[EN] ASYMMETRIC ELECTROPHILIC FLUORINATION USING AN ANIONIC CHIRAL PHASE-TRANSFER CATALYST [FR] FLUORATION ÉLECTROPHILE ASYMÉTRIQUE UTILISANT UN CATALYSEUR DE TRANSFERT DE PHASE CHIRAL ANIONIQUE
[EN] ASYMMETRIC ELECTROPHILIC FLUORINATION USING AN ANIONIC CHIRAL PHASE-TRANSFER CATALYST<br/>[FR] FLUORATION ÉLECTROPHILE ASYMÉTRIQUE UTILISANT UN CATALYSEUR DE TRANSFERT DE PHASE CHIRAL ANIONIQUE
申请人:UNIV CALIFORNIA
公开号:WO2013096971A1
公开(公告)日:2013-06-27
The discovery of distinct modes of asymmetric catalysis has the potential to rapidly advance chemists' ability to build enantioenriched molecules. As an example, the use of chiral cation salts as phase-transfer catalysts for anionic reagents has enabled a vast set of enantioselective transformations. A largely overlooked analogous mechanism wherein a chiral anionic catalyst brings a cationic species into solution is itself a powerful method. The concept is broadly applicable to a number of different reaction pathways, including to the enantioselective fluorocyclization of olefins, and dearomatization of aromatic systems with a cationic electrophile-transferring (e.g., fluorinating) agent and a chiral phosphate catalyst. The reactions proceed in high yield and stereoselectivity. The compounds and methods of the invention are of particular value, especially considering the scarcity of alternative approaches.
enantioselective bromocyclization of allylic amides catalyzed by phosphorus‐containing Lewis bases was examined in detail. A series of control experiments and NMR studies showed that a partially oxidized bis‐phosphine generated in situ serves as the actual enantioselective catalyst. The reaction mechanism involves distinct roles of two Lewis basic sites, P and P=O, with P+Br serving as a fine‐tuning element
ASYMMETRIC ELECTROPHILIC FLUORINATION USING AN ANIONIC CHIRAL PHASE-TRANSFER CATALYST
申请人:THE REGENTS OF THE UNIVERSITY OF CALIFORNIA
公开号:US20140350253A1
公开(公告)日:2014-11-27
The discovery of distinct modes of asymmetric catalysis has the potential to rapidly advance chemists' ability to build enantioenriched molecules. As an example, the use of chiral cation salts as phase-transfer catalysts for anionic reagents has enabled a vast set of enantioselective transformations. A largely overlooked analogous mechanism wherein a chiral anionic catalyst brings a cationic species into solution is itself a powerful method. The concept is broadly applicable to a number of different reaction pathways, including to the enantioselective fluorocyclization of olefins, and dearomatization of aromatic systems with a cationic electrophile-transferring (e.g., fluorinating) agent and a chiral phosphate catalyst. The reactions proceed in high yield and stereoselectivity. The compounds and methods of the invention are of particular value, especially considering the scarcity of alternative approaches.
<i>Anti</i>-Diastereoselective Synthesis of CF<sub>3</sub>-Containing Spirooxazolines and Spirooxazines via Regiospecific Trifluoromethylative Spirocyclization by Photoredox Catalysis
A novel synthesis of CF3-containing spirooxazolines and spirooxazines has been developed. Regiospecific trifluoromethylative spirocyclization (CF3-spirocyclization) of cyclic alkenes bearing an amide pendant mediated by photoredox catalysis is a useful strategy for construction of a C(sp(3))-CF3 bond and an spirooxazoline or spirooxazine ring onto C = C bonds via a single step. The key intermediate is alpha-CF3-substituted carbocationic species smoothly generated from single-electron-transfer (SET) photoredox processes, which results in diastereoselective spirocyclization. This is the first example of synthesis of CF3-containing spirooxazolines and spirooxazines in anti-fashion with respect to the CF3 group and the oxygen atom of the spirocycles.