21960-10-1Relevant academic research and scientific papers
Organocatalytic Arylation of α-Ketoesters Based on Umpolung Strategy: Phosphazene-Catalyzed SNAr Reaction Utilizing [1,2]-Phospha-Brook Rearrangement
Kondoh, Azusa,Aoki, Takuma,Terada, Masahiro
supporting information, p. 13110 - 13113 (2018/09/11)
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 SNAr reaction.
Br?nsted Base-Catalyzed Umpolung Intramolecular Cyclization of Alkynyl Imines
Kondoh, Azusa,Terada, Masahiro
supporting information, p. 3998 - 4001 (2018/03/23)
A novel “umpolung” intramolecular cyclization of alkynyl imines, in which the electrophilic imine sp2-carbon formally serves as a nucleophilic site, was developed under Br?nsted base catalysis. The reaction involves the unprecedented catalytic generation of α-aminoester enolates from α-iminoesters via the 1,2-addition of the anion of a secondary phosphite to an imine moiety followed by the [1,2]-rearrangement of a dialkoxyphosphoryl moiety from carbon to nitrogen, which is a formal umpolung process, and the intramolecular addition to an alkyne. This is a rare example of a [1,2]-rearrangement of a dialkoxyphosphoryl moiety from carbon to nitrogen to generate an α-amino carbanion and the first catalytic carbon–carbon bond forming reaction utilizing the resulting carbanion as a nucleophile.
A CONVENIENT PREPARATION OF α-PHOSPHONO ESTERS AND LACTONES VIA C-P BOND FORMATION
Lee, Koo,Wiemer, David F.
, p. 87 - 90 (2007/10/02)
The reaction of ester and lactone enolates with diethyl phosphorochloridite, followed by air oxidation of the immediate reaction products, has proven to be a general alternative to the traditional Arbuzov synthesis of α-phosphono esters and lactones.
