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Abstract Herein, we present an approach for catalytic orthogonal glycosylation utilizing earth‐abundant copper carbenes. This method operates under mild conditions and employs readily accessible starting materials, including benchtop stable enynal‐derived glycosyl donors, synthesized at the gram scale. The reaction accommodates a variety of glycosyl acceptors, including primary, secondary, and tertiary alcohols. The enynal‐derived copper carbenes exhibit remarkable reactivity and selectivity, allowing for the formation of glycosidic linkages with different protecting groups and stereochemical patterns. This approach provides access to both 1,2‐cis‐ and ‐trans‐glycosidic linkages. The product stereoselectivity is independent of the anomeric configuration of the glycosyl donor, which also has orthogonal reactivity to widely used alkynes and thioglycoside donors. An iterative synthesis of a trisaccharide further demonstrates the application of this orthogonal reactivity. 

Abstract Dual catalysis represents an alternative archetype in carbene chemistry that surpasses traditional single catalyst systems. By employing dual catalyst systems, one can improve the efficiency of existing reactions and enable new chemical transformations. Reactions involving dual synergistic catalysis are increasingly valuable as they offer convenient strategies for synthesizing challenging quaternary carbon centers and bioactive core structures. This review article focuses on trapping diazo‐derived, rhodium (II) zwitterionic intermediates with varying electrophiles such as Michael acceptors, alkynes, π‐allyl Pd(II) complexes, and the Nicholas intermediate. 

Abstract A Rh(II)/Au(I) catalyzed carbene cascade approach for the stereoselective synthesis of diverse spirocarbocycles is described. The cascade reaction involves a rhodium carbene initiatedsp²C−H functionalization followed by a gold catalyzed Conia‐ene cyclization. The cascade reaction accommodates a variety of aryl substituents as well as ring sizes and proceeds with high diastereoselectivity providing access to diverse spirocarbocycles. magnified image 

In this study, we investigate the reactivity of nitrous oxide (N₂O) with lithiated diarylmethylhydrazines, leading to the formation of diarylethanesviadinitrogen extrusion. 

Given the prevalence of nitrogen-containing heterocycles in commercial drugs, selectively incorporating a single nitrogen atom is a promising scaffold hopping approach to enhance chemical diversity in drug discovery libraries. We harness the distinct reactivity of sulfenylnitrenes, which insert a single nitrogen atom to transform readily available pyrroles, indoles, and imidazoles into synthetically challenging pyrimidines, quinazolines, and triazines, respectively. Our additive-free method for skeletal editing employs easily accessible, benchtop-stable sulfenylnitrene precursors over a broad temperature range (−30 to 150°C). This approach is compatible with diverse functional groups, including oxidation-sensitive functionalities such as phenols and thioethers, and has been applied to various natural products, amino acids, and pharmaceuticals. Furthermore, we have conducted mechanistic studies and explored regioselectivity outcomes through density functional theory calculations. 

Traditional glycosylation methods using thioglycosides often require harsh conditions or expensive metal catalysts. This study presents a more sustainable alternative by employing copper, an earth-abundant catalyst. We developed diazo-based thioglycoside donors that, through copper catalysis, undergo intramolecular activation to form glycosyl sulfonium ions, leading to the generation of oxocarbenium ions. This versatile approach efficiently accommodates a variety of O-nucleophiles, including primary, secondary, and tertiary, as well as complex bioactive molecules. It is compatible with various glycosyl donors and protecting groups, including superarmed, armed, and disarmed systems. Notably, the methodology operates orthogonally to traditional thioglycoside and alkyne donors and has been successfully applied to the orthogonal iterative synthesis of trisaccharides. Mechanistic insights were gained by studying the electronic effects of electron-donating (OMe) and electron-withdrawing (NO2) groups on the donors, offering a valuable understanding of the intramolecular reaction pathway.