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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Cobalt‐Catalyzed Photo‐Semipinacol Rearrangement of Unactivated Allylic Alcohols

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(35)

Published: June 7, 2024

We report a photochemical method for the semipinacol rearrangement of unactivated allylic alcohols. Aliphatic as well aromatic groups participate migrating groups, yielding variety α,α-disubstituted ketones. The reaction proceeds under mild conditions and is compatible with ethers, esters, halides, nitriles, carbamates, substituted arenes. operationally simple fully catalytic prescribe 1 mol % benzothiazinoquinoxaline organophotocatalyst, 0.5 Co-salen, 10 lutidinium triflate and, importantly, display reactivity complementary to procedures employing Brønsted acid. showcase utility protocol in late-stage drug diversifications.

Language: Английский

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β-Boron Effect Enables Regioselective and Stereospecific Electrophilic Addition to Alkenes

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7548 - 7558

Published: March 22, 2023

Electrophilic addition to alkenes is a textbook-taught reaction, yet it not always possible control the regioselectivity of unsymmetrical 1,2-disubstituted substrates. We report observation and applications β-boron effect that accounts for high in electrophilic reactions allylic MIDA (N-methyliminodiacetic acid) boronates. While well-established β-silicon bears partial resemblance observed reactivity, silyl group typically lost during functionalization. In contrast, boryl moiety retained product when B(MIDA) used as nucleophilic stabilizer. Mechanistic studies elucidate origin this demonstrate how σ(C–B) hyperconjugation helps stabilize incipient carbocation. This transformation represents rare example stereospecific hydrohalogenation secondary allyl MIDA-boronates proceeds syn-fashion.

Language: Английский

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Catalyst-Enabled Stereodivergence in Photochemical Atom Transfer Radical Addition (ATRA) of α-Iodoboronic Esters to Alkynes

ACS Catalysis, Journal Year: 2023, Volume and Issue: 14(1), P. 299 - 307

Published: Dec. 16, 2023

The atom transfer radical addition (ATRA) to alkynes is a valuable strategy for the synthesis of allylic substituted molecules, yet it has not been applied boronic acids or their esters, which are important building blocks in organic synthesis. inherent challenge ATRA reactions control geometric selectivity. By employing different alkene isomerization techniques, namely, photochemical uphill catalysis and manganese-catalyzed halogen-abstraction/radical rebound processes, we able synthesize both isomers iodinated esters stereoselective manner. Mechanistic investigations reveal dual functionalities catalysts, acting as catalysts processes. protocols feature broad substrate scope good functional group tolerance. Importantly, iodo boryl moieties within products provide orthogonal handles further synthetic manipulations. employed here should inspire more efforts toward alkynes.

Language: Английский

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Synthesis of highly substituted 1,3-dienes through halonium promoted 1,2-sulfur migration of propargylic thioethers

Chemical Communications, Journal Year: 2024, Volume and Issue: 60(13), P. 1794 - 1797

Published: Jan. 1, 2024

Highly regio- and diastereoselective synthesis of 2-thiorganyl 1-bromo or 1-iodo-1,3-dienes is reported via 1,2-sulfur migration propargylic sulfides. These dienes are precursors thiophenes selenophenes by reaction with sulfur selenium.

Language: Английский

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Cu-catalyzed carboboration of acetylene with Michael acceptors

Chemical Science, Journal Year: 2022, Volume and Issue: 13(25), P. 7604 - 7609

Published: Jan. 1, 2022

A copper-catalyzed three-component carboboration of acetylene with B 2 Pin and Michael acceptors was achieved. The small molecule enabled faster rate borylcupration easier C–C bond formation compared substituted alkynes.

Language: Английский

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Boron‐Copper 1,3‐Rearrangement: the New Concept Behind the Boryl Migration from C(sp²) in Alkenyl Boranes to C(sp³)

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(30)

Published: May 11, 2023

Regioselective borylcupration of borylated skipped (Z)-dienes generates diborylated alkylcopper species that are involved in an intramolecular stereospecific B/Cu 1,3-rearrangement by migration Bpin moiety from C(sp2 ) to C(sp3 ). DFT mechanistic studies showed boryl occurs through the formation 4-membered boracycle intermediate with a moderate free-energy barrier. Moreover, use KOMe forms stable Lewis base adducts moieties blocks reaction. Subsequently 1,3-boron shift, situ electrophilic trapping allows selective C-H, C-C and C-X bonds, followed cross coupling giving access cyclic functionalized alkylidenecyclohexanes or alkylidenecyclobutanes.

Language: Английский

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A Boron Scan of Ethyl Acetoacetate Leads to Versatile Building Blocks

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(15)

Published: Jan. 26, 2024

Abstract Discovered in the 19th century, ethyl acetoacetate has been central to development of organic chemistry, including its pedagogy and applications. In this study, we present borylated derivatives venerable molecule. A boron handle installed at either ‐ or ‐position by homologation acyl‐MIDA ( N ‐methyliminodiacetic acid) boronates with diazoacetates. Either alkyl boryl groups were found migrate regiochemistry being a function steric bulk diazo species. Boryl ‐ketoesters can be further modified into pyrazolones oximes, thereby expanding synthetic toolkit offering opportunities for additional modifications.

Language: Английский

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Radical Ring-Opening Fluorosulfonylation of Methylenecyclobutanols via Electron Donor–Acceptor Photoactivation

Organic Letters, Journal Year: 2024, Volume and Issue: 26(26), P. 5577 - 5581

Published: June 24, 2024

A visible-light-mediated catalyst- and additive-free method for radical ring-opening fluorosulfonylation of methylenecyclobutanols is reported. Sulfuryl chlorofluoride acts as a FSO

Language: Английский

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Divergent Synthesis of 1,1-Carbonyl Amino Alkyl Borons from Indoles

Organic Letters, Journal Year: 2023, Volume and Issue: 25(22), P. 4038 - 4043

Published: May 25, 2023

α-Boryl carbonyl species and α-boryl amino compounds are valuable important frameworks in organic synthesis. However, the strategies that could merge two scaffolds into one compound, named 1,1-carbonyl alkyl boron, elusive underdeveloped. Herein, we present an efficient method address this gap produce borons from readily accessible indoles via oxidation by m-CPBA or oxone. This reaction features operational simplicity, divergent synthesis, broad substrate scope, products.

Language: Английский

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