Formation of C-B, C-C, and C-X Bonds from Nonstabilized Aryl Radicals Generated from Diaryl Boryl Radicals.

With the development of organoboron chemistry, boron-centered radicals have become increasingly attractive. However, their synthetic applications remain limited in that they have been used only as substrates for addition reactions or as initiators for catalytic reactions. We have achieved a new reaction pathway in which tetraarylborate salts are used as precursors for aryl radicals via boron radicals, by introducing a simple activation reagent. In addition, we carried out a diverse array of transformations involving these aryl radical precursors, which allowed the construction of new C-B, C-C, and C-X bonds in the presence of visible light.

Alkylboronic acids as alkylating agents: photoredox-catalyzed alkylation reactions assisted by K3PO4.

Despite the ubiquity of alkylboronic acids in organic synthesis, their utility as alkyl radical precursors in visible-light-induced photocatalytic reactions is limited by their high oxidation potentials. In this study, we demonstrated that an inorganophosphorus compound can modulate the oxidation potentials of alkylboronic acids so that they can act as alkyl radical precursors. We propose a mechanism based on the results of fluorescence quenching experiments, electrochemical experiments, 11B and 31P NMR spectroscopy, and other techniques. In addition, we describe a simple and reliable alkylation method that has good functional group tolerance and can be used for direct C-B chlorination, cyanation, vinylation, alkynylation, and allylation, as well as late-stage functionalization of derivatized drug molecules. Notably, alkylboronic acids can be selectively activated in the presence of a boronic pinacol ester.

Correction: Visible-light-mediated photoredox minisci C-H alkylation with alkyl boronic acids using molecular oxygen as an oxidant.

Correction for 'Visible-light-mediated photoredox minisci C-H alkylation with alkyl boronic acids using molecular oxygen as an oxidant' by Jianyang Dong et al., Chem. Commun., 2020, 56, 12652-12655, https://doi.org/10.1039/D0CC05946C.

Light-Mediated Defluorosilylation of α-Trifluoromethyl Arylalkenes through Hydrogen Atom Transfer.

Herein, we report a direct, light-mediated defluorosilylation protocol for converting α-trifluoromethyl arylalkenes and alkyl silanes into γ,γ-difluoroallylic compounds via a combination of photoredox catalysis and hydrogen atom transfer. The clean, convenient protocol can be scaled to the gram level, and its mild conditions make it very suitable for late-stage functionalization of complex natural products and drugs.

Arylboronic Acid Deborylation Deuteration via Synergistic Thiol, Lewis Base, and Photoredox Catalysis.

A mild method for the deborylation deuteration of arylboronic acids with D2O, mediated by the synergistic combination of a thiol, a Lewis base, and photoredox catalysis, is reported. This reaction showed a broad substrate scope, excellent deuterium incorporation, and functional group tolerance. Therefore, this method is practical for the site-selective D-labeling of bioactive molecules and drug molecules.

Visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones.

Herein we report a mild, general protocol for visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones. The protocol permits efficient functionalization of sulfones with a broad range of cyclic and acyclic secondary and tertiary alkyl groups and is scalable to the gram level. Its excellent functional group tolerance and mildness make it suitable for late-stage functionalization of natural products and drug molecules.

Visible-Light-Mediated C-I Difluoroallylation with an α-Aminoalkyl Radical as a Mediator.

Herein, we report a protocol for direct visible-light-mediated C-I difluoroallylation reactions of α-trifluoromethyl arylalkenes with alkyl iodides at room temperature with an α-aminoalkyl radical as a mediator. The protocol permits efficient functionalization of various α-trifluoromethyl arylalkenes with cyclic and acyclic primary, secondary, and tertiary alkyl iodides and is scalable to the gram level. This mild protocol uses an inexpensive mediator and is suitable for late-stage functionalization of complex natural products and drugs.

Visible-Light-Mediated Alkenylation of Alkyl Boronic Acids without an External Lewis Base as an Activator.

Herein we report a protocol for the direct visible-light-mediated alkenylation of alkyl boronic acids at room temperature without an external Lewis base as an activator, and we propose a mechanism involving benzenesulfinate activation of the alkyl boronic acids. The protocol permits the efficient functionalization of a broad range of cyclic and acyclic primary and secondary alkyl boronic acids with various alkenyl sulfones. We demonstrated its utility by preparing or functionalizing several pharmaceuticals and natural products.

Light-Mediated Difluoromethylthiolation of Aldehydes with a Hydrogen Atom Transfer Photocatalyst.

A mild general method for difluoromethylthiolation of aldehydes with PhSO2SCF2H and a decatungstate photocatalyst under redox-neutral conditions has been developed. This reaction is highly efficient, scalable, and oxidant-free. The broad substrate scope and excellent functional group tolerance of the reaction make it suitable for generating libraries of difluoromethyl thioesters. We demonstrated the utility and sustainability of the method by synthesizing several structurally complex difluoromethyl thioesters.

Visible-light-mediated photoredox minisci C-H alkylation with alkyl boronic acids using molecular oxygen as an oxidant.

Herein, we report a protocol for direct visible-light-mediated Minisci C-H alkylation reactions of heteroarenes with alkyl boronic acids using molecular oxygen as the sole oxidant. This mild protocol uses an inexpensive, green oxidant; permits efficient functionalization of various N-heteroarenes with a broad range of primary and secondary alkyl boronic acids; and is scalable to the gram level. We demonstrated the practicality and sustainability of the protocol by preparing or functionalizing several pharmaceuticals and natural products.