Gold-Catalyzed Cyclizations of (<i>o</i>‑Alkynyl)phenoxyacrylates with External Nucleophiles: Regio- and Stereoselective Synthesis of Functionalized Benzo[<i>b</i>]oxepines

A catalytic approach to benzo[<i>b</i>]oxepines with high stereoselectivity by Au-catalyzed cyclization of (<i>o</i>-alkynyl)phenoxyacrylates with various nucleophiles under mild reaction conditions has been developed. Notably, the use of vinyl ether instead of alcohol could afford the same benzoxepines. The reaction may proceed by Au-catalyzed oligomerization of vinyl ether to release the alcohol, which then reacts with (<i>o</i>-alkynyl)phenoxyacrylates to furnish the benzoxepines

Gold-Catalyzed Cyclizations of (<i>o</i>‑Alkynyl)phenoxyacrylates with External Nucleophiles: Regio- and Stereoselective Synthesis of Functionalized Benzo[<i>b</i>]oxepines

A catalytic approach to benzo[<i>b</i>]oxepines with high stereoselectivity by Au-catalyzed cyclization of (<i>o</i>-alkynyl)phenoxyacrylates with various nucleophiles under mild reaction conditions has been developed. Notably, the use of vinyl ether instead of alcohol could afford the same benzoxepines. The reaction may proceed by Au-catalyzed oligomerization of vinyl ether to release the alcohol, which then reacts with (<i>o</i>-alkynyl)phenoxyacrylates to furnish the benzoxepines

Gold-Catalyzed Cyclizations of (<i>o</i>‑Alkynyl)phenoxyacrylates with External Nucleophiles: Regio- and Stereoselective Synthesis of Functionalized Benzo[<i>b</i>]oxepines

A catalytic approach to benzo[<i>b</i>]oxepines with high stereoselectivity by Au-catalyzed cyclization of (<i>o</i>-alkynyl)phenoxyacrylates with various nucleophiles under mild reaction conditions has been developed. Notably, the use of vinyl ether instead of alcohol could afford the same benzoxepines. The reaction may proceed by Au-catalyzed oligomerization of vinyl ether to release the alcohol, which then reacts with (<i>o</i>-alkynyl)phenoxyacrylates to furnish the benzoxepines

Gold-Catalyzed Cyclizations of (<i>o</i>‑Alkynyl)phenoxyacrylates with External Nucleophiles: Regio- and Stereoselective Synthesis of Functionalized Benzo[<i>b</i>]oxepines

A catalytic approach to benzo[<i>b</i>]oxepines with high stereoselectivity by Au-catalyzed cyclization of (<i>o</i>-alkynyl)phenoxyacrylates with various nucleophiles under mild reaction conditions has been developed. Notably, the use of vinyl ether instead of alcohol could afford the same benzoxepines. The reaction may proceed by Au-catalyzed oligomerization of vinyl ether to release the alcohol, which then reacts with (<i>o</i>-alkynyl)phenoxyacrylates to furnish the benzoxepines

Nucleophilic Addition of Grignard Reagents to 3–Acylindoles: Stereoselective Synthesis of Highly Substituted Indoline Scaffolds

3-Acylindoles undergo nucleophilic-type reactions with Grignard reagents to efficiently afford either <i>cis</i>- or <i>trans</i>-substituted indolines, depending on the different quenching procedures. The enolate intermediate could be trapped by aryl acyl chlorides to provide indolines bearing a quaternary carbon center with high stereoselectivity. In contrast, the use of benzyl bromide as an electrophile results in the fragmentation of the indole ring. The indoline products could be easily transformed into indoles through oxidation with DDQ in a one-pot manner

Environmentally Benign Synthesis of Indeno[1,2‑<i>b</i>]quinolines via an Intramolecular Povarov Reaction

A new synthetic route to indeno[1,2-<i>b</i>]quinolines via reactions of <i>o</i>-propargylbenzaldehydes with <i>N</i>-aryl amines based on an intramolecular aza-Diels–Alder (Povarov) reaction has been developed. This method offers several advantages such as no requirement for an oxidant, high efficiency, and a wide reaction scope

Nucleophilic Addition of Grignard Reagents to 3–Acylindoles: Stereoselective Synthesis of Highly Substituted Indoline Scaffolds

3-Acylindoles undergo nucleophilic-type reactions with Grignard reagents to efficiently afford either <i>cis</i>- or <i>trans</i>-substituted indolines, depending on the different quenching procedures. The enolate intermediate could be trapped by aryl acyl chlorides to provide indolines bearing a quaternary carbon center with high stereoselectivity. In contrast, the use of benzyl bromide as an electrophile results in the fragmentation of the indole ring. The indoline products could be easily transformed into indoles through oxidation with DDQ in a one-pot manner

Facile Synthesis of Fully Substituted Dihydro-β-carbolines via Brønsted Acid Promoted Cascade Reactions of α‑Indolyl Propargylic Alcohols with Nitrones

A straightforward synthesis of fully substituted β-carbolines via Brønsted acid promoted cyclizations of α-indolyl propargylic alcohols with nitrones is described. The use of nitrones bearing alkenyl or electron-rich aryl groups as the R⁴ substituent dramatically switches the reaction pathway to afford tetrasubstituted alkenes and amines, which is assumed to proceed through a rearrangement reaction involving N–O bond cleavage and 1,2-migration of the R⁴ group to an adjacent nitrogen atom

Facile Synthesis of Fully Substituted Dihydro-β-carbolines via Brønsted Acid Promoted Cascade Reactions of α‑Indolyl Propargylic Alcohols with Nitrones

A straightforward synthesis of fully substituted β-carbolines via Brønsted acid promoted cyclizations of α-indolyl propargylic alcohols with nitrones is described. The use of nitrones bearing alkenyl or electron-rich aryl groups as the R⁴ substituent dramatically switches the reaction pathway to afford tetrasubstituted alkenes and amines, which is assumed to proceed through a rearrangement reaction involving N–O bond cleavage and 1,2-migration of the R⁴ group to an adjacent nitrogen atom

Nickel-Catalyzed Highly Regioselective Hydrocyanation of Terminal Alkynes with Zn(CN)₂ Using Water as the Hydrogen Source

The first efficient and general nickel-catalyzed hydrocyanation of terminal alkynes with Zn­(CN)₂ in the presence of water has been developed. The reaction provides a regioselective protocol for the synthesis of functionalized vinyl nitriles with a range of structural diversity under mild reaction conditions while obviating use of the volatile and hazardous reagent of HCN. Deuterium-labeling experiments confirmed the role of water as the hydrogen source in this hydrocyanation reaction