Copper-Catalyzed 1,1-Alkylmonofluoroalkylation of Terminal Alkynes with Diazo Compounds and 2-Fluoro-1,3-dicarbonyl Compounds: Access toward (E)-β-Monofluoroalkyl-β,γ-unsaturated Esters or Ketones

Lithium Bromide-Promoted Formal C(sp3)-H Bond Insertion Reactions of β-Carbonyl Esters with Sulfoxonium Ylides to Synthesize 1,4-Dicarbonyl Compounds

A LiBr-promoted formal C(sp3)-H bond insertion reaction between β-carbonyl esters and sulfoxonium ylides is established. This practical reaction has a wide range of substrate scope for both β-carbonyl esters and sulfoxonium ylides to give a variety of 1,4-dicarbonyl compounds with 43-94% yields. The reaction features transition-metal-free reaction conditions and exclusive C-alkylation chemselectivity. The use of bench-stable sulfoxonium ylides overcomes previous methods that require transition metal as catalysts and unstable diazo compounds or toxic haloketones as alkylation reagents.

Recent advances in the application of alkynes in multicomponent reactions

Alkynes have two active positions to carry out chemical reactions: C[triple bond, length as m-dash]C and C-H. These two positions are involved and activated in different reactions using different reagents. In this study, we investigated the reactions of alkynes that are involved in multi-component reactions through the C-C and C-H positions and examined the progress and gaps of each reaction by carefully studying the mechanism of the reactions. Firstly, we investigated and analyzed the reactions involving the C[triple bond, length as m-dash]C position of alkynes, including the reactions between derivatives of alkynes with RN3, sulfur compounds (RSO2R', DMSO, S8, DABCO(SO2)2 and DABSO), barbituric acids, aldehydes and amines, COOH, α-diazoesters or ketones, and isocyanides. Then, we examined and analyzed the important reactions involving the C-H position of alkynes and the progress and gaps in these reactions, including the reaction between alkyne derivatives with amines and aldehydes for the synthesis of propargylamines, the reaction between alkynes with CO2 and the reaction between alkynes with CO.

Copper-Catalyzed Three-Component Tandem Reaction of Alkynes, α-Diazo Esters, and TMSN3 to Access N-Substituted 1,2,3-Triazoles

An efficient copper-catalyzed three-component tandem reaction of alkynes, α-diazo esters, and TMSN3 to construct triazoles has been developed. Through this strategy, a number of diverse N-substituted 1,2,3-triazoles were conveniently obtained in moderate to good yields from simple and readily available starting materials using K2CO3 as the base. The mechanism of the tandem Cu-catalyzed azide-alkyne cycloaddition (CuAAC) and Cu-carbenoid-participated C-N coupling reaction has been investigated.

Copper iodide nanoparticles (CuI NPs): an efficient catalyst for the synthesis of alkynyl esters

An environmentally benign protocol for the synthesis of alkynyl esters, by the cross-coupling of diazoacetate with various substituted alkynes under neat reaction conditions, has been described. Copper iodide nanoparticles (CuI NPs) were found to promote the Sonogashira-type coupling to afford the corresponding alkynyl esters in good yields. The CuI nanoparticles were characterized by PXRD, FESEM, EDAX, and Raman techniques. The developed methodology has several advantages such as a broad substrate scope, less reaction time, atom economy, avoidance of an additive/base/solvent, and enhanced values of green chemistry. The catalyst was recycled up to threefold without the loss of its catalytic activity.