Wang, Zhen; Wang, Dong-Chao; Xie, Ming-Sheng; Qu, Gui-Rong; Guo, Hai-Ming published an article in Organic Letters. The title of the article was 《Enantioselective Synthesis of Fused Polycyclic Tropanes via Dearomative [3 + 2] Cycloaddition Reactions of 2-Nitrobenzofurans》.Reference of (R)-(6,6′-Dimethoxybiphenyl-2,2′-diyl)bis[bis(3,4,5-trimethoxyphenyl)phosphine] The author mentioned the following in the article:
A straight synthetic approach to fused polycyclic tropane scaffold formation through an asym. dearomatization cycloaddition process of 2-nitrobenzofurans with cyclic azomethine ylides was successfully developed. In the presence of a chiral copper complex, derived from Cu(OAc)2 and a diphosphine ligand, a series of fused polycyclic tropane derivatives (e.g. I)were obtained in high yields (75-91%) with excellent enantioselectivities (90-98%). The utility of this method was showcased by the facile transformation of product. In the part of experimental materials, we found many familiar compounds, such as (R)-(6,6′-Dimethoxybiphenyl-2,2′-diyl)bis[bis(3,4,5-trimethoxyphenyl)phosphine](cas: 256390-47-3Reference of (R)-(6,6′-Dimethoxybiphenyl-2,2′-diyl)bis[bis(3,4,5-trimethoxyphenyl)phosphine])
(R)-(6,6′-Dimethoxybiphenyl-2,2′-diyl)bis[bis(3,4,5-trimethoxyphenyl)phosphine](cas: 256390-47-3) belongs to chiral phosphine ligands. Nucleophilic phosphine catalysis often involves the formation of Lewis adducts, namely phosphonium (di)enolate zwitterions, as reaction intermediates. These intermediates are formed through nucleophilic attack of the phosphine catalysts at electron-poor nuclei (normally carbon atoms) and then proceed through several steps to form new chemical bonds. Reference of (R)-(6,6′-Dimethoxybiphenyl-2,2′-diyl)bis[bis(3,4,5-trimethoxyphenyl)phosphine]
Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis