Decarboxylative C(sp3)–N cross-coupling via synergetic photoredox and copper catalysis

Radical alkylation of isocyanides with amino acid-/peptide-derived Katritzky salts via photoredox catalysis

A mild and practical protocol is developed for the synthesis of functionalized phenanthridines via C(sp³)–N bond activation upon visible-light irradiation.

Photoredox-catalyzed decarboxylative alkylation/cyclization of alkynylphosphine oxides: a metal- and oxidant-free method for accessing benzo[b]phosphole oxides

By photoredox-catalysis, alkylation/aryl cyclization of alkynylphosphine oxides towards benzo[b]phospholes has been realized under metal- and oxidant-free conditions at room temperature.

Rapid Synthesis of γ-Arylated Carbonyls Enabled by the Merge of Copper- and Photocatalytic Radical Relay Alkylarylation of Alkenes

The development of mild and practical methods for the γ-arylation of carbonyl compounds is an ongoing challenge in organic synthesis. The first formal γ-arylation of carbonyl compounds via radical relay cross-coupling of α-bromocarbonyl precursors with boronic acids in the presence of alkenes is reported. This directing-group-free protocol allows for the rapid and straightforward access to a wide range of γ-arylated esters, ketones, and amides under ambient conditions with excellent functional group tolerance.

Photocatalytic Oxyamination of Alkenes: Copper(II) Salts as Terminal Oxidants in Photoredox Catalysis

A photocatalytic method for the oxyamination of alkenes using simple nucleophilic nitrogen atom sources in place of prefunctionalized electrophilic nitrogen atom donors is reported. Copper(II) is an inexpensive, practical, and uniquely effective terminal oxidant for this process. In contrast to oxygen, peroxides, and similar oxidants commonly utilized in non-photochemical oxidative methods, the use of copper(II) as a terminal oxidant in photoredox reactions avoids the formation of reactive heteroatom-centered radical intermediates that can be incompatible with electron-rich functional groups. As a demonstration of the generality of this concept, it has been shown that diamination and deoxygenation reactions can also be accomplished using similar photooxidative conditions.

Simple ruthenium-catalyzed reductive amination enables the synthesis of a broad range of primary amines

The production of primary benzylic and aliphatic amines, which represent essential feedstocks and key intermediates for valuable chemicals, life science molecules and materials, is of central importance. Here, we report the synthesis of this class of amines starting from carbonyl compounds and ammonia by Ru-catalyzed reductive amination using H2. Key to success for this synthesis is the use of a simple RuCl2(PPh3)3 catalyst that empowers the synthesis of >90 various linear and branched benzylic, heterocyclic, and aliphatic amines under industrially viable and scalable conditions. Applying this catalyst, -NH2 moiety has been introduced in functionalized and structurally diverse compounds, steroid derivatives and pharmaceuticals. Noteworthy, the synthetic utility of this Ru-catalyzed amination protocol has been demonstrated by upscaling the reactions up to 10 gram-scale syntheses. Furthermore, in situ NMR studies were performed for the identification of active catalytic species. Based on these studies a mechanism for Ru-catalyzed reductive amination is proposed.

Cu-Catalyzed Decarboxylative Borylation

A simple method for the conversion of carboxylic acids to boronic esters via redox-active esters (RAEs) is reported using copper catalysis. The scope of this transformation is broad, and compared with the known protocols available, it represents the most inexpensive, rapid, and operationally simple option. In addition to a full exploration of the scope, a kinetic study was performed to elucidate substrate and reagent concentration dependences.

Decarboxylative sp3 C-N coupling via dual copper and photoredox catalysis

Over the past three decades, considerable progress has been made in the development of methods to construct sp2 carbon-nitrogen (C-N) bonds using palladium, copper or nickel catalysis1,2. However, the incorporation of alkyl substrates to form sp3 C-N bonds remains one of the major challenges in the field of cross-coupling chemistry. Here we demonstrate that the synergistic combination of copper catalysis and photoredox catalysis can provide a general platform from which to address this challenge. This cross-coupling system uses naturally abundant alkyl carboxylic acids and commercially available nitrogen nucleophiles as coupling partners. It is applicable to a wide variety of primary, secondary and tertiary alkyl carboxylic acids (through iodonium activation), as well as a vast array of nitrogen nucleophiles: nitrogen heterocycles, amides, sulfonamides and anilines can undergo C-N coupling to provide N-alkyl products in good to excellent efficiency, at room temperature and on short timescales (five minutes to one hour). We demonstrate that this C-N coupling protocol proceeds with high regioselectivity using substrates that contain several amine groups, and can also be applied to complex drug molecules, enabling the rapid construction of molecular complexity and the late-stage functionalization of bioactive pharmaceuticals.

Visible-light-mediated allylation of alkyl radicals with allylic sulfones via a deaminative strategy

A mild and simple protocol is developed for the synthesis of terminal alkenes via site-specific C–C bond formation upon visible-light irradiation.