Synthesis of Axially Chiral 1,1′‐Binaphthalenes by Palladium‐Catalysed Cross‐Coupling Reactions of Triorganoindium Reagents

Abstract

Abstract1,1′‐Binaphthalenes and heterocyclic analogues can be efficiently prepared by palladium‐catalysed cross‐coupling reactions between tri(1‐naphthyl)indium reagents and 1‐halonaphthalenes and haloisoquinolines. The reactions were usually carried out in THF at 80 °C with a slight excess of the indium reagent (40 mol‐%) and a low catalyst loading (4 mol‐% Pd) to afford the cross‐coupling products in good yields (45–99 %). The method allows the synthesis of sterically hindered 2‐substituted and 2,2′‐disubstituted 1,1′‐binaphthalenes and naphthylisoquinolines. In addition, the coupling reactions can be performed enantioselectively and the best enantiomeric excesses were obtained by using the chiral amino‐phosphane ferrocenyl ligand (R,S)‐PPFA.