Photocatalyzed Borylcyclopropanation of Alkenes with a (Diborylmethyl)iodide Reagent

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(38)

Опубликована: Авг. 2, 2023

Cyclopropane skeletons play a prominent role in the development of organic synthesis and pharmaceutical chemistry. Herein, we report design stable, multifunctional (diborylmethyl)iodide reagent (CHI(Bpin)2 ) for photoinduced cyclopropanation alkenes, providing an array 1,2-substituted cyclopropylboronates good yields. This α-haloboronic ester can be readily synthesized on multigram scale from commercially available starting materials. Furthermore, protocol displays high chemo- diastereoselectivity, excellent functional-group tolerance, allows late-stage borylcyclopropanation complex molecules. Mechanistic studies reveal that proceeds through radical addition/polar cyclization pathway mediated by photocatalyst fac-Ir(ppy)3 visible light.

Язык: Английский

---

Electrooxidative Activation of B−B Bond in B₂cat₂: Access to gem‐Diborylalkanes via Paired Electrolysis

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(14)

Опубликована: Фев. 1, 2023

This report describes the unprecedented electrooxidation of a solvent (e.g., DMF)-ligated B2 cat2 complex, whereby solvent-stabilized boryl radical is formed via quasi-homolytic cleavage B-B bond in DMF-ligated cation. Cyclic voltammetry and density functional theory provide evidence to support this novel activation strategy. Furthermore, strategy for electrochemical gem-diborylation gem-bromides paired electrolysis developed first time, affording range versatile gem-diborylalkanes, which are widely used synthetic society. Notably, reaction approach scalable, transition-metal-free, requires no external activator.

Язык: Английский

---

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

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(32)

Опубликована: Июнь 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.

Язык: Английский

---

Ir-Catalyzed Regioselective Dihydroboration of Thioalkynes toward Gem-Diboryl Thioethers

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(4), С. 2305 - 2314

Опубликована: Янв. 19, 2023

While 1,1-diboryl (gem-diboryl) compounds are valuable synthetic building blocks, currently, related studies have mainly focused on those alkanes without a hetero functional group in the α-position. gem-Diboryl with an α-hetero substituent, though highly versatile, been limitedly accessible and thus rarely utilized. Herein, we developed first α-dihydroboration of heteroalkynes leading to efficient construction gem-diboryl, hetero-, tetra-substituted carbon centers. This straightforward, practical, mild, atom-economic reaction is attractive complement conventional multistep strategy relying deprotonation gem-diborylmethane by strong base. Specifically, [Ir(cod)(OMe)]2 was found be uniquely effective for this process thioalkynes, excellent α-regioselectivity when delivering two boryl groups, which remarkable view many competitive paths including monohydroboration, 1,2-dihydroboration, dehydrodiboration, triboration, tetraboration, etc. Control experiments combined DFT calculations suggested that involves sequential hydroboration events. The second requires higher energy barrier due severe steric repulsion generating congested α-sulfenyl gem-diboryl center, structural motif almost unknown before.

Язык: Английский

---

A Novel Synthesis of Halogenated gem-Diboron Reagents

Chinese Journal of Organic Chemistry, Год журнала: 2023, Номер 43(2), С. 777 - 777

Опубликована: Янв. 1, 2023

A novel synthesis of halogenated gem-diboronates (X-CR(Bpin)2) was developed.The reagents are stable and easy to prepare in a large scale.Tetra-substituted can be prepared high yields when using alkylsubstituted gem-dihalides, providing new strategy for the gem-diboron compounds.

Язык: Английский

---

Palladium‐Catalyzed Cascade Heck Coupling and Allylboration of Iododiboron Compounds via Diboryl Radicals

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(18)

Опубликована: Март 6, 2024

Geminal bis(boronates) are versatile synthetic building blocks in organic chemistry. The fact that they predominantly serve as nucleophiles the previous reports, however, has restrained their potential. Herein we disclose ambiphilic reactivity of α-halogenated geminal bis(boronates), which first catalytic utilization was accomplished by merging a formal Heck cross-coupling with highly diastereoselective allylboration aldehydes or imines, providing new avenue for rapid assembly polyfunctionalized boron-containing compounds. We demonstrated this cascade reaction is efficient and compatible various functional groups, wide range heterocycles. In contrast to classical Pd(0/II) scenario, mechanistic experiments DFT calculations have provided strong evidence cycle involving Pd(I)/diboryl carbon radical intermediates.

Язык: Английский

---

Photogeneration of α-Bimetalloid Radicals via Selective Activation of Multifunctional C1 Units

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(23), С. 15850 - 15859

Опубликована: Май 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

Язык: Английский

---

PolyBorylated Alkenes as Energy‐Transfer Reactive Groups: Access to Multi‐Borylated Cyclobutanes Combined with Hydrogen Atom Transfer Event

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(25)

Опубликована: Апрель 11, 2024

Abstract While polyborylated alkenes are being recognized for their elevated status as highly valuable reagents in modern organic synthesis, allowing efficient access to a diverse array of transformations, including the formation C−C and C‐heteroatom bonds, potential energy‐transfer reactive groups has remained unexplored. Yet, this holds key generating elusive biradical species, which can be captured by olefins, thereby leading construction new highly‐borylated scaffolds. Herein, we report designed strategy photosensitized [2+2]‐cycloadditions poly‐borylated with various olefins enabling regioselective synthesis cyclobutane motifs, 1,1‐di‐, 1,1,2‐tri‐, 1,1,2,2‐tetra‐borylated cyclobutanes. In fact, these compounds belong family that presently lacks synthetic pathways. Interestingly, when α‐methylstyrene was used, reaction involves an interesting 1,5‐hydrogen atom transfer (HAT). Mechanistic deuterium‐labeling studies have provided insight into outcome process. addition, cyclobutanes then demonstrated useful selective oxidation processes resulting cyclobutanones γ‐lactones.

Язык: Английский

---

Enantio‐ and Regioselective Cascade Hydroboration of Methylenecyclopropanes for Facile Access to Chiral 1,3‐ and 1,4‐Bis(boronates)

Advanced Science, Год журнала: 2024, Номер 11(21)

Опубликована: Март 13, 2024

Abstract Chiral 1, n‐bis(boronate) plays a crucial role in organic synthesis and medicinal chemistry. However, their catalytic asymmetric has long posed challenge terms of operability accessibility from readily available substrates. The recent discovery the C═C bond formation through β‐C elimination methylenecyclopropanes (MCP) provided an exciting opportunity to enhance molecular complexity. In this study, catalyzed cascade hydroboration MCP is developed. By employing different ligands, various homoallylic boronate intermediate are obtained ring opening process. Subsequently, with HBpin or B 2 pin resulted enantioenriched chiral 1,3‐ 1,4‐bis(boronates) high yields, accompanied by excellent chemo‐ enantioselectivities. selective transformation these two distinct C─B bonds also demonstrated application potential synthesis.

Язык: Английский

---

Ketone Synthesis from Benzyldiboronates and Esters: Leveraging α-Boryl Carbanions for Carbon–Carbon Bond Formation

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(5), С. 2429 - 2437

Опубликована: Янв. 15, 2020

An alkoxide-promoted method for the synthesis of ketones from readily available esters and benzyldiboronates is described. The synthetic compatible with a host sterically differentiated alkyl groups, alkenes, acidic protons α to carbonyl tertiary amides, aryl rings having common organic functional groups. With bearing α-stereocenters, high enantiomeric excess was maintained during ketone formation, establishing minimal competing racemization by deprotonation. Monitoring reaction between benzyldiboronate LiO

Язык: Английский

---