Enantioselective Amino- and Oxycyanation of Alkenes via Organic Photoredox and Copper Catalysis

N-Heterocyclic Carbene/Organic Photoredox-Cocatalyzed Acyl Azolation of Alkenes with Acyl Azoles

We have developed the N-heterocyclic carbene/organic photoredox-cocatalyzed acyl azolation of styrenes using acyl azoles. The cooperative action of organic photoredox catalysis and NHC catalysis enabled C-N bond cleavage of the acyl azole and the insertion of the C-C double bond in styrene with complete regioselectivity. The radical cation species, generated by single electron oxidation of alkene, subsequently reacted with the nitrogen nucleophile and ketyl radical intermediate to accomplish insertion of alkene into the C-N bond.

Enantioconvergent Synthesis of α-Fluoroalkyl Alcohols Enabled by Photocatalytic Radical Brook Rearrangement

While radical Brook rearrangement has emerged as a powerful strategy in modern organic synthesis, enantioselective cross coupling involving radical Brook rearrangement remains unexplored. Herein, we report a photocatalytic radical Brook rearrangement followed by cross-coupling with aryl/heteroaryl bromides, enabling the enantioconvergent construction of chiral α-fluoroalkyl alcohols. Key to this transformation is a radical relay process involving sequential generation of aryl cation radicals, alkoxy radicals, and carbon-centered radicals through Brook rearrangement. The reaction exhibits exceptional scope (>40 examples), outstanding enantiocontrol (up to 99% ee), and broad functional group tolerance. The synthetic utility is demonstrated through formal syntheses of bioactive Odanacatib and LX-1031, along with diverse downstream derivatizations.

Photocatalyzed Dicyanation of Alkenes Enabled by Phosphorus Radical Cation Addition

While notable progress has been made in alkene cyanation for the synthesis of alkyl nitriles, catalytic strategies enabling the direct dicyanation of simple alkenes remain relatively under-explored. In this study, we introduce a synergistic phosphine-photoredox catalytic system that facilitates the direct dicyanation of styrenes using TMSCN in the presence of oxidant. This approach utilizes a phosphorus radical cation to initiate an oxidative radical-polar crossover with alkenes, followed by sequential nucleophilic cyanation. This protocol allows for the efficient synthesis of alkyl 1,2-dinitriles from alkenes under mild conditions. Notably, the method exhibits broad substrate scope and commendable efficiency, serving as a valuable complement to existing cyanation methodologies. The synthetic utility of the dinitrile products is further demonstrated through diverse derivatization reactions, highlighting their applicability in constructing nitrogen-rich molecular architectures. Mechanistic studies provide further insight into the reaction pathway and underscore the potential of phosphorus radical cations in alkene functionalization.

Transition Metal Catalysis for the Asymmetric Synthesis of 2-Arylethylamines: A Review of the New Millennium

The 2-arylethylamine motif is very well-known in medicinal chemistry because of its interesting properties when it comes to interacting with the Central Neural System thanks to its ability to pass the blood-brain barrier. This nitrogen-containing family of compounds is of great interest in synthetic organic chemistry and, when it comes to its asymmetric synthesis, great challenges can be faced in order to obtain the chiral purity required in the drug industry. Thus, we provide a concise transition metal review presenting the recent advances in the synthesis of chiral 2-arylethylamines using transition metals as the main catalysts in the introduction of chirality. Both conventional and photocatalysis methods will be covered, considering the main transition metal used in the studies.

Photoredox/Cr-catalyzed enantioselective radical-polar crossover transformation via C-H functionalization

Asymmetric multicomponent reactions that aim to control multiple chiral centers with high selectivity in a single step remain an on-gonging challenge. The realm of enantioselective radical-polar crossover transformation achieved through C-H Functionalization has yet to be fully explored. Herein, we present a successful description of a photoredox/Cr-catalyzed enantioselective three-component (hetero)arylalkylation of 1,3-dienes through C-H functionalization. A diverse array of chiral homoallylic alcohols could be obtained in good to excellent yields, accompanied by outstanding enantioselectivity. The asymmetric radical-polar crossover transformation could build two chiral centers simultaneously and demonstrates broad substrate tolerance, accommodating various drug-derived aldehydes, (hetero)aromatics, and 1,3-diene derivatives. Preliminary mechanistic studies indicate the involvement of a radical intermediate, with the chiral allylic chromium species reacting with various aliphatic and aromatic aldehydes through Zimmerman-Traxler transition states enabled by dual photoredox and chiral chromium catalysis.

