Silver-Catalyzed (Z)-β-Fluoro-vinyl Iodonium Salts from Alkynes: Efficient and Selective Syntheses of Z-Monofluoroalkenes
Alexi T. Sedikides,
Alastair J. J. Lennox
Abstract:Monofluoroalkenes are stable and lipophilic amide bioisosteres
used in medicinal chemistry. However, efficient and stereoselective
methods for synthesizing Z-monofluoroalkenes are
underdeveloped. We envisage (Z)-β-fluoro-vinyl
iodonium salts (Z-FVIs) as coupling partners for
the diverse and stereoselective synthesis of Z-monofluoroalkenes.
Disclosed herein is the development and application of a silver(I)-catalyzed
process for accessing a broad scope of (Z)-FVIs with
exclusive Z-stereoselectivity and regiosele… Show more
A new variant of Fisher indole synthesis involving Bronsted acid-catalyzed hydrohydrazination of unactivated terminal and internal acetylenes with arylhydrazines is reported. The use of polyphosphoric acid alone either as the reaction medium or in the presence of a co-solvent appears to provide the required balance for activating the C–C triple bond towards the nucleophilic attack of the hydrazine moiety without unrepairable reactivity loss of the latter due to competing amino group protonation. Additionally, the formal hydration of acetylenes to the corresponding ketones occurs under the same conditions, making it an alternative approach for generating carbonyl groups from alkynes.
A new variant of Fisher indole synthesis involving Bronsted acid-catalyzed hydrohydrazination of unactivated terminal and internal acetylenes with arylhydrazines is reported. The use of polyphosphoric acid alone either as the reaction medium or in the presence of a co-solvent appears to provide the required balance for activating the C–C triple bond towards the nucleophilic attack of the hydrazine moiety without unrepairable reactivity loss of the latter due to competing amino group protonation. Additionally, the formal hydration of acetylenes to the corresponding ketones occurs under the same conditions, making it an alternative approach for generating carbonyl groups from alkynes.
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