A Strategy for Selective Catalytic B–H Functionalization of o-Carboranes

Accounts of Chemical Research, Год журнала: 2021, Номер 54(21), С. 4065 - 4079

Опубликована: Окт. 24, 2021

ConspectusCarboranes are a class of polyhedral carbon-boron molecular clusters featuring three-dimensional aromaticity, which often considered as 3D analogues benzene. Their unique structural and electronic properties make them invaluable building blocks for applications ranging from functional materials to versatile ligands pharmaceuticals. Thus, selective functionalization carboranes has received tremendous research interest. In earlier days, the vast majority works in this area were focused on cage carbon via facile deprotonation CH, followed by reaction with electrophiles. On contrary, B-H activation is very challenging since 10 bonds o-carborane similar, how achieve desired transformation at specific boron vertex long-standing issue.As more electronegative than boron, property results different charges cage, follow order B(3,6)-H ≪ B(4,5,7,11)-H < B(8,10)-H B(9,12)-H. We thought that difference may trigger favorite interaction proper transition metal complex bond carborane, could be utilized solve selectivity issue. Accordingly, our strategy described follows: (1) electron-rich catalysts good most electron-deficient (connected both C-H vertices); (2) relatively B(8,9,10,12)-H (with no bonding either (3) directing-group-assisted catalysis appropriate only one vertex), whose lie middle range bonds. This been successfully applied laboratory other groups development series synthetic routes catalytic carborane resulting synthesis large number cage-boron-functionalized derivatives regioselective fashion. Subsequently, significant progress emerging made.In 2013 we reported tetrafluorination o-carboranes using an Pd(II) salt, [Pd(MeCN)4][BF4], catalyst. 2014 disclosed first example carboxy-directed alkenylation B(4) promoted Ir(III) 2017 presented Ir(I)-catalyzed diborylation also uncovered Pd-catalyzed asymmetric chiral-at-cage 2018. These proof-of-principle studies have greatly stimulated activities enabled catalysts. so far developed toolbox methods B-olefination, -arylation, -alkenylation, -alkynylation, -oxygenation, -sulfenylation, -borylation, -halogenation, -amination. recently expanded base catalysis. As field progresses, expect will invented, detailed Account promote these efforts.

Язык: Английский

---

Recent Advances in Transition Metal-Catalyzed Selective B-H Functionalization ofo-Carboranes

Bulletin of the Chemical Society of Japan, Год журнала: 2020, Номер 94(3), С. 879 - 899

Опубликована: Дек. 18, 2020

Abstract Carboranes are a class of carbon-boron molecular clusters, possessing extraordinary characteristics including three-dimensional aromaticity conjugated by σ-bonds, icosahedral geometry and inherent robustness. They finding growing applications as valuable building blocks in boron neutron capture therapy agents, pharmacophores, nanomaterials, optoelectronic, organometallic/coordination chemistry more. Therefore, the effective controlled functionalization carboranes has attracted enormous research interests, particularly regio- enantio-selective cage BH derivatization among ten chemically similar vertices o-carboranes. Only recent few years, significant progress been made transition metal catalyzed vertex-specific functionalization. This review summarizes advances this realm.

Язык: Английский

---

A Guide to Directing Group Removal: 8‐Aminoquinoline

Chemistry - A European Journal, Год журнала: 2021, Номер 27(33), С. 8411 - 8436

Опубликована: Фев. 10, 2021

The use of directing groups allows high levels selectivity to be achieved in transition metal-catalyzed transformations. Efficient removal these auxiliaries after successful functionalization, however, can very challenging. This review provides a critical overview strategies used for Daugulis' 8-aminoquinoline (2005-2020), one the most widely N,N-bidentate groups. limitations are discussed and alternative approaches suggested challenging substrates. Our aim is provide comprehensive end-users' guide chemists academia industry who want harness synthetic power groups-and able remove them from their final products.

Язык: Английский

---

Functional Group Directed B–H Activation of Polyhedral Boron Hydrides by Transition Metal Complexes (Review)

Russian Journal of Inorganic Chemistry, Год журнала: 2021, Номер 66(9), С. 1289 - 1342

Опубликована: Сен. 1, 2021

Язык: Английский

---

Ir-Catalyzed Selective B(3)-H Amination of o-Carboranes with NH₃

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(11), С. 4148 - 4153

Опубликована: Март 15, 2021

Ammonia gas, NH3, is a cheap and widely used industrial feedstock, which has received tremendous research interests in its functionalization. This work reports breakthrough catalytic selective cage B(3)-H amination of o-carboranes with NH3 via Ir-catalyzed B-H/N-H dehydrocoupling, offering convenient efficient access to series 3-NH2-o-carborane derivatives moderate high isolated yields broad substrate scope. The employment readily available gas as the aminating reagent H2 sole byproduct endows protocol economy, practicability, environmental friendliness. A plausible reaction mechanism proposed on basis control experiments.

