Tetrabromofluorescein potassium salt

The potassium salt of Eosin Acid C.I. No. 45380 (E561015), which is a photo-senseitive organic catalyst and has been used in the photocatalytic, diastereoselective additions of 1-sulfoximidoyl-1,2-benziodoxoles to styrenes, and in the stereoselective synthesis of 2-deoxyglycosides from glycals.