Copper-Catalyzed Cascade Cyclization Reactions of Diazo Compounds with tert-Butyl Nitrite and Alkynes: One-Pot Synthesis of Isoxazoles

A novel copper-catalyzed [3 + 2] cycloaddition reaction of alkynes with nitrile oxides generated in situ from the coupling reaction of copper carbene and nitroso radical has been developed. The three-component reaction provides a simple and efficient method for the construction of isoxazoles in a highly regioselective manner in a single step. On the basis of the experimental results and density functional theory calculations, a catalytic cycle (Cu^I-Cu^II-Cu⁰-Cu^I) for this cascade cyclization reaction is proposed.

Functionalized Acrylonitriles with Aggregation-Induced Emission: Structure Tuning by Simple Reaction-Condition Variation, Efficient Red Emission, and Two-Photon Bioimaging

Acrylonitriles with aggregation-induced emission (AIE) characteristics have been found to show promising applications in two-photon biomedical imaging. Generally, elaborate synthetic efforts are required to achieve different acrylonitriles with distinct functionalities. In this work, we first reported the synthesis of two different group-functionalized AIE-active acrylonitriles (TPAT-AN-XF and 2TPAT-AN) obtained simply by mixing the same reactants at different temperatures using a facile and transition metal-free synthetic method. These two AIE luminogens (AIEgens) exhibit unique properties such as bright red emission in the solid state, large Stokes shift, and large two-photon absorption cross section. Water-soluble nanoparticles (NPs) of 2TPAT-AN were prepared by a nanoprecipitation method. In vitro imaging data show that 2TPAT-AN NPs can selectively stain lysosome in live cells. Besides one-photon imaging, remarkable two-photon imaging of live tumor tissues can be achieved with high resolution and deep tissue penetration. 2TPAT-AN NPs show high biocompatibility and are successfully utilized in in vivo long-term imaging of mouse tumors with a high signal-to-noise ratio. Thus, the present work is anticipated to shed light on the preparation of a library of AIE-active functionalized acrylonitriles with intriguing properties for biomedical applications.

FeCl3-promoted tandem 1,4-conjugate addition/6-endo-dig cyclization/oxidation of propargylamines and benzoylacetonitriles/malononitriles: direct access to functionalized 2-aryl-4H-chromenes

An efficient and concise procedure has been developed for the synthesis of functionalized 2-aryl-4H-chromenes based on a tandem reaction of propargylamines and benzoylacetonitriles/malononitriles in the presence of FeCl3 as an environmentally friendly promoter. This reaction involves a highly efficient tandem sequence consisting of 1,4-conjugate addition, 6-endo-dig cyclization, and oxidation. This protocol tolerates a variety of functional groups, thereby providing a practical and efficient method for the fabrication of 2-aryl-4H-chromene skeletons.

Thermally induced formal [4+2] cycloaddition of 3-aminocyclobutenones with electron-deficient alkynes: facile and efficient synthesis of 4-pyridones

A thermally induced novel formal [4+2] cycloaddition of cyclobutenones with electron-deficient alkynes under metal-free conditions has been developed. The reaction provides a straightforward and efficient method for the synthesis of 4-pyridone derivatives in a single step.

Synthesis and Reactivity of Propargylamines in Organic Chemistry

Propargylamines are a versatile class of compounds which find broad application in many fields of chemistry. This review aims to describe the different strategies developed so far for the synthesis of propargylamines and their derivatives as well as to highlight their reactivity and use as building blocks in the synthesis of chemically relevant organic compounds. In the first part of the review, the different synthetic approaches to synthesize propargylamines, such as A³ couplings and C-H functionalization of alkynes, have been described and organized on the basis of the catalysts employed in the syntheses. Both racemic and enantioselective approaches have been reported. In the second part, an overview of the transformations of propargylamines into heterocyclic compounds such as pyrroles, pyridines, thiazoles, and oxazoles, as well as other relevant organic derivatives, is presented.

Ruthenium-catalyzed oxidative decyanative cross-coupling of acetonitriles with amines in air: a general access to primary to tertiary amides under mild conditions

C–CN activation catalyzed by Ru/C in open air was achieved, affording an efficient access to primary, secondary and tertiary amides under mild conditions.

A new avenue to the synthesis of highly substituted pyrroles: synthesis from N-propargylamines

Pyrroles have attracted much attention due to their potential biological activities.

New route to 1,4-oxazepane and 1,4-diazepane derivatives: synthesis from N-propargylamines

N-Propargylamines are one of the most useful and versatile building blocks in organic synthesis that are successfully transformed into many significant N-heterocycles.

New page to access pyridine derivatives: synthesis from N-propargylamines

The pyridine is one of the simplest, yet most important N-heterocycles.

DBU-mediated metal-free oxidative cyanation of α-amino carbonyl compounds: using molecular oxygen as the oxidant

A novel DBU-mediated oxidative cyanation of α-amino carbonyl compounds by using air as the sole oxidant was developed under mild metal-free conditions for the first time. The reaction involves a tandem oxidation/Strecker reaction/oxidation process and provides a new and efficient method for the construction of α-iminonitriles in good to high yields in a single step.

Nano-copper catalysed highly regioselective synthesis of 2,4-disubstituted pyrroles from terminal alkynes and isocyanides

Nano-copper(0) stabilized on alumina prepared from Cu–Al hydrotalcite has been reported for completely regioselective synthesis of 2,4-disubstituted pyrroles from unactivated terminal aromatic/aliphatic alkynes and isocyanides.