Efficient Electrochemical Coupling of Aptamer to Nanoelectrode for In Situ Detection of ATP in Single Cells

Nanoelectrodes, renowned for their small size, rapid mass transport, fast response, and high spatiotemporal resolution, have been recognized as a powerful tool in biosensing, especially for single-cell analysis. However, the nanoelectrode itself has no selectivity and cannot respond to nonelectroactive substances, limiting its wide application to some extent. Herein, we propose a simple and efficient electrochemical conjugation strategy to develop an electrochemical aptamer-coupled (E-AC) sensor for detecting adenosine triphosphate (ATP) in single living cells. Through simple electrochemical conjugation, ferrocene-labeled aptamers could be stably and efficiently coupled onto the surface of carbon fiber electrodes within 5 min. The small size (ca. 400 nm) and biocompatibility of the functionalized nanoelectrodes enabled the E-AC sensors to noninvasively and continuously monitor ATP content in single HeLa cells over 20 min, as well as the cellular ATP fluctuations under glucose starvation. Furthermore, the E-AC sensors exhibit superior specificity, sensitivity, and universality in the application of analysis of ATP in single living Hela cells and MCF-7 cells. They were also versatile for sensing other nonelectroactive targets through modification of the corresponding electroactive marker-labeled aptamers, showing great potential in cell-related physiological processes and drug screening.

Geminal Aminocyanation Enabled by Ylide Mediated Rearrangement

Herein, we describe experimental and computational studies to understand the features of oxycyanopyridinium ylides generated in situ from oxy-cyanopyridines and rhodium carbene. This chemistry has enabled the concomitant formation of both C-N and C-C bonds, providing a complementary approach for cyanation reactions. Density functional theory calculations indicate the sequential metal-bound ylide formation, rhodium-associated five-membered transition state, and 1,4-cyano group relocation. Moreover, the enantioselective rearrangement has been realized by using chiral dirhodium complexes as the catalysts.

Recent advances in C(sp3)-N bond formation via metallaphoto-redox catalysis

The C(sp3)-N bond is ubiquitous in natural products, pharmaceuticals, biologically active molecules and functional materials. Consequently, the development of practical and efficient methods for C(sp3)-N bond formation has attracted more and more attention. Compared to the conventional ionic pathway-based thermal methods, photochemical processes that proceed through radical mechanisms by merging photoredox and transition-metal catalyses have emerged as powerful and alternative tools for C(sp3)-N bond formation. In this review, recent advances in the burgeoning field of C(sp3)-N bond formation via metallaphotoredox catalysis have been highlighted. The contents of this review are categorized according to the transition metals used (copper, nickel, cobalt, palladium, and iron) together with photocatalysis. Emphasis is placed on methodology achievements and mechanistic insight, aiming to inspire chemists to invent more efficient radical-involved C(sp3)-N bond-forming reactions.

Cu(I)-Photosensitizer-Catalyzed Olefin-α-Amino Radical Metathesis/Demethylenative Cyclization of 1,7-Enynes

A demethylenative En-Yne radical cyclization of 1,7-enynes has been successfully developed to chemoselectively afford 3,4-dihyroquinolin-2-ones or quinolin-2-ones under the catalysis of Cu(I) photosensitizers PS3 and PS6 with different redox potentials. The preliminary mechanistic experiments revealed that the reaction underwent an unprecedented olefin-α-amino radical metathesis-type process. A reasonable mechanism was proposed to illustrate the catalyst-controlled chemoselectivity of the reaction based on preliminary mechanistic experiments and DFT calculations.