Boronic acids are centrally important functional motifs and synthetic precursors. Visible lightinduced borylation may provide access to structurally diverse boronates, but a broadly efficient photocatalytic borylation method that can effect borylation of a wide range of substrates, including strong C-O bonds, remains elusive. Herein, we report a general, metal-free visible light-induced photocatalytic borylation platform that enables borylation of electron rich derivatives of phenols and anilines, chloroarenes, as well as other haloarenes. The reaction exhibits excellent functional group tolerance, as demonstrated by the borylation of a range of structurally complex substrates. Remarkably, the reaction is catalyzed by phenothiazine, -a simple organic photocatalyst with MW<200 that mediates the previously unachievable visible light-induced single electron reduction of phenol derivatives with reduction potentials as negative as ~-3 V vs SCE by a proton-coupled electron transfer mechanism. Mechanistic studies point to the crucial role of the photocatalyst-base interaction.

Direct conversion of renewable biomass and bioderived chemicals to valuable synthetic intermediates for organic synthesis and materials science applications by means of mild and chemoselective catalytic methods has largely remained elusive. Development of artificial catalytic systems that are compatible with enzymatic reactions provides a synergistic solution to this enduring challenge by leveraging previously unachievable reactivity and selectivity modes. We report herein a dual catalytic dehydrodecarboxylation reaction that is enabled by a crossover of the photoinduced acridinecatalyzed O−H hydrogen atom transfer (HAT) and cobaloxime-catalyzed C−H-HAT processes. The reaction produces a variety of alkenes from readily available carboxylic acids. The reaction can be embedded in a scalable triple-catalytic cooperative chemoenzymatic lipase−acridine−cobaloxime process that allows for direct conversion of plant oils and biomass to long-chain terminal alkenes, precursors to bioderived polymers.

Phosphines are among the most widely used ligands, catalysts, and reagents. Current synthetic approaches to phosphines are dominated by nucleophilic displacement reactions with organometallic reagents. Here, we report a radical-based approach to phosphines that proceeds by a cross-electrophile coupling of chlorophosphines and redox-active esters. The reaction allows for the synthesis of a broad range of substituted phosphines that were not readily attainable with the present methods. Our experimental and DFT computational studies also clarified the catalytic, autocatalytic, and inhibitory roles of additives and intermediates, as well as the mechanistic details of the photocatalytic and zinc-mediated redox modes that can have implications for the mechanistic interpretation of other cross-electrophile coupling reactions.

Progress in the development of photocatalytic reactions requires a detailed understanding of the mechanisms underpinning the observed reactivity, yet mechanistic details of many photocatalytic systems, especially those that involve electron donor–acceptor complexes, have remained elusive. We report herein the development and a combined mechanistic and computational study of photocatalytic alkene 1,2-diacylation that enables a regioselective installation of two different acyl groups, establishing direct, tricomponent access to 1,4-diketones, key intermediates in heterocyclic and medicinal chemistry. The studies revealed the central role of the electron donor–acceptor complex formed from an N-heterocyclic carbene (NHC) catalyst-derived intermediate and an acyl transfer reagent, providing a detailed description of the structural and electronic factors determining the characteristics of the photoinduced charge-transfer process that mediates photocatalytic transformation. The in-depth investigation also illuminated the roles of other radical intermediates and electron donors relevant to the catalytic activities of N-heterocyclic carbenes in radical reactions.

Direct installation of the sulfinate group by a functionalization of unreactive aliphatic C–H bonds can provide an entry to most classes of organosulfur compounds, because of the central position of...