Jstevens

Synthesis of Poly(N‐isopropylacrylamide)‐Block‐Poly(tert‐Butyl Methacrylate) by Metal-Free ATRP

Abstract: Atom transfer radical polymerization (ATRP) is one of the most powerful methodologies for polymerization. Well‐controlled ATRP of N‐isopropylacrylamide (NIPAAm) could be obtained in organic‐water mixture solvent with conventional metal catalyst/ligand catalyst system. However, the mixture solvent is not suitable for copolymerization of NIPAAm with hydrophobic monomers. Moreover, further purification of metal was required for…

Photocatalytic Barbier reaction – visible-light induced allylation and benzylation of aldehydes…

Abstract: We report a photocatalytic version of the Barbier type reaction using readily available allyl or benzyl bromides and aromatic aldehydes or ketones as starting materials to generate allylic or benzylic alcohols. The reaction proceeds at room temperature under visible light irradiation with the organic dye 3,7-di(4-biphenyl)1-naphthalene-10-phenoxazine as a photocatalyst and DIPEA as sacrificial electron…

Photoinduced Controlled Radical Polymerizations Performed in Flow

Abstract: Photoinduced controlled radical polymerizations (CRPs) have provided a variety of approaches for the synthesis of polymers possessing targeted structures, compositions, and functionalities with the added capability for spatial and temporal control, presenting the potential for new materials development. However, the scalability and reliability of these systems can be limited as a consequence of dependence…

N,N-Diaryl Dihydrophenazines as Photoredox Catalysts for PET-RAFT and Sequential PET-RAFT/O-ATRP

Abstract: N,N-Diaryl dihydrophenazines are employed as organic photoredox catalysts (PCs) for photoinduced electron/energy transfer–reversible addition–fragmentation chain transfer (PET-RAFT) polymerization. The ability of these PCs to mediate PET-RAFT is heavily dependent on the ability of the PC to access a photoexcited intramolecular charge transfer state. The use of PCs displaying intramolecular charge transfer in the excited…

C–N Cross-Coupling via Photoexcitation of Nickel–Amine Complexes

Abstract: C–N cross-coupling is an important class of reactions with far-reaching impacts across chemistry, materials science, biology, and medicine. Transition metal complexes can elegantly orchestrate diverse aminations but typically require demanding reaction conditions, precious metal catalysts, or oxygen-sensitive procedures. Here, we introduce a mild nickel-catalyzed C–N cross-coupling methodology that operates at room temperature using an…

Endo and Exo Diels–Alder Adducts: Temperature-Tunable Building Blocks for Chemical Functionalization

Abstract: The development and application of a novel endo furan-protected maleimide building block is reported. The endo isomer undergoes deprotection at temperatures ∼50 °C below the exo derivative. This enables a simple and powerful approach to quantitatively and selectively introduce functional maleimide groups via temperature modulation. Reference: Discekici, E. H.; St. Amant, A. H.; Nguyen,…

Exploiting Charge-Transfer States for Maximizing Intersystem Crossing Yields in Photoredox Catalysts

Abstract: A key feature of prominent transition-metal-containing photoredox catalysts (PCs) is high quantum yield access to long-lived excited states characterized by a change in spin multiplicity. For organic PCs, challenges emerge for promoting excited-state intersystem crossing (ISC), particularly when potent excited-state reductants are desired. Herein, we report a design exploiting orthogonal π-systems and an intermediate-energy…

Structure–Property Relationships for Tailoring Phenoxazines as Reducing Photoredox Catalysts

Abstract: Through the study of structure–property relationships using a combination of experimental and computational analyses, a number of phenoxazine derivatives have been developed as visible light absorbing, organic photoredox catalysts (PCs) with excited state reduction potentials rivaling those of highly reducing transition metal PCs. Time-dependent density functional theory (TD-DFT) computational modeling of the photoexcitation of…

Decarboxylative Olefination of Activated Aliphatic Acids by Dual Organophotoredox/Copper Catalysis

Herein, we demonstrate a dual organophotoredox/copper catalytic strategy toward challenging decarboxylative olefination processes proceeding in high yields and selectivities. This operationally simple method uses photoactive organic molecules and Cu(II)-complexes as catalysts to provide rapid access to a wide variety of olefins from inexpensive synthetic and biomass-derived carboxylic acids under mild light-mediated conditions. Mechanistic investigations suggest…

Photocatalytic formation of carbon–sulfur bonds

Abstract: This review summarizes recent developments in photocatalyzed carbon–sulfur bond formation. General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways. Reference: Wimmer, A.; König, B.Beilstein J. Org. Chem.2018,14, 54–83 Read More