Язык: Английский

---

Visible-Light-Promoted Nickel-Catalyzed Cross-Coupling of Iodocarboranes with (Hetero)Arenes via Boron-Centered Carboranyl Radicals

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(18), С. 7960 - 7965

Опубликована: Апрель 22, 2022

A general strategy for the generation of hypervalent boron-centered carboranyl radicals at B(3), B(4), and B(9) positions has been developed first time via visible-light-promoted iodine atom abstraction from iodo-o-carboranes by low-valent nickel complex. These react with various (hetero)arenes to afford a wide range cage B-arylated carborane derivatives room temperature in very good excellent yields broad substrate scope. Their electrophilicities are dependent on vertex charges follow order B(3) > B(4) B(9). Both visible light catalyst proved critical radicals. The involvement boron is supported control experiments. reaction mechanism associated these reactions also proposed. This offers new protocol selected vertex, leading facile synthesis large class substituted molecules.

Язык: Английский

---

A variable bidentate traceless directing group for nickel-catalyzed regioselective B–H poly-chalcogenation of o-carboranes

Inorganic Chemistry Frontiers, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

A nickel-catalyzed direct cage B–H poly-chalcogenation of icosahedral carborane clusters, enabled by a variable bidentate 8-aminoquinoline traceless directing group, has been developed under oxidant-free and weakly basic conditions.

Язык: Английский

---

Recent Advance in Transition Metal‐Catalyzed Carboxylic Acid Guided B−H Functionalization of Carboranes

Advanced Synthesis & Catalysis, Год журнала: 2022, Номер 364(24), С. 4174 - 4188

Опубликована: Дек. 1, 2022

Abstract Carboranes, a three‐dimensional class of carbon‐boron molecular clusters with remarkable electronic, physical, chemical characteristics, have proved as useful building blocks in boron neutron capture therapy agents, supramolecular design, optoelectronics, nanomaterials and organometallic/coordination chemistry. Thus, various organic modifications the B−H C−H functionalities carboranes been developed. These methods great success utilize directing groups, such carboxylic acids, to achieve selective functionalization carboranes. The carboxyl group can be easily introduced then removed after reactions. On other hand, assisted by highly regioselective electrophilic attack at electron‐rich positions B(4) B(5) cage generates five‐membered metallacyclic intermediates, which undergo further transformation. In this review, we show that transition metal‐catalyzed decarboxylation cross coupling reactions offer an opportunity for direct activation magnified image

Язык: Английский

---

A strategy for regioselective B–H functionalization ofo-carboranesviabase metal catalysis

Organic Chemistry Frontiers, Год журнала: 2023, Номер 10(12), С. 3074 - 3079

Опубликована: Янв. 1, 2023

This frontier article summarizes the recent developments in base metal-catalyzed regioselective cage B–H functionalization of carboranes and discusses related challenging issues.

Язык: Английский

---

Directing Group Assisted Transition Metal Catalyzed Selective BH Functionalization of o-Carboranes

Synthesis, Год журнала: 2024, Номер unknown

Опубликована: Июнь 11, 2024

Abstract Carboranes are a type of molecular clusters consisting carbon, hydrogen, and boron atoms. They possess unique characteristics, such as three-dimensional aromaticity, icosahedral geometry, robustness. Functionalized carboranes have been utilized in various fields, including medicine, materials, organometallic/coordination chemistry. In this context, selective functionalization o-carboranes has received tremendous attention, specifically the regio- enantioselective modification ten chemically similar BH vertices within carborane cage. recent years, significant progress made catalytic vertex-specific functionalization, well achieving cage BH. This review provides an overview advancements research field. 1 Introduction 2 Carboxy-Assisted Functionalization 2.1 Formation B–C Bonds 2.2 B–N 2.3 B–O 2.4 B–X 2.5 Consecutive B–Y (Y = N, O) 3 N-Based Directing-Group-Assisted B–H 3.1 Acylamino Directing Group 3.2 Amide 3.3 Pyridyl 3.4 Imine 4 Phosphinyl-Assisted Cage 5 Bidentate-Directing-Group-Assisted 6 Other 7 Conclusions

Язык: Английский

---