Organocatalytic Asymmetric Synthesis of o-Carboranyl Amines

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 14, 2025

Carboranyl amines are distinct from typical organic amines. Due to the electronic influence of carborane cage, they have low nucleophilicity and reluctant alkylate. Moreover, asymmetric synthesis chiral carboranes is still in its infancy. Herein we achieved first catalytic N-alkylation o-carboranyl amine, providing general access diverse secondary with high efficiency enantioselectivity under mild conditions. For time, organocatalysis was introduced chemistry. Key success use situ generated (naphtho-)quinone methides as alkylating reagents suitable acid catalysts. This protocol also applicable S-alkylation 1-SH-o-C2B10H11. Control experiments kinetic studies provided important insights into reaction mechanism, which likely involves rate-determining generation quinone methide followed by fast enantio-determining nucleophilic addition.

Language: Английский

---

Recent Advances in C–H Functionalisation through Indirect Hydrogen Atom Transfer

Molecules, Journal Year: 2023, Volume and Issue: 28(16), P. 6127 - 6127

Published: Aug. 18, 2023

The functionalisation of C–H bonds has been an enormous achievement in synthetic methodology, enabling new retrosynthetic disconnections and affording simple equivalents for synthons. Hydrogen atom transfer (HAT) is a key method forming alkyl radicals from substrates. Classic reactions, including the Barton nitrite ester reaction Hofmann–Löffler–Freytag reaction, among others, provided early examples HAT. However, recent developments photoredox catalysis electrochemistry have made HAT powerful tool capable introducing wide range functional groups into bonds. Moreover, greater mechanistic insights stimulated development increasingly site-selective protocols. Site-selectivity can be achieved through tuning electron density at certain using additives, judicious choice reagent, solvent system. Herein, we describe latest methods functionalizing C–H/Si–H/Ge–H indirect between 2018–2023, as well critical discussion reagents, aspects, substrate scopes, background contexts

Language: Английский

---

Photoinduced Selective B–H Activation of nido-Carboranes

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(11), P. 7791 - 7802

Published: March 10, 2024

The development of new synthetic methods for B–H bond activation has been an important research area in boron cluster chemistry, which may provide opportunities to broaden the application scope clusters. Herein, we present a reaction strategy direct site-selective functionalization nido-carboranes initiated by photoinduced cage via noncovalent cage···π interaction. As result, nido-carborane radical is generated through single electron transfer from 3D 2D photocatalyst upon irradiation with green light. resulting transient could be directly probed advanced time-resolved EPR technique. In air, subsequent transformations active have led efficient and selective B–N, B–S, B–Se couplings presence N-heterocycles, imines, thioethers, thioamides, selenium ethers. This protocol also facilitates both late-stage modification drugs synthesis nido-carborane-based drug candidates neutron capture therapy (BNCT).

Language: Английский

---

Photocatalytic [3 + 2]-annulation via sodium tetraarylborate: a fundamental approach for synthesizing 1,4,2-diazaborole analogs

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Nitriles stabilize neutral diarylboryl radicals, generating the RCN-BAr 2 complex, an efficient boron-nitrogen synthon that reacts with imines and olefins for photocatalytic synthesis of boron–nitrogen heterocycles, such as 1,4,2-diazaboroles.

Language: Английский

---

Dative Bonding Activation Enables Precise Functionalization of the Remote B–H Bond of nido-Carborane Clusters

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 13, 2024

The innovation of synthetic strategies for selective B-H functionalization is a pivotal objective in the realm boron cluster chemistry. However, precise, efficient, and rapid bond carboranes that distant from existing functional groups remains intractable owing to limited approaches site-selective control established methods. Herein, we report dative bonding activation strategy nonclassical remote site

Language: Английский

---

Visible‐Light‐Induced Photoreduction of Carborane Phosphonium Salts: Efficient Synthesis of Carborane‐Oxindole‐Pharmaceutical Hybrids

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(31)

Published: April 29, 2023

Visible-light-induced photoreaction of carboranes is an effective approach to prepare carborane-containing compounds. While several methods involving boron-centered carboranyl radicals have been established, those for carbon-centered are underdeveloped, except the UV-light-promoted photohomolysis. Herein, we describe a simple but access by photoreduction carborane phosphonium salts under blue light irradiation without using transition metals and photocatalysts. The utility method was demonstrated successfully preparing range carborane-oxindole-pharmaceutical hybrids radical cascade reactions. Computational experimental studies suggest that generated single-electron transfer photoactive charge-transfer complexes between additive potassium acetate.

Language: Английский

---

“Sergeants-and-soldiers” effect and modified Ising model in chiral polymer materials

Science China Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 8, 2025

Language: Английский

---

Palladium-Catalyzed Cross-Coupling Reactions of Carboranes with Alkenes via Selective B–H Bond Activation

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 17, 2025

A palladium-catalyzed Heck-type cross-coupling reaction of carboranes with alkenes in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was realized. This shows good B(9) selectivity for m-carboranes and is also suitable o- p-carborane. Meanwhile, a series mono-, di-, trisubstituted were compatible substrates to afford the alkenylated products 16–89% yields. The 1,2-bis(carboranyl)ethylene first synthesized by vinyltrimethylsilane m-carborane. Further transformations C═C bond product examined hydroboration oxidation, hydroboration, bromination generate corresponding B(9)-functionalized m-carboranes.

Language: Английский

---

Oxidation-Induced Nucleophilic Substitution at Electron-Rich B(12) Vertex in [CB₁₁H₁₂]^– under Catalyst-Free Conditions

Chemical Science, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Highly regioselective B(12) substitutions of the monocarborane anion [CB11H12]- has been a challenge. Here, we synthesized stable B-O-N zwitterionic compound with an impressive yield (isolated up to 98%) and excellent regioselectivity at position under catalyst-free conditions. The kinetics, substituent effect, capture experiments are paired theoretical calculations, showing that reaction mechanism is oxidation-induced nucleophilic substitution. hydride abstracted by oxoammonium oxidant lower cleavage energy 4.2 kcal mol-1 than B(7-11) positions, thereby changing electronegativity upon conversion neutral [CB11H11], in turn giving very high for This work presents effective method synthesizing oxygen derivatives anion.

Language: Английский

---

Taming Inert B–H Bond with Low Energy Light: A Near-Infrared Light-Induced Approach to Facile Carborane Cluster-Amino Acid Coupling

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: April 1, 2025

The selective functionalization of inert B–H bonds in carborane clusters has been a formidable challenge. Recent advances have witnessed such reactions through photoredox methods utilizing ultraviolet or visible light irradiation. However, high-energy sources often suffer from poor energy efficiency, limited substrate scope, undesired side reactions, and low scalability. Here, we present the first successful bond under low-energy near-infrared (NIR) using carborane-based electron donor–acceptor complex. Both photophysical investigations theoretical modeling reveal facile single-electron transfer cage to electron-deficient photocatalyst, generating radical NIR follow-up pathway enables direct coupling carboranes with amino acids oligopeptides, yielding diverse array carborane-functionalized oligopeptides. Beyond expanding known chemical space boron cluster derivatives, further demonstrate that imaging targeting capabilities could serve as promising multifunctional carriers for neutron capture therapy. Thus, via not only provides straightforward practical strategy synthetic chemistry but also lays foundation development next-generation boron-containing biomolecules advanced functional materials.

Language: Английский

---