Amination of 3-Substituted Benzofuran-2(3H)-ones Triggered by Single-Electron Transfer

One-pot domino syntheses of 3-alkyl-3-N-substituted aminobenzofuran-2(3H)-ones based on alkali-promoted Michael addition and lactonization

In this paper, a novel cascade reaction of caesium carbonate-promoted Michael addition and lactonization for the one-pot synthesis of 3-alkyl-3-N-substituted aminobenzofuran-2(3H)-one derivatives has been established based on the screening of the alkaline reagents and optimization of reaction conditions, in which the N-substituted (ortho-hydroxy)aryl glycine esters were used as the Michael donors to react with different α, β-unsaturated carbonyl compounds. In the case of using the asymmetric starting material, the epimers could be successfully separated by conventional chromatography. In addition, plausible mechanisms were suggested and the absolute configuration of the epimer was analysed. All the chemical structures of unreported benzofuran-2(3H)-one derivatives were characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, IR and high-resolution mass spectrometry (HRMS).

Photoredox-Catalyzed Three-Component 1,2-Cyanoalkylpyridylation of Styrenes with Nonredox-Active Cyclic Oximes

Three-component alkene 1,2-difunctionalizations have emerged as a powerful strategy for rapid buildup of diverse and complex alkylpyridines, but the distal functionalized alkyl radicals for the alkene 1,2-alkylpyridylations were still rare. Herein, we report an example of regioselective three-component 1,2-cyanoalkylpyridylation of feedstock styrenes with accessible nonredox-active cyclic oximes through visible-light photoredox catalysis, providing a series of structurally diverse β-cyanoalkylated alkylpyridines. This protocol proceeds through a radical relay pathway including the generation of iminyl radicals enabled by phosphoranyl radical-mediated β-scission, radical transposition through C-C bond cleavage, highly selective radical addition, and precise radical-radical cross-coupling sequence, thus facilitating the regioselective formation of two distinct C-C single bonds in a single-pot operation. This synthetic strategy features mild conditions, broad compatibility of functional groups and substrate scope, diverse product derivatization, and late-stage modification.

Modular Synthesis of α-Aryl-α-Heteroaryl α-Amino Acid Derivatives via a Copper-Catalyzed Cross-Dehydrogenative-Coupling Reaction Using Air as the Sole Oxidant

A novel copper-catalyzed cross-dehydrogenative-coupling (CDC) process of arylglycine derivatives with N-heteroarenes for the straightforward synthesis of α-aryl-α-heteroaryl α-amino acid scaffolds has been successfully developed. This protocol exhibits a broad substrate scope with good functional group compatibility by utilizing air as the sole oxidant. The use of the reaction is also displayed through the late-stage functionalization of arylglycines bearing natural compounds or drug motifs.

Metal-Free C-H Sulfamidation of 1,4-Naphthoquinone in Water

Direct sulfamidation of 1,4-naphthoquinones using N-methoxy sulfonamides under metal-free conditions in water was developed. Base-mediated nucleophilic addition of N-methoxy sulfonamides, followed by N-O bond cleavage allowed the formation of enesulfonamides. Further, the synthesis of pyrrolonaphthoquinones proved the practicability of the current approach.

Modular Synthesis of α,α-Diaryl α-Amino Esters via Bi(V)-Mediated Arylation/SN2-Displacement of Kukhtin–Ramirez Intermediates

We report a concise and modular approach to α,α-diaryl α-amino esters from readily available α-keto esters. This mild, one-pot protocol proceeds via ketone umpolung, with in situ formation of a Kukhtin–Ramirez intermediate preceding sequential electrophilic arylation by Bi(V) and S_N2 displacement by an amine. The methodology is compatible with a wide range of anilines and primary amines - including derivatives of drugs and proteinogenic amino acids - Bi(V) arylating agents, and α-keto ester substrates.

Ultrasound Accelerated Expedient and Eco-Friendly Synthesis of Aryl Sulfonates Using I2 As Catalyst At Ambient Conditions

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Aryl sulfonates were developed by ssing an energy-saving and eco-friendly approach, through ultrasound-assisted coupling reaction of readily sodium sulfinates with N-hydroxyphthalimide, under metal-free and mild conditions within 10 min at room temperature.

Recent Advances on Benzofuranones: Synthesis and Transformation via C–H Functionalization

The benzofuranone structure is important in many fields, such as natural products, pharmaceuticals, building blocks, antioxidants, and dyes. The efficient synthesis and transformation of benzofuranones have attracted great attention in organic synthesis. They can be synthesized by the Friedel–Crafts reaction and intramolecular dehydration ring-closing and transition-metal-catalyzed reactions, among others. Their direct utilization in the preparation of other functional molecules further enhance their application. Due to their low pK a value and easy enolization, the transformation of benzofuranones via C(3)–H bond functionalization has been a hot issue since 2010. Herein, we highlight advances in the synthesis of benzofuranones and their transformation via C–H functionalization. Other transformations related to benzofuranones are also discussed.

