Asymmetric Friedel-Crafts reaction of 4,7-dihydroindoles with nitroolefins by chiral Bronsted acids under low catalyst loading was written by Sheng, Yi-Fei;Li, Gong-Qiang;Kang, Qiang;Zhang, An-Jiang;You, Shu-Li. And the article was included in Chemistry – A European Journal in 2009.Synthetic Route of C48H29O4P This article mentions the following:
By adding the substrate by a syringe pump, a highly efficient Friedel-Crafts reaction of 4,7-dihydroindoles with nitroolefins was realized with 0.5 mol% of a chiral phosphoric acid. The Friedel-Crafts alkylation, together with a subsequent oxidation of the product, led to 2-substituted indoles in excellent enantiomeric excesses, which can be easily transformed to enantio-enriched tetrahydro-γ-carbolines. In the experiment, the researchers used many compounds, for example, (11bS)-4-Hydroxy-2,6-di(phenanthren-9-yl)dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine 4-oxide (cas: 1043567-32-3Synthetic Route of C48H29O4P).
(11bS)-4-Hydroxy-2,6-di(phenanthren-9-yl)dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine 4-oxide (cas: 1043567-32-3) belongs to chiral phosphine ligands. At present, the synthesis of new chiral phosphines designed specifically for nucleophilic organocatalysis remains a significant challenge. Chiral phosphine catalysts: Nucleophilic phosphine catalysis often involves the formation of Lewis adducts, namely phosphonium (di)enolate zwitterions, as reaction intermediates.Synthetic Route of C48H29O4P
Referemce:
Phosphine ligand,
Chiral phosphines in nucleophilic organocatalysis