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Catalytic carbene transfer reactions are fundamental transformations in modern organic synthesis, which enable direct access to diverse structurally complex molecules. Despite diazo precursors playing a crucial role in catalytic carbene transfer reactions, most reported methodologies take into account only diazoacetates or related compounds. This is primarily because diazoalkanes, unless they contain a resonance stabilizing group, are more susceptible to violent exothermic decomposition. In this feature article, we present an alternative approach to carbene-transfer reactions based on the formation of highly electrophilic silver carbenes from N-sulfonylhydrazones, where the high electrophilicity of silver carbenes stems from the weak interaction between silver and the carbenic carbon. These precursors are readily accessible, stable, and environmentally sustainable. Using the strategy that employs highly electrophilic silver carbenes, it is possible to develop novel intermolecular transformations involving non-stabilized carbenes, including C(sp3)–H insertion, C(sp3)–C(O) insertion, cycloaddition, and defluorinative functionalization. The silver-catalyzed carbene transfer reactions described here have high efficiency, unusual reactivity, exceptional selectivity, and a reaction pathway that differs from typical transition metal-catalyzed reactions. Our research provided fundamental insight into silver carbene chemistry, and we hope to apply this mode of catalysis to other more general transformations, including asymmetric transformations. [ABSTRACT FROM AUTHOR]

The [2+1] cycloaddition of alkynes with diazo compounds represents one of the most powerful and reliable methods for the construction of cyclopropenes. However, it remains a formidable challenge to accomplish the cyclopropenation of alkynes with non-stabilized diazoalkanes, owing to the fact that such compounds are unstable and prone to detonation. Herein, we report a general silver-catalyzed cyclopropenation reaction of alkynes with unstable diazoalkanes, by for the first time the discovery and application of N-nosylhydrazones as room-temperature decomposiable diazo surrogates. This method allows for the efficient assembly a wide variety of cyclopropene derivatives that are otherwise difficult to access by conventional methods. [ABSTRACT FROM AUTHOR]

A new silver-promoted [3+2] cycloaddition of azomethine ylides with isocyanides has been described. The methodology provides an efficient and modular approach to 1,2,4-trisubstituted imidazoles of vital bioactive molecules and atypical antipsychotics analogues. [ABSTRACT FROM AUTHOR]

The first cyclization reaction between vinyl azides and N-sulfonyl-1,2,3-triazoles is reported. A Rh/Ag binary metal catalyst system proved to be necessary for the successful cyclization. By varying the structure of vinyl azides, such reaction allows the divergent synthesis of pyrroles and 2 H-pyrazines. The cyclization reactions feature a broad substrate scope, good functional group tolerance, high reaction efficiency, and good to high product yields. [ABSTRACT FROM AUTHOR]

Imidazole ring is an important five-membered aromatic heterocycle that is widely present in natural products and synthetic molecules. The isocyanide-isocyanide [3+2] cross-cycloaddition reaction constitutes a straightforward method to access imidazoles starting from the easily available chemicals. So far, only three successive reports are known and all lead to the formation of 1,4-disubstituted imidazoles. Here, we report the first isocyanide-isocyanide [3+2] cross-cycloaddition reaction allowing for the formation of 1,4,5-trisubstituted imidazoles under silver catalysis. An unexpected 1,2-migration of sulfonyl, alkoxycaybonyl, and carbamoyl groups took place during the cyclization process that is responsible for the formation of trisubstituted imidazoles. This report displayed a mechanistically novel synthetic method toward a variety of imidazole derivatives, which are otherwise difficult to access by conventional methods. [ABSTRACT FROM AUTHOR]

Decarbonylation of saccharins by nickel catalysis enables two kinds of CC bond-forming reactions; homocoupling of saccharins to form biaryls and cycloaddition with alkynes to form benzosultams. The former represents the first reported nickel-catalyzed decarbonylative CC homocoupling reaction, whereas the latter constitutes a powerful method to pharmaceutically relevant benzosultams. The reactions proceed with good functional-group tolerance and excellent regioselectivity. [ABSTRACT FROM AUTHOR]

An environmentally friendly route to fully substituted 4,5-dihydropyrroles was developed through the iron-catalyzed [4C+1N] cyclization of 4-acetylenic ketones with primary amines in 1,5-pentanediol. [ABSTRACT FROM AUTHOR]

A new and straightforward base-catalyzed 5- exo- trig cyclization of 2-propynyl-1,3-dicarbonyl compounds leads to the corresponding stereodefined 2-methylene-2,3-dihydrofurans in excellent yields. [ABSTRACT FROM AUTHOR]

Cyclopentadienes are valuable intermediates in organic synthesis and also ubiquitous as the Cp ligands in organometallic chemistry. As part of ongoing efforts to develop novel organic reactions that employ functionalized alkynes, a [3+2] cycloaddition of propargylic alcohols and ketene dithioacetals has been developed, which leads to fully substituted 2,5-dialkylthio cyclopentadienes in good to excellent yields. In an unusual dethiolating Diels-Alder reaction, the cyclopentadienes were further reacted with maleimides to afford a family of novel fluorescent polycyclic compounds. [ABSTRACT FROM AUTHOR]

The article presents a study which examines a novel silver-catalyzed isocyanide-alkyne cycloaddition. It states that the scope of internal alkynes that have been used in base-or copper-catalyzed procedures was further investigates to examine the generality of silver-catalyzed isocyanide-alkyne cycloaddition. It concludes that Ag2CO3 was discovered as a unique catalyst for isocyanides cycloaddition.

