Strongly reducing helical phenothiazines as recyclable organophotoredox catalysts.

Recyclable phenothiazine organophotoredox catalysts (PTHS 1-3, E 1/2 ox * = -2.34 to -2.40 V vs. SCE) have been developed. When the recycling performance was evaluated, PTHS-1 could be recovered at least four times without loss of its catalytic activity. These recyclable organophotoredox catalysts represent a promising tool for sustainable organic synthesis.