Photocatalytic C−F Bond Activation of Fluoroarenes, gem‐Difluoroalkenes and Trifluoromethylarenes

Abstract

Fluorine‐containing compounds have been widely applied on pharmaceuticals, agrochemicals, and materials. The synthetic methodology for the introduction of fluorine into organic motifs has witnessed dramatically development recently. Selective C−F bond activation and functionalization of the easily accessible fluorinated compounds has provided an efficient way to synthesize novel fluorinated products and degradate the extremely stable fluorinated pollutants. As the development of photocatalytic organic transformations, the light induced direct C−F bond activation under mild conditions leading to the production of various functionalities has become one of the most advanced and efficient methodologies available. This minireview summarizes the recent development of the photocatalytic C−F bond activations of fluorinated compounds, including fluoroarenes, gem‐difluoroalkenes and trifluoromethylarenes, and intends to illustrate the readers a comprehensive introduction of this research topic via demonstrating the representative examples and detailed mechanism according to reaction types for the C−F bond transformations.

Photoinduced C–H monofluoroalkenylation with gem-difluoroalkenes through hydrogen atom transfer under batch and flow conditions

“…5 However, there are few studies on the methods involving the radical-initiated functionalization of gem -difluoroalkenes in synthesizing monofluoroalkenes. 6…”

Visible-Light Photocatalytic Reduction of Aryl Halides as a Source of Aryl Radicals

“…The general process of visible-light-driven reduction of aryl halides to aryl radicals initiates by visible light-induced electron transfer from excited photocatalyst to aryl halide to generate an aryl halide radical anion, closely followed by the halide negative ion-mediated cleavage of carbon–halide bond, leaving halide ions (X – ) to generate a highly reactive aryl radical intermediate that can be used to construct various classes of aryl compounds ( Figure 1 ). Since aryl fluoride free radical anion intermediates, which are generated through photoinduced electron transfer from excited photocatalyst to the aryl fluoride compounds, can be attacked by electrophiles to leave fluoride ions and generate various aryl compounds [ 21 ], there is no formation of aryl radical intermediates in the whole process, so visible light-induced photocatalytic reduction of aryl fluorides is not discussed in this review.…”

Recent Advances in C-F Bond Cleavage Enabled by Visible Light Photoredox Catalysis

“…Although there have been several reviews on C-F bond cleavage recently, each review has its specific focus, such as C-F bond activation by phosphorus compounds [25], or by metalloenzymes [26], C-F functionalization of trifluoromethyl groups [27,28], catalytic enantioselective functionalization of allylic C-F bond [29], transition metal-catalyzed C(sp 2 )-F cleavage [30], and deconstructive modes of halodifluoromethyl reagents [31]. This review focuses on the C-F bond cleavage enabled by visible light photoredox catalysis since 2018, classified by the types of fluorosubstrates [32,33].…”