685139-81-5Relevant articles and documents
Development of a new class of chiral phosphorus ligands: P-chirogenic diaminophosphine oxides. A unique source of enantioselection in Pd-catalyzed asymmetric construction of quaternary carbons
Nemoto, Tetsuhiro,Masuda, Takamasa,Matsumoto, Takayoshi,Hamada, Yasumasa
, p. 7172 - 7178 (2007/10/03)
We have recently developed a new class of chiral phosphorus ligands: P-chirogenic diaminophosphine oxides. These pentavalent phosphorus compounds have been successfully applied to Pd-catalyzed asymmetric construction of tertiary and quaternary carbons. The actual ligand structure was the trivalent phosphorus species 17, which was generated in situ by BSA-induced P(V) to P(III) transformation of 6, the preligand. Detailed mechanistic studies, including asymmetric amplification and initial rate kinetics, revealed that complex 18 [Pd-17 (1:2) complex] was the active catalyst. The important function of the nitrogen atom on the sidearm in the ligands was also clarified. The source of enantioselection in the construction of asymmetric quaternary carbons was the secondary ligand substrate interaction mediated by N-Zn coordination.
P-Chirogenic Diaminophosphine Oxide: A New Class of Chiral Phosphorus Ligands for Asymmetric Catalysis
Nemoto, Tetsuhiro,Matsumoto, Takayoshi,Masuda, Takamasa,Hitomi, Tsukasa,Hatano, Keiichiro,Hamada, Yasumasa
, p. 3690 - 3691 (2007/10/03)
We successfully synthesized a novel P-chirogenic diaminophosphine oxide 4, which was applied to catalytic enantioselective construction of quaternary carbon centers using Pd-catalyzed asymmetric allylic substitution with various β-keto esters (up to 99% yield, 94% ee). Preliminary mechanistic studies indicated that two molecules of 8 coordinate to the Pd metal in a monodentate fashion, resulting in the formation of Pd complex 9 (Pd:8 = 1:2), which functions as the active species. Copyright