Cu2O as the catalyst in water was found to be quite robust for the azide-alkyne cycloaddition (AAC) reaction, which was verified by a wide variety of applicable azides and alkynes. Water was proved to play an essential role because of a significant rate acceleration compared with reactions using organic solvents and conducted under neat conditions. The high catalytic performance of Cu2O/H2O system was further argued by decreasing the catalyst loading to ppm levels. [ABSTRACT FROM AUTHOR]

Cu2O as the catalyst in water was found to be quite robust for the azide-alkyne cycloaddition (AAC) reaction, which was verified by a wide variety of applicable azides and alkynes. Water was proved to play an essential role because of a significant rate acceleration compared with reactions using organic solvents and conducted under neat conditions. The high catalytic performance of Cu2O/H2O system was further argued by decreasing the catalyst loading to ppm levels. [ABSTRACT FROM AUTHOR]

A novel Cu(ii)-catalyzed cyclization of α-diazo-β-oxoamides with amines has been developed, constituting a straightforward method to construct pyrrol-3(2H)-one rings. The intramolecular hydrogen bonding effect in α-diazo-β-oxoamides plays an essential role in this reaction. A plausible reaction mechanism involving divergent generation and subsequent [2 + 3] cyclization of ketene and α-diazoimine intermediates was proposed. [ABSTRACT FROM AUTHOR]

The oxidant iodosobenzene diacetate was combined with the cheap, environment-friendly FeCl as a chloride source to produce an efficient chlorinating agent for α-chlorination of ketene dithioacetals through direct C(sp)-H chlorination. Furthermore, the synthetic utility of α-chlorinated ketene dithioacetals was verified by the intermolecular cyclization with hydrazine hydrate, leading to the synthesis of pyrazoles, in which a 1,2-sulfur migration was involved. [ABSTRACT FROM AUTHOR]

A highly efficient iron-catalyzed approach to polysubstituted pyrroles has been developed through the [4C+1N] cyclization of 4-acetylenic ketones with primary amines, leading to the synthesis of a variety of tetra- and fully-substituted pyrroles as well as fused pyrrole derivatives in good to excellent yields. [ABSTRACT FROM AUTHOR]

N‐Nosylhydrazones were discovered as the first generation of room‐temperature decomposable diazo surrogates, which led to the development of silver‐catalyzed [2+1] cyclopropenation of alkynes with unstable diazoalkanes. More information can be found in the Communication by X. Bi et al. on page 4756 ff. [ABSTRACT FROM AUTHOR]

The combined chemistry of silver and isocyanides is unique in performance, proved with the number of recent achievements. With the aim of triggering further research in this field, this review assembles and comprehensively summarizes the silver-based reactions of isocyanides. In this review, we especially emphasize the uniqueness of silver catalysis in the activation of isocyanides, the reaction selectivity, and the mechanistic description. [ABSTRACT FROM AUTHOR]

This novel protocol, involving copper(II)-catalyzed oxidative N-N coupling and a non-oxidative C-N bond formation, provides an alternative to the conventional [3+2] methods. [ABSTRACT FROM AUTHOR]

The article presents a chemical reaction for the alkyne-azide cycloaddition of diynes.

Various N-aryl saccharins can be transformed to biphenyl-2,2′-disulfonamides of type (II) in the presence of PBu3/Ni(cod)2 followed by treatment with TfOH. [ABSTRACT FROM AUTHOR]

An atom-economic route to benzo[f]-1-indanone frameworks is developed starting from readily available gem-dialkylthio trienynes by intramolecular annulations. [ABSTRACT FROM AUTHOR]

An environmentally friendly route towards fully substituted 4,5-dihydropyrroles is provided. [ABSTRACT FROM AUTHOR]

An abstract of the article "Silver-Catalyzed Cyclization of 2-Pyridyl Alkynyl Carbinols with Isocyanides: Divergent Synthesis of Indolizines and Pyrroles" by Xianyu Meng and colleagues is presented.

The article presents chemical equations related to the [3 + 2] cycloaddition of propargylic alcohols and α-oxo ketene dithioacetals with the synthesis of functionalized cyclopentadienes by Z. Fang and others, published in the periodical "Angewandte Chemie International Edition" in 2014.

Ag2CO3 is described as robust catalyst for the [3 + 2] cycloaddition of isocyanide and terminal or internal alkynes to provide 2,3-disubstituted and 2,3,4-trisubstituted pyrroles. [ABSTRACT FROM AUTHOR]