MIDA‐ and TIDA‐Boronates Stabilize α‐Radicals Through B−N Hyperconjugation DOI Creative Commons
Antonio J. LaPorte,

Jack E. Feldner,

Jan C. Spies

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(40)

Published: Aug. 4, 2023

Abstract Multifunctional organoboron compounds increasingly enable the simple generation of complex, Csp 3 ‐rich small molecules. The ability boron‐containing functional groups to modify reactivity α‐radicals has also enabled a myriad chemical reactions. Boronic esters with vacant p‐orbitals have significant stabilizing effect on due delocalization spin density into empty orbital. coordinatively saturated derivatives, such as N‐methyliminodiacetic acid (MIDA) boronates and counterparts, remains less clear. Herein, we demonstrate that MIDA TIDA stabilize secondary alkyl via σ B‐N hyperconjugation in manner allows site‐selective C−H bromination. DFT calculated radical stabilization energies maps well LED NMR kinetic analysis photochemical bromination rates different boronic further these findings. This work clarifies α‐radical does not only proceed character boron p‐orbitals, but tetrahedral their ligand electron delocalizing play critical role. These findings establish ligands useful dial for tuning at α‐carbon.

Language: Английский

Visible Light Assisted Radical‐Polar/Polar‐Radical Crossover Reactions in Organic Synthesis DOI
Shivani Sharma, Jitender Singh, Anuj Sharma

et al.

Advanced Synthesis & Catalysis, Journal Year: 2021, Volume and Issue: 363(13), P. 3146 - 3169

Published: April 10, 2021

Abstract Chemists are generally familiar with polar reactions and radical reactions, in comparison, underdeveloped. In the last few years, however, novel concept of amalgamation above two form radical‐polar crossover (RPCO) polar‐radical (PRCO) has emerged as a valuable powerful tool. This methodology tends to bridge gap between well overcomes limitations both traditional chemistry. By bringing together unorthodox chemistry radicals orthodox carbocations carbanions, green quotient such is significantly improved. The development shaping up this area years synthetically important transformations summarised review. magnified image

Language: Английский

Citations

124
Visible-Light-Driven Organic Photochemical Reactions in the Absence of External Photocatalysts DOI
Wei Yi,

Quan‐Quan Zhou,

Fen Tan

et al.

Synthesis, Journal Year: 2019, Volume and Issue: 51(16), P. 3021 - 3054

Published: May 20, 2019

Visible-light-driven organic photochemical reactions have attracted substantial attention from the synthetic community. Typically, catalytic quantities of photosensitizers, such as transition metal complexes, dyes, or inorganic semiconductors, are necessary to absorb visible light and trigger subsequent transformations. Recently, in contrast these photocatalytic processes, a variety photocatalyst-free transformations been exploited for efficient formation carbon–carbon carbon–heteroatom bonds. In addition not requiring additional photocatalysts, they employ low-energy irradiation, mild reaction conditions, enable broad substrate diversity functional group tolerance. This review will focus on summary representative work this field terms different photoexcitation modes. 1 Introduction 2 Visible Light Photoexcitation Single Substrate 3 Reaction Intermediates 4 EDA Complexes between Substrates 5 6 Products 7 Conclusion Outlook

Language: Английский

Citations

135
Enantioselective Radical Addition/Cross‐Coupling of Organozinc Reagents, Alkyl Iodides, and Alkenyl Boron Reagents DOI
Matteo Chierchia, Peilin Xu, Gabriel J. Lovinger

et al.

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(40), P. 14245 - 14249

Published: Aug. 7, 2019

Abstract A hybrid transition‐metal/radical process is described that results in the addition of organozinc reagents and alkyl halides across alkenyl boron an enantioselective catalytic fashion. The reaction can be accomplished both intermolecularly intramolecularly, providing useful product yields high enantioselectivities manifolds.

Language: Английский

Citations

115
Photo-triggered self-catalyzed fluoroalkylation/cyclization of unactivated alkenes: synthesis of quinazolinones containing the CF2R group DOI

Jin Wook Yang,

Bin Sun, Hao Ding

et al.

Green Chemistry, Journal Year: 2020, Volume and Issue: 23(1), P. 575 - 581

Published: Dec. 10, 2020

A photo-triggered self-catalyzed fluoroalkylation/cyclization of quinazolinones containing unactivated alkenes with various fluoroalkyl bromides has been developed.

Language: Английский

Citations

92
α-Borylalkyl radicals: their distinctive reactivity in modern organic synthesis DOI Open Access
N. N. Bhuvan Kumar,

Reddy Rajasekhar Reddy,

Nadim Eghbarieh

et al.

