Stoichiometric Photochemical Carbene Transfer by Bamford–Stevens Reaction

Chemistry - A European Journal, Journal Year: 2019, Volume and Issue: 26(12), P. 2586 - 2591

Published: Dec. 11, 2019

The photolysis of diazoalkanes is a timely strategy to conduct carbene-transfer reactions under mild and metal-free reaction conditions, has developed as an important alternative conventional metal-catalyzed reactions. One the major limitations lies within rapidly occurring side carbene intermediate with remaining diazoalkane molecules that result in use excess partner thus impacts on efficiency. Herein, we describe protocol takes advantage situ generation donor-acceptor by Bamford-Stevens reaction. Following this strategy, concentration can be minimized reduce unwanted now photochemical transfer stoichiometric conditions. We have explored approach C-H N-H functionalization cyclopropanation N-heterocycles could demonstrate applicability method 51 examples.

Language: Английский

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Visible Light‐Mediated Cyclopropanation: Recent Progress

European Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 2022(44)

Published: Oct. 21, 2022

Abstract Cyclopropanes are one of the most important strained rings existing in various pharmaceutical products and secondary metabolites. They also widely used total synthesis natural products, medicinal chemistry, materials science. In past years, photochemical cyclopropanation has been gradually developed as a robust attractive synthetic method to prepare diverse cyclopropane backbones. this review, we summarize recent advances visible light‐mediated synthesis, especially using carbene transfer strategy photocatalytic radical reactions.

Language: Английский

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A Spiro Phosphamide Catalyzed Enantioselective Proton Transfer of Ylides in a Free Carbene Insertion into N−H Bonds

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(15)

Published: Feb. 14, 2023

Free carbene readily causes multiple side reactions due to its high energy, thus asymmetric transformation is very difficult. We present here our findings of high-pKa Brønsted acid catalysts that enable free insertion into N-H bonds amines prepare chiral α-amino derivatives with enantioselectivity. Under irradiation visible light, diazo compounds produce high-energy carbenes are captured by form ylide intermediates, and then the newly designed acids, spiro phosphamides, promote proton transfer ylides afford products. Computational kinetic studies uncover principle for rational design proton-transfer explain how accelerate this provide stereocontrol.

Language: Английский

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Cu(ii)-mediated direct intramolecular cyclopropanation of distal olefinic acetate: access to cyclopropane-fused γ-lactones

Chemical Science, Journal Year: 2023, Volume and Issue: 14(24), P. 6663 - 6668

Published: Jan. 1, 2023

A highly atom- and step-economy diastereoselective copper-mediated direct intramolecular cyclopropanation method to synthesize cyclopropane-fused γ-lactones lactams from distal olefinic acetate was disclosed.

Language: Английский

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Lewis Acid-Catalyzed [3 + 2]-Cyclization of Iodonium Ylides with Azadienes: Access to Spiro[benzofuran-2,2′-furan]-3-ones

Organic Letters, Journal Year: 2022, Volume and Issue: 24(41), P. 7502 - 7506

Published: Oct. 11, 2022

A highly regioselective synthesis of spiro[benzofuran-2,2'-furan]-3-ones has been explored via Lewis acid-catalyzed [3 + 2] cyclization iodonium ylides with azadienes. The acidity the acid was significantly strengthened strong hydrogen bond donors, thereby promoting enolization isomerization for subsequent cycloaddition. This reaction compatible a broad range substrates under mild conditions, and efficiently delivered spiro-heterocycles excellent stereoselectivity.

Language: Английский

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All‐Carbon Tetrasubstituted Olefins Synthesis from Diazo Compounds and Iodonium Ylides under Blue LED Irradiation

Advanced Synthesis & Catalysis, Journal Year: 2021, Volume and Issue: 364(3), P. 506 - 511

Published: Nov. 27, 2021

Abstract A route for the construction of all‐carbon tetra‐substituted olefins through visible‐light promoted coupling diazo compounds with iodonium ylides was developed. wide range obtained in moderate to good yields. The synthetic values current method were further approved by synthesis natural isolates modified alkenes and successful transformation final into important heterocycles. magnified image

Language: Английский

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Direct Synthesis of Indolines via Cyclization of Tertiary Aryl Amines with Iodonium Ylides under Sole Visible Light Irradiation

Advanced Synthesis & Catalysis, Journal Year: 2022, Volume and Issue: 365(1), P. 110 - 115

Published: Dec. 2, 2022

Abstract Herein we reported a direct synthesis series of indolines through cyclization tertiary aryl amines with iodonium ylides. This reaction occurred under sole visible‐light irradiation at room temperature without the addition any photocatalysts and additives. Preliminary mechanism studies revealed that an electron donor‐acceptor (EDA) complex between ylides should be formed during reaction. magnified image

Language: Английский

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A Spiro Phosphamide Catalyzed Enantioselective Proton Transfer of Ylides in a Free Carbene Insertion into N−H Bonds

Angewandte Chemie, Journal Year: 2023, Volume and Issue: 135(15)

Published: Feb. 14, 2023

Abstract Free carbene readily causes multiple side reactions due to its high energy, thus asymmetric transformation is very difficult. We present here our findings of high‐p K a Brønsted acid catalysts that enable free insertion into N−H bonds amines prepare chiral α‐amino derivatives with enantioselectivity. Under irradiation visible light, diazo compounds produce high‐energy carbenes are captured by form ylide intermediates, and then the newly designed acids, spiro phosphamides, promote proton transfer ylides afford products. Computational kinetic studies uncover principle for rational design proton‐transfer explain how accelerate this provide stereocontrol.

Language: Английский

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gem‐Dichlorocyclopropanation of Dicarbonyl Derivatives

Chemistry - A European Journal, Journal Year: 2019, Volume and Issue: 25(72), P. 16555 - 16563

Published: Oct. 24, 2019

A novel methodology for the 1,1-dichlorocyclopropanation of dicarbonyl conjugated olefins was described. The developed protocol is simple and uses readily accessible starting materials, allowing isolation desired adducts in moderate to excellent yields (up 99 %). Furthermore, reaction tolerated scale up gram scale; thus highlighting synthetic potential this transformation. Control experiments DFT studies revealed that proceeded through a Michael-initiated ring-closure process, which temperature played crucial role. Finally, these gem-dichlorocyclopropanes were also employed preparation trisubstituted naphthyl derivative diastereoselective reduction demonstrated.

Language: Английский

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σ‐Holes in Iodonium Ylides: Halogen‐Bond Activation of Carboxylic Acids, Phenols and Thiophenols May Enable Their X−H Insertion Reactions

Chemistry - A European Journal, Journal Year: 2022, Volume and Issue: 28(71)

Published: Sept. 29, 2022

The first systematic evaluation of the electrostatic potential energy maps iodonium ylides was conducted. We determined that they possess two σ-holes differing electron deficiencies, with more electropositive σ-hole located opposite dative I-C bond to β-dicarbonyl motif, and lesser iodoarene C-I bond. also conducted carboxylic acids, phenols thiophenols in O/S-alkylation reaction ylides. While acids were found be generally viable, only possessing electron-withdrawing substituents effective. This high-yielding highly chemoselective is believed involve halogen-bond activation heteroatoms, nicely complements existing diazo-based methods for alkylation acidic functional groups.

Language: Английский

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