Palladium/Xiao‐Phos‐Catalyzed Kinetic Resolution of sec‐Phosphine Oxides by P‐Benzylation

Abstract

P-stereogenic tert-and sec-phosphines have wide applications in asymmetric catalysis, materials, and pharmaceutical chemistry, however, their practical synthesis still constitutes a significant challenge. Herein, a successful kinetic resolution of rac-secondary phosphine oxides via the enantioselective P-benzylation process catalyzed by the palladium/ Xiao-Phos was designed. Both tert-and sec-phosphine oxides were delivered in good yield and excellent enantiopurity (selectivity factor up to 226.1). The appealing synthetic utilities are further demonstrated by the facile preparation of several valuable P-chiral compounds, precursors of bidentate ligands, as well as transition metal complexes.Scheme 1. Approaches to access to P-stereogenic phosphines.

Catalytic Asymmetric Benzylation of Azomethine Ylides Enabled by Synergistic Lewis Acid/Palladium Catalysis

“…With the chiral palladium complex as the catalyst, Legros, Fiaud, and co-workers and Hirano, Murai, and co-workers independently reported the seminal asymmetric benzylation of non-prochiral nucleophiles with secondary benzyl electrophiles, wherein the generation of point chirality was located at the benzylic position. To change the position of asymmetric induction from electrophiles to nucleophiles, the Trost group and Zhang group chose primary benzylic carbonates and phosphates as the electrophiles to finish the catalytic asymmetric benzylation of prochiral 3-aryl oxindole, azlactone, and racemic phosphine compounds, respectively. More recently, a similar process of chiral induction was also documented by Guo and co-workers, which afforded a series of enantioenriched indole-terpenoid frameworks in excellent yields .…”

Rh-Catalyzed Regio- and Enantioselective Allylic Phosphinylation

“…The development of catalytic asymmetric synthetic methods for chiral phosphorus-containing molecules is of great value. Transition-metal-catalyzed enantioselective hydrophosphinylation of carbon–carbon multiple bonds, propargylic substitution, and other reactions enable efficient and selective preparation of chiral organophosphorus compounds. Asymmetric allylic substitution (AAS) reactions are very powerful to connect carbon–carbon and carbon–heteroatoms.…”

Sulfur-Phenolate Exchange As a Fluorine-Free Approach to S(VI) Exchange Chemistry on Sulfonyl Moieties

“…As can be seen in Table , most products were formed with excellent yields (100%, as determined by NMR) after just 5 min of reaction time. Previous procedures to produce already-described products from Table involved stirring for 1–24 h, in dry solvents, on an ice bath, under an inert atmosphere, using phenylmethanesulfonyl chloride as the starting material . Here, we simply stir at room temperature under ambient atmosphere, using nondried deuterated acetonitrile.…”