Direct C–C Bond Formation from Alkanes Using Ni-Photoredox Catalysis

Ackerman, Laura K. G.; Alvarado, Jesus I. Martinez; Doyle, Abigail G.

doi:10.1021/jacs.8b09191

Cited by 210 publications

(153 citation statements)

References 54 publications

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“…Moreover, Ni itself can act as a photosensitizer [96,101]. Irradiation of 77 can induce homolytic bond cleavage to generate halide radicals that can abstract weak hydrogen atoms from ether [100] or alkane [102] substrates. Computational and ultrafast spectroscopic data reveal a long-lived triplet excited state of the photoexcited Ni(II) 76, opening opportunities for Ni to catalyze photoredox cross-coupling reactions alone [96].…”

Section: The Merger Of Ni With Photoredox Catalysis and Electrocatalysismentioning

confidence: 99%

Mechanisms of Nickel-Catalyzed Cross-Coupling Reactions

Diccianni

Diao

2019

Trends in Chemistry

411

329

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Section: The Merger Of Ni With Photoredox Catalysis and Electrocatalysismentioning

confidence: 99%

Mechanisms of Nickel-Catalyzed Cross-Coupling Reactions

Diccianni

Diao

2019

Trends in Chemistry

411

329

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“…24,25 To apply this method to various applications, such as grafting from an existing polymer or biomolecule, we recognized that using solvent quantities of C-H coupling partner may be inefficient. 15,[26][27][28] We therefore examined a number of C-H initiators in reagent quantities relative to disulfide. In C-H initiators with lower BDEs or more hydridic C-H bonds, 29 radical initiation becomes more facile and when THF was used as a solvent in a similar manner to Table 1, a completely uncontrolled polymerization was observed.…”

Section: Scheme 1 Design Of Hat-raft Polymerizationmentioning

confidence: 99%

Photocontrolled Radical Polymerization from Hydridic C–H Bonds

2020

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Given the ubiquity of C-H bonds in biomolecules and polymer backbones, the development of a photocontrolled polymerization from a C-H bond would represent a powerful strategy for selective polymer conjugation precluding several synthetic steps to introduce complex functionality. We have developed a hydrogen-atom abstraction strategy that allows for a controlled polymerization from a C-H bond using a benzophenone photocatalyst, a trithiocarbonate-derived disulfide, and visible light. We perform the polymerization from a variety of ethers, alkanes, unactivated C-H bonds, and alcohols as well as showcase the applicability of the method to several monomer classes. Our method lends itself to photocontrol which has important implications for building advanced macromolecular architectures. Finally, we demonstrate that we can graft polymer chains controllably from poly(ethylene glycol) showcasing the potential application of this method for controlled grafting from C-H bonds of commodity polymers. Main Text: Reversible-deactivation radical polymerizations (RDRPs) represent one of the most versatile strategies for controlling macromolecular architecture. Numerous synthetic methods have been developed to obtain control over chain length and dispersity. Reversible addition-fragmentation chain transfer (RAFT) has emerged as a powerful tool for controlling radical polymerizations. 1-4 Additionally, photoinduced electron transfer (PET-RAFT) processes have been established as a means to exact temporal and spatial control, finding numerous applications in photopatterning for designing complex 3D architectures. 5-10 To employ these methods, however, a prefunctionalized initiator must be installed into a macromolecule, biomolecule, or small molecule for a controlled polymerization. Despite the ubiquity of C-H bonds, a method for controlling polymerization from a C-H bond has not been demonstrated. 11,12 The development of such a strategy could allow the direct formation of protein-polymer bioconjugates or drug-polymer conjugates without prefunctionalization. 13 Furthermore, complex macromolecular architectures could be controllably accessed via grafting from existing polymers in a single step with spatial and temporal control. 14

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“…dual photoredox cross-coupling catalysis). 10,[30][31][32] Complexes with metal-hydride bonds would appear to be ideal candidates for photocatalytic reductions involving net hydride transfer to an organic substrate, but examples of photochemical organic transformations utilizing metal hydride complexes are scarce. 33 The lack of development is likely due to a challenge that is unique to metal-hydride photocatalysts: there is an inherent competition between hydride transfer and H 2 evolution.…”

Section: Introductionmentioning

confidence: 99%