[Cu(dap)₂Cl] As an Efficient Visible‐Light‐Driven Photoredox Catalyst in Carbon–Carbon Bond‐Forming Reactions

Abstract

Copper sees the light of day: [Cu(dap)(2)Cl] proved to be an excellent photoredox catalyst for atom-transfer radical addition reactions, as well as for allylation reactions (see scheme), providing an attractive alternative to commonly used iridium- and ruthenium-based catalysts.

Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis

“…Finally, photoredox ATRA reactions have also achieved using the copper photocatalyst Cu(dap) 2 + (see section 3.2). 109 The photoexcited species *Cu(dap) 2 + is sufficiently reducing ( E 1/2 II/*I = –1.43 V vs SCE) to donate an electron to a range of polyhalomethanes and acyl halides, initiating addition across alkenes via the typical atom transfer mechanism. 110 …”

“…109 Photoexcitation of Cu(dap) 2 + generates an excited species, which reduces the α -chloroketone 265 to give α -carbonyl radical 266 (Scheme 57). Addition of this radical to allyltributyltin ( 267 ), with concurrent release of stannyl radical 268 , provides the allylated product 269 .…”

Solar Synthesis: Prospects in Visible Light Photocatalysis

“…The majority of these have been ruthenium and iridium complexes, although copper and gold species have also recently been investigated in this context (11, 12). Figure 2 summarizes the key photochemical properties of Ru(bpy) 3 2+ [bpy is 2,2’-bipyridine] complex ( 1 ), the most well studied transition metal complex in the context of both synthetic photocatalysis as well as solar energy conversion.…”

Efficient Cu‐catalyzed Atom Transfer Radical Addition Reactions of Fluoroalkylsulfonyl Chlorides with Electron‐deficient Alkenes Induced by Visible Light

“…Recently, however, Cu(dap) 2 Cl was reported to be an efficient photocatalyst in the reaction of alkyl halides with electron-rich alkenes. [23] We thus speculated that Cu(dap) 2 Cl, with its excellent reductive ability in the excited state (E 1/2 II/I * = À1.42 V vs. SCE in MeCN), combined with good Cl transfer properties, might be a good choice for initiating and propagating the ATRA reaction of fluoroalkylsulfonyl chlorides with electron-deficient alkenes. Indeed, the reaction of a,b-unsaturated amide 2 a with CF 3 SO 2 Cl in MeCN resulted in formation of the desired adduct 3 aa in 57 % yield ( 2 Cl under visible light were examined.…”