Jason Williams

The various applications of hydrogen isotopes (deuterium, D, and tritium, T) in the physical and life sciences demand a range of methods for their installation in an array of molecular architectures. In this Review, we describe recent advances in synthetic C−H functionalisation for hydrogen isotope exchange.

Spoilt for choice: The various applications of hydrogen isotopes in the physical and life sciences demand a range of methods for the installation of deuterium and tritium in an array of molecular architectures. In this Review, recent advances in synthetic C−H functionalisation for hydrogen isotope exchange are discussed.

We describe a nickel-catalyzed cyanation reaction of aryl (pseudo)halides that employs butyronitrile as a cyanating reagent instead of highly toxic cyanide salts. A dual catalytic cycle merging retro-hydrocyanation and cross-coupling enables the conversion of a broad array of aryl chlorides and aryl/vinyl triflates into their corresponding nitriles. This new reaction provides a strategically distinct approach to the safe preparation of aryl cyanides, which are essential compounds in agrochemistry and medicinal chemistry.

Better together: A nickel-catalyzed cyanation reaction of aryl (pseudo)halides was developed that employs butyronitrile as a cyanating reagent instead of highly toxic cyanide salts. A dual catalytic cycle merging retro-hydrocyanation and cross-coupling enables the conversion of a broad array of aryl chlorides and aryl/vinyl triflates into their corresponding nitriles.

We report herein that 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) can directly reach an electronically excited state upon light absorption and trigger the generation of C(sp³)-centered radicals without the need for an external photocatalyst. Selective excitation with a violet-light-emitting diode turns alkyl-DHPs into strong reducing agents that can activate reagents through single-electron transfer manifolds while undergoing homolytic cleavage to generate radicals. We used this photochemical dual-reactivity profile to trigger radical-based carbon–carbon bond-forming processes, including nickel-catalyzed cross-coupling reactions.

Powered by Light: 4-alkyl-1,4-dihydropyridines 1 are primarily understood as hydride sources in their ground state. Excitation with a violet-light-emitting diode transforms them into strong reducing agents that can activate reagents through single-electron transfer while undergoing homolytic cleavage to generate alkyl radicals. This process was used to trigger radical-based C−C bond-forming processes, including nickel-catalyzed cross-coupling reactions.

A chiral rhodium complex catalyzes the highly enantioselective coupling of arylboronic acids, 1,3-enynes, and imines to give homoallylic sulfamates. The key step is the generation of allylrhodium(I) species by alkenyl-to-allyl 1,4-rhodium(I) migration.

A chiral rhodium complex catalyzes the highly enantioselective coupling of arylboronic acids, 1,3-enynes, and imines to give homoallylic sulfamates. The key step is the generation of allylrhodium(I) species by alkenyl-to-allyl 1,4-rhodium(I) migration. tAm=tert-amyl.

Out of bounds: Enantioselective rearrangement reactions are a long-standing challenge in organic synthesis. Recent advances are highlighted that led to the development of the first enantioselective Doyle–Kirmse reaction and enantioselective rearrangement reactions of iodonium ylides.

A C−N bond forming dearomatization protocol with broad scope is outlined. Specifically, bifunctional amino reagents are used for sequential nucleophilic and electrophilic C−N bond formations, with the latter effecting the key dearomatization step. Using this approach, γ-arylated alcohols are converted to a wide range of differentially protected spirocyclic pyrrolidines in just two or three steps.

A simple guide to complexity: A C−N bond forming dearomatization protocol with broad scope is outlined. Specifically, bifunctional amino reagents are used for sequential nucleophilic and electrophilic C−N bond formations, with the latter effecting the key dearomatization step. Using this approach, γ-arylated alcohols are converted to spirocyclic pyrrolidines in just two or three steps.

Sulfonimidamides are increasingly important molecules in medicinal chemistry and agrochemistry, but their preparation requires lengthy synthetic sequences, which has likely limited their use. We describe a one-pot de novo synthesis of sulfonimidamides from widely available organometallic reagents and amines. This convenient and efficient process uses a stable sulfinylamine reagent, N-sulfinyltritylamine (TrNSO), available in one step on 10 gram scale, as a linchpin. In contrast to classical approaches starting from thiols or their derivatives, our TrNSO-based approach facilitates the rapid assembly of the three reaction components into a variety of differentially substituted sulfonimidamides containing medicinally relevant moieties, including pyridines and indoles. Analogues of the sulfonamide-containing COX-2 inhibitor Celecoxib were prepared and evaluated.

Come and join us: The stable, readily prepared sulfinylamine reagent TrNSO is exploited as a linchpin to join organometallic reagents and amines to provide sulfonimidamides in a high yielding one-pot process. Good variation of both reaction components is possible.

Arylamines constitute the core structure of many therapeutic agents, agrochemicals, and organic materials. The development of methods for the efficient and selective construction of these structural motifs from simple building blocks is desirable but still challenging. We demonstrate that protonated electron-poor O-aryl hydroxylamines give aminium radicals in the presence of Ru(bpy)₃Cl₂. These highly electrophilic species undergo polarized radical addition to aromatic compounds in high yield and selectivity. We successfully applied this method to the late-stage modification of chiral catalyst templates, therapeutic agents, and natural products.

A radical solution: Protonated electron-poor O-aryl hydroxylamines give aminium radicals in the presence of Ru(bpy)₃Cl₂. These highly electrophilic species undergo polarized radical addition to aromatic compounds to give arylamines in high yield and selectivity. This method has a broad reaction scope and was successfully applied to the late-stage modification of chiral catalyst templates, therapeutic agents, and natural products.