1 Introduction

2 Synthesis of Benzofuranones

3 C–H Functionalization of Benzofuranones

4 Other Types of Reactions of Benzofuranones

5 Conclusion and Outlook

Visible Light Driven and Copper-Catalyzed C(sp3)-H Functionalization of O-Pentafluorobenzoyl Ketone Oximes

The C(sp³)-H functionalization of O-pentafluorobenzoyl ketone oximes was implemented under visible light irradiation with copper complexes as catalysts. The reactions involve iminyl-radical-mediated intramolecular hydrogen atom transfer as the key step, with the iminyl radicals being generated via copper-effected N-O cleavage. The reaction afforded 3,4-dihydro-2H-pyrroles under the conditions of [Cu(DPEphos)(bcp)]PF₆ and DABCO, while γ-pentafluorobenzoyloxy ketones were produced predominantly when [Cu(dpp)₂]PF₆ and InCl₃·4H₂O were used as catalysts.

Chiral Calcium Phosphate Catalyzed Enantioselective Amination of 3-Aryl-2-benzofuranones

A 4-tert-butyl-phenyl substituted (R)-[H₈]-BINOL chiral calcium phosphate catalyzed enantioselective amination of 3-aryl-2-benzofuranones with dibenzyl azodicarboxylate is described. The catalyst loading of the reaction is 1 mol %. This transformation is facile and has a high degree atom economy, which gave products with good yields and high enantioselectivities (79% to 99%). This reaction has excellent ee and a broad substrate scope with mild reaction conditions.

Catalyst-free amination of α-cyanoarylacetates enabled by single-electron transfer

A radical benzylic amination of α-cyanoarylacetates without the assistance of any transition-metal catalysts or external photosensitizers was realized.

Mechanistic insights and origin of chemoselectivity for S–O bond cleavage in dinitrobenzenesulfonic carbamates

A computational study on the NHC-catalyzed chemoselective S–O bond cleavage in dinitrobenzenesulfonic carbamates.

Electrochemically induced oxidative S–O coupling: synthesis of sulfonates from sulfonyl hydrazides and N-hydroxyimides or N-hydroxybenzotriazoles

A variety of sulfonates were synthesized from sulfonyl hydrazides and N-hydroxy compounds via electrochemically induced oxidative S–O bond formation.

N-Heterocyclic Carbene-Catalyzed Chemoselective S-O Bond Cleavage of Benzenesulfonic Carbamate

An unprecedented example of NHC-catalyzed chemoselective S-O bond cleavage of dinitrobenzenesulfonic carbamates is described. This protocol features several advantages, including mild reaction conditions, broad substrate scope, and operational simplicity, which allows it to be an attractive synthetic method for hydroxylamine synthesis. Notably, dinitrobenzenesulfonic carbamates not only work as "O" synthons but also serve as an efficient oxidant in this reaction.

Effect of methamphetamine on the fasting blood glucose in methamphetamine abusers

Methamphetamine is a popular psychostimulant worldwide which causes neurotoxicity and neuroinflammation. Although previous studies have characterized potential associations between addictive drugs and fasting blood glucose, the influence of methamphetamine on the blood glucose is still largely unknown. The present study was designed to investigate the change of fasting blood glucose of methamphetamine abusers and to confirm the impairment of liver and kidney. Fasting blood glucose was significantly decreased in methamphetamine abusers and in a high-fat diet mouse model with methamphetamine treatment discontinuation. Serum level of ALT, creatine kinase and creatinine were increased in methamphetamine abusers. Serum level of ALT and AST were increased in a high-fat diet mouse model after methamphetamine injection, but there was no significant difference in the anatomy of the liver and kidney in high-fat diet treated mice with or without methamphetamine. The levels of ALT and creatinine were also increased in the methamphetamine abusers. This study demonstrated that the level of glucose was decreased in methamphetamine abusers and in high-fat diet-fed mice after methamphetamine treatment discontinuation. The effect of methamphetamine on the levels of blood glucose may provide the evidence that methamphetamine abusers should be keep energy balance due to the low blood glucose.

Metal-Free Direct Amidation of Naphthoquinones Using Hydroxamic Acids as an Amide Source: Application in the Synthesis of an HDAC6 Inhibitor

A novel synthetic approach to amidoquinones by the reaction of naphthoquinones with hydroxamic acids under basic conditions was developed. The reaction is mild and operationally simple, and it affords high yields of amidoquinones. With this new method, a novel, very strong HDAC6 inhibitor, which showed high toxicity to AML cells, was successfully synthesized.