Organocatalytic Arylation of α‐Ketoesters Based on Umpolung Strategy: Phosphazene‐Catalyzed S_NAr Reaction Utilizing [1,2]‐Phospha‐Brook Rearrangement

Abstract

An organocatalytic arylation of α-ketoesters was developed on the basis of umpolung strategy. Phosphazene P2-tBu efficiently catalyzes the three-component coupling reaction of α-ketoesters, a silylated secondary phosphite, and electron-deficient fluoroarenes to provide α-hydroxyester derivatives possessing an electron-deficient aryl group at the α-position. The reaction involves the catalytic generation of α-oxygenated ester enolates from α-ketoesters through the [1,2]-phospha-Brook rearrangement followed by the S Ar reaction.

Organocatalytic Nucleophilic Substitution Reaction of gem-Difluoroalkenes with Ketene Silyl Acetals

“…The fluoride then directly activates ketene silyl acetal 2 , completing the catalytic cycle. Whereas catalytic S N Ar reactions of silylated pronucleophiles with fluoroarenes, where the eliminated fluoride is utilized for the catalyst turnover, have been reported, the related catalytic substitution reaction of gem -difluoroalkenes is rare . Herein, we report that phosphazene P4- t Bu effectively catalyzes the reaction under mild conditions to provide monofluoroalkenes possessing an alkoxycarbonylmethyl group in high yields with high Z selectivities.…”

Role of donor‐acceptor functional groups in N3P3 cyclic‐triphosphazene backbone. Unraveling bonding characteristics from natural orbitals within an extended transition state‐natural orbital for the chemical valence scheme

“…Phosphazene compounds depict an important class of compounds because they exhibit outstanding properties that can be involved in the development of new applications, such as liquid crystals, and in the obtaining of photosensitive materials . Such systems give rise to potential applications including drug delivery systems, biological activity, and catalysis . Such systems have also been used as base support for the formation of nanomaterials, as well as heterocyclic‐triphosphazenes that can form interacting host‐guest systems.…”

Synthetic Methodologies for Perfluoroaryl-Substituted (Diaryl)methylphosphonates, -Phosphinates via SNAr Reaction

“…Perfluoroaryl groups show not only the electron-withdrawing substituent effect , but also unique interactions with other molecules , leading to chemical biology , and synthesis of functional materials. , Perfluoroaryl groups are known to readily undergo S N Ar reaction with various nucleophiles. − Although S N Ar reactions of perfluoroarenes via α-substituted diethyl methylphosphonates have been reported, these methods cannot be applied to the synthesis of dialkyl (diarylmethyl)­phosphonates because of the necessity of the electron-withdrawing group at the α-position. , …”