupling
Gergely Knorr, Mariano L. Bossi, Alexey N. Butkevich, Stefan W. Hell
9H-thioxanthen-9-one 10,10-dioxide; sulfone-fluorescein; sulfone-fluorones; fluorescent dyes
Our report describes the facile and scalable preparation of 9H-thioxanthen-9-one 10,10-dioxides via Pd-catalyzed sulfonylative homocoupling of the appropriately substituted benzophenones. This transformation provides a straightforward entry to previously unreported sulfone-fluoresceins and -fluorones. Several examples of these red-fluorescent dyes have been prepared, characterized and evaluated as live-cell permeant labels compatible with super-resolution fluorescence microscopy with 775 nm stimulated emission depletion.