The author of 《Inverse-Electron-Demand Palladium-Catalyzed Asymmetric [4+2] Cycloadditions Enabled by Chiral P,S-Ligand and Hydrogen Bonding》 were Wang, Ya-Ni; Xiong, Qin; Lu, Liang-Qiu; Zhang, Qun-Liang; Wang, Ying; Lan, Yu; Xiao, Wen-Jing. And the article was published in Angewandte Chemie, International Edition in 2019. Electric Literature of C51H42O3Pd2 The author mentioned the following in the article:
Catalytic asym. cycloadditions of ambident Pd-containing dipolar species with nucleophilic dipolarophiles, namely, inverse-electron-demand cycloadditions, are challenging and underdeveloped. Possibly, the inherent linear selectivity of Pd-catalyzed intermol. allylations and the lack of efficient chiral ligands are responsible for this limitation. Herein, two cycloadditions of such intermediates with deconjugated butenolides and azlactones were accomplished by using a novel chiral hybrid P,S-ligand and hydrogen bonding [e.g., vinyl carbamate I + butenolide II → dihydroquinol-2-one III (92%, 93% ee, >95:5 d.r.)]. By doing so, highly functionalized, optically active dihydroquinol-2-ones were produced with generally high reaction efficiencies and selectivities. Preliminary DFT calculations were performed to explain the high enantio- and diastereoselectivities. After reading the article, we found that the author used Tris(dibenzylideneacetone)dipalladium(0)(cas: 51364-51-3Electric Literature of C51H42O3Pd2)
Tris(dibenzylideneacetone)dipalladium(0)(cas: 51364-51-3) is the most widely used PdO precursor complex in synthesis and catalysis, in particular as a catalyst for various coupling reactions. Electric Literature of C51H42O3Pd2 It is used as a catalyst precursor for palladium-catalyzed carbon-nitrogen bond formation, conversion of aryl chlorides, triflates and nonaflates to nitroaromatics.
Referemce:
Metal catalyst and ligand design,
Ligand Template Strategies for Catalyst Encapsulation – NCBI