A synthesis of fuctionalized 2-amino-3-cyano pyrroles from terminal alkynes, sulfonyl azides and phenacylmalononitriles

A new strategy for the construction of functionalized 2-amino-3-cyano pyrroles has been developed. The reactions involved a copper-catalyzed azide-alkyne cycloaddtion reaction between terminal alkynes and sulfonyl azides followed by generation of N-sulfonoketenimine intermediates. Interception of these reactive ketenimines by phenacylmalononitriles in the presence of copper(I) iodide and Et₃N afforded the expected products. The reaction proceeded smoothly in THF at ambient temperature to afford the target compounds in 70-92% yields and excellent regioselectivity. Evidence for the structure of a typical product is obtained from single-crystal X-ray analyses.

Efficient synthesis of cyclic amidine-based fluorophores via 6π-electrocyclic ring closure

Novel 10π-electron cyclic amidines with excellent fluorescence properties were synthesized by a general and efficient 6π-electrocyclic ring closure of ketenimine and imine starting from N-sulfonyl triazoles and arylamines. The photophysical properties of cyclic amidine fluorophores have been studied in detail and have shown good properties of a large Stokes shift, pH insensitivity, low cytotoxicity and higher photostability, which have great potential for biological imaging. Furthermore, this novel fluorophore was successfully applied to the localization of the NK-1 receptor in living systems.

Novel 10π-electron cyclic amidines with excellent fluorescence properties were synthesized by a general and efficient 6π-electrocyclic ring closure of ketenimine and imine starting from N-sulfonyl triazoles and arylamines.

One-Pot Synthesis of 4-Sulfonyliminotetrahydropyrimidin-2-one Derivatives through a Copper-Catalyzed Tandem Reaction

A novel and efficient synthesis of 4-iminotetrahydropyrimidin-2-one derivatives was developed through a Cu(I)-catalyzed three-component tandem reaction employing propargylamines, isocyanates, and sulfonyl azides as starting materials. A wide range of polysubstituted 4-sulfonyliminotetrahydropyrimidin-2-ones, which might be useful in biological chemistry and medicinal science, were conveniently and efficiently assembled in one pot.

Copper-Catalyzed Diversity-Oriented Synthesis (DOS) of 4-Amino-2H-chromen-2-imines: Application of Kemp Elimination toward O-Heterocycles

We report herein a copper-catalyzed sequential multicomponent reaction of benzo[d]isoxazoles with terminal alkynes and sulfonyl azides, which produced divergent 4-amino-2H-chromen-2-imines with excellent chemical selectivity. The reaction tolerated a broad range of functional groups, and released only N₂ as the sole byproduct. The sulfonyl imino group could be removed to give biologically active free 4-amino-2H-chromenone in good yield.

A new and facile approach to 1,2-dihydroisoquinolin-3(4H)-imines by the Cu(i)-catalyzed reaction of 2-ethynylbenzyl methanesulfonates, sulfonyl azides and amines

A new, step-economical and operationally simple access to unsubstituted 1,2-dihydroisoquinolin-3(4H)-imines by Cu-catalyzed MCRs under mild conditions is described.

1,3-Dien-5-ynes: Versatile Building Blocks for the Synthesis of Carbo- and Heterocycles

1,3-Dien-5-ynes have been extensively used as starting materials for the synthesis of a wide number of different carbo- and heterocycles. The aim of this review is to give an overview of their utility in organic synthesis, highlighting the variety of compounds that can be directly accessed from single reactions over these systems. Thus, cycloaromatization processes are initially commented, followed by reactions directed toward the syntheses of five-membered rings, other carbocycles and, finally, heterocycles. The diverse methodologies that have been developed for the synthesis of each of these types of compounds from 1,3-dien-5-ynes are presented, emphasizing the influence of the reaction conditions and the use of additional reagents in the outcome of the transformations.

Copper-catalyzed three-component cascade reaction of alkynes, sulfonyl azides and simple aldehydes/ketones

A copper-catalyzed dimethylzinc-promoted three-component cascade reaction of alkynes, sulfonyl azides, and simple aldehydes or ketones is described, which delivers polysubstituted olefins expeditiously in one pot under mild conditions.

Potentially antibreast cancer enamidines via azide–alkyne–amine coupling and their molecular docking studies

Potentially antibreast cancer enamidines were synthesized and evaluated against human breast cancer cell line MCF7 displaying GI₅₀values lower than doxorubicin.

Regioselective synthesis of functionalized dihydroisoquinolines from o-alkynylarylaldimines via the Reformatsky reaction

A novel approach for the synthesis of functionalized 1,2-dihydroisoquinolines from o-alkynylarylaldimines via the Reformatsky reaction without the aid of an external Lewis acid has been described.

One-pot synthesis of hydrazono-sulfonamide adducts using Cu(BTC) MOF catalyst and their remarkable AIEE properties: unprecedented copper(ii)-catalyzed generation of ketenimine

One pot & simple operation; short reaction time; no column purification; very less catalyst loading; scalable.

Iron(iii) halide or iodine-promoted synthesis of 3-haloindene derivatives from o-alkynylarene chalcones

The treatment of o-alkynylarene chalcones with ferric halides/iodine affords 3-haloindene derivatives in good yields.

Selective C(sp2)-C(sp) bond cleavage: the nitrogenation of alkynes to amides

Breakthrough: A novel catalyzed direct highly selective C(sp2)-C(sp) bond functionalization of alkynes to amides has been developed. Nitrogenation is achieved by the highly selective C(sp2)-C(sp) bond cleavage of aryl-substituted alkynes. The oxidant-free and mild conditions and wide substrate scope make this method very practical.

An efficient approach for the construction of benzazepine and benzoxepine derivatives

A novel and facile synthetic protocol for the construction of benzazepine and benzoxepine derivatives through a copper(I)-catalyzed reaction of 2-(2-ethynylphenyl)-1-tosylaziridine or 2-(2-ethynylphenyl)oxirane with sulfonyl azides is disclosed. A ketenimine is the key intermediate during the reaction process.

Unexpected catalytic reactions of silyl-protected enol diazoacetates with nitrile oxides that form 5-arylaminofuran-2(3H)-one-4-carboxylates

Silyl-protected enol diazoacetates undergo dirhodium(II)-catalyzed reactions with nitrile oxides to form acid-labile ketenimines via dipolar cycloaddition of nitrile oxides to a donor/acceptor cyclopropene and Lossen rearrangement of the dipolar adduct; acid catalysis converts the ketenimine to the furan product.

An efficient route to tetrahydroindeno[2,1-b]pyrroles via a base-promoted reaction of (E)-2-alkynylphenylchalcone with 2-isocyanoacetate

A base-promoted cascade reaction of (E)-2-alkynylphenylchalcone with 2-isocyanoacetate provides a novel and efficient route for the synthesis of tetrahydroindeno[2,1-b]pyrroles. The reaction proceeds smoothly in air under mild conditions with high efficiency.