Radical 1,2-Nitrogen Migration Cascades of β-Bromo α-Amino Acid Esters to Access β-Amino Acid Motifs Enabled by Cooperative Ni/Diboron Catalysis

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(8), P. 5491 - 5502

Published: March 28, 2024

Amino acid esters serve as crucial intermediates in protein synthesis and common structural elements biologically active natural compounds. Herein, we present an efficient radical cascade reaction involving 1,2-nitrogen migration C(sp2)–H intramolecular cyclization, enabling access to a diverse array of β-amino motifs. Upon cooperative Ni/diboron catalysis, π-system-independent 1,2-N-shift β-bromo α-amino is achieved, which allows the formation two new bonds, including C(sp3)–C(sp2) bond C(sp3)–N bond. The exhibits extensive substrate compatibility high diastereoselectivity proceeds without need for oxidants, toxic initiators, and/or elevated temperatures. It has been observed that diboron compounds both activating reagent inert C–N cleavage/migration reductant Ni catalytic cycle. This sheds light on remote N-functionalities π-systems. cascades followed by intermolecular halogenation or selenation are also demonstrated.

Language: Английский

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Strategies and Mechanisms of First-Row Transition Metal-Regulated Radical C–H Functionalization

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(17), P. 10192 - 10280

Published: Aug. 8, 2024

Radical C–H functionalization represents a useful means of streamlining synthetic routes by avoiding substrate preactivation and allowing access to target molecules in fewer steps. The first-row transition metals (Ti, V, Cr, Mn, Fe, Co, Ni, Cu) are Earth-abundant can be employed regulate radical functionalization. use such is desirable because the diverse interaction modes between metal complexes species including addition center, ligand complexes, substitution single-electron transfer radicals hydrogen atom noncovalent complexes. Such interactions could improve reactivity, diversity, selectivity transformations allow for more challenging reactions. This review examines achievements this promising area over past decade, with focus on state-of-the-art while also discussing existing limitations enormous potential high-value regulated these metals. aim provide reader detailed account strategies mechanisms associated

Language: Английский

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Dual Nickel/Photoredox‐Catalyzed Site‐Selective Cross‐Coupling of 1,2‐Bis‐Boronic Esters Enabled by 1,2‐Boron Shifts

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(34)

Published: July 2, 2022

Abstract Site‐selective transition‐metal‐catalyzed mono‐deboronative cross‐couplings of 1,2‐bis‐boronic esters are valuable methods for the synthesis functionalized organoboron compounds. However, such limited to reaction sterically less hindered primary boronic ester. Herein, we report a nickel/photoredox‐catalyzed arylation that is selective coupling more secondary/tertiary position. This achieved by taking advantage 1,2‐boron shift β‐boryl radicals thermodynamically favored radicals, which subsequently intercepted nickel catalyst enable arylation. The mild conditions amenable broad range aryl halides give β‐aryl ester products in good yields and with high regioselectivity. method also allows stereodivergent cyclic cis ‐1,2‐bis‐boronic trans ‐substituted products.

Language: Английский

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

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

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Three-Component Photochemical 1,2,5-Trifunctionalizations of Alkenes toward Densely Functionalized Lynchpins

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(43), P. 23814 - 23823

Published: Oct. 18, 2023

Radical remote 1,n-difunctionalization reactions (n > 2) of alkenes are powerful tools to efficiently introduce functional groups with selected distances into target molecules. Among these reactions, 1,5-difunctionalizations an important subclass, leading sought-after scaffolds, but typically suffer from tailored starting materials and strict limitations for the formed group in 2-position. Seeking address issues make radical more applicable, we report a novel three-component 1,2,5-trifunctionalization reaction between imine-based bifunctional reagents two distinct alkenes, driven by visible light energy transfer-catalysis. Key achieving this selective one-step installation three different via choreographed formation four bonds was utilization 1,2-boron shift rigorous capitalization polarities stabilities. Thorough mechanistic studies were carried out, synthetic utility obtained products demonstrated various downstream modifications. Notably, addition functionalization individual groups, their interplay gave rise unique array cyclic products.

Language: Английский

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Alkyl Radical Generation from Alkylboronic Pinacol Esters through Substitution with Aminyl Radicals

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(16), P. 8770 - 8775

Published: April 14, 2023

Alkylboronic pinacol esters (APEs) are highly versatile reagents in organic synthesis. However, the direct generation of alkyl radicals from commonly used, bench-stable APEs has not been well explored. In this communication, radical through reaction with aminyl is reported. The readily generated by visible-light-induced homolytic cleavage N-N bond N-nitrosamines, and C occurs nucleohomolytic substitution at boron. As an application, efficient photochemical alkyloximation alkenes N-nitrosamines under mild conditions presented. A wide range primary, secondary, tertiary engage transformation that easily scaled up.

Language: Английский

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Decarboxylation of β-boryl NHPI esters enables radical 1,2-boron shift for the assembly of versatile organoborons

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Sept. 14, 2023

In recent years, numerous 1,2-R shift (R = aliphatic or aryl) based on tetracoordinate boron species have been well investigated. the contrary, corresponding radical migrations, especially 1,2-boryl for construction of organoborons is still in its infancy. Given paucity and significance such strategies chemistry, it urgent to develop other efficient alternative synthetic protocols enrich these underdeveloped 1,2-boron before their fundamental potential applications could be fully explored at will. Herein, we demonstrated a visible-light-induced photoredox neutral decarboxylative cross-coupling reaction, which undergoes give translocated C-radical further capture versatile acceptors. The mild reaction conditions, good functional-group tolerance, broad β-boryl NHPI esters scope as acceptors make this protocol applicable modification bioactive molecules. It can expected that methodology will very useful tool an strategy primary via novel mode.

Language: Английский

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Enantioselective Suzuki cross-coupling of 1,2-diboryl cyclopropanes

Chemical Science, Journal Year: 2023, Volume and Issue: 14(6), P. 1575 - 1581

Published: Jan. 1, 2023

Herein, we describe the catalytic enantioselective cross-coupling of 1,2-bisboronic esters. Prior work on group specific cross coupling is limited to use geminal bis-boronates. This desymmetrization provides a novel approach prepare enantioenriched cyclopropyl boronates with three contiguous stereocenters, that could be further derivatized through selective functionalization carbon-boron bond. Our results suggest transmetallation, which enantiodetermining step, takes place retention stereochemistry at carbon.

Language: Английский

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Challenges and Future in Ni Laterite Ore Enrichment: A Critical Review

Mineral Processing and Extractive Metallurgy Review, Journal Year: 2023, Volume and Issue: 45(6), P. 539 - 563

Published: May 24, 2023

Nickel is a strategic element whose production and consumption in over decade has increased to 39% 71%, respectively. Generally, due their complex mineralogy, laterites, the current attractive source of Ni, are subjected hydrometallurgy pyrometallurgy techniques without enrichment order extract Ni. Therefore, numerous investigations vogue on laterite performed spanning from 1964 date were reviewed this article, future directions proposed through critical synthesis. The possibilities obtaining both higher recoveries increase grade for Ni noticed using selective comminution-classification method followed by flocculation-flotation strategy. Hence, improve reported yields process, one ways could be subject ore multi-stage subjecting obtained concentrate technique. findings investigation would aid upscaling meet demand.

Language: Английский

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The current utility and future potential of multiborylated alkanes

Nature Reviews Chemistry, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 26, 2024

Language: Английский

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