Rh(II)-Catalyzed Chemoselective Oxidative Amination and Nucleophilic Trapping of <i>gem</i>-Dimethyl Alkynyl-Tethered Sulfamates

A Rh­(II)-catalyzed chemoselective oxidative amination and nucleophilic trapping of <i>gem</i>-dimethyl sulfamates has been presented. For 2,2-dimethyl-4-arylbut-3-yn-1-yl sulfamates, the reactions underwent a metallonitrene-initiated alkyne oxidation along with nucleophilic trapping of H₂O upon oxidation, giving aroyl group containing heterocycles. For 2,2-dimethyl-4-arylpent-3-yn-1-yl sulfamates, the α-iminometal carbene intermediate was trapped by aryl group migration, delivering a styryl group containing heterocycles

Pd(II)-Catalyzed Tandem Heterocyclization of 1‑(1-Alkynyl)cyclopropyl Oxime Derivatives for the Synthesis of Functionalized Pyrroles

An efficient approach for the synthesis of highly functionalized pyrroles has been developed by a Pd­(TFA)₂-catalyzed tandem heterocyclization of 1-(1-alkynyl)­cyclopropyl oxime derivatives under mild conditions. The reaction first proceeded via an intramolecular nucleophilic attack followed by a ring-opening process and then intermolecular nucleophilic attack as well as protonation to afford the desired products in moderate to excellent yields

Rh(II)-Catalyzed Chemoselective Oxidative Amination and Cyclization Cascade of 1‑(Arylethynyl)cycloalkyl)methyl Sulfamates

A Rh­(II)-catalyzed chemoselective oxidative amination and cyclization cascade of 1-(arylethynyl)­cyclo­alkyl)­methyl sulfamates has been presented. For a cyclopropyl or cyclobutyl moiety containing alkynyl sulfamates, the reactions underwent a metallonitrene-initiated alkyne oxidation along with cyclopropyl ring expansion or alkoxyl moiety migration to give cyclobutane-fused or methylene­cyclobutane-containing heterocycles. In the case of a cyclopentyl or cyclohexyl moiety containing sulfamate, the reaction underwent a direct C–H bond insertion event to afford the corresponding nitrogen-containing heterocyclic product

Rhodium(I)-Catalyzed Pauson–Khand-type [3 + 2 + 1] Cycloaddition Reaction of Ene-Vinylidenecyclopropanes and CO: A Highly Regio- and Stereoselective Synthetic Approach for the Preparation of Aza- and Oxa-Bicyclic Compounds

In this paper, a novel Rh­(I)-catalyzed Pauson–Khand-type [3 + 2 + 1] cycloaddition reaction of ene-vinylidenecyclopropanes (Ene-VDCPs) and carbon monoxide (CO) has been developed to furnish a series of aza- and oxa-bicyclic compounds in moderate to good yields in a highly regio- and diastereoselective manner, which provides an alternative and efficient synthetic approach for the access of bicyclic cyclohexanone frameworks. The substrate scope and limitations and a plausible mechanism are discussed

Rhodium(I)-Catalyzed Pauson–Khand-type [3 + 2 + 1] Cycloaddition Reaction of Ene-Vinylidenecyclopropanes and CO: A Highly Regio- and Stereoselective Synthetic Approach for the Preparation of Aza- and Oxa-Bicyclic Compounds

In this paper, a novel Rh­(I)-catalyzed Pauson–Khand-type [3 + 2 + 1] cycloaddition reaction of ene-vinylidenecyclopropanes (Ene-VDCPs) and carbon monoxide (CO) has been developed to furnish a series of aza- and oxa-bicyclic compounds in moderate to good yields in a highly regio- and diastereoselective manner, which provides an alternative and efficient synthetic approach for the access of bicyclic cyclohexanone frameworks. The substrate scope and limitations and a plausible mechanism are discussed

Synthesis of Polysubstituted Polycyclic Aromatic Hydrocarbons by Gold-Catalyzed Cyclization–Oxidation of Alkylidenecyclopropane-Containing 1,5-Enynes

A gold-catalyzed tandem cyclization–oxidation of alkylidenecyclopropane-containing 1,5-enynes with 3,5-dibromo-pyridine <i>N</i>-oxide via a noncarbene model was developed, providing a range of synthetically valuable and useful arylacetaldehyde derivatives in moderate to good yields without oxidation of alkynes. Moreover, the corresponding aldehydes can be further transformed into polycyclic aromatic hydrocarbons in the presence of a catalytic amount of Lewis acid In­(OTf)₃. The reaction represents an example of gold-catalyzed halide-free Kornblum-type oxidation through the oxidation of the cyclopropane moiety

Synthesis of Polysubstituted Polycyclic Aromatic Hydrocarbons by Gold-Catalyzed Cyclization–Oxidation of Alkylidenecyclopropane-Containing 1,5-Enynes

A gold-catalyzed tandem cyclization–oxidation of alkylidenecyclopropane-containing 1,5-enynes with 3,5-dibromo-pyridine <i>N</i>-oxide via a noncarbene model was developed, providing a range of synthetically valuable and useful arylacetaldehyde derivatives in moderate to good yields without oxidation of alkynes. Moreover, the corresponding aldehydes can be further transformed into polycyclic aromatic hydrocarbons in the presence of a catalytic amount of Lewis acid In­(OTf)₃. The reaction represents an example of gold-catalyzed halide-free Kornblum-type oxidation through the oxidation of the cyclopropane moiety

Cascade Amination/Cyclization/Aromatization Process for the Rapid Construction of [2,3‑<i>c</i>]Dihydrocarbazoles and [2,3‑<i>c</i>]Carbazoles

An intramolecular cascade amination/cyclization/aromatization reaction of functionalized alkylidenecyclopropanes has been developed in the presence of silver acetate, affording a variety of [2,3-<i>c</i>]­dihydrocarbazoles and [2,3-<i>c</i>]­carbazoles in moderate to excellent yields. The mechanistic investigations revealed that this cascade reaction proceeds through a radical initiated process. Moreover, further transformations for the synthesis of eustifoline-D and an OLED exhibit a potential synthetic utility of this method

Palladium-Catalyzed Asymmetric Formal [3+2] Cycloaddition of Vinyl Cyclopropanes and β,γ-Unsaturated α‑Keto Esters: An Effective Route to Highly Functionalized Cyclopentanes

Palladium-catalyzed asymmetric formal [3+2] cycloaddition of vinyl cyclopropanes and β,γ-unsaturated α-keto esters proceeded smoothly in the presence of chiral imidazoline–phosphine ligands to give the corresponding highly functionalized cyclopentanes in good yields along with high diastereo- and enantioselectivities under mild conditions

Cascade Amination/Cyclization/Aromatization Process for the Rapid Construction of [2,3‑<i>c</i>]Dihydrocarbazoles and [2,3‑<i>c</i>]Carbazoles

An intramolecular cascade amination/cyclization/aromatization reaction of functionalized alkylidenecyclopropanes has been developed in the presence of silver acetate, affording a variety of [2,3-<i>c</i>]­dihydrocarbazoles and [2,3-<i>c</i>]­carbazoles in moderate to excellent yields. The mechanistic investigations revealed that this cascade reaction proceeds through a radical initiated process. Moreover, further transformations for the synthesis of eustifoline-D and an OLED exhibit a potential synthetic utility of this method