Chemical Communications, Journal Year: 2019, Volume and Issue: 56(1), P. 13 - 25

Published: Nov. 27, 2019

Organoborons are extremely important for synthetic organic chemistry; they can serve as advanced intermediates a variety of transformations. Such well-known transformation involves the loss boron moiety, creating alkyl radicals. Although these originally developed protocols radical generation remain in active use today, recent years their α-boryl carbon-centred radicals have been joined by new array strategies that offer unique reactivity to forge wider diversity organoborons often operate under mild and benign conditions. Herein, we will highlight stability α-borylalkyl remarkably advances order further utilise them C-C C-heteroatom bond formation. Their this purpose has reported over last decade an attempt guide community. Various transition-metal metal-free methods presented, more photoredox approaches discussed, mainly period 2009-2019.

Language: Английский

Citations

79
Radical‐Induced 1,2‐Migrations of Boron Ate Complexes DOI Creative Commons
Marvin Kischkewitz,

Florian W. Friese,

Armido Studer

et al.

Advanced Synthesis & Catalysis, Journal Year: 2019, Volume and Issue: 362(11), P. 2077 - 2087

Published: Dec. 24, 2019

Abstract 1,2‐Boron ate rearrangements represent a fundamental class of transformations to establish new C−C bonds while retaining the valuable boron moiety in product. In established ionic processes, complex is activated by an external electrophile induce 1,2‐migration from adjacent sp 3 or 2 carbon atom. Recently, two complementary radical polar crossover approaches have been explored for both classes, 1,2‐migrations and centers. This review describes general concepts this emerging research field summarizes recent developments radical‐induced carbon. magnified image

Language: Английский

Citations

78
The Impact of Boron Hybridisation on Photocatalytic Processes DOI Creative Commons

Alessandro Marotta,

Callum E. Adams,

John J. Molloy

et al.

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(38)

Published: June 24, 2022

Recently the fruitful merger of organoboron chemistry and photocatalysis has come to forefront organic synthesis, resulting in development new technologies access complex (non)borylated frameworks. Central success this combination is control boron hybridisation. Contingent on photoactivation mode, as its neutral planar form or tetrahedral boronate can be used regulate reactivity. This Minireview highlights current state art photocatalytic processes utilising compounds, paying particular attention role hybridisation for target transformation.

Language: Английский

Citations

55
Ir‐Catalyzed Enantioselective Synthesis of gem‐Diborylalkenes Enabled by 1,2‐Boron Shift DOI

Jianfei Ge,

Xi‐Zhang Zou,

Xinru Liu

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(32)

Published: June 15, 2023

Abstract Asymmetric cross‐couplings based on 1,2‐carbon migration from B‐ate complexes have been developed efficiently to access valuable organoboronates. However, enantioselective reactions triggered by 1,2‐boron shift remained be unaddressed synthetic challenge. Here, Ir‐catalyzed asymmetric allylic alkylation enabled was developed. In this reaction, we disclosed that excellent enantioselectivities were achieved through an interesting dynamic kinetic resolution (DKR) process of carbonates at the elevated temperature. Notably, highly (bis‐boryl)alkenes array diversifications versatile molecules. Extensive experimental and computational studies conducted elucidate reaction mechanism DKR clarify origin enantioselectivities.

Language: Английский

Citations

27
Photogeneration of α-Bimetalloid Radicals via Selective Activation of Multifunctional C1 Units DOI Creative Commons

Lewis McGhie,

Alessandro Marotta,

Patrick O. Loftus

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(23), P. 15850 - 15859

Published: May 28, 2024

Light-driven strategies that enable the chemoselective activation of a specific bond in multifunctional systems are comparatively underexplored comparison to transition-metal-based technologies, yet desirable when considering controlled exploration chemical space. With current drive discover next-generation therapeutics, reaction design enables strategic incorporation an sp3 carbon center, containing multiple synthetic handles for subsequent space would be highly enabling. Here, we describe photoactivation ambiphilic C1 units generate α-bimetalloid radicals using only Lewis base and light source directly activate C–I bond. Interception these transient with various SOMOphiles rapid synthesis organic scaffolds (B, Si, Ge) orthogonal activation. In-depth theoretical mechanistic studies reveal prominent role 2,6-lutidine forming photoactive charge transfer complex stabilizing situ generated iodine radicals, as well influential boron p-orbital activation/weakening This simple efficient methodology enabled expedient access functionalized 3D frameworks can further derivatized available technologies C–B C–Si

Language: Английский

Citations

13
Recent Advances in Radical Addition to Alkenylboron Compounds DOI
Gabriel J. Lovinger, James P. Morken

European Journal of Organic Chemistry, Journal Year: 2019, Volume and Issue: 2020(16), P. 2362 - 2368

Published: Nov. 21, 2019

The addition of carbon-centered radicals to alkenylboron compounds provides a useful method for the construction organoboron reagents which are versatile in chemical synthesis. While first examples this type or process appeared 70 years ago, until recently, attention reaction has been limited. A number reactivity have demonstrated and strategies emerging that allow tuning reagent structure order modulate reactivity. This review surveys recent advances class reaction.

Language: Английский

Citations

75