Unveiling the Synthetic Potential of 1,3,5-Tri(10H-phenothiazin-10-yl)benzene-Based Optoelectronic Material: A Metal-Free and Recyclable Photocatalyst for Sequential Functionalization of C(sp2)-H Bonds.

1,3,5-Tri(10H-phenothiazin-10-yl)benzene (3PTZ) is endowed with unique redox and photoresponsive characteristics and has been utilized as a p-type redox center for organic battery cathode material and a room-temperature phosphorescence (RTP) material, respectively. Conversely, its exploration in other research fields, particularly organic synthesis, remains unknown. Here, we demonstrate that 3PTZ-POP synthesized via cross-linking of 3PTZ is capable of harvesting visible-light photons and selectively converting solar energy to chemical energy. Specifically, 3PTZ-POP functions as a metal-free and recyclable photocatalyst to promote the sequential C(sp2)-H functionalizations of N-arylacrylamides with readily available trifluoromethylsulfonyl chloride as the radical precursor. An array of 3,3-disubstituted 2-oxindoles bearing a pharmaceutically important CF3 moiety are delivered in moderate to excellent yields under mild and sustainable conditions.